While it is well recognized that vitamin D is necessary for optimal bone health, emerging evidence is finding that adequate vitamin D intake reduces risk for conditions such as stress fracture, total body inflammation, infectious illness, and impaired muscle function. Studies in athletes have found that vitamin D status is variable and is dependent on outdoor training time (during peak sunlight), skin color, and geographic location. Although research has found that athletes generally do not meet the U.S. dietary reference intake for vitamin D, inadequate endogenous synthesis is the most probable reason for insufficient/deficient status. Given the recent findings, it is imperative that sports dietitians and physicians routinely assess vitamin D status and make recommendations to help athletes achieve a serum 25(OH)D concentration of >or=32 and preferably >or=40 ng.mL(-1). Further research is needed to determine the effect of vitamin D status on injury, training, and performance in athletes.

A surprisingly high prevalence of vitamin D insufficiency and deficiency has recently been reported worldwide. Although very little is known about vitamin D status among athletes, a few studies suggest that poor vitamin D status is also a problem in athletic populations. It is well recognized that vitamin D is necessary for optimal bone health, but emerging evidence is finding that vitamin D deficiency increases the risk of autoimmune diseases and nonskeletal chronic diseases and can also have a profound effect on human immunity, inflammation, and muscle function (in the elderly). Thus, it is likely that compromised vitamin D status can affect an athlete's overall health and ability to train (i.e., by affecting bone health, innate immunity, and exercise-related immunity and inflammation). Although further research in this area is needed, it is important that sports nutritionists assess vitamin D (as well as calcium) intake and make appropriate recommendations that will help athletes achieve adequate vitamin D status: serum 25(OH)D of at least 75 or 80 nmol/L. These recommendations can include regular safe sun exposure (twice a week between the hours of 10 a.m. and 3 p.m. on the arms and legs for 5-30 min, depending on season, latitude, and skin pigmentation) or dietary supplementation with 1,000-2,000 IU vitamin D 3 per day. Although this is significantly higher than what is currently considered the adequate intake, recent research demonstrates these levels to be safe and possibly necessary to maintain adequate 25(OH)D concentrations.

Background and purpose:The extra-skeletal functions of vitamin D -including its role in inflammatory modulation -are now well recognized but have not yet been investigated in an athletic population. Thus, the purpose of this study was to investigate the relationship between vitamin D status and pro-and anti-inflammatory cytokines (as markers of inflammation and immune system function) in endurance athletes.

Alterations in meal-induced responses of ghrelin and PYY(3-36) but not meal-induced thermogenesis may be responsible in part for the potential "obesity protective" effect(s) of honey consumption. A blunted glycemic response may be beneficial for reducing glucose intolerance. Further research is required to determine if these findings hold true for obese individuals, for males, or with habitual consumption.

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