2023.01 Plant Based Treasure Valley
Source: NutritionFacts.org
https://nutritionfacts.org/video/vitamin-d-may-explain-higher-bone-fracture-risk-in-vegans/
Dr. Greger noted in his previous video, “Do Vegans Have Lower Bone Mineral Density?”, that vegetarians had a slightly lower bone mineral density in their spines.
The difference was basically within the margin of error for the test, noting if the bone quality really is compromised, it could lead to collapsed vertebrae and increased spinal fracture risk, but there has been no evidence for this.
The incidence of vertebral fracture was ascertained in older women who had been vegan for 34 years on average.
Although the vegans had a higher prevalence of vitamin D deficiency, and lower dietary calcium intake overall, the two factors were not associated with bone loss. In fact, the annual loss in bone mineral density in the hips of vegans was less than half that of the meat-eaters, though the difference did not reach statistical significance.
Vegetarian women had not been found to be at higher risk of any kind of fractures, including wrist fractures, in this case, though among vegetarians, those who consumed the least vegetable protein intake were at the highest risk for fracture.
Those who ate beans every day, or nuts, or something like veggie burgers, only had a third of the wrist fractures compared to vegetarians who only ate beans or other higher protein foods less than three times a week.
Dr Greger reported that those who consume a vegan or vegetarian diet may be at increased risk of fracture unless an adequate quantity and variety of foods high in protein (such as whole grains, nuts, and legumes such as beans, split peas, chickpeas, or lentils) are in the diet.
(The Daily Dozen app recommends eating whole grains and legumes every day.)
Hip fractures. Those eating legumes like beans every day reduced their risk of hip fracture by more than 60 percent, compared to 40 percent lower risk from meat protein, with plant-based meats coming in between, with about 50 percent lower risk of hip fracture.
The bottom-line on plant-based diets and bone health, according to this 2020 review, indicates that theoretically, a long-term plant-based diet may reduce the risk of osteoporosis, (but that has yet to be demonstrated).
What we do know is that plant-based diets, when ensuring adequate calcium and vitamin D levels, don’t appear to have any detrimental effects on bone health. But this was published in August 2020.
In November 2020, the 12-year follow-up to the study that Dr Greger discussed in his previous video, on comparative fracture risk in vegetarians vs. non-vegetarians, was published, finding that non-meat eaters, especially vegans, had higher risks of total bone fractures, including at sites associated with osteoporosis such as hip fractures. It translates to about 20 more cases in vegans for every 1000 people over 10 years.
So, if indeed this is cause-and-effect, eating vegan there would be an annual 1 in 500 chance of having a bone fracture that you otherwise might not have had.
The question was posed: Was it because they weren’t eating enough beans? Apparently not, since vegans getting more protein still apparently had higher risk.
Dr Greger posed: Could the higher fracture rate be due to people not getting enough calcium? Apparently not, since vegans getting more calcium still apparently had higher risk.
What about bone and vitamin B12? The EPIC-Oxford study studied 30,000 British vegans. More than half the vegans in the study were B12-deficient because they weren’t adequately supplementing with B12 or B12-fortified foods. B-12 deficiency can lead to high homocysteine levels, which not only increases stroke risk, but may increase the activity of bone-eating cells.
High serum homocysteine may be regarded as a factor that can reduce both bone mass and bone quality. Homocysteine-lowering treatment failed to reduce the risk of bone fracture. So, in the end, the effect of B12 deficiency in bone health remains to be established.
How can the higher fracture rates found among vegans be explained? The investigators conclude that their findings suggest that bone health in vegans requires further research, but there were some clues.
The elevated fracture risk, both for total fractures and for hip fractures specifically, was only significant for those under a BMI of 22.5, (under about 130 pounds for a woman of average height). So, part of the problem is that vegans tend to be so slender on average.
Why are overweight and obese individuals protected from fractures? They have cushioning during a fall. There’s more of a cushion on your hips. Also, there’s an enzyme in fatty tissue that churns out estrogen, which is why women increase their breast cancer risk a percentage point for every pound they gain in adulthood. But estrogen can also have a bone-preserving effect. Overweight and obese individuals also may have stronger bones just from increased weight-bearing.
Dr Greger suggests that you can get the best of both worlds by consuming soy foods, preventing bone loss while at the same time being associated with lessening breast cancer risk for both estrogen receptor positive tumors and estrogen receptor negative tumors. In summary, the risk differences they saw between vegans and meat eaters were likely at least partially due to differences in BMI.
The EPIC-Oxford studies (of 30,000 vegans) took place over a period of 5 years and indicated that low Vitamin D may be a factor in fractures.
The sun’s rays are at such an angle during the winter months that the vitamin D levels among British vegans in the wintertime dropped down to suboptimal levels. Ideally, Dr Greger states, we should be up around 75 nanomoles per liter or 30 nanograms per milliliter, depending on what units you’re using, which the vegans nail in the summer. It is the sunshine vitamin, after all. But in the winter, if vegans aren’t supplementing Vitamin D, their vitamin D levels may drop too low.
Randomized controlled trials show that increasing vitamin D alone doesn’t seem to reduce fracture rates, but boosting people’s vitamin D and calcium at the same time does. Dr Greger states: “Perhaps it was a combination of the relatively low vitamin D and calcium intakes among the vegans that led to their higher fracture rates”.