How much B could B12 be, if B12 could be 12?

Dear Doctor Ninja,

I recently had my annual physical where I told my physician about my endless battle with canker sores. To figure out what was going on we did some basic blood work and found out that I have a deficiency in Vitamin B12.

I’ve been taking over the counter B12 supplements for about 6 weeks now, but my canker sores are still just as prevalent as before. My question is really a few questions. How long does it take for oral, over the counter supplements to kick in to fix this kind of issue? Would the B12 shots be a better option for this? And finally, do supplements really fix this kind of issue to begin with, or is it just a way to cover up some low blood test results?


Cankered Out

There is one trial examining how effective vitamin B12 is at reducing both how long canker sores last as well as how often people get them. This study showed a dramatic reduction in both how long sores lasted as well as the number of sores per month, with an average starting rate of 27.6 sores per month down to 3.9 sores per month. In this study, the participants took 1000mcg of vitamin B12 every day before going to bed.

There was another study looking at whether a multivitamin would do the same thing, and showed that it didn’t, but the dose of vitamin B12 was at the recommended daily allowance level, which is about 2.4mcg.

Since it seems the lowest dose of vitamin B12 commonly sold is 1000mcg though, getting the dose doesn’t seem to be a problem.

The positive study looked at sores every month. The first major drop in the number of sores per month happened at the 2-month mark, with another major drop at the 5-6 month mark.

Participants who were taking the placebo also noticed a drop in the number of sores per month, which was similar to the B12 group at the 3-4 month mark, but nowhere near the B12 group at the 5-6 month mark.

Whether or not a B12 shot would be “better” would depend entirely on whether a shot would keep your levels of B12 high enough between injections comparable to taking 1000mcg in a pill or tablet. But injections haven’t been studied specifically for canker sores.

One thing to note is that people who had underlying diseases that are associated with canker sores (Behcet disease, rheumatoid arthritis, and lupus, for example) were not studied; so if you fall into any of these categories, these results would not apply.

People who had an existing B12 deficiency were also not studied, so in your case, WHY you were B12 deficient becomes an important aspect of whether or not this research would apply specifically to you. If you were deficient for purely dietary reasons, then adjusting your diet to be not-deficient and then supplementing ON TOP of that, would put you more into the category of the studied participants. However, if you were/are deficient for other reasons (e.g. an absorption problem), then addressing that particular issue might be necessary.

But even if you don’t fit strictly into the category, the question for most people in your circumstance might look more like this:

“If I take 1000mcg of vitamin B12 every day, could it hurt me?”

And the answer to that question is almost certainly, “No,” from a physical point of view. Financially, vitamin B12 is quite cheap, but I don’t know how strapped you are for cash. And then there’s the “mental” cost of remembering to take it every night (which you could do by putting it next to your toothbrush, if you brush your teeth every night).

The costs of taking vitamin B12 every night for 6 months appear pretty low, for a potential dramatic fix.

If you’re looking to really give this a shot, you would want to make sure that you’re getting 1000mcg per day; and probably stick to it for 6 months before deciding it’s not working.

The other question you might ask yourself is:

“If this works, am I prepared to take vitamin B12 every night possibly indefinitely?”

And that’s an answer only you know, depending on how annoying your canker sores are and whether you’re willing to pay the price to control them (if the B12 solution works).

The good news is that you have an end date to decide whether or not to stop. If there’s no real change within 6 months, then your results would be outside what we would expect to see. I wouldn’t waste any more time or money at that point and definitely wouldn’t pile another thing on top of it to see if they “work together” which can be a common trap people fall into for fear that they’re missing a critical component in a mix of solutions. In this case, the timeline is pretty clear.

Reference: Volkov I, Rudoy I, Freud T et al. Effectiveness of Vitamin B12 in Treating Recurrent Aphthous Stomatitis: A Randomized, Double-Blind, Placebo-Controlled Trial, J Am Board Fam Med January 2009, 22 (1) 9–16; DOI:

Vimms, Vigor, and Foursomes

Dear Doctor Ninja,

I’m very fair and burn easily so I cover up and wear a lot of sunscreen in the summer. That got me wondering about Vitamin D and vitamins. I’m not sure whether or not I should I be taking Vitamin D supplements, or any other supplements for that matter.

On the one hand, we’re told that we can get all of the essential vitamins and nutrients that we need from our food. On the other hand, many experts say that it’s just not possible to eat a diverse enough diet to get everything we need from food. But then, just to confuse things more, every few years a new study comes out claiming that vitamin supplements are actually bad for you! Argh! How can I decide whether or not to take vitamins?


D. Ficient

The latest study to tell us taking vitamins can be bad, D. Ficient, is the 2018 Jenkins study, which looked at all the randomized-controlled trials on vitamin supplementation and risk of death. An increased chance of death was reported for niacin (when combined with a statin), and antioxidants. This often called “all-cause mortality” not because they studied death from all causes, but because all of the studies that were combined measured death by a variety of causes, and “all-cause mortality” is shorter than writing, “death from heart attack, stroke, breast cancer, prostate cancer, lung cancer, and so on and so on”.

