This week is not starting of well for those who hope to make money from selling vitamin supplements, particularly multivitamins. As summarized in this article three major studies published indicated that the use of a multivitamin did help ward off problems that strike fear into the hearts of many Americans: cancer, cognitive decline, and cardiovascular events.
One of the highlights of this article was this quote: "I think this is a great example of how our intuition leads us astray," Salzberg told Shots. "It seems reasonable that if a little bit of something is good for you, them more should be better for you. It's not true. Supplementation with extra vitamins or micronutrients doesn't really benefit you if you don't have a deficiency." (emphasis mine).
When I pasted this article on my Facebook feed I people point out that they take [insert vitamin here] for [insert medical problem here]. Yes, of course you do. You are taking a SPECIFIC vitamin at a SPECIFIC dose for a SPECIFIC problem. That is different than throwing a random bunch of things and a problem that may or may not exist and not have any evidence that it's helping you. "But I don't eat right" is another admission that I've heard from my patients over the years. Well, you probably don't, but if you take a multivitamin to make up for your, lack of vegetables, you might still be getting too much of one thing and too little of another to really help. And of course, as stated in the news article, some people take a multi w/o regard for how certain vitamins might actually increase the risk for certain conditions at high doses, might exacerbate a condition you already have, or might interact with a medication that you are taking.
I have actually covered a similar topic over a year ago in this post, which includes info on why taking a multi probably doesn't help your less than stellar diet, and also talked about who may or may not benefit from a vitamin D supplement. Some of you are probably still wondering if you might need to have a supplement for a specific condition, so here are some questions to ask yourself. And of course, get a blood test to verify that you are deficient and discuss your supplementation with a trusted physician and/or pharmacist so that you do not do yourself any harm.
1) Do I have a health condition that might keep my body from absorbing certain vitamins or minerals? For example, if you have had gastric bypass surgery, you might need to supplement with B-12 as you may not produce enough of a substance call intrinsic factor to effectively absorb this from food.
2) Do I follow a diet that eliminates certain food groups/is considered restrictive by the culture I live in? For example, if you are vegan, you won't get B-12 from plant sources because plants do not typically store B-12. The "usual" plant sources, like seaweed, can actually contain substances that can keep you from absorbing B-12 (link), so you might be better off taking a supplement.
3) Do I take medications that can cause me to be deficient in certain vitamins/minerals? I have a lot of patients that are on diuretics ("water pills") for congestive heart failure, etc. This medicine also can cause them to lose a lot of potassium in the urine, and so they need to take potassium supplements to compensate. The supplements are usually pretty large doses, however, so they need regular lab work to make sure the potassium doesn't go to high (which could be fatal).
4) If I have a known deficiency, can I realistically eat the amount of food required to measure up to the amount in a supplement? For example, if you go to donate blood and find that your blood test was a tenth of a point off, you could probably just be extra conscious about your iron intake until your next attempt at giving blood. If your iron levels are low enough that your physician is recommending a supplement, however, you might have to eat the equivalent of 2-2.5 pounds of liver per day to get the supplement equivalent. I like liver, but not that much, nor would I want to pay for it. I would take a supplement.
5) Do I have a condition that can be helped by large doses of a certain vitamin/mineral (that is backed by evidence)? See my previous post about supplementation with omega-3 in the presence of high triglycerides in HIV/AIDS patients treated with anti-retrovirals. And remember, you will have to be monitored frequently to make sure that the potential side effects of those large doses are not outweighing the benefits.
Take home message--Find out if you really are deficient in something before taking a supplement that you don't need or could actually harm you. If you do need to supplement, work closely with your physician to make sure you are getting the amount that you need of that specific vitamin/mineral.