Wednesday, November 13, 2013
Vitamins, Protein, Water: Can too much be bad?
When it comes to "good nutrition", the attitude seems to be that if a little is good then more must be better. But of course nutrition couldn't be that black and white. Not everything is best in large quantities.
1. Vitamins and Minerals
Multivitamins as well as individual vitamin and mineral supplements are very popular among athletes. They are often used as an "insurance policy" in case needed amounts are not met with food. While this may not seem harmful, some vitamins and minerals in large quantities are in fact harmful. Two examples are Vitamins A and E. The theory was that vitamins A and E from food act as antioxidants in the body, so taking supplemental vitamin A and E should only enhance this effect and provide further protection. However, a meta-analysis showed that in high quantities, supplemental doses actually increased rather than decreased risk of death - Vitamin A by 16% and Vitamin E by 4%. One reason is that these are both fat-soluble vitamins, which means they more easily build up in the body rather than being excreted, as seen with water-soluble Vitamin C (1).
Because I work with athletes every day, I see plenty who believe that - when trying to build muscle - if one scoop of protein is good, then two...three...four...is even better. Aside from leading to excess caloric intake and fat mass gain, too much protein is taxing to the kidneys and dehydrating to the body. The upper limit for the majority of athletes is 2gm/kg of body weight, but that is still unnecessarily high for most.
Our body is made up primarily of water, so it seems that you can never drink too much, right? This may not be true, depending on the situation. One example is a slower-paced marathon runner. Slower runners can easily drink water at each aid station they pass. Because of the slower pace, by the time they reach the finish line, some take in far more total water than is needed. This can dilute the blood, leading to "hyponutremia" or low sodium. To combat this, endurance athletes - especially slower paced ones - should know their sweat rate and drink only to that sweat rate...and not much more. This will ensure enough fluid comes on board, but not too much. Incorporating sports drinks, diluted fruit juice or electrolyte supplementation can help too, as long as appropriate amounts are taken.
1. Goran Bjelakovic, Dimitrinka Nikolova, Lise Lotte Gluud, Rosa G. Simonetti, and Christian Gluud. Mortality in Randomized Trials of Antioxidant Supplements for Primary and Secondary Prevention; Systematic Review and Meta-analysis. JAMA 2007;297:842-857. Vol. 297 No. 8, February 28, 2007
Picture source: http://www.flickr.com/photos/stevendepolo/