The way to keep your health is to eat what you don't want, drink what you don't like, and do what you'd rather not.
—Mark Twain
You are what you eat—and drink. When you focus on nutrition, I want you to think about both. But in no way is it as bad as Mark Twain maintained! I promise, I am not going to mandate that you that munch on sardines or dig into tofu, unless, of course, you truly enjoy those foods.
There are no quick fixes, no special diets. Instead, healthy nutrition is a way of life. Eating smart, for your general health and for your bones, means a long-term approach. It is part of your healthy lifestyle. Since the effect of your nutrition is lifelong, evaluating a small slice of time does not provide the whole picture. As a result, differing opinions abound on the subject of dietary enhancement and bone health.
However, the value of calcium and vitamin D for bone health is well established. You will find thorough discussions of calcium and vitamin D in the next two sections.
GENERAL PRINCIPLE OF NUTRITION
As with most things in life, moderation is the key Too little or too much may be harmful. This “u-shaped” relationship holds for most of nutrition and bone health. I like to refer to it as the Goldilocks Principle. You don't want too little or too much, but a “just right” amount. The challenge is knowing what that is.
Protein
A steady supply of protein is essential for your bones and all cells in your body. Meat, poultry, fish, eggs, beans, nuts, soy, and dairy products are good sources of protein. You also will find items such as protein bars and protein powders stocked on the shelves of grocery and health food stores.
What kind of protein, and how much, sound like simple questions, but these are the basis of considerable debate. Proteins contain amino acids with sulfur that metabolizes to generate sulfate. The sulfate increases the acidity of the urine and causes greater amounts of calcium to be excreted in it. Both animal and plant sources of protein contribute to calcium loss in the urine. The proteins of plants can have either lower or higher amounts of amino acids containing sulfur than the proteins of animals. Most cereals, nuts, and seeds have higher concentrations than animal foods, while legumes have lower concentrations.
The amount of calcium loss in the urine is proportional to the amount of protein ingested. As the intake of dietary protein increases, the amount of calcium excreted in the urine increases. Also, some calcium is lost in the feces. The Recommended Daily Allowance (RDA) for calcium intake was set to cover the calcium losses associated with protein eaten in the average American diet.
Recent analyses of multiple studies (called meta-analysis) give a summary view of what has been published on this subject. The evidence shows that the effect of dietary protein on the skeleton appears to be favorable to a small extent and not detrimental. Regardless of the source of protein (animal or plant), the key is adequate calcium intake to cover protein-induced calcium losses.
As a geriatrician, I do not worry about too much protein intake; I worry more about deficits. Older individuals tend to decrease the protein in their diets. Cooking for one? Decreased enjoyment in eating? Limited resources? These could all be contributing causes.
Older men and women may benefit from a higher protein intake. Inadequate protein intake is common in patients who suffer a hip fracture. A low protein diet predisposes them to a greater rate of bone and muscle loss. The Framingham Study and the Rancho Bernardo Study both found that the greatest bone loss was associated with the lowest protein intake in older women. In the Rancho Bernardo Study, a high animal protein intake had a protective effect against bone loss. The greatest bone losses occurred in women with the highest vegetable protein intake. In a third study of older women, the Iowa Women's Health Study, those who had the highest animal protein intake had a decreased risk of hip fracture. In patients with a recent hip fracture, protein supplementation reduced the medical complication rate and recovery time.
A decline in caloric intake with age may be the appropriate adjustment for a reduction in energy expenditure. However, a reduction in protein intake may be detrimental for maintaining the integrity and function of bone and muscle. Increasing dietary protein to the normal intake (defined in the box below) is beneficial for bone health. But consider subtracting other foods so that the total number of calories is not increased.
Protein by the Numbers
Recommended Dietary Allowance for Protein
| Grams of protein needed each day | Grams per kilogram a day | |
| Children ages 1–3 | 13 | 1.1 |
| Children ages 4–8 | 19 | 0.95 |
| Children ages 9–13 | 34 | 0.95 |
| Girls ages 14–18 | 46 | 0.85 |
| Boys ages 14–18 | 52 | 0.85 |
| Pregnancy & Breastfeeding | 71 | 1.1 |
| Women ages 19–70+ | 46 | 0.8 |
| Men ages 19–70+ | 56 | 0.8 |
The grams per day recommendations are the estimated requirement for a healthy person. To individualize your daily protein requirement use the grams per kilogram per day column and make a couple of calculations:
Step 1—Convert your weight from pounds to kilograms by dividing your weight in pounds by 2.2
Step 2—Multiply your weight in kilograms by the specific grams per kilogram listed in the far right column above according to your age and gender
Example: If you are a woman and weigh 140 pounds,
Step 1 140 pounds/2.2 = 63.6 kilograms
Step 2 63.6 kilograms × 0.8 = 50.8
51 grams is your recommended daily amount of protein
Repeat these steps for all members of your family.
