- The UV rays from the sun that cause skin to produce vitamin D cannot penetrate glass, or sunscreen. It is almost impossible to get enough vitamin D through a normal diet.
Think of it as a great big orange vitamin pill in the sky. One that everyone can share, free of charge. It’s the sun, and if you’re like most Americans, you could use more of the vitamin D that your skin makes when you’re exposed to it. Apart from the long-known benefit of aiding the development of healthy bones, a proper level of vitamin D in the body is also correlated with reduced risk of cancer, according to more recent research.
“I think the benefits of vitamin D are unbelievable,” says Dr. Lynn Kohlmeier, director of the Spokane Osteoporosis Centers. “When people start looking into this, they see that it reduces the risk of prostate cancer and breast cancer, or at least reduces the severity of breast cancer when vitamin D levels are good.”
Kohlmeier cautions against excess exposure to the sun due to the risk of skin cancer and premature aging of the skin. She also argues that the inconsistency of weather and the ability of any particular individual to make vitamin D through the skin — especially older people and those with dark skin — may make supplements necessary for some. (People should consult a doctor before gulping vitamin D pills.)
“But the benefits of being outside in the sunshine go way beyond vitamin D for our health and our mood,” she says. “If the kids are just sitting inside and drinking soda and playing Nintendo, and are not getting any sunshine, then not only are they going to get diabetes and be overweight, they’re going to have thin bones because they’re not loading their skeleton,” she says. “And they’re not getting enough vitamin D. It’s a huge problem.”
The primary function of vitamin D is to help get calcium and phosphorous from the intestine into the blood. When this doesn’t happen, it results in thin and fragile bones: Osteoporosis.
“It’s important for bone, but it’s important for other tissues as well,” says Dr. Daniel Bikle, professor of medicine and dermatology at the University of California, San Francisco, noting that most cells in the body have vitamin D receptors, suggesting they respond to it. (Kohlmeier invited Bikle to speak at the Spokane Internal Medicine Meeting last year.) “There appears to be a relationship between vitamin D deficiency and increased risk of cancer — and that’s true of a number of cancers,” he says. According to Bikle, it’s also associated with autoimmune diseases such as multiple sclerosis as well as types 1 and 2 diabetes.
Assuming a level of 30 nanograms per milliliter of blood as adequate — a debatable standard — Bikle says that about 70 percent of Caucasians, 80 percent of Hispanics and 90 percent of African Americans in the U.S. are vitamin D deficient.
Does that mean people can benefit from more sun?
“I would argue that that’s the case,” Bikle says, “because the skin is a very efficient source of vitamin D, and that won’t work unless it’s exposed to sunlight.”