Have you ever wondered if there’s a natural way to lower your high blood pressure, guard against Alzheimer's, lose weight, and feel better? Well as it turns out there is. Michael Greger, M.D. FACLM, founder of NutritionFacts.org, and author of the instant New York Times bestseller “How Not to Die” celebrates evidence-based nutrition to add years to our life and life to our years.

All About Vitamin B12: Part 2

More on that elusive and highly desirable vitamin B12.

This episode features audio from The Healthiest Food Sources of Vitamin B12, The Optimal Vitamin B12 Dosage for Kids, Pregnancy, and Seniors, and The Best Type of Vitamin B12: Cyanocobalamin or Methylcobalamin?. Visit the video pages for all sources and doctor’s notes related to this podcast.


Today, on the show – the mighty Vitamin B-12. Did you know B-12 is an essential nutrient that your body can’t make usably on its own; so, you need to get it from your diet or supplements. Today, we start with the best green-light sources of B-12.

A regular, reliable source of vitamin B12 is critical for anyone eating a plant-based diet––either vitamin B12 supplements or vitamin B12-fortified foods. I’ve talked about my B12 supplement recommendations: either 50 micrograms a day or once-a-week doses of 2,000 micrograms. I think that’s the simplest, cheapest way—taking it once a week. That’s how I do it. But if you don’t want to take supplements, you’d have to rely on B12-fortified foods––in which case you’d have to eat three separate servings of B12-fortified foods, each ideally containing at least 190 percent of the so-called “Daily Value” on the product’s nutrition facts label. How does that make any sense? And what’s the term “Daily Value” even mean? The term Daily Value is used to designate both the Daily Reference Values (DRVs) and Reference Daily Intakes (RDIs) that are based on the Recommended Daily Allowances, all to limit consumer confusion. See, aren’t you less confused now?

Anyway, the daily value of B12 was set at 6, but was recently changed to 2.4 in 2020, making it all the more confusing; and so, 190 percent of 2.4 is about 4.5. Plug that into the equation I detailed in the last video, and you get about 1.16 absorbed from each serving, times three times a day, and poof—there’s your 3.5 for the day.

Okay, so how much nutritional yeast would that be, a commonly B12-fortified food source? It depends on the brand. Going alphabetically, Bob’s Red Mill brand has 730 percent per quarter cup; so, you’d only need about four times less than that to make up a serving, so around one tablespoon. So, one tablespoon of this brand sprinkled on each meal and your B12 would be taken care of.

Bragg’s says it’s even more potent at 563 percent per tablespoon; so, just a teaspoon three times a day should suffice. Dr. Fuhrman’s brand is explicitly unfortified; and so, contains zero B12; so, that’s an important lesson. You can’t just assume nutritional yeast has B12. So, if you find it in the bulk section, you have no idea what it contains unless you actually see the package. Same with the Frontier Co-op brand: zero vitamin B12. KAL brand has 500 percent of the daily value of B12 per three rounded tablespoons; so, one rounded tablespoon should suffice as one of the servings. NOW brand has more, with two teaspoons sufficing. Red Star has 333 percent per one-and-a-half heaping tablespoons; so, a serving would be like one tablespoon; but note, only some of Red Star’s nutritional yeast varieties have any B12 at all. So, just remember to check the label. And finally, Trader Joe’s looks like 1.5 tablespoons could count as one serving. So, it looks like Bragg’s is the most potent currently available.

There are all sorts of other B12-fortified foods, from plant-based meats and milks to breakfast cereals and energy drinks, but are there any other green light sources––meaning plant foods from which nothing bad has been added, and nothing good has been taken away?

What about various algae-type products, like spirulina, which are advertised as natural vitamin B12 sources? Not only do they not actually contain B12 that’s useable for humans; it’s even worse than that. They may contain B12 analogues: look-alike molecules that can even block your absorption of real B12.

I was excited to see that there was an herbal tea with B12, but so little you’d have to quadruple bag it. If you didn’t want to take a pill, which again I think is really the best way, the easiest option would probably be LeafSide foods. I’ve always loved them because they center their ingredients around my Daily Dozen.

Unfortunately, people see them citing my science and think I have some sort of financial relationship, but of course I have no financial ties to any food company, drug company, supplements, kitchen gadgets—no personal financial ties with any commercial entity whatsoever, ever. Happy to voluntarily plug LeafSide, though, as their food has kept me from starving on the road on many occasions. They’re freeze-dried; so, they’re light and easy to travel with, and I just use my hotel room coffee maker to make hot water, and poof.

But anyway, each of their meals has 75 mcg of B12; so, one a day and you’d get all your B12 without having to take supplements—but, it’s only 100 percent green light if you specify you want the salt-free versions. They have no added salt/fat/sugar versions of all their products at no extra cost, but you have to specify that when you order.