SOURCE: Food and Nutrition Board, Institute of Medicine of the National Academies. Dietary Reference Intakes for Energy, Carbohydrate. Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (2002/2005). Washington, DC: National Academies Press.
Adequate protein intake during childhood and adolescence is essential to support normal growth and skeletal development. The adolescent years are particularly important for providing adequate nutrition to maximize peak bone mass, though the specific role of protein and protein-diet interactions in the achievement of optimal peak bone mass is not clear.
The available evidence on protein suggests that protein has a biphasic or “U-shaped” effect on bone health. The upper and lower thresholds are not defined. You have to take into account overall diet, calcium intake, health status, and age to determine your individual needs. Dietary protein in the range of usual intakes is beneficial, not harmful, to bone health.
Carbohydrates and Fat
Invoking the Goldilocks Principle: Too little or too many calories and too much fat can negatively impact bone health. Fat is metabolically active, producing inflammation and other factors that may be influencing the bone. Obese children have a greater risk of fractures. And adolescent girls with more abdominal fat have lower measures of microstructure of bone. In other words, they develop poorer quality bone. In the Rancho Bernardo Study, older adults with obesity and high blood sugars had higher bone density at the hip but a higher risk of fracture. On the other end of the spectrum, being malnourished and underweight is also associated with bone loss and higher risk of fracture.
Vitamin ABCs
Vitamins are classified as either water-soluble or fat-soluble. Water-soluble vitamins B and C dissolve in water and are not stored. Instead, the unused amounts are excreted through your urine. Fat-soluble vitamins need dietary fat in order to be absorbed in the small intestines. The fat-soluble vitamins A, D, E, and K are stored in the liver and fat tissues.
Vitamin A
There are two basic types of vitamin A. Retinol is from animal products such as oily fish, liver, cheese, and eggs. Beta-carotene is found in fruit and vegetables that are orange, including carrots, sweet potato, apricots, and others such as tomatoes and spinach.
In Norway and Sweden, where there are high rates of herring and salmon consumption, researchers made the first association of high dietary intake of vitamin A with reduced bone mineral density and increased risk for hip fracture. Subsequently, other population studies have reported that either high intake of vitamin A or high serum concentration of retinol increased the risk of fracture in both men and women.
The risk of fracture increased with increasing amounts of retinol. Dietary intake of retinol greater than 1.5 mg a day is harmful for bone health. In the Rancho Bernardo Study, intakes slightly above the recommended amounts (seen predominantly in supplement users) were harmful for skeletal health. However, the majority of supplements now contain vitamin A as beta-carotene, which has no link to bone. (Caution to supplement users: beta-carotene supplementation is linked to an increased risk of lung cancer in former smokers.)
Vitamin B
B vitamins play an indirect role in bone health. Folate (or folic acid) and vitamins B12 and B6 help regulate homocysteine. High homocysteine levels, which you may have heard about in association with cardiovascular disease, are also associated with a significantly greater risk of fractures in women and men. A diet rich in B vitamins and a standard multivitamin can keep homocysteine levels in the normal range. Foods high in folic acid include green, leafy vegetables, and grain products fortified with folic acid.
Vitamin C
Nobel Prize-winning US chemist Linus Pauling made vitamin C popular, promoting it in the 1980s as a treatment for everything from the common cold to terminal cancer. Vitamin C, which continues to be the most used supplement today, may have a protective effect on bone health. It is essential for collagen formation and normal bone development. When we looked at vitamin C use in the Rancho Bernardo Study, the highest bone density was associated with 1,000 mg of supplemental vitamin C a day in older women. Other studies have shown less bone loss and lower fracture risk at the hip with vitamin C supplements.
Vitamin K
Vitamin K is best known for its role in helping blood clot properly, but it also activates at least three proteins involved in bone health. After observational studies suggested that vitamin K is associated with decreased risk of hip fractures, a flurry of further research resulted.
Vitamin K occurs as either phylloquinone (K1) or menaquinones (K2). The major dietary form of the vitamin is K1, which is found in dark green vegetables such as broccoli, kale, spinach, cabbage, asparagus, and dark green lettuce. (Chlorophyll is the substance in plants that provides both their green color and the vitamin K.) Gut bacteria makes K2 but they do not contribute appreciably to your vitamin K status. Menaquinones can also be found in fermented foods such as cheeses or in natto, a soybean product.