What are vitamins for?

First let’s put vitamins in context. Vitamins were discovered only in 1912. That’s barely over 100 years ago. That means we had a cure for scurvy (citrus fruits) before we knew there was such a thing as Vitamin C. It also means that we’ve had comparatively little time to really investigate them. But this isn’t a question about vitamins so much as it is a question about vitamin pills or vitamins as supplements.

Vitamins as supplements weren’t available until 1920, and later marketed with brand names like Vimms and Stams. With a slightly tumultuous history of who was going to control their quality, vitamins went from being approved by the American Medical Association, to being classified as food, thereby bypassing some of the stricter regulations present in the pharmaceutical industry. They captured the imagination of the public, fuelled by advertisers, coinciding with futuristic ideas of “food pills” as being miraculous; and since true nutritional deficiency was a problem in the Depression and World War II, the effects of vitamins used to reverse deficiency diseases made for a very powerful story.

What is enough?

Recommended Daily Allowances date back to 1941, based largely on prevention of newly-discovered diseases linked with vitamin deficiencies. But today, Recommended Daily Allowances are based on different things for different vitamins:

The RDA for niacin is 16mg/day for men and 14 for women, which is based on preventing pellagra (the disease that occurs in niacin deficiency). Centrum contains about 16-20mg per tablet, depending on which source you use. The niacin dose in the largest of the 3 trials used to support the idea (published in the Jenkins study) that niacin when taken with a statin might be harmful was 2g of niacin for the majority of the trial (4 years duration roughly). “More than enough” in this case, is 20x what you would get in a multivitamin and more than you could reasonably eat in food.

The daily intake recommended to prevent rickets is 400IU, but Vitamin D’s RDA is actually 600IU per day, because its rationale is based largely on fracture prevention (and in particular, in women around the onset of menopause). It assumes all vitamin D is being consumed by mouth, and where people have minimal sunlight exposure. Six minutes of sun exposure (UV index 3 or higher) can produce 10 000 IU’s. This is harder to achieve in places where winter is cold or where sunscreen prevents enough UV exposure for your body to make enough vitamin D.

So understanding what is considered “more than enough” requires an understanding of where the idea of “enough” comes from.

I think that we can all agree that there is a point where too much vitamin is too much vitamin. It doesn’t matter where you get it. It can be easier to take them by pill because getting the same high dose through food might involve a lot more food than you might be able to eat in a day.

The idea of being “super-healthy”

There’s also an unspoken conversation going on when it comes to vitamins and that’s the idea that there is a state beyond healthy. Some experts call this “optimal”, but never provide a point of reference from which you could compare “optimal” from “not-optimal”. This “science” claims that preventing deficiency disease isn’t enough; that there is a level of vitamins in the body at which we can become “super-healthy”, as opposed to just, “not-deficient”. There’s a lot of overlap between this camp and the camp of people who say that it’s impossible to get enough vitamins through food alone (to reach this state of “super-health”) as it would require too much food.

An unwanted foursome

So we are left with one science telling us that we are potentially getting more than enough of a good thing (leading to a bad thing); another science telling us that we aren’t getting enough of a good thing (even if we are meeting the so-called minimum), and that we can’t get enough, so take this pill; and yet another science telling us that we can get enough of a good thing without taking a pill. It’s a foursome from hell, you’re in the middle, and the other three don’t look like they’re interested in each other. Being the centre of attention can be fun at first, but it gets exhausting fast when everyone wants you for themselves.

As in all encounters of this kind, whether you join in the fun depends not so much on what the party thinks of you, but rather, what you think of the party. In this case, every potential partner has a different definition of enough. The thing is: They’re not actually trying to entice you on whether you should take the vitamins or not, they’re trying to entice you to think differently on what “enough” means.

Depending on who you’re most attracted to, “enough” ranges from “enough to prevent a deficiency disease” to “enough to make yourself effectively immortal.” The partner you choose (because it’s not really a party of four, if the other three aren’t into each other), and the course of action you take has to do with which story you want to believe most.

Most research has been classified as low-to-moderate quality in this area, but does seem to agree that vitamin supplementation above and beyond deficiency prevention doesn’t help you live longer.

The mythology of vitamins is such a well-crafted story that is so strong that millions of dollars are spent to study it moderately-well. What we want to believe has to be tempered by what we can believe.

Who decides what is enough is you. And who decides whether you are healthy enough today to warrant taking supplemental vitamins is you.


Jenkins DJA, Spence JD, Giovannnucci EL et al. Supplemental Vitamins and Minerals for CVD Prevention and Treatment. Journal of the American College of Cardiology 71(22): 2570-84, 2018.