It is natural to have nutritional questions and concerns when transitioning to a plant-powered diet. After all, it is not how most of our family and friends eat. You will likely have similar concerns, or have well-meaning loved ones ask questions. This section is intended to help answer some of the most frequent and obvious questions when eating plant-based.
This section is not a comprehensive nutritional guide. For more comprehensive analysis and answers to these nutritional issues, I recommend these books:
• The Complete Idiot’s Guide to Plant-Based Nutrition (by Julieanna Hever, MS, RD, CPT)
• Becoming Vegan (by Brenda Davis, RD, and Vesanto Melina, MS, RD)
• Vegan for Life (by Jack Norris, RD, and Virginia Messina, MPH, RD)
For our purpose here—to address these frequently asked questions concisely with expertise—I recruited some assistance from a colleague, Heather Nicholds. Heather is a registered holistic nutritionist and is well known through her work on heathernicholds.com. Read on as Heather helps clarify commonly asked questions.
What about Protein, Iron, and Calcium?
A few key nutrients are well associated with animal foods, and a lack of knowledge about plant sources for them might scare some people away from improving their diets. If you eat a variety of healthy, whole plant foods you’ll get enough of nearly all the nutrients you need, including protein, calcium, and iron.
It’s not nearly as hard as people think to get enough protein from plant foods. All whole plant foods have some protein in them. If you eat enough calories from a balanced diet, and include legumes (beans, lentils, and peanuts), you should get enough protein and all the essential amino acids for normal daily needs.
| Protein RDA (Recommended Daily Allowance)2 | |
|---|---|
| 0–6 months | 9.1g/day |
| 7–12 months | 11g/day |
| 1–3 years | 13g/day |
| 4–8 years | 19g/day |
| 9–13 years | 34g/day |
| Males | |
| 14–18 years | 52g/day |
| 19 years+ | 56g/day |
| Females | |
| 14–18 years | 34mg/day |
| 19 years+ | 46g/day |
| Pregnancy and lactation | 71g/day |
| Protein as % of calories | |
| 1–3 years | 5–20% |
| 4–18 years | 10–30% |
| 19 years+ | 10–35% |
See Nutrition Charts for top plant protein foods (page 277).
You can find iron in most beans, as well as in the leafy greens and molasses. The iron intake of most vegans and vegetarians is actually pretty high, since iron per calorie is higher in plant foods than animal foods.
The iron in plant foods is a different form than the iron in animal foods, and it can be more difficult to absorb. But there are some simple things you can do to counteract that and get plenty of plant-based iron. Vitamin C helps your body absorb plant food sources of iron, so eating vitamin C–rich foods is a great way to improve your iron levels. Leafy greens are a great source of vitamin C as well as iron, so they do double duty. Citrus, berries, and bell peppers are good sources of vitamin C as well. Vegans and vegetarians who eat a lot of fresh vegetables and fruit have a pretty high intake of vitamin C, and it tends to offset the lower absorption rate of plant sources of iron.
The tannins in coffee and tea (black or green) interfere with iron absorption when you drink it at the same time as you eat foods with iron. Drinking coffee and tea only between meals seems to be totally fine. Phytic acid (in things like seeds, beans, grains, and raw spinach and chard) also interferes with iron absorption, but vitamin C helps counteract that effect. It’s also broken down when you soak and/or cook those foods properly.
The government recommendations are based on a mix of animal and plant sources of iron. For vegans, who only eat plant sources, the government recommendation is to get nearly twice that amount because of the lower absorption rate.
| Iron RDA (Recommended Daily Allowance)4 | |
| 0–6 months | 0.27mg/day |
| 7–12 months | 11mg/day |
| 1–3 years | 7mg/day |
| 4–8 years | 10mg/day |
| 9–13 years | 8mg/day |
| Males | |
| 14–18 years | 11mg/day |
| 19 years+ | 8mg/day |
| Females | |
| 14–18 years | 15mg/day |
| 19–50 years | 18mg/day |
| 51 years+ | 8mg/day |
| Pregnancy | 27mg/day |
| Lactation | 9–10mg/day |
See Nutrition Charts for top plant sources of iron (page 277).
