One farmer says to me, “You cannot live on vegetable food solely, for it furnishes nothing to make the bones with”; and so he religiously devotes a part of his day to supplying himself with the raw material of bones; walking all the while he talks behind his oxen, which, with vegetable-made bones, jerk him and his lumbering plow along in spite of every obstacle.
Human bodies are never entirely at rest. During the day and throughout the night, the body remodels bones, builds enzymes and thyroid hormones, forms red blood cells, and maintains the precise acid-base balance in body fluids that sustains life. Minerals are a vital part of these dynamic systems, and food is the body’s source of minerals.
But where do these minerals come from? As part of the cycle of nature (with the help of bacteria and fungi), decaying plant matter releases minerals into the soil; these minerals are then absorbed by newly growing plants. As a result, plant-based diets can provide optimal amounts of every essential mineral, without exception. Yet, both health professionals and the general public are inundated with messages that link calcium and strong bones with dairy products and that associate iron with meat consumption rather than with plant foods.
It’s important to recognize that plants can provide all the necessary minerals—no need for animal products. Of particular interest to vegans are calcium, iron, zinc, and iodine. Following is a review of the functions of various minerals, including recommended intakes, vegan sources, and special issues.
The bioavailability of minerals (the ease with which they’re absorbed from the intestine) is affected by numerous factors:
• Minerals can be bound (for example, as components of plant oxalates and phytates) and thus be unavailable.
• A person’s nutrient status affects mineral absorption. For example, someone who has a low serum ferritin level will absorb iron from plant foods far more efficiently than someone with abundant iron stores.
• Age or life circumstances can be a factor. A woman’s intestinal absorption of calcium might double during pregnancy, and an infant’s ability to absorb calcium to accommodate rapidly growing bones is also high. In contrast, after people reach 40 years of age, the percentage of calcium absorbed declines.
• Calcium, copper, iron, magnesium, and zinc compete for absorption sites; taking a single-mineral supplement may lessen the absorption of other minerals. Thus, for example, calcium supplements should be taken between meals by people who want to maximize their absorption of iron, magnesium, and zinc from food.
• When a smaller quantity of calcium, iron, or zinc is consumed, the body absorbs a higher percentage of the dose, compared to its absorption from a large quantity. Thus, two 250 mg calcium supplements taken at different times during the day deliver more calcium than a single 500 mg dose.
• Foods or beverages that accompany mineral intakes can affect absorption negatively or positively. For example, the amount of iron absorbed can vary sixfold or more, depending on whether factors that inhibit absorption (such as cow’s milk, black tea, and wheat bran) or factors that enhance absorption (such as vitamin C–rich foods) are part of a meal.
• Normal gastric acidity (hydrochloric acid) ionizes minerals, increasing their bioavailability. Low gastric acidity, which can occur with age or with frequent use of antacids, reduces mineral absorption.
The combination of so many possible influences on mineral bioavailability makes each individual’s situation rather complex.1–3
Refining whole foods—particularly grains—significantly impacts their mineral content (for more information, see page 162). Minerals are soluble in water; if cooking water is discarded, they can be lost. Steaming leads to greater nutrient retention. Minerals can survive very high temperatures; for example, they form the ash that remains after a fire. When preparing corn dishes, the Hopi Indians, whose diets were mainly plant based, traditionally used the ash from burnt corn cobs, bean vines, juniper bushes, and other plants to fortify meals with calcium, copper, iron, phosphorus, and zinc.4,5
To put mineral requirements in perspective, it helps to consider their form within foods, because this can affect ease of absorption. In whole plant foods, calcium, iron, magnesium, and zinc can be bound with phosphorus in compounds called phytates. These bound minerals are less available for direct absorption. However, they’re released by common food practices that are traditional among populations that rely on legumes, whole grains, nuts, and seeds.6–10
Vegans often soak, sprout, ferment, blend, or juice plant foods, which significantly increases mineral availability. In nature, sprouting releases minerals to support growing seedlings. When seeds, nuts, mung beans, lentils, and whole grains are soaked or sprouted for food, the naturally present phytases (phytate-splitting enzymes) become active, and the bound minerals are released. When plant foods are juiced or blended, their cell walls are broken, releasing phytases and increasing mineral bioavailability.1,6–9
Phytases also are present in bacteria, yeast, and fungi. When plant foods are fermented, as when soy is made into tempeh or miso, more than half the phytates are broken down. Yeast has a similar effect on wheat; plus, with the acidity that results from sourdough fermentation, phytate breakdown increases to as much as 97 percent. These common food preparation processes release bound calcium, iron, magnesium, and zinc for absorption.4,6,7,10–12
Diet also affects the population of microbes that are present in intestines to process phytate. Compared to nonvegetarians, vegetarians (whose diets are naturally high in phytates) have intestinal bacteria that are far more capable of breaking down phytate-mineral complexes.13 There may be an impression that phytates themselves are harmful, yet their presence also brings benefits. These compounds are antioxidants that appear to provide protection against cancer, cardiovascular disease, and diabetes.6,11,12 Vegans typically don’t need added bran because they get enough fiber; bran is a concentrated source of phytates that can significantly impact mineral availability. (Wheat germ is low in phytates and isn’t an issue.)
Oxalates are tightly bound combinations of oxalic acid and minerals (calcium, iron, magnesium, or zinc) that resist breakdown during food preparation and digestion. Amaranth, beets, beet greens, cassava, chives, chocolate soy milk, lamb’s-quarters, miso, parsley, purslane, sorrel, spinach, star fruit, Swiss chard, and whole sesame seeds are among the most oxalate-dense plant foods. (For specific amounts, search online for the US Department of Agriculture list, “Oxalic Acid Content of Selected Vegetables.”)14
Of the minerals mentioned above, calcium is most tightly bound by oxalic acid. For example, although spinach is calcium-rich, only about 5 percent of its calcium may be absorbed by the body; the rest is transported out in the feces, bound by oxalic acid. Much of the iron in spinach can still be absorbed, because the oxalate is primarily bound with calcium. Despite mineral binding, such greens are still valuable dietary additions because they provide abundant folate, vitamin K, beta-carotene, and numerous other protective nutrients and phytochemicals unaffected by oxalates.15,16
The Institute of Medicine (IOM) of the National Academy of Sciences has developed sets of recommended intakes—known as Dietary Reference Intakes—of the various nutrients for healthy people. These values include the Recommended Dietary Allowance (RDA), the Adequate Intake (AI), and the Tolerable Upper Intake Level (UL).
The RDA is the average daily intake that meets a nutrient requirement of 97 to 98 percent of healthy individuals. Al is a value listed when there’s insufficient research to determine an RDA; it can be viewed as a sort of “best guess.” UL is the highest level of intake that won’t pose a risk of adverse effects for most healthy people when used indefinitely on a daily basis without medical supervision.
