Plant-based Diets: What the Research Says

Have you cut back on how much meat you eat? Are you considering a more plant-based diet?

If so, you’re part of a worldwide trend. People in many countries are interested in diets that skip — or at least scale back — meat and other animal products. Not only are Americans buying more meat alternative products, but even countries like Brazil and Argentina (both famous for beef) are joining a boom in plant-based eating that’s been on the rise in recent years.

The reasons for rethinking a meat-centric diet are many, including environmental and animal welfare concerns, as well as better health. An August 2019 study in the Journal of the American Heart Association found plant-based diets are linked to a lower risk of heart disease among middle-aged adults, and studies have linked the Mediterranean diet, which emphasizes plant foods and only a small amount of meat, to a lower risk of heart disease, diabetes and cancer. The Mediterranean diet also is associated with a slower rate of mental decline and a reduced risk of cognitive impairment in older adults, according to research studies.

But is a completely meat-free diet really best as you grow older?

A November 2020 British study, published in the journal BMC Medicine, suggests a possible drawback to consider: Compared with meat eaters, vegans and vegetarians may be at a higher risk for bone fractures, especially hip fractures.

In an analysis of more than 17 years of data from nearly 55,000 men and women enrolled in the long-running EPIC-Oxford study, researchers found that compared with meat eaters, vegans — who don’t eat meat, fish, dairy or eggs — may face a 43 percent higher risk for bone fractures.

Vegans, along with vegetarians (who eat dairy and eggs but not meat or fish) and pescatarians (who eat fish but not meat), were also at a higher risk for hip fractures. Vegans were at the highest risk, some “2.3 times higher than in people who ate meat, equivalent to 15 more cases per 1,000 people over 10 years,” possibly because “low intakes of calcium and protein have been linked to poorer bone health,” lead author Tammy Tong, a nutritional epidemiologist at the University of Oxford, said in a statement.

But hold on — this doesn’t mean you can justify eating a double bacon cheeseburger to help your bones. Here are some things to know about the study:

• Researchers had no data on whether those in the study took calcium supplements, or about the causes of the bone fractures — such as osteoporosis as opposed to accidents.
• Vegans and vegetarians tend to weigh less and low body mass has been associated with higher fracture risk, possibly because of less cushioning during a fall or low bone mineral density that can cause weaker bones. 
• Non-meat eaters in the study had, on average, a lower amount of calcium and protein in their diet, which are important for bone health. Calcium intake was particularly low among vegans because they do not consume dairy products, a major source of dietary calcium.
• People in the study were predominantly white Europeans, meaning results may not apply generally to other populations.

Despite this, a vegetarian diet “actually offers many advantages to bone health,” nutritional epidemiologist Katherine Tucker, director of the Center for Population Health at the University of Massachusetts Lowell, said in an email. The emphasis on fruits and vegetables, which are rich sources of B and C vitamins and minerals like potassium and magnesium, are important for strong bones.

But bone is a complex structure that requires a balance of nutrients — notably protein, calcium and vitamin B12 — to remain strong, especially as people age, Tucker said. To maintain bone health, vegan and vegetarian diets require close attention to ensure the body gets enough of these nutrients.

For example, the calcium in dairy products like cheese and yogurt is more easily absorbed by the body than the calcium in many vegetables. The calcium in green leafy vegetables is partially blocked by two naturally occurring compounds called oxalate and phytate. For vegans to get enough calcium to be absorbed by their bones, they may need to eat more of certain kinds of vegetables or the right balance, Tucker said.

Vegans can also bolster their bone-strengthening calcium, protein and B12 levels with plant-based foods like tofu, enriched cereal and soy milk or with supplements.

“The bottom line is dietary quality and balance to ensure that all nutrient requirements are met,” Tucker said.

What you should know:

If you’re interested in more plant-based eating while still protecting your bone health, here are some tips from nutrition experts:

• Try the Mediterranean diet. Dietitian Lauri Wright, an associate professor at the University of North Florida and a spokeswoman for the Academy of Nutrition and Dietetics, said in an email that the Mediterranean diet is one of the most healthful diets, including for brain health. And because it includes low amounts of fish and lean meat, it may be easier to fulfill the nutrient requirements for strong bones.
  
• Go meatless one night a week. For those trying to switch to more plant-based eating, try a meatless dinner once a week. Some suggestions: a plant-based burger on a multigrain bun or alternative-meat crumbles (similar to ground beef) in a hearty sauce over pasta. Or try these Butternut Squash & Black Bean Tostadas.
• Get calcium from a variety of sources. Bone-strengthening calcium is in both plant-based and animal foods. These include dairy products, tofu, calcium-fortified soy milk and orange juice, calcium-fortified breakfast cereals and waffles, and canned salmon with bones, according to nutrition experts with the National Institutes of Health.