The best way to get usable calcium is to eat a variety of plant foods, especially quinoa, chickpeas, sesame seeds, and broccoli. The dark green leafy vegetables are particularly good sources. The great thing about these sources of calcium is that, unlike milk, they also have magnesium and vitamin D, which help your body absorb and use the calcium. These three nutrients work together in your body, and none of them will be properly utilized unless they are in the right balance. Unless you get vitamin D and magnesium from other sources, the calcium in dairy won’t get fully used.
Lack of calcium can happen because of low calcium intake, but more often the cause of calcium deficiency is poor utilization or low absorption. Low liver function or low stomach acid levels are also a really common cause of a lack of calcium. Calcium is a very difficult mineral for our bodies to absorb. Making sure that your stomach is active enough to fully digest it is the first thing to look at in correcting a deficiency. Taking a digestive enzyme is a great way to help your stomach keep up, although eating smaller meals with whole plant foods—and chewing properly—is even more helpful and is free.
One thing to keep in mind is calcium’s interaction with other nutrients. Excess phosphorus (there is lots in bran, wheat germ, cheese, and soybeans) displaces calcium, and foods with oxalic acid (rhubarb, raw spinach, and chocolate) interfere with the absorption of calcium. A lack of vitamin D or magnesium can be an indirect cause of calcium deficiency because they’re necessary for calcium utilization.
The best way to maintain a good calcium intake is through lots of good-quality fresh vegetables and fruit, along with a variety of grains, beans, nuts, and seeds. If you’re doing that and still have signs of a lack of calcium, take a look at your digestion and the levels of other nutrients that can help or hinder calcium absorption as possibilities for the root cause of calcium deficiency. If you do need to take a supplement, be sure to research a high-quality source.
| Calcium RDA (Recommended Daily Allowance)5 | |
| 0–6 months | 210mg/day |
| 7–12 months | 270mg/day |
| 1–3 years | 500mg/day |
| 4–8 years | 800mg/day |
| 9–18 years | 1,300mg/day |
| 19–50 years | 1,000mg/day |
| 51 years+ | 1,200mg/day |
| Pregnancy and lactation | |
| 14–18 years | 1,300mg/day |
| 19 years+ | 1,000mg/day |
See Nutrition Charts (on page 277) for top plant sources of calcium.
What Are Healthy Fats?
The standard American diet is far too high in fats, and usually includes a lot of unhealthy fats. So for someone transitioning from that to a healthier diet, it makes sense to focus on reducing fat. The aspect that often gets overlooked, though, is that it’s just as important to look at the quality of the fats you’re eating.
Fat itself isn’t the enemy. Eating unhealthy fats—like animal fats and trans fats—and eating too much fat are the problems for most people these days. People may find they have great results in losing weight and feeling healthier from a sudden reduction of fat, and that’s fantastic. The trouble is, if someone stays for too long on an intensely low-fat diet, it can interfere with normal metabolism, hormone production, and nutrient absorption.
Your body needs enough fat to function, maintain its metabolism, absorb and utilize nutrients, and be healthy. And to be clear, eating healthy fat doesn’t make you fat. You gain weight when you have more calories coming in than going out. That equation isn’t limited to just eating too much and/or exercising too little. Your metabolism (the rate at which you burn calories) can speed up or slow down based on what you eat, or if you have an imbalance in your glands, hormones, or other system.
It’s a lot easier to eat too many calories when you eat higher-fat foods, because fats are more calorie dense than are carbohydrates or protein. But that doesn’t mean you should avoid fat entirely! A lack of fat in your diet can actually cause that glandular imbalance that leads to weight gain.
