Many studies show that vegetarians have a significantly reduced risk for certain cancers (BMC Med, 2022;20(1):73) and heart attacks (Eur Heart J, 2021;42(12):1136-43), but there is some controversy on the effects of vegetarian diets on bone fractures. Vegetarians may be at increased risk for osteoporosis and bone fractures (BMC Med, 2020;18(1):353; BMC Med, 2022;20(1):275), although some studies show no increased risk (AMA Netw Open, 2023;6(3): e234714).
The most inclusive study to date on the effects of a vegetarian diet on risk for bone fractures followed 413,914 UK women for an average of 12.5 years, and 3503 suffered hip fractures. Vegetarians developed 50 percent more hip fractures than occasional meat eaters or fish eaters (BMC Medicine, July 27, 2023;21(278)). That comes out to 3.2 more hip fractures per 1000 people over 10 years. This could partially be explained by the fact that vegetarians weighed significantly less than meat eaters. Also, compared to meat eaters, vegetarians had slightly lower:
• muscle and bone size
• blood levels of vitamin D
• IGF-1, a hormone that enhances muscle growth
However, meat eaters also had an increased history of diabetes, heart attacks and cancer. In this study, vegetarians had the same heel bone density and hand grip strength as meat eaters. There was no significant difference in hand grip strength between vegetarians and meat eaters, but some previous studies have reported slightly lower bone strength and muscle strength (Am J Clin Nutr, 2018;107(6):909-20; Nutr Rev, 2019;77(1):1-18).
This study found that vegetarians took in less dietary protein, iron, iodine, niacin, selenium, vitamin B12, and vitamin D than other diet groups. Vegetarians were 17 percent less likely to meet protein recommendations than meat eaters. Inadequate protein intake has been associated with increased hip fracture risk (Clin Nutr, 2022;41(12):2825-32).
The EPIC-Oxford study followed 29,380 meat eaters, 8,037 fish eaters, 15,499 vegetarians, and 1,982 vegans for an average of 17.6 years, and found a marked increase in fractures in all the non-meat-eater groups with the most fractures of all in the vegans (BMC Medicine, Dec 2020;18(353)). Overall, compared to meat eaters, vegans had higher risks of total, hip, leg, and vertebral fractures, while fish eaters and vegetarians had higher risk of hip fractures. Other studies show that vegetarians have lower bone densities than meat eaters (Am J Clin Nutr, 2018;107:909-20; Public Health Nutr, 2008;11:564-72), possibly because they weigh less and take in less calcium (Nutr Res, 2016;36:464-77) and protein (Nutrients, 2019;11:1-18).
Be Sure Your Diet Contains Adequate Protein and Vitamin B12
Vegan diets are recommended by many researchers and doctors because they may help to prevent heart attacks and some cancers, but a diet that excludes all animal products can increase risk for deficiencies in dietary protein and vitamin B12. Older people, in particular, can be harmed by vegan diets because these deficiencies may increase their chances of suffering from muscle weakness, osteoporosis, lack of coordination, falls and broken bones (Advances in Nutrition, Feb 2, 2022). All people lose muscle, bone and coordination as they age, and after age 50, people can be expected to lose about 1-2 percent of the size of their muscles each year (Am J Clin Nutr, 2002;76(2):473-81).
You Can Get All The Protein You Need From Plants
You need 21 amino acids, the protein building blocks that make up the muscles and other cells in your body, and nine of these amino acids must be taken in from the food that you eat (the “essential amino acids”). Meats and other foods from animals contain all of these essential amino acids, but plants that are used for food do not contain all nine. For example, beans do not contain methionine, but corn does, and corn does not have lysine or tryptophan, which are found in beans, so if you eat both corn and beans, you can provide your body with all nine essential amino acids. You do not need to eat the corn and beans at the same meal; just eat a variety of these foods over the week. Plant protein sources include nuts and seeds, non-dairy milks, beans, peas, lentils, soy foods such as tofu and tempeh, whole grains, broccoli, spinach, leafy greens and more.
Almost No Vitamin B12 In Plants
Vitamin B12 deficiency in North America occurs in about 20 percent of people over age 60 (BMJ, Sept 4, 2014;349:g5226). A deficiency of vitamin B12 can lead to anemia, fatigue, muscle weakness, intestinal problems, nerve damage, dementia and mood disturbances. Vitamin B12 is found only in animal food sources such as meat, fish, chicken and eggs. The recommended daily amount of vitamin B12 for adults is 2.4 micrograms. However, the absorption of vitamin B12 is very low and requires both stomach acidity and a chemical called intrinsic factor. With aging, a person loses stomach acid, so the incidence of B12 deficiency increases significantly with aging, even in some people who take B12 supplements. I recommend having your blood level of B12 checked regularly, and if it is below 250 picograms per milliliter (pg/mL) or 184 picomoles per liter (pmol/L), check with your doctor about correcting the deficiency. See Vitamin B12: One Supplement You May Need
Fighting Loss of Bones with Resistance Exercise
I believe that everyone should do some form of resistance exercises to help protect their bones and muscles. If you are not already doing strength-training exercise, first check with your doctor to make sure you do not have any condition that may be harmed by exercise. Then see Resistance Exercise Becomes Even More Important As You Age
Strength Training to Help Prevent and Treat Osteoporosis
Resistance Exercise You Can Do at Home
My Recommendations
• Vegetarian and vegan diets are associated with decreased risk for heart attacks and certain cancers, but they are also associated with increased risk for nerve damage and loss of muscles and bones. I do not think it is necessary to avoid all animal products.
• I recommend a plant-based diet that includes salmon, trout, sardines and other small fish, because they contain omega-3 fatty acids and do not contain significant amounts of heavy metals. Fish contain lots of B12 and all the protein building blocks.
• I recommend doing some form of resistance exercise; check with your doctor. You can help to slow bone and muscle loss by performing resistance exercises and eating an adequate amount of protein-rich food (Nutrients, Feb 2018;10(2):180).
