Vegetarian and Vegan Diets: What They Mean for Bone

Studies from around the world document that a diet high in whole-food vegetables, fruits, nuts, seeds, herbs, and spices reduces disease risk. Witness a new study from Iran (1) reporting reduced inflammation and lower bone breakdown in those consuming more plant foods; a Spanish study (2) linking higher plant intake to lower blood pressure; a large US study (3) revealing how high plant intake supports healthy brain aging; another (4) showing variety in fruit and vegetable intake can reduce the risk of life-threatening heart disease; and another study that focuses on kidney failure. (5)

Further, a diet high in nutrient dense plant foods has shown benefits for bone in the form of reduced bone loss and decreased risk of fracture. (6, 7)

Vegetables are great for our bones, but how does our skeleton fare on a diet that excludes all foods of animal origin?

A whole-foods, plant-centered diet helps protect us from the plague of modern degenerative disease, this is clear. In addition, as far as bone goes, both vegetarian and vegan diets exhibit a reduced acid load which favors bone. But, as we evolved eating all sorts of plants and animals it is only logical to ask if a diet limited only to plant food sources supports lifelong bone strength?

For some time, scientists have tried to tease apart the impact on bone health of both vegetarian and vegan diets. This is not an easy task as there are many types of vegetarian diets. A lacto-ovo vegetarian diet can vary substantially from an “ovo” or “no ovo” vegetarian diet, etc. The research we have looks at how individuals identify themselves (vegetarian, vegan, or omnivore) and this is what we see:

Vegetarian diets and bone density

• Vegetarians are found to have lower bone mineral density than their omnivore companions (8). One study (9) calculated vegetarians to have a 4% lower bone mineral density than meat eaters.
• The study mentioned above (6) from Taiwan found that although bone density may be lower, aging bone loss among long-term ovo-lacto vegetarians was not affected significantly.

Vegetarian diets and fracture risk

• Data (6) suggest vegetarians likely have a slightly increased risk of fracture.
• Specifically, a large British study (10) calculated that vegetarians had a 25% increased risk of hip fracture.
• Most researchers consider this increased risk fracture among vegetarians to be slight, and likely reduced by higher intakes of protein, vitamin/minerals, and omega-3 fats.

Veganism and bone

A vegan diet can be quite a different animal than the vegetarian diet (forgive the pun) and tends to be less nutrient dense. In Western societies, the vegan dietary pattern is associated with lower bone density and higher fracture risk, as reported below. But this may not be true for Eastern cultures where this dietary pattern evolved. Historically veganism was practiced amongst Buddhist nuns following the doctrine of “ahimsa,” which exhorts followers to “do no harm” to any living creature. Recent small studies (11, 12) suggest that these isolated and peaceful long-term vegan nuns did not experience an elevated risk of low bone density or fracture as compared to their omnivore counterparts.

Veganism and bone density in Western societies

• Vegans as a group exhibit a lower bone density in the spine, hip, and total body than do vegetarians, and certainly substantially lower than that found in omnivores. (9, 10)
• A recent in-depth German study (13) compared 36 vegans to 36 omnivores and found that the vegans had markers of lower bone density and a lower concentration of nutrients important to bone health. Vegans have lower levels of vitamins A and B2, lysine, zinc, selenium, omega-3 fats, iodine, and calcium.
• Vegans experience substantially more fractures than either vegetarians or omnivores. (12, 14)
• The large British EPIC-Ox study (10) found vegans to have nearly three times the risk of hip fracture as non-vegans.
• Additionally, vegans exhibited a 50 to 100% increase in total fractures as compared to meat eaters.

Bone-enhancing nutrient suggestions for vegans and vegetarians

My clinical observations confirm the research finding that vegans and many vegetarians would do well to fortify their diet to support bone. Specifically, think of the following nutrients:

• Calcium

Calcium intake is low in vegans, putting them at a higher risk for fracture. One study showed that calcium levels below 525 mg a day put women at a 75% higher risk of fracture. (15) Ensure a calcium intake of at least 600 to 800 mg (from diet and supplements together).

• Vitamin D

Vitamin D deficiency has been commonly noted in vegans and increases the risk of fracture. (15). Test your vitamin D level and supplement with sufficient vitamin D to reach a 40 to 60 ng/mL level. (An at-home test for vitamin D is now available in our Shop.)

• Vitamin B-12

Vitamin B-12 is essential for bone health. Unfortunately, it is one of the vitamins that is most difficult for vegetarians and vegans to obtain because it is mainly found in animal products. One study showed that low vitamin B-12 levels were detected in 11% of omnivores, 77% of vegetarians, and 92% of vegans. Prevalence of osteoporosis was seven times higher in vegan and vegetarian women with low B-12 concentrations. Low B-12 also leads to an elevation in homocysteine, which increases the risk for fracture. A meta-analysis study showed that vegans and vegetarians were at a 4% greater fracture risk for every µmol/L increase in homocysteine. (15)

Supplement with methylated B12, at a dose of 1,000 mcg once or twice a day (have your B-12 level tested if necessary).

• Zinc

Zinc is important for bone health. The RDA is 6.8 mg/day for women and 9.4 mg/day for men. The USDA suggests that 17% of women and 11% of men are not meeting these recommended daily intakes on zinc. (16)

Zinc from plant sources is harder for the body to break down and use because of phytates, which make the zinc less bioavailable. The Food and Nutrition Board recommends that vegetarians and vegans should consume 50% more zinc than the recommended daily amount. (15)

• Other bone building minerals

A dozen minerals are essential to support life-long bone strength. Assess your intake of the key bone-building minerals. While vegan and vegetarian diets may well be high in potassium, are you consuming enough bone-essential micro-nutrients minerals like zinc, manganese, copper, and boron?

Consider testing for your personal mineral adequacy with the Alkaline for Life Diet Starter Kit. Low pH readings suggest mineral inadequacy.

• Protein

Protein is another key nutrient in bone health. Low protein levels may increase the risk of fracture. One study showed that vegans and vegetarians in the lowest quartile of protein consumption were at a significantly increased risk of hip fracture when compared to those who ate adequate amounts. (15)

Another study looking only at wrist fractures showed that when vegetarians ate adequate amounts of protein, the risk of wrist fracture was reduced by 68%. The same study showed that vegetarians who did not consume enough plant protein were at a higher risk for wrist fracture. (17)

Consume adequate protein. At the Center for Better Bones, we suggest 50 to 70 g of protein for the average person with 1 g of protein per kilogram of body weight as optimal.

• Omega-3 fats

Vegetarians and vegans typically underconsume EPA and DHA, the Omega-3 fats that support bone health. In a vegetarian or vegan diet the main source of these fats (fish) is not consumed. The body can convert ALA (which comes from sources like flax, hemp, and chia) to EPA and DHA, however the conversion is limited. Therefore, ALA is not a significant source of EPA and DHA.

Research documents that those who consume omega-3 fats have a lower risk of hip fracture. Seaweed, algae, and algae oil with EPA/DHA supplements are good ways to obtain these essential fatty acids. An optimum omega-3 EPA/DHA intake is 2,000 to 3,000 mg/day.

• Last, but not least, consume adequate calories

Bone is very metabolically active tissue requiring a high energy intake to build and maintain bone. Being underweight and losing weight is generally associated with low bone density and increased fracture risk.

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