From lower food costs to less environmental impact and some very significant heart health advantages, there are plenty of potential benefits to eating a plant-based diet. But as far as bone health goes, new research suggests that a meatless meal plan might not be the best strategy.
The UK-based study involved more than 26,000 women ages 35 to 69, who were classified as meat eaters (if they had five or more servings of meat per week), occasional meat eaters (if they had less than five servings), pescatarian (meaning they ate fish, but not meat), or vegetarian (that’s no meat at all and no fish either). The results were based on a food frequency questionnaire, completed between 1995 and 1998, and included a follow-up time of about 22 years. Incidents of hip fractures were recorded via hospital statistics up to March 2019.
The results showed that vegetarians, but not the occasional meat-eater or pescatarian, were at greatest risk of hip fractures—they had about 33% higher risk—compared to regular meat eaters.
In terms of nutrient intake, the researchers also found that the regular meat-eaters had the highest protein, vitamin D, and vitamin B12 intake, with vegetarians having the lowest intake of those three nutrients. The vegetarian women also tended to have lower body mass index (BMI) levels, which could have played a role in the fracture rates (the study authors call out the “protective roles of bone mass, fat mass, and muscle mass, which have each been inversely associated with hip fracture risk”), but even after adjusting for BMI’s potential role, they found a link between a vegetarian diet and fracture risk. This is likely due to a few common nutrient shortfalls.
Today, roughly one in every 20 Americans follows a vegetarian or vegan diet, according to scientific estimates. This new research doesn’t mean you need to ditch a vegetarian diet if you want to maintain your bone strength. You can still protect your joints by getting enough of the right nutrients. And by the way, simply being physically active can help ensure strong bones.
Here’s what medical and nutrition experts tell Bicycling you need to know to help yourself stay fracture-free and meat-free throughout your lifespan.
Why Vegetarians May Be at Greater Risk of Hip Fractures
The researchers of the BMC Medicine study suggest that, in addition to BMIs of vegetarians potentially contributing to increased hip fracture risk, lower intake of nutrients important to bone health could also be to blame.
In the study, they found vegetarians had lower intake of protein, vitamin D, and vitamin B12—but similar intake of calcium. While the researchers say more studies are needed to confirm the nutrient disadvantages of following a vegetarian diet, particularly when it comes to hip fracture risk, they do point to vitamin D in particular as a potential risk factor.
Other experts agree and point to nutrient intakes leading to these risk factors for decreased bone health.
“Vegetarians typically have a lower protein intake than meat-eaters, as plant-based protein options do not contain as much protein per gram as chicken, fish, and other cuts of meat,” says Kevin R. Stone, M.D., an orthopedic surgeon at The Stone Clinic in San Francisco.
“Protein helps repair, build, and give strength to our muscles, bones, and even skin. We have to consume protein from food, and without enough daily protein you may lose strength in all these areas of your body, which overtime could lead to a [higher risk of] fracture,” explains Roxana Ehsani, R.D., C.S.S.D., a Miami-based board certified sports dietitian and a national media spokesperson for the Academy of Nutrition and Dietetics.
Due to the caloric and muscular demands of exercise, athletes in particular would benefit from more protein than their less active peers. The general population should aim for 0.8 grams of protein per kilogram of body weight (translation: about 65 grams of protein per day for a 180-pound person). For an athlete, the American College of Sports Medicine recommends 1.2 to 1.7 grams of protein per kilogram (98 to 139 grams of protein per day for a 180-pound person) for optimal muscle growth, repair, and maintenance during the between-workout recovery process.
Other Nutrients That Might Influence Bone Health
Stone says fractures are most often related to other nutrient deficiencies. Those who eat a plant-based diet are more likely than their animal product-consuming peers to fall short in these bone-bolstering vitamins and minerals:
Omega-3 fatty acids
Vitamin D, zinc, vitamin B12 and calcium are especially important, according to Lauren Ranley, M.S., R.D., a Norfolk, Massachusetts-based dietitian. And your needs might change based on not only the type of diet you follow, but also how old you are. “Some of these nutrients we may need in higher amounts as we get older,” Ehsani says, since seniors lose muscle mass at a quicker clip than when they were younger. “That means a person may be meeting the needs earlier in life, but then fall short as they age.”