Note you have to throw all these recommendations out the window for anyone over age 65, and go straight to high daily supplement doses, which I’ll cover in my next video, as well as my recommendations during pregnancy, breastfeeding, infancy, and childhood.

In our next story, we look at the optimal vitamin B-12 dosage for kids, pregnant women, and seniors.

Universal improvement of B12 status appears “to be a nutritional imperative with possibly profound beneficial effects,” particularly at the bookends of life—at old age and infancy. I’ve explained the rationale for my recommendations to take vitamin B12 supplements once a week or once a day, or alternately, eat sufficient daily B12-fortified foods. But for those over age 65, those guidelines go out the window. The recommendations change to everyone taking a high daily dose of 1,000 mcg every day.

Starting at age 50, everyone––meat-eaters and vegans alike––should be taking B12 supplements or eating B12-fortified foods. But over age 65, 50 a day may not do it. Even 100 a day doesn’t seem sufficient. Researchers investigated three doses, and found that most didn’t normalize their MMA until after the 1,000 microgram dose. (MMA suppression is a measure of B12 sufficiency.) But they just tested 25, 100, and 1,000. Maybe 250 or 500 would do it?

Researchers set out to find an adequate dose at that age, and it seems we need at least about 650 to 1,000 a day in most people, hence my 1,000-a-day recommendation after age 65.

Okay, what about the other end of the life cycle? The consequences of B12 deficiency and insufficiency can be devastating in infancy and childhood. And this is not just a problem for plant-based pregnancies. “Vitamin B-12 insufficiency during pregnancy is common even in nonvegetarian populations.” About a quarter of all pregnant women aren’t getting enough B12, and that number rises to nearly one in three by the third trimester. But, insufficiency isn’t as bad as frank deficiency, which can manifest in cases like cerebral atrophy, meaning brain shrinkage, in a “Vitamin B12-deficient Infant of a Vegetarian Mother.” Thankfully, even severe brain atrophy can be substantially reversed with B12 supplementation, but better not to become deficient in the first place.

The solution proposed by a group of French pediatricians is to recommend against raising vegan kids at all, since B12 supplementation is necessary. And they’re not alone. To vegan or not to vegan. In 2016, two professional organizations, the U.S. Academy of Nutrition and Dietetics and the German Nutrition Society, issued conflicting statements. The U.S. Academy said that even strictly plant-based diets are appropriate for all stages of the life cycle, whereas the German group echoed the French group, saying since you have to take B12, we can’t recommend a vegan diet for pregnant women, lactating women, infants, children, or adolescents. To confuse the matter further, the American Academy of Pediatrics appeared to have it both ways; in one place repeating the U.S. Academy’s position, while in another place it stated that vegan diets should not be recommended for children. But I think they’re just saying the same thing. Everyone agrees that a non-B12 supplemented plant-based diet is a bad idea—that’s part of what the U.S. Academy means by “well-planned.” Everyone eating plant-based, but especially pregnant and breastfeeding women, must ensure a regular, reliable source of vitamin B12, meaning B12 supplements or B12-fortified foods. But then you may be able to get the best of both worlds.

That’s why there are reviews with titles like this, Plant-based pregnancies: danger or panacea? Danger if you don’t take your B12, but “following a plant-[based] diet during pregnancy may be protective against the development of preeclampsia, pre-gravid obesity, and minimize the exposure to [DNA-damaging] agents.” It may also protect our newborns “from the onset of pediatric diseases, such as pediatric wheezing, diabetes, neural tube defects, orofacial clefts, and some pediatric tumors.” “Vegan pregnant women have a lower-than-average rate of cesarean section, less postpartum depression, and lower neonatal and maternal mortality, with no complications or negative outcomes that are higher than average.” In addition, a lower incidence of what used to be called toxemia, a potentially dangerous pregnancy complication known as preeclampsia. “Overall, plant-based diets seem to confer protection to both mothers and newborns” by not only “reducing the risk of several pregnancy-related issues” but decreasing the risk of childhood disease. “Children following plant-based diets might have a lower risk of developing obesity,” obviously are less exposed to drugs used in animal production, and have a favorable anti-inflammatory profile of cell-signaling factors. But again, everyone on a plant-based diet has to get enough B12.

Pregnant and breastfeeding women can just follow my 50 micrograms a day recommendation for nonpregnant adults, or 2,000 a week, though they suggest breaking up those doses into two halves to boost absorption. After infants are weaned, they can start on 5 micrograms a day; from ages 4 through 10, they can take half the adult dose of 25 a day; and then at age 11, they can take 50 a day or 2,000 a week. You don’t have to worry about taking too much. It’s water-soluble, and you’ll just end up with expensive pee.

In our last story, about liquid B-12 – we’ve got one word for you – cyanocobalamin. Say that five times fast.

