Vitamin B12 Necessary for Arterial Health

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The cardiovascular benefits of plant-based diets may be severely undermined by vitamin B12 deficiency.

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

This is not the only study to look at the arterial walls of those eating plant-based diets. This new study from China, for example, found that compared to omnivores, those that ate egg-free and meat-free diets had all the typical benefits of eating more plant-based: lower body mass index, blood pressure, triglycerides, total cholesterol, bad cholesterol; fewer free radicals; maybe better kidney function, better blood sugar control, etc. But, does all that translate to actual differences in their arteries? Yes. Indeed, the omnivores had comparatively thickened arterial linings—all of which suggests about a tripling in the probability of developing cardiovascular disease. They therefore “recommend that more vegetables should be eaten instead of meat,” and it’s “never too late” to improve one’s diet.

Having said that, if those on plant-based diets don’t get enough vitamin B12, levels of an artery-damaging compound called homocysteine can start to rise in the bloodstream, and may counteract some of the benefits of eating healthy. In this study from Taiwan, the arteries of vegetarians were just as stiff as those of the omnivores, and they had the same level of thickening in their carotid arteries—perhaps because of the elevated homocysteine levels in their blood.

“The negative findings of these studies should not be considered as evidence of neutral cardiovascular effects of vegetarianism, but do indicate an urgent need for modification of vegan diets through vitamin B12 fortification or supplements.” “[V]itamin B12 deficiency is a very serious problem, leading ultimately to anemia, neuropsychiatric disorders, irreversible nerve damage,” and these high levels of artery-damaging homocysteine in the blood. “Prudent vegans should include sources of vitamin B12 in their diets.”

One study of vegetarians whose B12 levels were really hurting even had thicker, more dysfunctional arteries than the omnivores. How do we know B12 was to blame? Well, when they were given B12 supplements, they got better. Their arterial lining started to shrink back, and the proper functioning of their arteries returned.

Without B12-fortified foods or B12 supplements, when omnivores are switched to a vegan diet, they develop vitamin B12 deficiency. Yes, it may take dropping down to around 150 picomoles per liter to develop classic signs of B12 deficiency—like the anemia, and our spinal cord rotting from the inside out. But, way before that, we may start getting increased risk of cognitive deficits and brain shrinkage, stroke, depression, and nerve and bone damage, as well as having our homocysteine shoot through the roof. And, that may “attenuate the beneficial effects of a vegetarian diet on cardiovascular health.” “The beneficial effects of vegetarian diets on [cholesterol and blood sugars] need to be advocated,” but, at the same time, “efforts to correct vitamin B12 deficiency in vegetarian diets can never be overestimated.”

Please consider volunteering to help out on the site.

Images thanks to Coolmikeol, Lisaclarke, Marcos Vasconcelos Photography, massdistraction and Rob Swatski via flickr. Thanks to Ellen Reid for her image-finding expertise, and Jeff Thomas for his Keynote help.

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

This is not the only study to look at the arterial walls of those eating plant-based diets. This new study from China, for example, found that compared to omnivores, those that ate egg-free and meat-free diets had all the typical benefits of eating more plant-based: lower body mass index, blood pressure, triglycerides, total cholesterol, bad cholesterol; fewer free radicals; maybe better kidney function, better blood sugar control, etc. But, does all that translate to actual differences in their arteries? Yes. Indeed, the omnivores had comparatively thickened arterial linings—all of which suggests about a tripling in the probability of developing cardiovascular disease. They therefore “recommend that more vegetables should be eaten instead of meat,” and it’s “never too late” to improve one’s diet.

Having said that, if those on plant-based diets don’t get enough vitamin B12, levels of an artery-damaging compound called homocysteine can start to rise in the bloodstream, and may counteract some of the benefits of eating healthy. In this study from Taiwan, the arteries of vegetarians were just as stiff as those of the omnivores, and they had the same level of thickening in their carotid arteries—perhaps because of the elevated homocysteine levels in their blood.

“The negative findings of these studies should not be considered as evidence of neutral cardiovascular effects of vegetarianism, but do indicate an urgent need for modification of vegan diets through vitamin B12 fortification or supplements.” “[V]itamin B12 deficiency is a very serious problem, leading ultimately to anemia, neuropsychiatric disorders, irreversible nerve damage,” and these high levels of artery-damaging homocysteine in the blood. “Prudent vegans should include sources of vitamin B12 in their diets.”

One study of vegetarians whose B12 levels were really hurting even had thicker, more dysfunctional arteries than the omnivores. How do we know B12 was to blame? Well, when they were given B12 supplements, they got better. Their arterial lining started to shrink back, and the proper functioning of their arteries returned.

Without B12-fortified foods or B12 supplements, when omnivores are switched to a vegan diet, they develop vitamin B12 deficiency. Yes, it may take dropping down to around 150 picomoles per liter to develop classic signs of B12 deficiency—like the anemia, and our spinal cord rotting from the inside out. But, way before that, we may start getting increased risk of cognitive deficits and brain shrinkage, stroke, depression, and nerve and bone damage, as well as having our homocysteine shoot through the roof. And, that may “attenuate the beneficial effects of a vegetarian diet on cardiovascular health.” “The beneficial effects of vegetarian diets on [cholesterol and blood sugars] need to be advocated,” but, at the same time, “efforts to correct vitamin B12 deficiency in vegetarian diets can never be overestimated.”

Please consider volunteering to help out on the site.

Images thanks to Coolmikeol, Lisaclarke, Marcos Vasconcelos Photography, massdistraction and Rob Swatski via flickr. Thanks to Ellen Reid for her image-finding expertise, and Jeff Thomas for his Keynote help.

Doctor's Note

Be sure to check out the “prequel” to this video: Arteries of Vegans vs. Runners.

I have dozens of other videos on B12. For a quick cut-to-the-chase, see my Q&A What is the best way to get vitamin B12? 

And, for further context, see my associated blog post Vegan B12 deficiency: putting it into perspective. Vitamin B12 supplementation with fortified foods or supplements is critical on a plant-based diet.

2019 Update:  My vitamin B12 recommendations have changed to reflect the latest science and labeling changes. If you’re relying on getting all your B12 from fortified foods, make sure you get at least one serving at each meal containing at least 190% of the Daily Value listed on the nutrition facts label (based on the new labeling mandated to start January 1, 2020–the target is 4.5 mcg three times a day). Probably easier to just follow my supplement recommendations instead, which have also changed: at least 50 micrograms of cyanocobalamin once a day or 2000 micrograms of cyanocobalamin once a week.

I put out some new B12 videos in 2020. Please see all of my newest videos on the topic page. 

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