As we’ve said goodbye to summer and welcomed fall, many of us will be spending less time outdoors and less time soaking in the ‘sunshine vitamin,’ vitamin D. A critical part of our physiology, vitamin D does more than strengthen bones – it helps support the entire body.
“Vitamin D is vitally important for our health,” says Dr. Edward Rylander with In His Image at St. John Medical Center in Tulsa. “It is part of our bodies’ immune system to fight off infections, our cancer prevention system, and [it] is critically important for bone health. Vitamin D deficiency increases the risk of a host of chronic diseases, multiple forms of heart disease and some cancers, as well as multiple sclerosis. Infections including tuberculosis and the flu are easier to acquire and harder to fight off for people with low levels of vitamin D.”
“Recently, it has become more evident that vitamin D is important for many other functions in the body, including the prevention of falls and fractures in those over 65 – felt to be the result of better muscle function as well as stronger bones,”
Rylander adds that, worldwide, an estimated one billion people have inadequate levels of vitamin D in their blood.
“These deficiencies can be found in all ethnicities and age groups,” he says. “In several countries, physicians are seeing a resurgence of rickets, which is the bone weakening disease that was largely eradicated through vitamin D fortification of food in the past.”
Dr. Kathryn E. Reilly, a family medicine physician with OU Physicians in Oklahoma City, explains that vitamin D is also important to normal calcium absorption in the gut as well as maintaining the balance between calcium and phosphorus in the body. In addition, inadequate levels of vitamin D are associated with osteoporosis and a higher risk of all-cause mortality.
“Recently, it has become more evident that vitamin D is important for many other functions in the body, including the prevention of falls and fractures in those over 65 – felt to be the result of better muscle function as well as stronger bones,” says Reilly. “It has been associated with decreased risk of developing cancers of the breast, prostate and probably colon.”
She says other areas that seem to benefit from adequate vitamin D include improved immune function and the decreased risk of autoimmune diseases, cardiovascular diseases, diabetes, muscular weakness, infertility and adverse pregnancy outcomes. Vitamin D also has been associated with a decreased risk of dementia and depression in the elderly.
To maintain adequate vitamin D levels, experts agree that a combination of sun exposure (with the understanding that too much exposure to UV rays can cause skin cancer), a healthy diet and a vitamin supplement works best.
“If you draw a line in our country at the level of San Francisco, anyone living north of this line is unable to obtain enough vitamin D simply from sun exposure and requires vitamin D supplementation,” says Rylander. “For the majority of people, the amount of time exposed to sunlight outdoors is insufficient no matter where they live in our country. Most physicians now recommend supplementing your sunlight and vitamin D [from] food.”
Reilly suggests that a few minutes in the sun is probably enough for most people, and she recommends a 2,000 (IU) vitamin D supplement to her patients.
“The skin is the organ that helps the body make vitamin D,” says Reilly. “Use of sunscreen can decrease the amount made by up to 95 percent, although that assumes using large amounts of sunscreen. Clothing does not allow penetration of the UV rays that cause vitamin D to be made. Exposure to sun in midday for 20-30 minutes at least three days per week with at least face, neck and arms exposed, is probably adequate in summer months in southern states.”
She points out that many foods have either intrinsic vitamin D or are supplemented with the vitamin. Good sources include salmon, tuna, sardines, mackerel and shrimp, as well as cod and fish oils, beef liver, egg yolks and some mushrooms. Items that may be supplemented include milk, cheese, yogurt and orange juice.
“Many people are at higher than average risk for developing vitamin D deficiency,” says Reilly. “Obese people need more vitamin D; the elderly do not make vitamin D as efficiently as younger people; and people with darker skin need more sun exposure.”