Finally, the Nutrition Facts panel required by the US Food and Drug Administration on food labels lists one Daily Value (DV) each for vitamins A and C, calcium, and iron, as well as other micronutrients the food may contain (for example, as a result of fortification or enrichment). DV is based on a 2,000-calorie diet and on past recommended intakes, some of which are similar to current RDAs and Als.98,99
To see RDAs and Als for various age groups and for women during pregnancy and lactation, see page 445. For further information online, see Resources on page 449.3,20,38,81,84,89
RDA—Recommended Dietary Allowance |
UL—Tolerable Upper Intake Level |
AI—Adequate Intake |
DV—Daily Value |
When foods are soaked and the soaking water discarded, some oxalates are disposed of along with bound minerals. Research has shown that boiling can reduce the total oxalate content in spinach by 60 percent and in lentils by 16 percent. Losses result from a combination of leaching into the cooking water plus some breakdown of the calcium-oxalate complex.4,7,10,15–18
Oxalates are found in body fluids. However, when these stone-forming salts become too concentrated in urine and the urine pH is acidic, sediments can form prickly-surfaced calcium oxalate salts (the most common type of kidney stones). Limiting calcium intake hasn’t proved effective in preventing such stones; on the contrary, calcium can bind oxalate in the intestine, preventing its absorption. Instead, eating alkali-forming foods (vegetables and fruits) to reduce urine acidity, avoiding animal protein, limiting high-oxalate foods, consuming calcium citrate supplements with meals, and drinking plenty of water provide more-successful solutions.19
Calcium is the most common mineral in the body. Humans acquire calcium from direct consumption of plant foods, through milk from a human or other mammal, or from other dietary sources, such as powdered lime used to process corn for tortillas.
Before the advent of animal husbandry, humans in many parts of the world had dairy-free diets that were calcium-rich (averaging 2,000 mg per day or more). However, many of the plants and plant parts they consumed aren’t commonly eaten in modern times. Much of the produce in supermarkets has been bred for sweetness or ease of transport rather than for nutritional excellence. As a result, it’s far lower in calcium than plant foods gathered by early humans.21–23
Meanwhile, nutrition-education campaigns and dairy advertisements lead the public to believe that humans require cow’s milk to meet their calcium needs. Although the food guides of most Western countries might imply otherwise, the milk of other mammals, such as cows, has not been a cornerstone of the human diet throughout history. The practice of dairying appears to be a recent phenomenon, conducted only in specific areas of the world. In these regions, natural selection favored a genetic adaptation that allowed people to drink milk after the age of weaning. Normally, after the first few years of life, as much as 70 percent of the world’s population shows diminished production of the enzyme lactase (a trait known as lactase nonpersistence) and lose the ability to digest lactose, the sugar in the milk of humans, cows, and other mammals. In South America, Africa, and Asia, more than 50 percent of the population has lactase nonpersistence after they’ve passed the age of weaning; these individuals can experience abdominal pain, bloating, flatulence, and diarrhea when cow’s milk is consumed. In some Asian countries and among Native Americans, this rate is close to 100 percent.22–24
Calcium is best known for its structural role: giving hardness to bones and teeth. Bone is a dynamic tissue that’s continually formed and resorbed, with formation taking the lead during stages of growth and early adulthood, and resorption prevailing in the elderly. The body achieves peak bone mass by about age 28. A few decades of minimal change in total bone mass follow, and then a period of loss, estimated at 1 to 2 percent per year in women after menopause and in the elderly of both genders. Adequate calcium intakes during growth and adolescence help to avoid fractures in later life.25
Calcium also has crucial nonstructural functions, though these involve just 1 percent of the calcium in the body. These include roles in blood coagulation (required after injury), muscle relaxation (without calcium, muscles remain tight after contracting), nerve cell transmissions, and the regulation of cell metabolism (such as the storage of energy as glycogen). Maintaining calcium intakes at recommended levels also may help to prevent hypertension.
Calcium is vital for survival, and the body must keep the calcium levels in blood and in interstitial fluid within a specific and narrow range. A drop in calcium levels is registered by the parathyroid gland, which produces parathyroid hormone, activating vitamin D. This action quickly raises calcium levels by increasing the efficiency of intestinal absorption, decreasing urinary losses, and if necessary, breaking down bone to release this mineral.3,20 For more information on the role of calcium and other nutrients in building and maintaining bone, see page 68.
The calcium RDA for adults is 1,000 mg per day, and 1,200 mg per day for women over 50 and men over 70. The UL has been set at 2,500 mg per day to age 50 and 2,000 mg for those older than 50.3,20
Since 1954, worldwide studies have shown that average vegan intakes of calcium range from about 500 to 940 mg daily, providing about 50 to 94 percent of recommended levels for adults to age 50.26–30 In many of these studies, fortified products weren’t available to vegans; this situation is changing. Since the late 1990s, fortified nondairy beverages have been sold across North America, and these and other calcium-rich vegan foods can be obtained in many other regions, as well. (Interestingly, the average calcium intakes of nonvegetarians in the United States also were well below recommended intakes for every age and gender group, especially for females and for adults older than 50.20,31,32)
A higher risk of bone fractures in vegans has been linked with relatively low calcium intakes, though overall, plant-based diets don’t appear to increase risk of osteoporosis.30 In addition to the dietary sources listed below, supplemental calcium can easily help vegans reach recommended intake levels.
Calcium is abundant in a wide assortment of vegetables, particularly low-oxalate greens (broccoli, bok choy, kale, napa cabbage, watercress, and mustard and turnip greens); from these, the body absorbs 40 to 60 percent of the calcium present.29,100 Collard and dandelion greens are considered medium-oxalate greens and thus are fair calcium sources. Absorption is poor—about 5 percent—from high-oxalate greens (beet greens, spinach, and Swiss chard).29,100
This mineral is well absorbed (about 50 percent) from juices fortified with calcium citrate malate. It’s added to fortified nondairy milks and tofu, making these good sources (check labels); the body absorbs 30 to 32 percent of the calcium in both (about the same rate as from cow’s milk and some mineral waters).33–35
The fractional absorption of calcium from sesame tahini and from assorted beans is about 20 percent. 29,100 From almonds, which contain phytates, the body absorbs 14 to 21 percent of the calcium; however, absorption is increased after almonds are soaked for eight to twelve hours.100 Calcium is present in oranges, figs, organic blackstrap molasses, and (in smaller amounts) in many plant foods. The Vegan Plate (page 434) devotes a column to calcium-rich foods in all food groups. Also see table 6.2 (page 204).
• Follow The Vegan Plate guidelines (page 434). This healthful eating plan provides the whole team of bone-building nutrients, which includes protein; essential fatty acids; the minerals boron, calcium, copper, fluoride, magnesium, manganese, phosphorus, and zinc; and the vitamins B12, B6, C, D, folate, and K.
