Monday, January 26, 2009

Which Vitamin Should I Take?

A staff member in my office asked me which vitamin(s) I would recommend for her to take. She stated her energy was down and wanted to know the best vitamins. This is also a common question I get asked by patients. The staff member seemed a little surprised when I told her I didn't really recommend any vitamins.

There is little proof that vitamins (and other dietary supplements for that matter) can actually help you. On the contrary, if anything the evidence shows that vitamins might even harm you! I have blogged in the past about this, mentioning a review of 68 trials in over 200,000 patients published in February 2007 in JAMA showed that treatment with beta carotene, vitamin A, and vitamin E may increase your risk of death!

Benefits of vitamins like E and C were linked to their antioxidant properties, and have been suggested to prevent colds, improve memory and extend life. However, I have blogged previously about a study on Vitamin E and C that was published in the Journal of the American Geriatrics Society that studied thousands of seniors showing that this did not prevent dementia. In addition, an extensive review of the literature found that vitamin C did not prevent the common cold.

The list of studies goes on and on. There is just no convincing data that these things are helpful. Part of the reason may be that supplements work when you have a diet lacking vitamins and minerals. In the US, our diets are not healthy, but clearly we are getting some nutrition given that the majority of us are overweight or obese. There are a few exceptions where vitamins and supplements may actually help:

1. Folic acid for women of child bearing age. This prevents neural tube defects in babies .
2. Calcium. Calcium is recommend for most adult women to prevent osteoporosis. However, even here there is no data to support that calcium prevents fractures. Yet, it is an important part of bone metabolism, so it is recommended.
3. Vitamin D. We are learning more and more about Vitamin D. I have blogged before about a study published in the Annals of Internal Medicine showing that women with low vitamin D levels have a much greater risk of fracture than women with normal or high vitamin D levels, and it just today it was reported that a low level of vitamin D in older patients is associated with a higher risk of cognitive impairment.

Why Does it Matter?
So what? Even if there are no studies to prove that vitamins and supplements work, they are probably safe, and may help. This is for the most part true. In addition, one can argue that research is lacking because there is no financial incentive (unlike the drug companies) to do the research needed. However, I don't like to recommend things for patients which they will need to pay out of pocket for unless I know it will help them. Whereas some pharmacies are giving away generic antibiotics, and charging only $4 for some generic medications, some women's multivitamins sell for over $34 a bottle (and that's just at Target).

Bottom Line
It's not clear whether or not vitamins really help. If you are a women of child bearing age, you should probably take calcium and folic acid. If you are a senior, you should probably take calcium and vitamin D. If you want to take a multi-vitamin, a generic, inexpensive, once daily mutli-vitamin should be fine. I would not take extra doses of other vitamins or supplements, especially vitamins A, C, or E.

13 comments:

Mr. MedSaver said...

That was a really good post Dr. Mintz. You could also possibly add Fluoride to your list as well.

Anonymous said...

Got some links to some peer reviewed, primary research there on the problems with vitamins? Or are you just quoting people who support your bias?

As for JAMA, any medical journal that feels the need to publish papers on political issues has as much credibility as The Lancet. AKA none.

Anonymous said...

First - there is a tremendous difference between a study which fails to demonstrate a benefit of an intervention and a study which "proves" no benefit. Most physicians recieve only cursory training in statistics and believe that the two are equivalent. It is easier to think about when we look at harmful substances. Imagine stating that a study that has one group smoke a cigarette a day for a year and another group not smoke and demonstrates no difference in the cancer rate after a year "proves" that cigarettes do not cause cancer. This is the sort of fallacy which led MD's to be so passive on the smoking issue for so many decades.

Second - there are few, if any, published peer reviewed papers which legitimize the notion that supplementation does harm... this is largely urban legend.

Third - if you have an open mind -and unfortunately few of us MD's still do - check out www.foodmatters.tv and watch the film. I have absolutely no affiliation or involvement in the film --- but it did get me to actually think. (Most of us think that we think when we regurgitate the party line.) You may not agree with all that is said, but it may cause you to read the studies published in places other than JAMA and NEJM.

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Alison Cummins said...

I'd add B vitamins for some people at risk. For instance, depressed people often eat badly. This puts them at risk for low B6, which in turn is a risk factor for depression and irritability. Since depression treatment is often a question of chipping away at contributors, B6 supplements can be part of the armamentarium of people at risk for depression.

Med School Fool said...

As a medical student, trying to decipher all the information regarding supplements make me crazy. I want to agree with you, and I believe most physicians do, but sometimes it may be easier to say something doesn't work since there is no proof. It is harder to take the chance and say there is not enough research published in reputable journals, but theoretically our highly processed diet may be lacking in the essential vitamins/minerals. I'm so confused as to what to think!

Dr. Matthew Mintz said...

