A New York Times article this past December outlined how the lack of regulation and oversight of vitamin supplements can result in significant problems. (1) Contaminants and impurities regularly find their way into vitamins and the amounts listed on the labels can be different from what’s actually in the supplement. Obviously, this can be very dangerous and pose serious health risks. It turns out, that even if the ingredients are pure and the label is accurate, you may be better off avoiding some supplements altogether.
A recent study out of Norway found that individuals training for an endurance event were negatively impacted by supplementing with moderate doses of vitamin C and vitamin E (2). The study separated 54 participants, all in their mid-twenties, into two groups. The test group was given 1000 mg of vitamin C and 350 IU of vitamin E a day for 11 weeks. The control group was given a placebo.
At the end of the study, the supplement group had a statistically significant smaller increase in markers for the production of new muscle mitochondria, indicating a reduction in the beneficial cellular adaptions to exercise. Despite doing the same training, simply taking a Vitamin C and E supplement resulted in less of a training benefit when compared to the placebo group.
Previous studies have found that multivitamin supplements can dampen other beneficial effects of exercise such as improved insulin sensitivity and boosting the body’s natural antioxidant system (3).
The take home message here is that, before taking any vitamin supplements, it is important to understand the potential adverse effects. If you have any questions or concerns, please feel free to contact us.
(1)Paul Offit and Sarah Erush.”Skip the supplements”. The New York Times December 15, 2013:SR7
(2) Goran Paulsen, Kristoffer Cumming, Geir Holden, Jostein Hallen, Bent Ronney Ronnestad, Ole Sveen, Arne Skaug, Ingvild Paur, Nasser Bastani, Hege Nymo Ostgaard, Charlotte Buer, Magnus Midttun, Fredrik Freuchen, Havard Wiig, Elisabeth Tallaksen Ulseth, Ina Garthe, Rune Blomhoff, Haakon Benestad, Truls Raastad. “Vitamin C and E supplementation hampers cellular adaptation to endurance training in humans: a double-blind randomized controlled trial.” The Journal of Physiology February 3, 2014.
(3) Peterneli TT, Coombes JS. “Antioxidant supplementation during exercise training: beneficial or detrimental?” Sports Medicine December 1, 2011: 1043-1069.