• Eat dark green vegetables daily. Include broccoli, kale, collard greens, bok choy, and napa (Chinese) cabbage on the shopping list. Find a nearby market with great produce, grow greens in the garden or on the balcony, or arrange for a weekly organic produce delivery. Learn delicious ways to prepare greens. Use the mineral-rich cooking water in soups or in grain preparation.
• Use calcium-set tofu. Tofu is versatile; it can be a main ingredient for tasty items from soup to dessert. Check the label for calcium content; the Daily Value (DV) is 1,000 mg. The protein and isoflavones in tofu, tempeh, and soy milk also benefit bone.94
• Drink calcium-fortified beverages. Fortified nondairy milks and juices can help bring total calcium intake to recommended levels. For good calcium suspension, shake the container well.
• Make almonds, almond butter, sesame tahini, and blackstrap molasses a part of meals and snacks. Replacing 2 tablespoons (30 ml) of peanut butter with an equal amount of almond butter boosts calcium intake by 73 mg. Replacing 1 tablespoon (15 ml) of jam with blackstrap molasses can add a surprising 80 to 200 mg of calcium (check labels).
• Monitor intakes of calcium thieves. Avoid high intakes of salt, alcohol, and caffeine—and don’t smoke.
• Take some sun (or vitamin D). Walk outside in the sunshine during midday to allow the body to form the day’s supply of vitamin D. (For more on this topic, see page 69.) When sunlight isn’t available, take a vitamin D supplement to ensure adequate intake.
• Exercise. Walk, jog, dance, play ball, hike, and participate in aerobics classes or other weight-bearing exercise to strengthen bones.
• Top up dietary intakes with a supplement. If necessary to reach recommended levels, add a daily calcium supplement.
Many vegan adults would benefit from a few hundred milligrams of supplementary calcium to top up daily intakes. Multivitamin-mineral supplements typically contain about 200 to 400 mg of calcium; much more would make the pill too large to swallow. Many calcium supplements are best absorbed in the presence of stomach acid, and thus are better assimilated when taken with a meal. However, calcium citrate and calcium citrate malate can be taken anytime. If taken between meals, these forms won’t hinder iron and zinc absorption from food. Because vitamin D is essential for optimal calcium absorption, a calcium-vitamin D combination that includes at least 15 mcg (600 IU) of vitamin D would be beneficial.
High salt or sodium intakes result in increased calcium losses. Each teaspoon (6 g) of salt contains 2.3 grams of sodium. When excreted by the kidneys, this amount of sodium draws with it 24 to 40 mg of calcium. Over time, such urinary losses can markedly influence bone loss. It’s been estimated that, in adult women, each gram of sodium beyond daily needs will result in an additional rate of bone loss of 1 percent per year if all the related calcium loss comes from the skeleton.20
In the past, nutrition texts rated nonheme iron from plant foods as inferior to heme iron in meat, because the body generally absorbs a lower percentage of nonheme iron. We’re now aware that relying on nonheme iron gives the body more control over absorption efficiency, by allowing it to adjust uptakes to suit its needs. If its iron reserves are low, the body absorbs more iron from plant foods; if iron reserves are abundant, the intestines can absorb a lower proportion of nonheme iron. (Food preparation and combinations also affect absorption of nonheme iron.)2,29,36–40
The heme form of iron found in meat and blood tends to be more readily absorbed—even when the body doesn’t need any iron. Once iron has been absorbed, the body has limited mechanisms for ridding itself of any excess. Because iron is a prooxidant, too much in the body may damage DNA and other molecules. New research also indicates that high iron intakes and a burden of excess iron in the body have been associated with Alzheimer’s and Parkinson’s diseases, arthritis, type 2 diabetes, cardiovascular disease, and colorectal and other cancers. To avoid iron overload, consuming the nonheme form found in plants is recommended.2,29,36–40
Although the oxidative stress of excess iron is best avoided, the body does need enough for vital functions. Iron-deficiency anemia is no more prevalent among vegans and other vegetarians than among nonvegetarians. Yet iron deficiency is the primary nutritional deficiency worldwide for people on any diet, especially for women of childbearing age, infants, and teens. In the United States, the prevalence of iron-deficiency anemia among youths and adults is estimated at 2 to 5 percent among females and 1 to 2 percent among males.2,29,38,41
As a constituent of red blood cells, iron plays a central role in transporting oxygen throughout the body, releasing this life-giving substance where needed, and carrying away the metabolic waste product, carbon dioxide. In myoglobin, iron delivers oxygen to working muscles. As part of many enzyme systems, iron is a key element in the production of cellular energy, in immune system functioning, in detoxification, and in the mental processes surrounding learning and behavior.20
The body continuously breaks down red blood cells and builds new ones, efficiently recycling the iron reclaimed from spent red blood cells. However, each day tiny amounts of iron are lost in cells sloughed from the skin and from the inner lining of the intestine; these losses must be replaced from food or supplements.
Other causes can contribute to iron deficiency. Women of childbearing age have menstrual iron losses in the range of an extra 30 to 45 mg each month, making their dietary requirements higher than those of men. Growth and the building of new cells can deplete the small reserves of iron in infants and children. Teens experience the challenges of a powerful growth spurt and notoriously poor eating habits; in addition, girls have menstrual losses. Young obese women on poorly designed weight-loss diets are another group at risk for iron deficiency. People with blood loss for any reason (such as ulcers or blood donation) have an increased need for iron. Athletes have somewhat higher requirements due to increased oxygen demands and greater iron losses (see chapter 13).38,49
The RDAs for men and postmenopausal women are set at 8 mg of iron per day and for women of childbearing age at 18 mg of iron per day. Although a separate RDA hasn’t been set for vegetarians (including vegans), the Institute of Medicine (IOM) advises aiming for 1.8 times as much iron as nonvegetarians due to the lower bioavailability of nonheme iron from plant foods. Following this guide, vegetarian women of childbearing age are advised to get 32.4 mg of iron per day, and other adults are urged to get 14.4 mg of iron. For other ages, see page 447 and multiply recommended intakes for iron by 1.8.29,38,42,43,49
The higher recommendation for vegetarians is controversial, because it was based on a single poorly designed study. In this study, participants consumed vegetarian diets low in components known to enhance iron absorption (such as vitamin C and organic acids from fruits and vegetables) and high in substances known to interfere with iron absorption (such as tannins). In addition, the study wasn’t conducted on vegetarians or vegans, who typically develop lower serum ferritin levels that optimize absorption. Vegans who include vitamin C–rich foods as part of their meals and who don’t routinely include tea, coffee, or calcium supplements with meals are less likely to need this suggested level of iron intake. Still, there’s widespread agreement that vegetarians, including vegans, should aim for more iron than nonvegetarians.29,38,42,43,49
