Although best known for its role in bone health, there is increasing evidence of the additional health benefits of vitamin D. Sun exposure induces cutaneous vitamin D synthesis which is dependent on many factors such as skin pigmentation, latitude, season, outdoor activity, the duration of sun exposure, and the amount of skin exposed. Dietary sources of vitamin D include foods such as fish liver oils and flesh of fatty fish. Small amounts of vitamin D are also found in beef, liver, egg yolks, and cheese. Because adequate intake of vitamin D is unlikely to be achieved solely through intakes of unfortified foods, fortification programs and vitamin D supplementation are often necessary for people to satisfy their requirements for this important nutrient. To determine whether there have been changes in dietary or total usual intakes of vitamin D among Canadians, a study conducted by Hassan Vatanparast (University of Saskatchewan) and colleagues examined nationally representative nutrition data from the Canadian Community Health Survey Cycle 2004 and in 2015.
The study represents 30,074,236 Canadians in 2004 and 33,946,610 in 2015 who were aged > 1 y and had provided plausible dietary information. Dietary intake data were collected with the use of two 24-h dietary recalls and dietary supplement use was determined by questionnaire. National Cancer Institute methods were used to determine the usual intake of vitamin D and the prevalence of vitamin D inadequacy.
Study results, published in The Journal of Nutrition, suggest that the usual intake of vitamin D from food significantly decreased by 1 mcg/d only in vitamin D supplement nonusers. However, the prevalence of vitamin D supplement use and the percentage contribution of vitamin D from supplemental sources has increased in the Canadian population over an 11-y period. Total usual intake of vitamin D from food and supplements significantly increased from 15.1 mcg/d in 2004 to 31.5 mcg/d in 2015.
In contrast to vitamin D supplement nonusers, the prevalence of vitamin D inadequacy significantly decreased from 20.6% to 14.1% among those taking vitamin D supplements. Vitamin D supplement users were more likely to be female, older, higher income, higher education level, food secure, and reside in urban areas compared to nonusers. According to senior author Hassan Vatanparast, “The decreasing trend in the intake of vitamin D from food sources emphasizes the importance of vitamin D supplements to maintain appropriate blood vitamin D levels in a situation that the current vitamin D fortification policies do not fully address the needs.”
Reference Vatanparast H, Patil RP, Islam N, Shafiee M, Whiting SJ. Vitamin D Intake from Supplemental Sources but Not from Food Sources Has Increased in the Canadian Population Over Time. J Nutr 2019 Dec 11 (Epub ahead of print; DOI: https://doi.org/10.1093/jn/nxz291).
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