By Marc Sorenson, EdD, Sunlight Institute
Nearly all research shows a positive association between sunlight and bone strength. One of the most interesting of these studies measured heel-bone stiffness (a measurement of bone strength) and various lifestyle factors among Okinawan men with and without type-two diabetes.[i]
The research demonstrated that among the group with type-two diabetes, there were a significant negative correlation between cigarette smoking heel bone stiffness. That negative correlation also was evident with age. Other factors did not produce a significant correlation in the diabetic group; however, in the non-diabetic (control) group, a significant positive correlation was shown between heel-bone stiffness and two other factors: (1) sunlight exposure and (2) consumption of small fish. Of the two, sunlight exposure predicted greater bone strength.
It is probable that the vitamin D produced by sunlight exposure led to increased heel bone strength in the control group. It is also possible that lack of sunlight in the diabetic group may have been one of the predisposing factors that initially led to diabetes in the diabetic group, as it has been shown that vitamin D supplementation in pre-diabetic subjects predict a dramatically reduced risk of developing the full-blown disease.[ii] Sunlight exposure, of course, is the most natural way to produce vitamin D.
Keep your heels—and the rest or your bones—strong by obtaining plenty of non-burning sunlight!
[i] Michiko Gushiken, Ichiro Komiya, Shinichiro Ueda, Jun Kobayashi. Heel bone strength is related to lifestyle factors in Okinawan men with type 2 diabetes mellitus. J Diabetes Invest 2015; 6: 150–157
[ii] Pittas, A. et al. The effects of calcium and vitamin D supplementation on blood glucose and markers of inflammation in nondiabetic adults. Diabetes Care 2007;30:980-86.