Regardless of the number of candles you blew out on your last birthday cake, there’s one sure way to tell if you’re deficient in any of these vitamins and minerals: a blood test.
If the blood tests prove you’re falling short then you can aim to score of these nutrients via your diet or get them from supplements. (The National Center for Complementary and Integrative Health offers tips on how to choose a safe supplement if you, and your doctor, decide that’s the best approach.)
Calcium and vitamin D are an especially important duo, Stone explains. Calcium is the major component of bone, and a diet high in calcium helps us retain bone mass and skeletal strength, and vitamin D is essential for absorption of calcium.
“Calcium is responsible for the structural integrity of the bones and teeth, with 99 percent of all calcium being stored in bones, and you’ll score calcium in the highest doses in dairy and seafood,” Ranley says. “There are few foods that naturally provide us with vitamin D, except for some oily fish.”
“While zinc can be found in beans and grains, when it comes from these vegetarian sources, it’s not as easily absorbed by the body,” Ranley says, as it is from animal sources of zinc such as oysters, beef, pork, and turkey.
Low levels of vitamin B12 have also been associated with lower bone density, research suggests, and with lower levels of markers related to bone formation. Both of these details could make those bones at risk for fracture. And B12 plays a role in the synthesis of all of our body’s DNA, including the genes in bone cells and red blood cells (which are created in the bone marrow).
Here’s how much adults need of these MVP minerals for bone strength, per the National Institutes of Health Office of Dietary Supplements:
Calcium: 1,000 mg for males 19 and older and females 19 to 50; 1,200 mg for females 51 and older
Vitamin D: 600 IU/15 mcg for males and females 19 to 70; 800 IU/20 mcg for males and females 71 and older
Zinc: 11 mg for males; 8 mg for females
Vitamin B12: 2.3 mcg for adults
14 of the Best Plant-Based Foods for Stronger Bones
Stock up on these vegetarian and vegan ingredients to stoke your diet with two or more of these bone-building nutrients in each bite. (Nutrition information based on USDA and NIH data.)
Per 4-ounce (½ cup) serving: 7 g protein, 138 mg calcium
Per ½ cup cooked: 15.5 g protein, 131 mg calcium
Per 1 cup: 7 g protein, 340 mg calcium, 114 IU vitamin D, 2.6 mcg vitamin B12
Per 1 cup raw: 34 g protein, 184 mg calcium, 0.1 mcg vitamin B12
Per ½ cup boiled spinach: 3 g protein, 123 mg calcium
Per 1 cup of 1%: 28 g protein, 138 mg calcium
Per 1 cup plain low-fat: 13 g protein, 415 mg calcium, 1 mcg vitamin B12
Per ½ cup canned and drained: 8 g protein, 54 mg calcium
Per 1 large: 6 g protein, 44 IU vitamin D, 0.6 mg zinc
Fortified breakfast cereals and oats
Per serving (varies by product): 2.8 mg zinc, 0.6 mcg vitamin B12
Per 1 ounce roasted: 8.5 g protein, 2.2 mg zinc
Per ½ cup boiled: 9 g protein, 1.3 mg zinc
Per 2 tablespoons (varies by product): 8 g protein, 15 mcg vitamin B12
Per 1 cup of 1%: 8 g protein, 310 mg calcium, 1.5 mcg vitamin B12, 1 mg zinc
The Bottom Line on Vegetarians and Bone Health
Because plant-based diets can be lower in important nutrients for bone health—protein, vitamin D, calcium, zinc, vitamin B12—than animal-inclusive meal plans, vegetarians can be at increased risk for hip fractures, research suggests. That doesn’t mean you have to ditch your meat-free meal plan, though. While adding fish or even just the occasional meaty bite to your menu can help to protect against deficiencies in these nutrients, making sure you get enough of the above foods can also ensure your bones stay healthy.
Beyond infusing your menu with foods that support bone health, aim to keep up with those outdoor bike rides and add some weight-bearing exercise (such as running and strength training) to your agenda. Since the sun is a major source of vitamin D and your bones need to work against gravity to stay strong, these lifestyle factors can also support your skeleton, Stone says.
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