B Vitamins, Fish Oil, and Cancer

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AUTHOR:
Alvin B. Lin, MD, FAAFP

Associate Professor of Family and Community Medicine, University of Nevada School of Medicine

Adjunct Professor of Family Medicine and Geriatrics, Touro University Nevada College of Medicine

Advisory Medical Director, Infinity Hospice Care

Medical Director, Lions HealthFirst Foundation

Dr. Lin maintains a small private practice in Las Vegas, NV. The posts represent the views of Dr. Lin, and in no way are to be construed as representative of the above listed organizations. Dr. Lin blogs about current medical literature and news at http://alvinblin.blogspot.com/.

B vitamins continue to receive lots of press, deservedly or not. Same for fish oil. Most of the studies look at an association with heart disease. While the observational studies are at least suggestive, if not supportive, the randomized controlled trials are not. But perhaps we're looking for the wrong link. Unfortunately, a secondary analysis of the Supplementation With Folate, Vitamins B6 and B12 and/or Omega-3 Fatty Acids (SU.FOL.OM3) demonstrated no association with cancer outcomes either, as published early in the Archives of Internal Medicine last week.

In case you're not familiar with SU.FOL.OM3 (neither was I), it was a fascinating double-blind placebo-controlled trial wherein 2501 French men and women (average age 61 years and with cardiovascular disease) were randomized to either B vitamins alone, omega 3 fatty acids alone, both B vitamins and omega 3 fatty acids, or placebo in a 2 by 2 factorial design and then followed for 5 years. To cut to the chase, the authors found no benefit in cancer and cardiovascular outcomes from supplementation with what they admitted were "relatively low doses of B vitamins and/or omega-3 fatty acids."

So what did we learn from this study? Strict interpretation of the data tells us that 0.56 mg of 5-methyl-tetrahydrofolate, 3mg of pyridoxine hydrochloride, and 0.02 mg of cyanocobalamin and/or 600 mg of omega-3 fatty acids made no difference over 5 years. But while this finding as stated is consistent w/other randomized controlled trials, they tell us nothing of what might happen from larger doses for longer periods of time. More importantly, we should consider if we're actually taking the proper supplements.

For instance, a good portion of the population is unable to convert 5-methyl-tetrahydrofolate into L-methylfolate, the active form. And what of the conversion of pyridoxine into pyridoxal-5-phosphate, its active form? Likewise, cyanocobalamin versus methylcobalamin? In fact, while I do not shill for any pharmaceutical company or manufacturer of medical foods, I do know that there is at least one supplement composed of 3 mg of L-methylfolate, 35 mg of pyridoxal-5-phosphate, and 2 mg of methylcobalamin. It seems to me that this would be the better, if not optimal, supplement to study.

And while 600 mg of fish oil is better than none, consider that 4 g (4000 mg) are indicated and approved by the Food and Drug Administration for those with hypertriglyceridemia. In other words, much larger doses are used in other situations.

Don't get me wrong. I don't advocate taking one or more handfuls of pills every day. Instead, I recommend to my patients that we attempt to eat right in the first place and only consider supplementation if deemed necessary. So before you throw the baby out with the bath water when reading glib headlines and listening to 10-second sound bites, take the time to critically read the actual study.