Dispelling nutrition myths, ranting, and occasionally, raving

Vitamin supplements: deadly or life saving?

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Last week everyone was getting worked up because an editorial in the Annals of Internal Medicine advised against taking vitamin supplements. I wish that I could unequivocally state that they were correct (or incorrect) in this assessment. Unfortunately, this is a complicated issue and I don’t think that we have all of the answers yet.

We know that there are problems with the supplement industry. It’s not well-regulated. Some herbal supplements were recently found to contain ingredients other than those stated on the label, some even contained none of the sole ingredient they claimed to contain. It’s not a stretch to presume that this issue extends to supplements beyond the herbal variety. Last year researchers found that vitamin D supplement often contained hugely variable quantities of vitamin D, even within the same bottle.

An issue unique to multivitamins is that some minerals impede absorption of other minerals when consumed together (for example, zinc and copper). Other vitamins and minerals actually work better together (think calcium, magnesium, and vitamin D). When we’re taking a multivitamin we’re almost certainly not absorbing many of the vitamins and minerals listed on the label (assuming the label is correct in the first place). Does this mean that we should give up on supplements altogether? Possibly not.

The editorial refers to three specific studies. The important thing to note if that these studies looked at people who were not nutrient deficient. The problem with this is that many of us are nutrient deficient. Canadians have difficulty meeting their nutrient needs for calcium, magnesium, and vitamin D through food alone. We also tend to fall short in consumption of potassium as well as EPA and DHA (essential omega-3 fatty acids). There is also the fact that individual nutrient needs vary and that increased nutrients are needed during specific life stages. For example, folic acid is needed early in pregnancy to prevent neural tube defects in infants (1) and many nutrient needs are increased during pregnancy and lactation. Smokers have increased vitamin C needs and athletes have increased needs for nearly everything. Infants require vitamin D supplementation to avoid rickets. Vegans and seniors need vitamin B12 supplements. Etc.

Another problem with the basis on which the authors of the anti-supplement editorial made their recommendation is that they were looking at extremes. They asked: Do multivitamins prevent cancer? Cognitive decline? Heart attacks? Just because vitamin supplements don’t seem to prevent these conditions doesn’t mean that there aren’t other potential benefits to supplementation. More “minor” aliments may be ameliorated by consumption of supplements. We also may have been simply too late to see benefit from supplementation in those involved in those studies. As with osteoporosis which is a pediatric disease with geriatric consequences, these diseases are likely a result of exposures and lifestyles starting in utero.

So, should we take vitamin and mineral supplements or not? I think that it’s a bit of a gamble either way. On one hand you may not be getting what you bargained for in a supplement. On the other hand, you might be risking nutrient deficiency by avoiding all supplements.

Obviously it’s best to try to meet your nutrient needs through food. Realistically, most of us do not do this. If you’re able to determine what specific nutrients you’re lacking in your diet then it’s best to supplement with only those nutrients. Try to select supplements that have an NHP number on them to ensure a minimal level of regulation. And, of course, too much of anything can be a bad thing. Unless advised by your MD or nurse practitioner to take a high dose (and even then, you might want to question them) of any supplement avoid reaching or surpassing the upper limit.

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Author: Diana

I'm a registered dietitian from Nova Scotia, living and working in Ontario, Canada. My goal is to help people relearn how to have a healthy relationship with food.

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