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?
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.