It would be natural to assume that vegans are at greater risk of osteoporosis. After all, vegans do not consume dairy products, and millions of North Americans and Europeans get most of their bone-building calcium from milk. But the reality is, countries with more vegans have fewer cases of osteoporosis. Is that due to differences in genetics, or is a vegan diet more bone-friendly than its detractors realize?
Vegans get more of some nutrients and less of others
Dr Katherine L Tucker of the University of Massachusetts at Lowell made a comprehensive study of the role of diet in bone health in vegans and vegetarians. Her review of the research revealed that vegans (and vegetarians) get more of some nutrients that are important to bone and less of others:
- Plant-based diets contain smaller amounts of calcium, vitamin D, vitamin B-12, protein, and n–3 (omega-3) essential fatty acids.
- Vegans and vegetarians get about the same amount of zinc in their diets as omnivores, although it is in a less completely absorbed form.
- Plant-based diets contain larger amounts of vitamin C and vitamin K, along with other antioxidant and anti-inflammatory phytonutrients.
- Vegans and vegetarians eat more vegetables and fruit, which are good sources of potassium. This potassium helps the kidneys retain calcium rather than excreting it into urine.
- Vegan and vegetarian diets tend to provide more vitamin C. The Framingham Health Study found that this vitamin is particularly important for bone health in men. Men who received the most vitamin C had the fewest bone fractures after age 60.
- Diets rich in beans, peas, lentils, nuts, and whole grains tend to be better sources of magnesium, which is deficient in the population as a whole. Magnesium regulates calcium absorption through the intestines and increases bone strength. Women who have osteoporosis tend to be deficient in magnesium.
- Diets rich in carotenoids (alpha-carotene, beta-carotene, gamma-carotene, lutein, lycopene, and zeaxanthin) from colorful vegetables are associated with less osteoporosis and fewer fractures. The most bone-protective carotenoid is lycopene, the red pigment in tomatoes and watermelons.
There are two additional important considerations:
- A plant-food diet places lower burden on the kidneys to maintain healthy pH. When the kidneys have to process large amounts of highly acidifying urea that is the waste product from digesting excessive protein, they have get alkaline compounds from elsewhere in the body. One of the sources of "alkali" the kidneys use to maintain a healthy pH is the calcium in bone.
- Plant fats can be healthy or unhealthy. Algae-derived omega-3 essential fatty acids, primarily DHA, are unquestionably beneficial to bone health. Other plant-based fats are only helpful if they are consumed in the right ratios. Vegans and vegetarians and everyone else tend to get too many pro-inflammatory n-6 fatty acids from less expensive oils such as cottonseed, sunflower, corn, and soybean. Olive oil contains neutral fats that neither help nor harm bone.
Vegans tend to have issues with osteoporosis
With all the healthy aspects of vegan diet, do vegans have better bones? The findings of research are limited and inconclusive. However, they give nutritional goals for healthy bones.
- A study of women in Taiwan who had been long-term vegans found that they were four times more likely to suffer osteopenia, a condition of low bone mineral density that can be considered a kind of "pre-osteoporosis," than women who ate some animal-based foods in their diet.
- The European Prospective Investigation into Cancer and Nutrition–Oxford cohort, which studied 7947 men and 26,749 women aged 20 to 89, found that vegans who consumed less than 525 mg of calcium per day were at greater risk of breaking bones than ovo- and lacto- and ovolacto-vegetarians and omnivores. However, the data were not significant, meaning that a different sample of vegans might have found more fractures or might have found fewer.
What should vegans do for healthy bones?
The bottom line of research is not that vegans should not be vegans to avoid osteoporosis. But they do need to be sure to get enough of certain nutrients.
- Calcium. The magic number for calcium consumption seems to be 525 mg per day. A single 100 gram/3-1/2 ounce serving of firm tofu provides 698 mg of calcium. Half an ounce (15 g) of fortified breakfast cereal provides 500 mg of calcium. Two-and-one-half cups (450 g) of green leafy vegetable provides 450 mg of calcium.
- Vitamin D. The target for vitamin D to prevent fractures is 400 IU per day. Most non-vegans get their vitamin D from fortified dairy products. Vegans can get 420 IU vitamin D from four cups of almond milk, soy milk, or rice milk to which vitamin D has been added. A cup of mushrooms that have been exposed to UV light (such as sunlight) will provide 632 IU of D.
- Vitamin B12. The body can store B12. It is not necessary to consume it every day. The target bloodstream concentration for preventing osteoporosis is 434 pg/mL (which is equivalent to 320 pmol/L in the units more often used outside the United States). See your doctor for B12 testing and get an injection if needed.