Plant Eaters Listen Up: Are You Getting Enough B12?

A carefully planned plant-based diet has been shown to have a number of health benefits. But B12 is one vitamin that is difficult to obtain without including any animal products in your diet.

April 11, 2016
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Plant-based diets are beneficial to your health. They lower your risk of diabetes, heart disease, and cancer, and can even help with weight loss. But one nutrient that must come from animal sources is B12. Vegans especially are more likely to be deficient in this critical B vitamin, which can lead to symptoms such as weakness, fatigue, constipation, and vision loss, and mental problems that include memory loss and depression.

What’s B12 anyway?

We humans need B12 to make red blood cells and for maintenance of the nervous system, synthesis of DNA, and for the basic smooth functioning of the body’s systems. Specifically, our nerves are covered in a sheath called myelin; over time a B12 deficiency can cause a breakdown in this covering, which can cause permanent (yes permanent!) damage to the nervous system.

B12 is also crucial to a child’s growth and development. So if you’re pregnant or breastfeeding, it’s especially important to ensure that you’re not deficient. Deficiencies can cause anemia, fatigue, neuropathy, stroke, degeneration of the nervous system, and poor resistance to infection.

How do I know if I’m deficient?

Unfortunately, deficiencies are sneaky and can catch up to us with little warning. Strict vegans who don’t eat any animal products are at risk, as are people with digestive disorders like Crohn’s and celiac disease who have difficulty with nutrient absorption. The inability to properly absorb B12 is actually much more common than a dietary deficiency. Those who often take medicines like Zantac and Nexium for stomach acid are also at risk.

You may want to get your levels checked if you fall into any of the categories above or if you’re over the age of 50. The average adult needs 2.4 micrograms daily to avoid deficiency.

What foods contain B12?

Cooked clams are the best source of B12, with 84 mg in 3 ounces. Beef liver, mackerel, crab, salmon, fish eggs, tuna, sardines, grass-fed beef, milk, raw cheese, eggs—as well as bran cereal and tofu that’s fortified with B12—are also good sources.

Although some have claimed that algae like spirulina contain B12, further analysis has shown that this is not the case. Instead, algae actually contain similar B12 compounds that are not absorbable to humans.

A Vegan Deficiency

Vegans are at a real risk of being deficient in B12 because they eat very few food sources that contain the nutrient. In fact, famous vegan cookbook author and television chef Christina Pirello of Christina Cooks spoke candidly about how a B12 deficiency likely partially caused her brain aneurysm in 1998. Pirello, who is also a registered nutritionist, claims that the fact that she had avoided animal products for a decade likely contributed to her serious health scare (along with some hereditary health issues). Today Pirello recommends getting a blood test to check levels and supplementing B12 in your diet if necessary. When you don’t get enough in your diet it usually takes about five years for symptoms of a deficiency to crop up.

Should vegans supplement B12?

As Pirello says, if you think you’re deficient, talk to your doctor about blood tests. But according to the Vegan Society, you can get enough B12 in a vegan diet by eating foods that are fortified with B12—such as tofu, cereal, and plant-based milks—at least three times per day. Yeast extracts like agar, vegemite, and nutritional yeast, which are often used in vegetarian recipes, are also good sources of B12.

But if you do want to supplement, you can take a daily 10 mg supplement or a weekly 2,000 mg supplement. B12 is best absorbed in small amounts, although it is water soluble so you can’t overdo it like you can with fat-soluble vitamins like vitamin D. Other herbivorous animals get B12 from bacteria in their own digestive system, but humans aren’t able to do this.

A carefully planned plant-based diet has been shown to have a number of health benefits. But B12 is one vitamin that is difficult to obtain without including any animal products in your diet. In some cases, you may be getting enough in your diet, but your body’s inability to absorb the nutrient may be causing a deficiency. Either way, if you’re feeling some of the sneaky symptoms listed above or you’re in a vulnerable group, consider getting a blood test and then talking to your doctor about supplementation.

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