Research has shown vegans have average iron intakes that are similar to or higher than those of nonvegetarians and higher than the RDA, though they don’t generally reach the higher levels of 32.4 mg iron per day suggested for vegetarian women of childbearing age. Studies have shown vegan women in the United States have average intakes of about 22 to 23 mg iron daily, higher than those of nonvegetarian controls; vegan women in Germany had average intakes of 20 mg iron daily. Average iron intakes of vegan men in the United States were significantly higher than those of nonvegetarians. For both genders, the average iron status of vegan groups—as shown by hemoglobin, hematocrit, and ferritin levels—was adequate and, where reported, compared favorably with nonvegan controls.29,30
A number of routine laboratory tests reflect iron status. These include hemoglobin (showing the amount of this iron-containing protein), hematocrit (indicating the concentration of red blood cells), and serum ferritin (a measure of the amount of stored iron). Vegetarians typically have lower serum ferritin levels than nonvegetarians. This common situation doesn’t affect how a person feels and isn’t an issue if a person’s diet continues to replenish lost iron. Unless a period of starvation occurs, there’s no apparent benefit to having more than minimal iron stores. In fact, lower levels of serum ferritin may be an advantage and are linked with better insulin sensitivity and reduced risk of type 2 diabetes.2,36,36,40,44 Researchers also are exploring the possibility of links between lower serum ferritin and reduced risk of coronary artery disease, colon cancer, and inflammatory conditions.2,29,45
With iron depletion, however, there can be a decrease in other indicators of iron status. A tired feeling and sensitivity to cold may develop. Iron-deficiency anemia occurs when blood hemoglobin drops below the normal range. When the body’s oxygen-delivery system is impaired, people are likely to feel exhausted, irritable, and lethargic and have headaches; the skin may appear pale. Iron deficiency is easily diagnosed; doubts can be resolved with a blood test, and progress can be tracked as the situation is remedied.46
Legumes are good plant sources of iron. They provide 3 to 6 mg of iron per 1 cup (250 ml) of beans or lentils or per ½ cup (125 ml) of soybeans or tofu (see table 6.2 on page 204). A serving of fortified breakfast cereal can supply as much as 18 mg of this mineral. Iron intake can quickly reach recommended levels with an assortment of vegetables, oatmeal or other whole grains, pumpkin seeds, and dried fruit. Dark chocolate or molasses (especially blackstrap) offer sweet ways to increase iron intake. Because molasses can also be a concentrated source of pesticides, organic brands should be chosen. Finally, when acidic foods (such as tomato sauce) are prepared in iron cookware, the sauce takes up some iron from the pan.2
The percentage of nonheme iron absorbed from plant foods varies, based on the body’s needs, on food preparation methods, and on the food and beverage combinations eaten. Although iron (and zinc) deficiencies are associated with marginal plant-based diets of impoverished people in some parts of the world, this isn’t the situation in regions where the food supply and variety are sufficient.1,2,6,8,38,47,48
As noted in the section on phytates (page 181), soaking, fermenting, yeasting, and sprouting plant foods increases the body’s absorption of iron and other valuable minerals.48 Oxalate appears to have a variable, and sometimes minimal, impact on iron availability from calcium- and iron-rich foods such as spinach, for example, because its calcium is preferentially bound.15,16
Absorption from iron-rich plant foods increases markedly when foods high in vitamin C (such as red bell peppers or strawberries) are eaten at the same time because iron is converted from a ferric form to a more readily absorbed ferrous form. The citric acid in citrus fruits also enhances iron absorption. Obsolete food-combining rules that insist fruit must be eaten separately from other foods can be ignored, especially by consumers low in iron. The beta-carotene in yellow, red, and orange foods also aids iron absorption.2,6
Vegans eat plenty of fruits and vegetables, and typically get more than one and a half times as much vitamin C as nonvegetarians—a clear advantage when it comes to iron absorption. For example, 5 ounces (150 ml) of orange juice containing 75 mg of vitamin C has been shown to increase the absorption of iron from foods eaten at the same time by a factor of four. Other studies show 50 mg of vitamin C to enhance iron absorption sixfold. Eating ¾ cup (185 ml) of any of the following provides 50 mg of vitamin C: broccoli, Brussels sprouts, cauliflower, collard greens, bell peppers, snow peas, cantaloupes, citrus fruits and juices, guavas, papayas, strawberries, and vitamin C–fortified juices; so does having a kiwifruit, ¼ cup (60 ml) of sweet red bell pepper, or a big salad.
Even after cooking, some vitamin C remains; for example, vegetables retain about 85 percent of their vitamin C when microwaved, 70 percent when steamed, and 50 percent when boiled. (Losses vary with cooking time and temperature.) A large baked potato retains 30 mg of vitamin C after baking.2,49–51
Onions and garlic can increase the availability of iron (and zinc) from grains and legumes by 50 percent, further boosting iron intake.52
In contrast, absorption of dietary iron decreases in the presence of tannins and other polyphenols in black tea, coffee, cocoa, and red wine. Calcium supplements also inhibit iron absorption.2,6 To maximize iron absorption, it’s wise to consume these inhibitors an hour apart from iron sources.
For people whose blood tests show they’re anemic, iron supplements or iron as part of a multivitamin-mineral supplement can be helpful. However, excessive amounts of this prooxidant mineral in supplements are best avoided. When the deficiency has been resolved, a diet that features good plant sources of iron—combined with vitamin C–rich foods—is a better choice for long-term maintenance.46
Measures of iron status are readily available and commonly done; testing for zinc is less prevalent. Severe zinc deficiency is reflected in low zinc levels in plasma, red blood cells, hair, and urine; it also results in stunted growth, reduced immune defenses, diarrhea, poor appetite, and impaired ability to taste. Marginal zinc deficiency can be difficult to detect. With a shortage, the body may shift its available zinc to the most crucial areas of need, absorb zinc more efficiently, and recycle what it has.2,53,93
Zinc-deficient individuals may be smaller in stature through childhood and adolescence and into adulthood. Three decades ago in Iran and other parts of the Middle East, the effects of zinc deficiency were observed among poor people whose diets were high in phytates and low in overall variety. Whole wheat flatbreads with little or no yeast leavening provided 50 to 75 percent of the calories—and sometimes more—in their diets. Though the flour contained sufficient zinc, calcium, and magnesium, the bioavailability of these minerals was low. Even when yeast was used, the bread-making process was speedy, giving insufficient time for the yeast’s phytase to break down the phytate-mineral complex.54 The resultant zinc deficiency could have been alleviated if:
• a more extensive yeasting process were used
• zinc-rich legumes, seeds, or tahini were affordable
• onion or garlic were added to the meal, increasing zinc bioavailability52,54
Impoverished people with limited diets in south and southeast Asia, sub-Saharan Africa, Central America, and the Andes have similar plights; in fact up to 20 percent of the world’s population is lacking in adequate zinc intake or absorption.53 The effects are particularly apparent during the stages of rapid growth from pregnancy through adolescence.