The best source of healthy fat is whole plant foods—avocados, nuts, seeds, and nut/seed butters. Grains and beans also have some healthy fat in them, and there are even small amounts in fruits, vegetables, spices, and pretty much every food. Oats, for example, are 15 percent fat by calories.
Oils are 100 percent fat, and aren’t something you necessarily need to eat, but they may be important for infants, toddlers, and young children where caloric intake needs to be increased and/or whole fats from plant foods aren’t an option. For instance, babies should not consume nuts too early to reduce the risk of allergies, and some babies have sensitivities to foods like avocados. Growing children have different nutritional needs than adults do, so it’s important to recognize that difference. It’s also important to remember that if you do use oils, choose the right kinds and use them in small quantities with minimal exposure to heat.
Our bodies need two specific fatty acids from our diet; the others can be produced in our bodies if we eat enough fat in general. Those two fatty acids are omega-3 and omega-6. The other important thing here is that our bodies need a certain ratio of omega-3 to omega-6. The ideal ratio is somewhere between 2:1 and 5:1 (omega-6:omega-3). The ratio in an average Western diet is 15–16:1.6
You can increase your relative intake of omega-3 by eating certain foods, including ground flax, chia seeds, and sacha inchi. The trouble is, those foods aren’t always digested easily, and in that case, the omega-3 isn’t properly absorbed. Young children’s digestive systems aren’t as effective at getting the omega-3 out of flax seeds, even if they’re ground up, because their digestive systems are still developing. As a parent, it can sometimes be challenging to ensure toddlers and young children consume adequate amounts of omega-3-rich foods. Young children may not eagerly accept foods like chia, flax, walnuts, and leafy greens, or not in the quantities needed to ensure their nutritional needs are being met. This is a case where supplementing with omega-3-rich oils (ex: flax, sacha inchi) can make sense, in order to get a more easily digested and concentrated form of the essential fats that growing bodies need.
Although it’s crucial to get healthy fats in your diet, remember that fat calories add up quickly and you don’t need large portions to get enough.
To reach your full daily fat intake (based on a 2,000-calorie diet) from a variety of whole foods, you can eat 1/2 cup of oats, 2 tablespoons of ground flax (which gives you your daily needs for omega-3, provided you absorb it effectively), 1/4 cup of walnuts, 2 tablespoons of pumpkin seeds, an avocado, 1/2 cup of chickpeas, 1 tablespoon of tahini (to make hummus with those chickpeas), and 1 ounce of green olives. Then, of course, you have the rest of your food for the day, including lots of fresh veggies and fruit, which will add minimal amounts of healthy fats. This is just one example of how you can reach the daily recommendation; there are infinite combinations to make up a day of plant-sourced healthy fats.
Here’s the breakdown for those who are curious about the numbers: A 2,000-calorie diet, at 25–30 percent fat, would need 500– 600 calories from fat.8
See Nutrition Charts for top plant sources of healthy fat (page 277).
| Omega-3 Adequate Intake | |
| 0–12 months | 0.5g/day |
| 1–3 years | 0.7g/day |
| 4–8 years | 0.9g/day |
| Males | |
| 9–13 years | 1.2g/day |
| 14 years+ | 1.6g/day |
| Females | |
| 9 years+ | 1–1.1g/day |
| Pregnancy and lactation | 1.3–1.4g/day |
| Fat as percent of calories | |
| 1–3 years | 30–40% |
| 4–18 years | 25–35% |
| 19 years+ | 20–35% |
| Omega-6 | 5–10% |
| Omega-3 | 0.6–1.2% |
Which Supplements Do We Need?
Whole foods are the best source of your daily needs for nutrients. Choosing locally grown organic produce, and eating a mostly whole food vegan diet, is important to getting as many nutrients in their natural form as possible.
