Even if you don’t have rickets (a disease caused by a lack of vitamin D that was common in the 19th century), if you live in a part of the world where the sun does not shine for a considerable number of hours each day, there is a good chance that you are deficient in vitamin D. Our modern lifestyle has brought us indoors for the greater part of the day, whereas once we spent much of our day outside in the course of our work. Add to that the extensive use of sunscreen meant to protect us from damaging solar rays (which are the same ones responsible for spurring vitamin D production) and you get large numbers of the population with a vitamin D deficiency.
Who Is Most Affected?
The author of the book, “The Vitamin D Solution,” Dr. Michael Holick, who is a leading expert on vitamin D, believes that many Americans are not getting nearly enough of the vitamin. He states, “We want everyone to be above 30 nanograms per milliliter, but currently in the United States, Caucasians average 18 to 22 nanograms and African-Americans average 13 to 15 nanograms.” As an example, Holick mentions that the prevalence of cancer is higher in the Northeast, which gets considerably less sun than in the South, where rates of the disease are lower. In addition, rates of heart disease, high blood pressure and prostate cancer are higher among Americans with dark skin than among whites.
People who follow low-fat diets (due to vitamin D’s fat solubility), who have digestive problems (as vitamin D is absorbed in the digestive tract), who live in northern climates (due to lack of sufficient sunlight) and the elderly are particularly prone to a deficiency.
Benefits of Vitamin D
Vitamin D works along with calcium to strengthen the bones and helps to support the health of the whole musculoskeletal system, and it has been shown to reduce the progression of senile dementia and Alzheimer’s disease. It also reduces the risk of osteoporosis, cancer (particularly of the prostate, breast and colon) and diabetes.
Vitamin D is one of the fat-soluble vitamins that the skin makes when it is exposed to the UVB rays in sunlight. Although we have been admonished for decades to put on sunscreen whenever we go out in the sun, this advice may be somewhat misguided. While it is good to protect ourselves from getting too much sun, it is equally important to ensure that we get enough of it. And while it is not so easy to get enough vitamin D through our diet, it is relatively simple to get it from the sun.
Ways to Ensure You Get Enough Vitamin D
It is possible to get your annual supply of vitamin D in the summer months (as the body can store it). Although it is difficult to provide a blanket recommendation for sun exposure due to the wide range in the amount of sunlight in different locations, Dr. Holick suggests that you get out in the summer months wearing minimal clothing and no sunscreen (apart from your face, which should be protected) for 5 to 10 minutes two to three times a week between the hours of 10 am and 3 pm. Getting out in the sun in the winter for those who live north of about 35 degrees latitude is virtually useless as far as vitamin D production, as the UVB rays do not penetrate the atmosphere above that latitude.
If you cannot get sufficient vitamin D from sun exposure, you must get it through a combination of diet and supplementation. Even if you do get sufficient sun in the summertime, experts estimate that we need an additional 2,000 IU per day in winter to fill the deficit due to lack of winter rays. Although there are a few food items that provide some of the vitamin D you need, you likely will not be able to fulfill your daily requirement through diet alone.
Foods that are highest in vitamin D are fatty fish such as sardines, salmon and mackerel, milk, eggs, some mushrooms and foods that are fortified with the vitamin. You would likely need to consume about 2 or 3 servings of fatty fish per day to meet the daily requirement, so unless you like eating a lot of fish (which is not recommended due to the danger of toxicity from mercury buildup), supplementation is likely your best option. And while it is not possible to get too much vitamin D from exposure to the sun, it is possible if you take excessive amounts of the dietary supplement, so be sure to follow the directions on the label.