The fault can lie with limited diets composed mainly of either whole or refined grains. When grains are refined, they lose most of the phytates that limit zinc absorption, but they also lose most of the zinc. Diets centered on refined-grain products and sugar- and fat-laden foods and beverages also can be low in zinc.55,56 In North America, marginal, rather than severe, zinc deficiency is more likely to occur, particularly among pregnant women (sometimes resulting in preterm delivery) and among children in low-income families.55
Zinc is essential to cell division and plays key roles in growth during pregnancy and from infancy through adolescence. Zinc is important for the immune response and is necessary for wound healing. It’s also a catalyst for about three hundred different enzyme systems and is critical for nerve development. The ability to taste is highly dependent on zinc. Certain tissues and fluids in the body contain relatively high concentrations of zinc, including the iris and retina of the eye, and also the prostate, sperm, and seminal fluid.38,57,58 Zinc is also a factor in regulating men’s serum testosterone levels.59
The RDA is 8 mg of zinc daily for women and 11 mg for men. Men’s requirements are higher in part because they lose zinc in semen—0.6 mg per seminal emission.38 (Ardent vegans might want to keep a bowl of cashews or pumpkin or sunflower seeds by their beds.)
The IOM has suggested that vegetarians with high intakes of unrefined grains and phytate may need 50 percent more zinc than recommended. However, due to the lack of sensitive clinical measures of marginal zinc status, this hasn’t been confirmed.38,93
In seven studies conducted in the United States, the United Kingdom, Canada, Australia, and Germany, vegan women and men met or exceeded the standard recommended intakes for zinc, on average.29,30 In two studies in the United States and the United Kingdom, average zinc intakes fell about 10 percent short of recommended intakes.29 Vegans with particularly low caloric intakes tend to have low intakes of this mineral. Some elderly people, regardless of diet, have low zinc intakes related to limited food consumption, insufficient variety, or a focus on refined foods.60
Typically, zinc is available from the same vegan foods as iron: seeds, nuts, legumes and tofu, and whole grains, including oatmeal and brown rice. One study determined that despite less-efficient absorption, participants gained 50 percent more zinc from whole wheat bread than from white bread because of the higher zinc content in the whole-grain product.2 A glance at table 6.2 (page 204) will show that seeds and seed butters can be zinc superstars in vegan diets. Hummus and whole-grain bread or crackers make a zinc-rich snack for children and adults.
Food preparation methods, such as fermentation, leavening (of bread), soaking (of nuts, seeds, legumes, and whole grains), sprouting, and the use of sourdough can greatly improve zinc absorption. The acids present in foods or produced during fermentation break down phytates that bind zinc, increasing the bioavailability of zinc.2,7,49 Adding garlic to hummus or rice enhances zinc uptake from the chickpeas, tahini, and grains.52
If the body is short of zinc, its ability to absorb this mineral becomes more efficient and body losses are reduced. Absorption efficiency and conservation of zinc also occurs in times of greater need, such as during pregnancy. Adaptation to somewhat lower intakes may also occur.49,58,93
Iodine is required in miniscule amounts—but it’s absolutely critical to life and health. Most of the world’s iodine is found in the oceans. The soil content of this mineral varies greatly from one region to another; as a result, some crops are rich in iodine, while others contain very little.38,61
Before the 1920s, iodine deficiency was common around the Great Lakes and in Appalachia and the northwestern United States. Since 1924, North American salt manufacturers have fortified salt with iodine to provide this essential nutrient to the general population and prevent the tragedies of iodine deficiency that were common in some regions.61 This action has been powerfully effective. However, iodine deficiency remains an issue in some parts of Europe, Africa, and Asia and for some individuals whose diets lack either iodized salt or sea vegetables.
Iodine is an essential component of thyroid hormones (triiodothyronine, or T3, and thyroxin, or T4), which influence most of the organ systems in the body. Iodine is essential for energy metabolism; iodine deficiency can result in depressed metabolic function (also known as hypothyroidism).
Iodine exerts its effects via the thyroid gland located in the lower part of the throat. Hypothyroidism can result in a growth called a goiter, in which the thyroid gland becomes greatly enlarged due to its efforts to trap iodine. Other symptoms of iodine deficiency are skin problems, weight gain, and increased cholesterol levels, all of which can be reversed in adults by increasing iodine intake. Insufficient iodine has been linked with fibrocystic breast disease.38
Iodine deficiency during pregnancy is a more tragic story, because the maternal thyroid hormones that depend on iodine for their production are essential for normal brain development in the fetus. Their lack causes the world’s most important—and most easily preventable—cause of developmental disabilities, an irreversible condition known as cretinism. Even a mild deficit can impair cognitive ability.38,61–66
The adult RDA is 150 mcg of iodine per day. Excess iodine can be toxic; the UL is set at 1,100 mcg of iodine per day (unless medically prescribed).
Research has shown iodine intakes to be low in Swedish, German, and British vegans.29 In a group of 62 vegans in the Boston area, just one in three used a supplement containing iodine (14 people) or consumed iodized salt (3 people) or kelp (1 person). Without such sources, iodine intake from a vegan diet may be about 10 percent of recommended levels. These people had been vegan for an average of 5.6 years and weren’t showing iodine-deficiency symptoms at the time of the study.67 (With high intakes of seaweeds, diets can provide amounts above the UL.80)
Among nonvegans, dairy products can be significant sources because of contamination of milk with iodine-containing cleaning solutions; these are used to remove mastitis-related pathogens from milking equipment and cows’ teats.61 Bread has contained iodine due to dough conditioners, though this is decreasingly common.
Iodine intakes of people on vegan diets may be insufficient unless they use iodized salt, sea vegetables, or a supplement that contains iodine. Iodine deficiency is particularly risky during pregnancy.
In 200 nations, including Canada, iodization of table salt is mandatory. In the United States, where this is voluntary, about 70 percent of table salt is iodized. In both countries, standards decree that about ½ teaspoon (3 g) of iodized salt should deliver the day’s recommended intake of 150 mcg of iodine. In practice, amounts may vary from one sample of iodized salt to another.61,68 In the United Kingdom, iodization is voluntary and less common, and iodized salt contains only about 25 percent as much iodine as that in North America.
Only a small proportion of sea salt is iodized (check labels), and tamari, soy sauce, Bragg Liquid Aminos, and miso are not. In addition, the vast majority of salt in Canada and the United States, which is used in food processing and in fast foods, isn’t iodized—this represents more than two-thirds of the salt consumed in these nations.61
Plants grown in iodine-rich soil can be good sources; however, the iodine levels in produce aren’t generally known, so it’s difficult to determine intakes. Plant foods from the ocean (seaweeds) can be excellent sources; the challenge lies in knowing how much iodine they provide, because amounts can vary as much as eightfold from one batch to another. For example, quantities are higher in seaweed that grows near coral reefs. Amounts of iodine also can vary depending upon how the seaweeds were dried and stored. It can be difficult to find a supplier with accurate information about iodine content. To confirm amounts in salts and sea vegetables, check labels and contact manufacturers.61,69
Kelp tablets may deliver stated amounts of iodine. Some people use a guideline of ¼ teaspoon (1.5 ml) of kelp every four days to meet their recommended intake of iodine (see table 6.1 on page 194). However, amounts of the mineral can vary greatly in kelp and regular, moderate intakes can easily exceed the UL. Though hijiki seaweed is rich in minerals, consumers are advised to avoid it because it commonly contains excessive amounts of arsenic. To meet recommendations, it’s preferable to consume iodine in small but frequent amounts several times a week, rather than to consume a large dose less frequently.29,62–64,69–71
Soy foods, flaxseeds, and foods from the cabbage family (broccoli, Brussels sprouts, cabbage, cauliflower, collard greens, kale, and kohlrabi) tend to be nutritious staples in vegan diets. These foods can trigger thyroid problems only if a person is deficient in iodine. If iodine is in short supply, isoflavones in soy foods or thiocyanates in the other foods may interfere with thyroid metabolism.