There are a few key nutrients that require attention on a plant-based diet. Some may wonder why we need to supplement at all if a plant-based diet is so healthy. The reality is, there are a number of complex reasons why we need some or all of these supplements. However, this doesn’t detract from the overall benefits of eating a whole-foods plant-based diet. There are very few dietary plans (if any) that don’t require some type of nutritional or digestive support, particularly when we’re very young and as we age. A balanced plant-based diet along with a few key supplements is a perfect way to be exceptionally healthy while avoiding the contamination, detrimental health effects, environmental impact, and ethical concerns of animal foods.
Vitamin B12 supplements are essential for vegans, and also for anyone with digestive issues and for older adults. If someone suggests eating eggs or other animal foods to correct a vitamin B12 deficiency, keep in mind that B12 isn’t created by animals—it’s generated by bacteria.
Supplements made from bacterial sources of B12 are a more direct form of the vitamin. There are different types of B12 supplements: tablets, capsules, and liquid. I tend to like liquid supplements because they don’t need to be broken apart physically by your system, so they have the best chance to be fully absorbed. There are chewable tablets, which are great, and capsules tend to be easily dissolved as well. Sublingual (under the tongue) supplements are often positioned as a better option, and they may well be, but there’s no conclusive evidence that it makes a significant difference in the absorption rate.
The U.S. RDA minimum for vitamin B12 is 2.4 mcg per day for adults and 2.8 mcg for pregnant or nursing women. More recent studies put the ideal intake at 4–7 mcg per day.9 Since B vitamins stimulate energy and the nervous system, it’s better to take them in the morning and early afternoon.
You can take B12 as one large weekly dose, or more often in smaller doses, whichever schedule works better for you. Our bodies only absorb and utilize part of what we ingest, so you need to get much more than the RDA as a supplement. Taking a supplement of 250 mcg per day or 2,500 mcg per week will both get you enough B12 .
Vitamin B12 is a nutrient that you can’t overdose on, because your body flushes any excess in your urine. If you notice bright yellow urine after taking a supplement, that means you’ve taken more than enough.
Some fortified plant foods (nondairy milks, meat replacements) are fortified with B12 (and other nutrients). Since it can be difficult to calculate intake day to day with these foods, and we don’t want to over-rely on processed foods, it is preferable to choose a high-quality B12 supplement to take regularly.
Do not rely on unfortified plant foods for B12 . While there are some plant foods (algae, tempeh, etc.) that list vitamin B12 in the nutritional information, these foods have a form of B12 that’s called an analogue and haven’t been shown to prevent or correct a B12 deficiency.
If children don’t get enough B12 during childhood, their levels can be corrected, but the period where they didn’t have enough can have permanent effects on their brain and nerve function. Always give your children B12 supplements. Most taste fine and children don’t mind taking them. Also, for expectant and new mothers, it is crucial to maintaining your own B12 levels while pregnant and breastfeeding. Consult with your health care practitioner, as you may need to increase your supplementation.
| B12 Adequate Intake | |
| 0–6 months | 0.4 mcg/day |
| 7–12 months | 0.5 mcg/day |
| 1–3 years | 0.9 mcg/day |
| 4–8 years | 1.2 mcg/day |
| 14 years+ | 2.4 mcg/day |
| Pregnancy | 2.6 mcg/day |
| Lactation | 2.8 mcg/day |
Without vitamin D, you won’t absorb and use calcium properly, and the lack of both calcium and vitamin D will weaken the structure of your bones. Researchers are also starting to link vitamin D deficiency with all kinds of health problems and diseases, like asthma and cancer.
Meat-eaters should be just as concerned about deficiency here. The results of a 2009 study showed that the majority of both vegetarians (59 percent) and meat-eaters (64 percent) do not have sufficient blood levels of vitamin D.10 Diet contributed less than half the RDA for vitamin D of 400 IU, whether it included meat or not.