Anonynmous is correct that "there is a tremendous difference between a study which fails to demonstrate a benefit of an intervention and a study which "proves" no benefit," but the later is much harder to do and thus rarely done.
Med School Fool-
There is a big difference in vitamins to supplement nutritional deficient diets and vitamins as a supplement to a normal diet for some therapeutic benefit. Given the obesity in our country, it is doubtful that most Americans are nutritionally deficient. Since we are not eating healthy foods, it is possible that we are calorically replete but nutritionally deficient. I am not aware of data to support this, but would be suspect since even a Big Mac and Fries will give you about 25% of the RDA of calcium, iron, and vitamin C (not that I recommend this).
Thus, for individuals who are not getting enough nutrition (for example kids who are extremely picky eaters), a multi-vitamin would be absolutely beneficial. However, my post is in regards to people who eat a regular American diet, and in addition to too many calories, likely give them enough vitamins and minerals needed.
What I generally tell my patients is that if they want to take a multivitamin, though studies have yet to prove benefit, it may help and probably won't hurt. I also tell them that I don't specifically recommend them because since there is no proof that they work, I can't recommend they spend their out of pocket dollars on them, though they can if they want to. I do generally recommend of the higher doses of extra vitamins, especially E and C since they have been shown to cause harm. The exception is calcium and vitamin D, especially for women and folic acid for young women. I also don't disagree with Alison Cummins regarding B vitamins. Though again, this is for nutriciently deficient folks, the elderly, even those who are not depressed, may have some lack of B vitamins, also because of decreased absorption.

Derick said...

Vitamins are necessary for the proper functioning of the body. Here are two studies that may help you to see that multi-vitamins do play a role in supporting good health:
British Journal of Nutrition, November 2008, Volume 100, Pages 1086-1096, doi:10.1017/S0007114508959213
“Cognitive and mood effects in healthy children during 12 weeks' supplementation with multi-vitamin/minerals”
There is also an interesting article on how omega 3 supplements helped children to score higher on their test scores! (http://www.durham.gov.uk/durhamcc/pressrel.nsf/Web+Releases/9B151A656B3FD9AB802574CF002D51F1?OpenDocument)
The fact that most Americans fall under the category of being overweight or obese does not mean they are getting enough nutrition. Poor dietary habits will, in fact, compromise good health and lead to a higher risk of chronic disease. And when you think about it, how many of us can say that our diets alone adequately meet all our nutritional needs? A good multi-vitamin, like MutliVescence, will support heart health, immune health and digestive health.

Dr. Matthew Mintz said...

Derick,
The fact that you link to a commerical vitamin site in your posts makes me suspect that you might have some bias.
That said, the first study you cited is somewhat weak in that it was small, and some of the kids on vitamins actually did worse in one of the tasks. The second study is not a randomized clinical trial, and therefore has a lot of bias.
You are correct that vitamins are necessary for proper functioning of the body. The issue is whether vitamin supplementation is someone eating a normal diet has any benefit. With your studies included, the evidence for any major benefit is weak at best, and in some cases (Vitamin E and C) shows harm.

Anonymous said...

While in general I agree with your post about vitamins/minerals to take, I would add a word of caution for those who suffer from sarcoidosis. Those people (and yes, I am one) need to be mindful of their calcium levels and both types of Vitamin D levels. I had issues with high calcium way before they diagnosed the sarcoidosis, and have avoided Vitamin D supplements by showing my doc that while my 25-D was borderline low (not a common occurence for me), my 1,25-D was fine and to supplement was contraindicated.

Many with sarcoidosis, and their doctors, don't check on this kind of thing, so anywhere that advocates supplementing as a matter of course should add this kind of caveat.

Dolev said...

Dr. Mintz,

I'm curious how much time you've spent studying vitamins. I've spent the last 12 years doing so, and I've seen probably 10,000 studies showing the benefits of vitamin supplementation. You should be ashamed of such a shallow blog.

Dolev Gilmore, Nutritionist
Author of Nutrition and Your Child's Soul.

Dolev said...

Mr. MedSaver,

Adding fluoride as a supplement? Very good. Vitamin C, necessary to so many important body processes, backed by thousands of studies and 70 years of clinical experience is no good, but fluoride, with no proven need for humans, which blocks iodine in the thyroid and breaks hydrogen bonds, is good for internal consumption with no clinical or experimental evidence for the practice.

Dr. Matthew Mintz said...

Dolev,
I am sure there are many studies on vitamins, but I am aware of very few randomized, controlled clinical trials showing a specific health outcome benefit for vitamins. The few trials that have tried to do this, i.e. vitamin C and E or Folic Acid for heart disease failed.
It's not that I am against vitamins, its just that the evidence for vitamin supplementation is weak. I practice in the inner city, and especially in this economy, patients can not afford vitamins, medicine or even healthy food. Patients have to make choices about what to spend their money on. I can't recommend that a patient go out and buy something unless I know there is proof that it works.