TABLE 6.1. Iodine in salt and dried sea vegetables
The solution is not to avoid these foods but instead to solve the iodine deficiency by consuming a good source of the mineral.29,77,78 In Asia, soy and seaweeds are viewed as complementary foods.78 Fermentation (as in making kimchi) causes thiocyanates to disappear. In addition, the study of Boston vegans (page 182) showed that thiocyanate intakes weren’t associated with thyroid problems in vegans.67
Perchlorates (solid-fuel by-products that cause water pollution) and various minerals from fertilizers and pesticides can amplify thyroid problems in people who are iodine deficient or whose intakes are low. Selenium deficiency also can worsen marginal iodine deficiency.79
The Bottom Line: Get enough iodine (but not too much). Supplements, such as multivitamin-mineral supplements that provide iodine, are most reliable in delivery of a known amount.62
Chromium helps with carbohydrate metabolism by supporting the action of insulin.38
Because there’s insufficient evidence to establish an RDA for chromium, an AI has been set instead. For those up to age 50, it’s 35 mcg daily for men and 25 mcg daily for women; for older adults, the AI decreases by 5 mcg.38
Vegan intakes of chromium have not been assessed.
The amount of chromium in foods seems to vary considerably from one sample to another. Also, no large databases quantify these amounts, in part because the presence of chromium in laboratory testing equipment has interfered with accurate testing.81
Whole grains, ready-to-eat bran cereals, green beans, broccoli, grape juice, and spices are relatively rich in chromium. Although the total amounts of chromium available may be inconsistent from one batch to another, 1½ cups (375 ml) of broccoli may supply a day’s requirement of chromium, for example. Other vegetables and fruits supply small amounts that add up over the course of a day. Vitamin C–rich foods likely improve chromium absorption.81
Diets high in sugar (sucrose) have been found to promote chromium loss. Refined grains have lost their natural chromium content.20,29,38,81
Copper plays a key role in energy metabolism as part of the enzyme cytochrome-c oxidase, which allows the body to store energy from food for bursts of activity. Other copper-containing enzymes can latch on to potentially damaging free radicals, preventing them from harming cells. This mineral also is part of specific enzymes essential to the normal function of the brain and nervous system, as well as other enzymes throughout the body. Copper aids in formation of connective tissue, bones, and red blood cells. As part of the pigment melanin, copper plays a key role in producing color in skin, hair, and eyes.38
Adults require 900 mcg daily.
Studies show vegan intakes of copper to be higher than those of nonvegetarians and more than adequate.29
Rich sources of copper include asparagus, avocados, beans, coconuts, cucumbers, dried fruit, durians, guavas, kale, kiwifruit, lentils, parsnips, peas, potatoes, mangoes, mushrooms, nuts, seeds, spinach, spirulina, sun-dried tomatoes, water chestnuts, and whole-grain products. One ounce (30 g) of cashews, chocolate, hazelnuts, or seeds (pumpkin, sunflower, or sesame) or ½ cup (125 ml) of cooked lentils provides an entire day’s supply, and then some.
Lively discussions about whether plant-based diets provide excessive amounts of copper have raised concern among vegan consumers. Although vegan protein sources are higher in copper than animal protein sources (especially relative to zinc content), research shows that copper absorption is significantly lower in vegetarian diets compared to nonvegetarian diets. Over time, plasma copper tends to decrease for those on vegetarian diets; fractional absorption is known to decrease with higher intakes, and also, adaptation may occur. Although such studies have been conducted on vegans, a similar—or even greater—reduction in copper absorption could be expected.97
Single-mineral zinc supplements above the RDA can interfere with the body’s absorption of copper.20,29,38 Because copper is a prooxidant, copper supplements are best avoided—and aren’t needed in typical vegan diets.
Magnesium is present in bones, teeth, muscles, and cell membranes. Bones are less brittle when they contain sufficient magnesium. This mineral also performs an essential role in more than three hundred metabolic reactions in the body, more than any other nutrient. Magnesium affects muscle contraction and heart rhythms, helps transport minerals across cell membranes, and supports the transmission of nerve impulses. It’s part of the team of minerals and vitamins responsible for energy production and has a role in building protein and DNA. Magnesium-rich diets (those rich in vegetables and fruit) are associated with lower blood pressure, and a reduced risk of type 2 diabetes, heart disease, and stroke.20,82,83
The RDA for young women is 310 mg of magnesium daily, increasing to 320 mg after age 30. The RDA for young men is 400 mg daily, increasing to 420 mg after 30.
Studies show average vegan intakes of magnesium are significantly higher than those of nonvegetarians and are more than adequate.29,30
Magnesium is abundant in vegetables, fruits, whole grains, and nuts. It’s a central element in the chlorophyll molecules that provide the green pigment in plants and is fundamental to photosynthesis. It follows that green leafy vegetables are rich in magnesium. A varied diet that includes greens, whole grains, and other plant foods can easily meet recommended intakes. Magnesium is one of many nutrients that are lost in the refining process. (A slice of whole wheat bread contains 30 mg of magnesium, but a slice of white bread has only 5 mg.) The magnesium intakes of elderly people can fall short when they rely on refined foods or consume few calories. The amount of magnesium in drinking water varies from one region to another and is higher in hard water.
Magnesium absorption could be an issue in high-phytate diets. Leavening bread dough with yeast, as well as other food preparation practices, such as sprouting, soaking, and fermenting, increases the availability of this and other minerals.
Excess magnesium from food doesn’t cause problems in healthy people because the kidneys simply excrete unneeded amounts. High intakes from supplements can result in diarrhea, sometimes with nausea and cramping; magnesium is a constituent of certain laxatives and antacids. Unless medically prescribed, adults shouldn’t take amounts higher than 350 mg daily in the form of supplements; the UL for children from supplements is much lower. Larger amounts can result in more-serious side effects.20,29
Manganese is part of the main antioxidant enzyme in mitochondria, the cells’ energy factories. Manganese supports the activity of other enzymes and is required for the formation of bone and cartilage and for wound healing.20,38
The RDA is 2.3 mg daily for men and 1.8 mg daily for women.