Our skin produces vitamin D when it’s exposed to sunlight. It’s a hard thing to measure and rely on, because we produce different amounts depending on skin color and some other factors. The farther north you are, the more winter will affect vitamin D levels. Even in the spring and fall, we would need more sun exposure than in the summer to produce the same amount of vitamin D because the sun is at a lower angle in the sky. A general recommendation of 20 minutes per day might not be enough. Supplementing with vitamin D is very inexpensive and can be very helpful. Discuss with your health care practitioner, depending on personal circumstances.
The RDA set by the government has recently been raised to 600 IU (from 400 IU), and the amount is the same from infancy to adulthood. Many health experts say that this is still too low, that it only prevents a severe deficiency and isn’t enough for supporting health. Supplementation in the range of 1,000–2,000 IU daily seems to be a good level for most people.
The active forms of vitamin D are cholecalciferol (D3) and ergocalciferol (D2). Most supplements get D3 from the lanolin in sheep wool. D2 is derived from plant sources. There are some new supplements with plant-sourced D3, which is great because D3 is the more active form in your body and better for correcting a deficiency. They’re a bit more expensive, so the good news is that D2 is just fine for maintaining healthy levels.
DHA (docosahexaenoic acid) is a form of omega-3 that is absolutely crucial to proper brain development. Because it’s difficult to digest, absorb, and synthesize from whole foods, supplements may be important, and necessary, for children.11 Luckily, there are some wonderful forms of plant-based DHA, sourced from algae.
When breastfeeding, infants and young children obtain DHA from their mother’s milk. That means it’s important for mothers to make sure they’re getting sufficient DHA through diet and/or supplements. Breastfeeding is recommended for up to two years of age.12 During those later months of breastfeeding, it can be difficult to know whether DHA intake is adequate because there aren’t any deficiency symptoms. It can bring peace of mind to supplement with a high-quality vegan DHA product, and it certainly doesn’t do any harm to a growing child.
Other times during childhood can warrant supplementation. For instance, when toddlers or preschool children are going through picky phases and you aren’t sure whether they are consuming enough omega-3 fatty acids, it’s prudent to supplement. There’s no risk associated with supplementing DHA, particularly when taking plant-based DHA that has drastically less potential for mercury or other toxin contamination than does fish-based DHA, so it can also be taken throughout adulthood to ensure healthy brain, nerve, and heart function.13
DHA isn’t studied for RDAs, but omega-3s are converted into DHA, so you can follow those guidelines on page 270.
Probiotics are the good bacteria that live in your digestive tract, and they serve a lot of useful purposes. If their population gets too low, they have trouble keeping their claim on your system, and bad forms of bacteria and yeasts take over.
Along with a balanced diet low in processed sugars, taking a probiotic regularly helps keep the good bacteria population up, which supports a healthy immune system. A probiotic supplement doesn’t need to be taken daily unless you’ve had a course of antibiotics or a severe imbalance. There’s no standard recommendation, so if you want to support your family’s health with probiotic supplementation, talk to your health care practitioner. There are different options for supplementation, such as adding a powdered children’s probiotic to water or stirring it into a nondairy yogurt. Your health care practitioner will help advise.
What about Soy?
When focusing on a plant-based or vegan diet, people often come across a lot of information out there saying that soy is a wonder food and a lot of other information saying that soy is very unhealthy. Soy is a bean—just a bean. It has some amazing benefits, as do most beans and other plant foods, and is nothing to be scared of. Much of the information demonizing soy is unfounded, and the nutrition science shows that there is no harm in eating soy.
Soy shares the wonderful benefits of other beans and plant foods—it’s rich in vitamins, minerals, fiber, and antioxidants—but there are a few areas where it really shines:
•Protein: Soy has one of the highest levels of protein among beans, about 32 percent, and is even higher in tofu at 38 percent.
•Iron: Soy has a particular type of iron that’s really well absorbed, compared to other plant sources of iron.
•Convenience: Tofu and tempeh make easy additions to dinners and packed lunches, and when flavored properly, kids love it. Organic soy milk is a great option for cereal or for an alternative to chocolate milk.