Natto is a popular food in Japan, where studies show decreased hip fracture risk. Also, many of the vitamin K intervention studies are from Japan. Japanese researchers have used menaquinone (MK-4) in doses considered to be medical intervention rather than nutritional supplementation.
Intervention studies using different K vitamins either in doses attainable in your diet or in supernormal doses have yielded conflicting results. Vitamin K1 supplementation in a dose attainable in the diet (500 micrograms) does not appear to confer any additional benefit for bone health at the spine or hip when taken with calcium and vitamin D.
The recommended intake for adult women (90 micrograms a day) and adult men (120 micrograms a day) is based on its function in blood. The amount needed for bone health is not clear. To meet the RDA for vitamin K, one serving of a dark green vegetable a day easily does it—two or three stalks of broccoli are all you need. Anyone taking blood thinners (Coumadin®) needs to be cautious about introducing more vitamin K into his or her diet because vitamin K decreases the effectiveness of Coumadin.
Minerals
Phosphorus
Phosphorus is a mineral essential for normal function of every cell in your body. The majority of your phosphorus is in bone. It makes up bone's major structural component in the form of a calcium phosphate salt called hydroxyapatite.
Phosphorus is a nutritional requirement for healthy bone. The good news is that phosphorus deficiency is rare. Phosphorus is abundant in most common foods, so no supplementation is needed. Phosphorus content of soft drinks has been implicated as a cause of low bone density. However, studies indicate that the displacement of calcium-rich milk is the actual culprit rather than the ingredients of soft drinks. The current RDA for adults is 700 mg and for preteens and teenagers it is 1,250 mg.
Magnesium
Although roughly more than half of the body's magnesium resides in the bone, its function is not entirely known. Magnesium is an important factor for many physiologic functions, especially for the cardiovascular system. Low dietary magnesium has been implicated as a risk factor for osteoporosis. The Framingham Study showed that low dietary magnesium was associated with low bone density. In general, magnesium's role in bone health has been poorly studied.
Magnesium is often combined with vitamin D and calcium as a supplement for bone health, but I have not found any convincing intervention data in the literature to support the use of magnesium as a supplement. In one three-year study, ninety-nine healthy postmenopausal women were randomly assigned to diet instruction alone, calcium and vitamin D supplement, or a multinutrient supplement that consisted of calcium, vitamin D, and assorted micronutrients, including 600 mg of magnesium. The dietary group was instructed to consume at least 800 mg of calcium a day with a goal of 1,450 mg, which was the calcium supplement dose for the two other groups. No differences were observed in bone mineral density at the hip, spine, and whole body at one, two, or three years. The addition of assorted micronutrients that included 600 mg of magnesium conferred no obvious skeletal effect beyond that of calcium and vitamin D alone.
The only individuals who may need supplementation are those with absorption problems such as celiac disease or inflammatory bowel disease; those on water pills such as Lasix® (furosemide), bumetanide, or torsemide; and those with a high daily caffeine intake (caffeine causes excess loss of magnesium in the urine). Supplementation should be discussed with your doctor in these cases.
The bottom line is that you should be getting enough magnesium in your diet. If not, nuts such as almonds and cashews are high in magnesium, as are spinach and soybeans. Three ounces of halibut tops the list of magnesium-containing foods with 90 mg. These are some of the same foods that are also good sources of either calcium or vitamin D. Adult men over thirty require 420 mg of magnesium per day, which is the highest for any age, and 320 mg per day are required for women.
Beverages
Alcohol
“Moderate” intake of alcohol appears to be positive for the bone, and for men and postmenopausal women it is even better than no alcohol consumption at all. More than two glasses of alcohol a day is harmful and is a risk factor for osteoporosis. The mechanisms involved in the benefits of moderate alcohol intake remain unclear and require further study. Beer is described as “good for bones” based on its silicon levels. But the conclusion was not based on an intervention trial, much to the disappointment of beer lovers. The link was based on the Framingham Study, which showed that higher silicon intake was associated with higher bone density.
Teas
As a beverage absent in calories and rich in antioxidants and other bioactive substances, the role of tea in health promotion has gained traction over the last decade. Tea contains large amounts of nutrients called flavonoids, particularly those called catechins. Green and black teas are a rich source of these catechins.
In countries that have large numbers of regular tea drinkers, studies have suggested that tea is good for the bones. In a British study, those who added milk to their tea had even higher bone density. However, not all studies have reported positive results for tea. The large Women's Health Initiative study found that the effect of regular tea drinking on bone density was small and did not alter the risk of fractures among older American women.
In animal observations, the bioactive components in tea seem to increase bone formation and decrease the actions of the osteoclasts. How this applies to humans is not known.
Learn more about soft drinks and coffee in the next section, which deals with calcium's role in bone health.
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The Bare Bones
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