Vegan diets easily meet and exceed the recommended intakes for manganese.29
Rich sources include leafy vegetables, nuts, teas, and whole grains. Any of the following provide approximately one day’s supply: 1 cup (250 ml) of cooked brown rice or oatmeal, 20 pecans, 1½ cups (375 ml) of pineapple or cooked spinach, or 3 cups (750 ml) of green tea.
Manganese is potentially toxic in large amounts, though excessive intakes would occur from taking single-mineral supplements, not from consuming foods. Manganese is a prooxidant; supplemental manganese isn’t needed or advisable in typical vegan diets.20,38
Next to calcium, phosphorus is the most abundant mineral in the body. About 85 percent of the body’s phosphorus resides in bones, where it’s a structural component along with calcium and protein. Every cell needs phosphorus to produce and store energy from food. It’s part of cell membranes and genetic material and helps maintain the body’s acid-base balance.20
The adult RDA is 700 mg of phosphorus per day.
Studies in Canada, Finland, Germany, and the United States have consistently shown the average phosphorus intakes of vegans to be well above recommended levels.29,30
Phosphorus is present in seeds and plays a structural role in plants in the form of phytates. In typical diets, about half the phosphorus is available for absorption and half is bound. When food preparation includes soaking, yeasting, fermenting, leavening, or sprouting, most of the phosphorus and bound minerals are released. Yeasts possess phytases; when whole grains are made into leavened (yeasted) breads, the available amount of phosphorus increases significantly. Between 100 to 200 mg of phosphorus is present in ½ cup (250 ml) of cooked lentils, two slices of whole wheat bread, or 2 ounces (60 g) of almonds or peanuts.
Excess phosphorus intake—especially in relation to calcium—is more common than insufficient dietary phosphorus; the two minerals must be kept in balance for good bone health. High intakes are often due to overconsumption of meat and poultry (which can have ten to twenty times as much phosphorus as calcium) and of colas (which can have 500 mg of phosphorus per serving). These excesses aren’t typical of vegan diets; the fact that some phosphorus in plant foods is bound in phytates and is essentially unavailable may turn out to be an advantage.
Regular consumers of aluminum-containing antacids risk phosphorus deficiency, because the aluminum can bind phosphorus in the intestine and prevent its absorption.20,29
Early humans consumed plenty of high-potassium plant foods, and they ate their meals without salt shakers. Thus, prehistoric cultures consumed potassium and sodium in a 7:1 ratio; conversely, modern Western diets provide these minerals in a 1:3 ratio. It’s believed these altered proportions may contribute to many chronic diseases.21,23,25,90
Potassium-rich foods (fruits and vegetables) have the ability to shift the body’s acid-base balance in an alkaline direction. With adequate consumption of protein and calcium, a diet that emphasizes fruits and vegetables may reduce the risk of osteoporosis. Higher potassium intakes seem protective against strokes, hypertension, and kidney stones.20,84,90
The body’s transmission of nerve impulses, its muscle contractions, and the beating of the heart rely on potassium’s presence and function inside cells. As a positive ion, potassium can conduct electricity, just as sodium can. In fact, life itself depends on the relative locations of potassium (primarily inside cells) and sodium (primarily outside). The maintenance of an electrical gradient or potential across cell membranes is based on the differing concentrations of these substances in the body.20,84
Because there was deemed insufficient data to set an RDA for potassium, the AI for adults is 4,700 mg.20,84
Surveys show typical American intakes of potassium to be low, averaging 2,300 mg per day for women and 3,100 mg for men; 97 percent of those surveyed failed to meet the recommended daily intake.29,60 Vegans do much better, though intakes aren’t always above recommended levels. Potassium intakes average between 3,931 and 6,400 mg for various vegan groups studied in the United States; between 3,817 and 4,855 mg for vegan groups in Great Britain; 3,587 mg for Canadian vegans; and 4,460 to 5,460 mg for German vegan groups.29,30
Plenty of fruits and vegetables are high in potassium, so a vegan diet can easily provide enough. Though the banana is often hailed as the queen of potassium-rich foods, in fact, Brussels sprouts, cantaloupes, grapefruits, green beans, strawberries, and tomatoes all have more potassium per calorie than bananas. Dried fruits, avocados, nuts, seeds, and legumes also are excellent sources.
To boost potassium intake:
• Start the day with a fruit smoothie, with or without added greens.
• Encourage children to drop fruit into the blender for a smoothie and to arrange cut vegetables or fruit pieces on a snack tray; they’ll develop an early appreciation for these nourishing foods.
• Include a big salad at lunch, supper, or both. Shop for new varieties of produce at the supermarket.
• Add potassium-rich foods (see table 6.2 on page 204) to the shopping list.
• Use fruit to feed a sweet tooth and replace sugar with dried fruits in desserts.
• Eat the skin on baked potatoes and the edible skins of other vegetables and fruits.
• Add beans to soups, stews, and salads.
• Use nut or seed butters as spreads on bread or toast.
• Sprinkle nuts and seeds on cereal, salads, and main dishes.
• Feature avocado in salads, sandwiches, smoothies, and raw soups.
The body needs only miniscule amounts of selenium. It’s used to build powerful antioxidant enzymes known as selenoproteins, which protect cells from damage by free radicals, reducing the risk of cancer and heart disease. Other selenoproteins help regulate thyroid function, synthesize DNA, and participate in fertilization.20,79,85
The adult RDA is 55 mcg of selenium per day.
Studies of vegans in the United States, Britain, and New Zealand showed them to meet recommended selenium intakes. Among North Americans, there appears to be little difference between the average selenium status of those on plant-based diets and nonvegetarians; adequate intake from plant sources is thought to be due to efficient food distribution from regions with different soil levels.29 European vegans in regions with low soil levels of selenium, such as Sweden, have relatively low intakes. Research has shown that German vegetarians and vegans have adequate levels of the protective selenoprotein glutathione peroxidase 3, while some indicators of selenium status were 70 to 80 percent of the maximal levels.29,86
The Brazil nut (which is botanically a seed, not a nut, and more often comes from Bolivia rather than Brazil) has become known as the selenium superstar. If it’s been grown in selenium-rich soil, just half a big Brazil nut provides a day’s selenium supply; however, many nuts come from regions where soil has less of this mineral, so intake can vary. The daily recommended intake of selenium may also be obtained from 1½ cups (375 ml) of whole wheat spaghetti. Beans, grains, nuts, and seeds also can be good sources.20,87–89
Plant foods provide selenium in amounts that vary with local soil content. For example, soils in Nebraska and the Dakotas are rich in selenium; other areas in the United States have much less. Many nations have soils that are low in selenium; in fact, Finland includes selenium in its fertilizers. Eating foods sourced from different locations can help ensure adequate intake.2,85
Selenium is toxic in excess; the UL is 400 mcg per day for adults. Avoid supplements at higher than recommended levels, and don’t eat more than three or four Brazil nuts a day.29,85,86,88,89
The human body evolved on a diet far lower in sodium than today’s fast-food fare.22,23,90 Historically, salt wasn’t always easy to come by and therefore was highly valued (hence the saying “the salt of the earth”). Although the body requires sodium to replenish that lost in perspiration, urine, tears, and other body fluids, getting too much sodium is more of an issue today. Even people who rarely add salt when preparing food or at the table may have significant salt intakes. Current research shows that 77 percent of the sodium consumed by North Americans comes from processed and restaurant foods, 5 percent is from salt added during cooking, 6 percent is sprinkled on at the table, and 12 percent is that which occurs naturally in foods.84,91
Due to its hygroscopic nature, sodium plays an important role in maintaining the proper amount of fluid between the body’s cells. It’s a central part of internal communication systems, because sodium is essential for the electrical current that allows transmission of nerve impulses. This mineral also is a part of digestive secretions from the pancreas.84
Although rarely a concern for most people, sodium deficiency—with symptoms of headache, nausea, vomiting, muscle cramps, fatigue, disorientation, and fainting—can occur when considerable salt is lost through perspiration during long hours of physical labor or endurance athletic events, particularly in hot environments.
