For many of us living in Wisconsin, winter can be a long, cold, depressing season. The days are getting shorter and the snow can be unpredictable. You may not be feeling depressed because it’s cold, you may be feeling sad because you need the sun. Same difference? Probably not.

Vitamin D has been called the Sunshine Vitamin. It is the superhero of all vitamins. Our bodies make vitamin D when we are exposed to sunlight. Unfortunately, in Wisconsin, the sun does not rise high enough in the sky during the winter months to get the proper vitamin D. When you are outside, if your shadow is longer than you are, the sun is not high enough in the sky for you to make the appropriate amount of vitamin D.

Why do we need vitamin D? Vitamin D has many purposes. One of the functions of vitamin D is to increase the efficiency of calcium and phosphorus absorption. We need vitamin D for healthy bones. As time goes on and more research is being conducted, we are finding that vitamin D does so much more than keep our bones strong. Vitamin D is an inhibitor of abnormal cellular growth which is important for cancer prevention. It is a stimulator of insulin secretion which assists a body to have normal blood sugars. It acts as a renin producer which helps to control blood pressure. It is also an important component for our immune systems.

Vitamin D deficiency has been linked to many illnesses and diseases. Some of these include hyperparathyroidism, cardiovascular disease, low bone density, cancer, and autoimmune diseases such as rheumatoid arthritis, diabetes, inflammatory bowel disease and multiple sclerosis. We are all at risk during the winter months, but some populations are at an increased risk of deficiency year-round. These include the elderly, people with darker skin pigmentation, people with liver or kidney disease, people who have had gastric bypass surgery, people who are homebound, obesity, and other conditions such as celiac sprue, short bowel syndrome, and cystic fibrosis. There are also certain medications that will interfere with vitamin D absorption.

There are conflicting opinions on how much supplementation is adequate for the average adult. The RDA is currently 400 IU per day. There is research that shows this is not enough. Most will argue that 1000 − 2000 IU per day is the range most likely to benefit an individual. While not impossible, vitamin D toxicity is unlikely. Most people would need to consume 10,000 IU per day for a period of 3 months to become toxic. You can talk to your healthcare provider to have a simple blood draw to test your current vitamin D levels. Together, you can determine an appropriate dose based on your lab values, medications you take, and your ongoing risk factors.