The way soy usually causes trouble is that vegans and vegetarians often rely on fake meats, processed foods, and/or tofu to replace meat, and on soy milk to replace dairy milk, without changing anything else about their diet. What happens is that they often wind up eating too much soy, or maybe just too much processed soy, and don’t get enough overall variety in the foods they eat. Also, so many processed foods use soy that anyone—not just vegans—can be overexposed. An excessive amount of any food can cause digestive issues, sensitivities, and allergies.
There are a few things to consider in choosing how to eat soy healthfully, just as there are with any other foods, and the main thing to remember is to choose high-quality sources. Some great soy choices that can be a regular part of a healthy balanced diet (always choose organic) include tempeh, tofu (especially sprouted tofu), soy milk, miso, and tamari. For more processed soy products, keep in mind that they don’t need to be totally avoided, but rather kept in the same place as any highly processed food— consumed minimally.
Soy contains compounds called goitrogens, which deplete iodine in your body. In Japan, where soy has been eaten for a long time, they also eat a lot of seaweeds, which are very rich in iodine. Modern cultures adopting soy as part of their diet aren’t usually eating much seaweed. Including nori or other sea vegetables can balance this problem with iodine. An easy way to do this is to use a sea salt that includes kelp, or use Herbamare, which tastes fantastic and has kelp in it.
Because soy is used in so many processed foods and as animal feed, it’s one of the three main crops grown in North America. Being grown in massive monocultures means that soy is susceptible to pests and is a major focus for genetic modification. Organic standards require non-GMO seeds, so buying organic soy is a great way to avoid this issue. It’s easy to find organic tofu, tempeh, tamari, and soy milk. Read labels, and look for certified organic and non-GMO.
Soy isn’t necessary for vegans or vegetarians to get a balanced diet. You can get the nutrients you need from other foods. Soy has been shown to have some amazing health benefits, and it is much healthier as a complete package when you compare it to a steak or a glass of cow’s milk, which have saturated fats, cholesterol, and toxins.
Like any food, though, when eaten in excess, soy can cause some issues. Soy gets overemphasized so often in vegan and vegetarian diets, but it can be a wonderful part of a healthy diet when enjoyed in balance with other healthy whole plant foods.
1Institute of Medicine of the National Academies. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, D.C.: The National Academies Press, 2002.
2For more insight, see one of the referenced books mentioned in the introduction, and also this article: veganhealth.org/articles/protein.
3For more information on iron, refer to this detailed article: veganhealth.org/articles/iron.
4Institute of Medicine of the National Academies. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, D.C.: The National Academies Press, 2001. These reports may be accessed via nap.edu.
5Institute of Medicine of the National Academies. Dietary Reference Intakes for Calcium, Phosphorous, Magnesium, Vitamin D, and Fluoride. Washington, D.C.: The National Academies Press, 1997. These reports may be accessed via nap.edu.
6A.P. Simopoulos, “The importance of the ratio of omega-6/omega-3 essential fatty acids,” Biomedicine & Pharmacotherapy 56.8 (2002): 365–379.
7Institute of Medicine of the National Academies. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, D.C.: The National Academies Press, 2002.
8Nutritional data from nutritiondata.self.com.
9More information on optimum levels of B12 supplementation can be found here: nutritionfacts.org/videos/vitamin-b12-recommendation-change.
10J. Chan, K. Jaceldo-Siegl, and G.E. Fraser, “Serum 25-hydroxyvitamin D status of vegetarians, partial vegetarians, and nonvegetarians: the Adventist Health Study-2,” The American Journal of Clinical Nutrition 89.5 (2009): 1686S–1692S. Analysis of the data quoted can be found at veganhealth.org/articles/bones#recvitd.brainlife.org/reprint/2001/vieth_r010201.pdf
11ajcn.nutrition.org/content/57/5/703S.1.short