The AI for sodium is 1,500 mg per day for adults up to age 50, 1,300 mg per day for those between 50 and 70, and 1,200 mg per day for those 70 and older. The UL is 2,300 mg per day, although this upper limit has been questioned and is controversial.84,91
The minimum biologic requirement for survival is between 180 and 500 mg per day. It’s estimated that Paleolithic humans managed on 660 to 770 mg of sodium per day, though of course intakes varied with their geographical region and whether it was inland or coastal.22,23 To cover routine sodium losses that may occur, such as in perspiration on warm days, the lower intake limit has been set at a level higher than necessary for survival. In contrast, individuals engaging in prolonged periods of physical activity in hot environments may need more sodium—in the short term—than the UL because of losses in sweat.
Sodium is essential to the body; after hours of intense work or vigorous exercise, people do need to restore the sodium lost in perspiration. However, in the absence of these activities, follow these guidelines to prevent excessive sodium consumption:
• Use lemon juice and exotic vinegars to help beat salt cravings and bring out the flavor of foods.
• Use salt-free seasonings or prepare a mixture of herbs for use as seasoning.
• Use salty condiments sparingly. Buy low-sodium tamari, dilute it, and keep it in a spray bottle. Dilute Bragg Liquid Aminos with an equal amount of water and spray the mixture on food rather than pouring it.
• To stretch the flavor of added salt, sprinkle a little on food surfaces rather than mixing it in. This surface salt touches taste buds for maximum sensation without excess sodium.
• Buy fewer processed foods, because these contribute most to intakes of dietary sodium.
• Check the labels of soups or similar packaged items and choose those with less sodium. For example, the sodium content of a ½-cup (125 ml) serving of tomato sauce can vary from about 20 to 700 mg.
• Consumption of certain foods is best minimized or avoided: pickles (a single pickle can deliver 900 mg of sodium), olives, salty snack foods, and some canned goods. Check the labels of vegan meat substitutes, crackers, cereals, breads, and baked goods.
Excess sodium intakes (above 2,300 mg per day) are particularly problematic for older people with established hypertension. Among those with hypertension, about 50 percent of African-Americans and 25 percent of American Caucasians are salt sensitive; the rates increase with age or with reduced kidney function.20,29,84,91 People who want to determine whether they’re salt sensitive should check their blood pressure, cut down on salt intake for four days, and then see if this results in a lower blood pressure. Some people can reduce the risk of developing hypertension by avoiding high salt intakes and consuming amounts within or at the lower end of the recommended ranges. High sodium chloride intakes and high sodium to potassium ratios also can be linked to calcium losses from bone and in the urine.92
In vegan diets of the Americans, Canadians, and Germans studied, average sodium intakes are generally within the recommended range. These moderate sodium intakes may be due in part to many (though not all) vegans’ preference to avoid processed foods. A favorable balance between relatively low sodium intakes and high potassium intakes is a positive feature of many vegan diets. However, average vegan sodium intakes of North Americans in the Adventist Health Study-2, British, and Vietnamese were somewhat high, ranging between 2,500 to 3,100 mg.29,30
1. Eat whole plant foods, guided by The Vegan Plate (page 434). Minerals are found in all food groups, but in far smaller quantities in refined foods.
2. Make sure caloric intake is adequate. If on a weight-loss diet, consider using a multivitamin-mineral supplement.
3. Include some foods fortified with calcium, zinc, iron, and iodine. Although it’s possible to meet recommended intakes without such foods, these can make it easier to reach the goal.
Still, the average sodium intakes of American nonvegetarians are significantly higher—about 3,400 mg per day, equivalent to 1½ teaspoons (7 ml) of salt—well above the UL and about five times the estimated intake from the Paleolithic diet.84,91
Sodium is naturally present in celery, spinach and other leafy greens, carrots and carrot juice, sweet potatoes, and sun-dried tomatoes; sea vegetables are high in sodium. Salt is added to many vegan processed foods: canned tomatoes, soups, and beans; peanut butter; vegan meat substitutes, burgers, and hot dogs; bread and other baked goods; bottled sauces and dressings; vegetable bouillon and stock; olives; miso; snack foods, such as chips, crackers, and popcorn; vegan pizzas; and ready-to-eat entrées. The condiments tamari, Bragg Liquid Aminos, and nama shoyu each provide between 212 and 320 mg of sodium per teaspoon (5 ml). Check labels for exact amounts.
Many vegans choose sea salt rather than regular table salt, which has been refined and then enriched with iodine. Iodized table salt is a good source of the mineral iodine, but sea salt lacks this mineral; it’s lost in the drying process and most sea salt isn’t fortified. Although sea salts are advertised as containing trace minerals, these are usually present in miniscule amounts and also include tiny amounts of heavy metals, such as lead. Tamari, Bragg Liquid Aminos, and miso also are not enriched with iodine. Vegans who use noniodized salt should be sure to include a reliable source of iodine.
The amounts of minerals in vegan foods are shown in table 6.2 (page 204). For menu-planning purposes, compare these with the recommended mineral intakes for women and men shown at the top of each column.
TABLE 6.2. Minerals in vegan foods
Key: Dashes indicate that no data is available.
*RDA for iron (see page 187).
**Based on recipe with kale, romaine lettuce, lemon juice, cucumber, apple, celery, and lemon (from Becoming Raw).
***Or see label.
For menus and delicious recipes that meet recommended intakes of all essential minerals and other nutrients, see Cooking Vegan by Vesanto Melina and Joseph Forest (Book Publishing Company, 2012). For raw vegan menus and recipes, see Becoming Raw by Brenda Davis and Vesanto Melina (Book Publishing Company, 2010).
