By Marc Sorenson, EdD, Sunlight Institute…
We all know that high sunlight exposure in adults leads to higher vitamin D levels. However, a most interesting piece of research also shows that your birth month has a considerable influence on vitamin D levels. In an Italian study, it was found that those who were born in winter, rather than spring and summer, were 11% more likely to develop vitamin D deficiency later in life.[i] This is an important finding, since many diseases are related in one way or another to season of birth. For example, a greater risk of obesity risk is observed in Canadians born in winter. Nevertheless, other factors such as inactivity are more important than season of birth.[ii]
This is another study that ties sunlight to vitamin D. But the question may still be asked: Is the relationship of birth seasonality to disease due to vitamin D or sunlight, or both? Whatever the answer, sunlight is the factor that makes vitamin D, so safely soak up the sun whenever you have the opportunity, and when it is too cold or overcast, safely use a sun lamp or tanning bed.
[i] Lippi G, Bonelli P, Buonocore R, Aloe R. Birth season and vitamin D concentration in adulthood. Ann Transl Med. 2015 Sep;3(16):231.
[ii] Wattie N1, Ardern CI, Baker J. Season of birth and prevalence of overweight and obesity in Canada. Early Hum Dev. 2008 Aug;84(8):539-47.