I’ve talked about the optimal dose of vitamin B12 supplements for adults, as well as in childhood, pregnancy, and old age to prevent vitamin B12 deficiency. But what if you already have it? How much do you have to take to treat it?

Your doctor might want you to get vitamin B12 injections, but oral B12, even for those who can’t absorb it well, has long been considered one of medicine’s best kept secrets. It is now considered well-known that orally administered B12 supplements are “as effective in overcoming deficiency states as intramuscular” injections when you get up to taking 1,000 micrograms a day. How long do you have to take 1,000 a day for? It depends how low your levels start out.

Because B12 status in pregnancy is so critical, there is a suggestion that plant-based women get it checked throughout pregnancy and to adjust supplementation as necessary. This is how much you should take if you’re low. Note the recommendations for pregnant and breast-feeding women are the same as everyone else over the age of 10. So, if you’re a teen or adult diagnosed with vitamin B12 deficiency, you’d take 1,000 micrograms a day for one to four months, depending on how low you start out, before going back to a regular maintenance dose of 50 a day or 2,000 a week, with toddlers and small children taking smaller doses.

There are two main types on the market, though: methylcobalamin, marketed as methyl B12, and cyanocobalamin, typically marketed as just vitamin B12. Methyl is more expensive so it must be better, right? Wrong. Cyanocobalamin “is the most used form due to its high stability.” See, “methylcobalamin is less stable than cyanocobalamin, and it is particularly susceptible to photodecomposition,” meaning destruction from being exposed to light. “There is no advantage to using the light-sensitive forms of cobalamin, such as methyl B12…, instead of the stable cyano…forms, which are readily converted in the body” into the type you need, where you need it.

The one major exception may be kidney failure, though. Methylcobalamin may be better for those with impaired kidney function. It’s been speculated that oral methylcobalamin or injected hydroxycobalamin may also be preferable in smokers, though it has yet to be confirmed. Because methylcobalamin is less stable, you’d probably want to take much higher doses. So, for example, in those with kidney failure you’d be taking one to two thousand micrograms a day, compared to just 50 micrograms of cyanocobalamin in someone with normal kidney function. Another reason to use the cyanocobalamin as opposed to the more expensive kinds is that it has a track record of safety and efficacy, whereas for example, in one study even up to 2,000 micrograms a day of methylcobalamin wasn’t enough to correct vitamin B12 deficiency in one of three vegans they tested it on.

The bottom line is that so-called coenzyme forms of B12, like methyl B12 and adenyl B12 (also known as adenosyl B12), “are not likely to be superior to cyanocobalamin,” which is more stable. Cyanocobalamin “appears to be best suited for oral supplementation,” which is why I specify its use in my recommendations.

Note, I also recommend ideally taking it separately as a chewable, sublingual, or liquid supplement. Why can’t you just get it as part of a multivitamin or something? Because various vitamins and minerals mixed into the same pill can “destroy” active B12, forming B12 analogues, B12-look-alikes that not only can our body not use, but the analogues can be “potentially harmful” because they can inhibit the transport of what little B12 is left. That’s why using multivitamins can even be counterproductive for the supplementation of vitamin B12. And this isn’t just in theory. There was a tragic case of severe vitamin B12 deficiency in an infant born to a vegan mother who thought she was doing everything right taking a multivitamin that contained B12, though it may have also just been inadequate dosing.

Why chewable or sublingual? Absorption is boosted when the B12 mixes with saliva, since you secrete a B12 binding protein from your salivary glands that helps transport B12 safely through the digestive tract. Having people chew a tablet of B12 and their B12 levels go up ten times more than just simply swallowing the exact same pill. Check it out. Vegans boosted out of deficiency chewing a B12 supplement, but nothing in those who just swallowed it whole. Maybe they had some sort of absorption problem or something? No, because then if you tell them to start chewing it instead of swallowing it whole, their levels shoot right up as well.

In my latest book How Not to Diet, I suggest a third option to B12-fortified foods and supplements—brushing twice daily with a B12-fortified toothpaste—specifically this brand, which was put to the test in two double-blinded, randomized, placebo-controlled studies. “Participants were instructed to use the toothpaste two times a day for two minutes at a time,” and indeed, it was able to correct the markers of B12 insufficiency in the blood of vegans and among the elderly, but that was on average. Unfortunately, it didn’t work in every last person, which is why it’s not included in my recommendations. Though, look, if you get your levels tested before and after brushing for a few months and they go up, you could presumably stick with it.

In summary, vitamin B12 deficiency is not to be messed around with, with the potential to cause a wide range of disorders of the gut, blood, brain, and nervous system. “With the ever-increasing demand for cleanliness in our food chain”—which is a very good thing—”it is of special importance that we secure” a regular reliable source, and the safest, cheapest, healthiest source is B12 supplements or green light B12-fortified foods.

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