Hardened against Antioxidant Vitamin Supplements? Maybe you should Reconsider
WebMD defines antioxidants as ‘man-made or natural substances that may prevent or delay some types of cell damage. Antioxidants are found in many foods, including fruits and vegetables. They are also available as dietary supplements.’ The antioxidant vitamins are: C, A, E and β-carotene. Yesterday’s blog shared CDC data reporting a marginal trending increase in fruit consumption but no change in vegetable intake among adolescents. What is the impact of not eating enough fruit, vegetables and whole grains?
Arterial stiffness is a risk factor for a first cardiovascular event. In a new systematic review, researchers report a significant protective effect of antioxidant vitamin supplementation on arterial stiffness. Not surprisingly, the benefit of vitamin C and E supplementation was greatest when plasma concentrations were lowest. Ashor and colleagues used plasma vitamin C concentrations of 44 µmol/L as their cut-off for low status. Based on nationally representative data, ~38% of adults 20y and older have plasma vitamin C levels below this value. Regardless of plasma vitamin E concentration, there was a significant effect of vitamin E supplementation (p < 0.02). Basically, everyone benefitted by increasing vitamin E intake.
Ashor and associates also examined effect of quantity of vitamin consumed on outcome. This approach is less informative because of the leaky bucket concept. To change a vitamin-related outcome, there has to be a significant shift in vitamin status. For example, if plasma vitamin C concentrations are at saturation (~70 µmol/L), supplementation will not affect function and urinary excretion will increase. If vitamin status isn’t adequate, then supplementing with amounts that increase status meaningfully can change function.
So what do we know? Most people are not eating recommended number of servings of fruit, vegetables and whole grains and are certainly not meeting nutrient recommendations. According to the meta-analysis, antioxidant vitamin supplementation reduces arterial stiffness. Supplementation is especially beneficial in persons with low plasma antioxidant vitamin concentrations.
Multivitamin-mineral supplements are an important source of nutrients for many people. If you aren’t eating the recommended servings of fruit, vegetables, and whole grains, consider using a multivitamin/mineral supplement.
Ashor AW, Siervo M, Lara J, Oggioni C, Mathers JC. Antioxidant vitamin supplementation reduces arterial stiffness in adults: A systematic review and meta-analysis of randomized controlled trials. 2014 J Nutr doi: 10.3945/jn.114.195826
Mitchell GF, Hwang S-H, Vasan RS, Larson MG, Pencina MJ, Hamburg NM, Vita JA, Levy D, Benjamin EJ. Arterial stiffness and cardiovascular events. The Framingham Heart Study. 2010 Circ doi: 10.1161/CIRCULATIONAHA.109.88655
Fulgoni VL, Keast DR, Bailey RL, Johanna Dwyer. Foods, fortificants, and supplements: Where do Americans get their nutrients? 2011 J Nutr doi:10.3945/jn.111.142257