tamin D? Ask an expert Dr. Beth Mansfield
To further explore the Vitamin D topic, SIRC asked Dr. Beth Mansfield, Registered Dietitian, Certified Exercise Physiologist and member of the Canadian Academy of Sport & Exercise Medicine (CASEM), her thoughts.
SIRC: What are your recommendations for high performance athletes living in Canada regarding their vitamin D status? BM: Studies in athletes suggests that Vitamin D status is dependent on outdoor training time during peak sunlight. The effective sunlight wavelength is not present between October and March in countries above latitude 52 degrees north, which includes most of Canada. It has been suggested that sun exposure (usually 5–10 min of exposure of the arms and legs or the hands, arms, and face, 2 or 3 times per week) and increased dietary and supplemental vitamin D intakes are reasonable approaches to guarantee vitamin D sufficiency (Holick, MF. American Journal of
intake of Vitamin D alone (spring test). Sports dietitians and physicians can then make recommendations to help athletes achieve a serum 25(OH) D concentration of ≥32 and preferably ≥40 ng•mL−1. Further research is needed to determine the effect of vitamin D status on injury, training, and performance in athletes. (Larson-Meyer and Wills, 2010. Vitamin D and Athletes.
For low solar elevation angles common at higher latitudes, Vitamin D status should be monitored by regular blood tests (spring and fall) to determine impact of sunlight exposure over the spring and summer (fall test) and the impact of their dietary
(Holick, MF. American Journal of Clinical Nutrition Dec 2004 Vol 80 No 6 pp 1678S-1688S).
Dr. Elizabeth (Beth) Mansfield, PhD, MSc, RD, is a Sport Nutrition Specialist, Registered Dietitian and Certified Exercise Physiologist with Peak Performance.
Clinical Nutrition Dec 2004 Vol 80 No 6 pp 1678S-1688S.)
Current Sports Medicine reports: Vol 9 Issue 4 pp 220-226)
SIRC: Should athletes who are vegetarian or vegan be concerned with vitamin D consumption? BM: Athletes following a more plant based diet, including different types of vegetarians as well as vegans, should be able to make sufficient vitamin D if they regularly spend time outdoors in spring, summer and early fall. For those who may not be making enough of their own vitamin D, there are different forms of supplemental vitamin D, including those derived from lichen that would be suitable for vegans. SIRC: Can vitamin D be absorbed in conjunction with use of sunscreen? BM: The body’s production of Vitamin D is dependent on season, latitude, and time of day as well as skin pigmentation, aging, sunscreen usage and glass. An SPF of 15 is enough to block 98% of the vitamin D production For those athletes such as sailors, surfers, wake boarders, a fine line exists between adequate UV exposure for vitamin D3 synthesis and a risk of sun burn (Webb & Engelsen. Calculated ultraviolet exposure levels for a healthy Vitamin D status. Photochemistry and Photobiology Vol 82, Issue 6 PP 1697-1703, 2006).
“Sunshine vitamin”
V
itamin D (sometimes called the ‘sunshine vitamin’) is unique in that it requires the skin to be exposed to ultraviolet-B radiation for optimal absorption. Because it is present in very few foods and many people use sunscreen to protect themselves from the harmful effects of UV rays, it has become common for athletes to use supplements to obtain vitamin D.
Why should athletes consider vitamin D? Vitamin D functions to maintain normal levels of calcium and phosphorus in the blood, as well as aiding in the absorption of calcium to form and maintain strong bones. It is a fat-soluble hormone that body can receive from food and supplements although the primary method is from direct exposure to sunlight. • Strengthens bones and teeth and protects athletes from stress fractures • Prevents cold and flu and improves immunity • May prevent cancer, depression or seasonal affective disorder (SAD), osteoporosis, hypertension, inflammation, asthma and heart disease Read more
Am I at risk? Factors that may contribute to vitamin D deficiency include skin pigmentation, early or late day training, indoor training, geographic location and sunscreen use. Athletes that may be at higher risk are those that spend the most time indoors; gymnasts, ballet dancers, figure skaters, and wrestlers. 1. Do you have dark skin? 2. Do you train indoors? 3. Do you wear sunscreen daily? 4. Do you have a spinal cord injury? 5. Do you train fully covered e.g. skiers? 6. Do you live in Canada in the winter? Source: Vitamin D: Are you getting enough? – Canadian Sport Centre Pacific