A study from the Netherlands suggests that vegetarian and vegan diets may not be preferred for older adults because they are often deficient in protein, and that can increase the rate of muscle loss with aging (Advances in Nutrition, May 2022;13(3):712-725). This muscle loss increases risk for falls, heart attacks, heart failure and premature death (The Lancet, Feb 2, 2022;44:101264).
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). Up to 50 percent of older adults suffer from significant loss of muscle called sarcopenia (Nutrients, May, 2020;12(5):1293). Many older people favor vegetarian, vegan or near-vegetarian diets because animal sources of protein (meat, dairy, eggs) have been associated with increased risk for heart attacks and premature death (Critical Reviews in Food Science and Nutrition, July 21, 2021). With aging, these people may not meet their needs for protein because they eat less food and less protein, and absorb less protein from what they have eaten (J Am Geriatr Soc, 2010;58:2129-2134). The combination of decreased protein intake and decreased physical activity lead to a very high incidence of sarcopenia. Increasing protein intake and exercising can markedly slow this loss of muscle, prevent disease and prolong lives (Nutrients, Jan 2022;14(1):52).
One in three older adults don’t eat enough protein to maintain muscle size and strength (Contemp Clin Trials, 2017 Jul; 58: 86-93). In addition to avoiding animal sources of protein, older people may not get enough protein because of:
• decreased appetite
• dental disease or loss of teeth
• decreased senses of taste or smell
• difficulty swallowing
• limited finances
Older people who ate the most protein were 30 percent less likely than those who ate the least protein to be incapacitated by loss of muscle strength and coordination (The Journals of Gerontology, Jan, 2020;75(1):123-130). Older people who ate the least protein were twice as likely to have difficulty walking or climbing steps as those who ate the most (J of the American Geriatrics Soc, Jan 2019;67(1):50-56).
Vegetarians Are at Increased Risk for Broken Bones
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 hip, leg, and vertebral fractures, while fish eaters and vegetarians had higher risk of hip fractures. Other studies show that vegetarians have lower bone density 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).
Differences in Protein from Meat or Plants
You can meet your needs for protein by eating only foods that come from plants, but you have to know how to do it. You can get protein in tree nuts and peanuts, seeds, grains, legumes, tofu, soy milk and other soy products. Vegetarians need to be sure they are getting enough “complete proteins.” A complete protein source is one that contains all 21 amino acids. You need 21 amino acids, the protein building blocks that make up the muscles, 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, so if you eat corn together with beans, you can provide your body with all nine essential amino acids. (Corn does not have lysine or tryptophan, which are found in beans). Vegetarians who eat little or no animal sources of protein need to take in a wide variety of plants to provide their bodies with enough protein to maintain muscle size and strength.
Lack of B12 Can Damage Your Brain and Nerves
In addition to meeting protein needs, vegetarians need to be sure they are getting enough vitamin B12, which is not found 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 and chicken. 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 tested, and if it is low, check with your doctor about correcting the deficiency.
• Vegetarian and vegan diets are associated with decreased risk for heart attacks and certain cancers, but they are also associated with increased risk for loss of muscle tissue and bones, and for nerve damage. The older you become, the more likely the plant-based diet is to cause protein and B12 deficiencies.
• 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 complete proteins and vitamin B12.
• I recommend that everyone who is healthy do some form of resistance exercise to strengthen their bones and muscles. Check with your doctor. You can help to slow muscle loss by performing resistance exercises and eating an adequate amount of protein-rich foods (Nutrients, Feb 2018;10(2):180).
Dr. Gabe Mirkin is a Villager. Learn more at www.drmirkin.com