You have probably heard vitamin D referred to as the “sunshine vitamin.”
This is that the best way to benefit from it is through direct exposure to sunlight, specifically ultraviolet B (UVB). Although there are some foods that are fortified with vitamin D, their levels are nowhere near that which the human body requires.1 In fact, a 2011 study in Nutrition Research estimated the prevalence of vitamin D deficiency among the general adult population to be as high as 41.6 percent.2
This presents a dilemma for people who live in regions that may not get as much sunlight during the winter months compared to other regions further south. In essence, the closer a region is to the Arctic Circle, the shorter the days will be during winter.3
Given that vitamin D is crucial for preventing bone loss, it’s easy to see why people may have a greater incidence of bone loss if they live further north than people who are located further south. In light of this dilemma, how can you ensure that your patients are getting an adequate daily intake of vitamin D?
How much sun is enough?
This is a somewhat difficult question to address, as there can be many variables. It can depend on how much pigmentation there is in the skin, how much of the body is exposed to direct sunlight, and both the season and latitude.
However, the general consensus appears to be that the optimal amount of time is slightly less than the amount of time it would take for somebody to first develop a sunburn. For example, somebody with fair skin wearing shorts and a t-shirt during the summer would achieve optimal sun exposure faster than a person with darker skin, if all other variables were identical.
Unfortunately, some regions simply do not get enough sunlight during the winter months to provide adequate levels of vitamin D. A 1988 article, published in the Journal of Clinical Endocrinology & Metabolism, examined the effects of season and latitude on vitamin D exposure during winter in the cities of Boston and Edmonton.4
A later article, published in Photodermatology, Photoimmunology & Photomedicine, suggested the use of UVB lamps as a promising alternative to direct sun exposure.5 Such a lamp may not only provide your patients with a means to increase their vitamin D levels, but may also treat conditions such as wintertime seasonal affective disorder.
Vitamin D supplementation
The Office of Dietary Supplements at the National Institutes of Health recommends that children between the ages of 1 and 17 take 15 mcg of vitamin D per day.1 Adults between the ages of 18 and 70 can take the same amount. Adults age 70 and older should increase their daily vitamin D intake from 15 mcg to 20 mcg.1
Fortified foods, such as milk and some cold cereals, can also help your patients increase their vitamin D intake, as well as fatty fish such as salmon.
While it is still important for your patients to obtain as much of their vitamin D as possible through sun exposure, this can present a challenge in colder, northern climates during winter.
A combination of sun lamps that put out UVB light, vitamin D supplements and food that is fortified with vitamin D can help them make it through the winter without increasing their risk for dangerously low levels of vitamin D.
- Vitamin D. NIH Office of Dietary Supplements. Accessed 1/24/2018.
- Forrest KY, Stuhldreher WL. (2011). Prevalence and correlates of vitamin D deficiency in US adults. Nutrition Research 31(1), 48-54.
- De Fabo EC. (2005). Arctic stratospheric ozone depletion and increased UVB radiation: potential impacts to human health. International Journal of Circumpolar Health. 64(5):509-522.
- Webb AR, Kline L, Holick MF. (1988). Influence of season and latitude on the cutaneous synthesis of vitamin D3: Exposure to winter sunlight in Boston and Edmonton will not promote vitamin D3 synthesis in human skin. Journal of Clinical Endocrinology & Metabolism, 67(2), 373-378.
- Chandra P, Wolfenden LL, Ziegler TR, et al. (2007). Treatment of vitamin D deficiency with UV light in patients with mal-absorption syndromes: A case series. Photodermatology, Photoimmunology & Photomedicine, 23(5), 179-185.