Let’s set the record straight: Vitamin D, also playfully known as the sunshine vitamin, is technically a hormone since it is predominately produced in the body. Vitamins, aside from supplementation, are substances we normally get from food.
Vitamin D was first discovered in the early 1900s by researchers studying rickets. They found that dogs who were fed cod liver oil did not get rickets and those who had rickets recovered. It was thought to be a vitamin since it came from a food. D was the next letter to be named. It wasn’t until later that it was discovered that humans made vitamin D from exposure to the sun, technically classifying it as a hormone.
So, it is true that we do get vitamin D from the sun, however it must go through several conversions before it is in a form the body can use. The sun’s UV light reacts with a type of cholesterol that is on layers of the skin to create pre-vitamin D. This then reacts with UVB rays to convert to a pre-vitamin D3. This process takes about a day. Perfectly applied sunscreen blocks UVB rays.
Pre-vitamin D3 spontaneously changes into vitamin D3, which goes to the liver and is converted into 25-hydroxy vitamin D. You may see this type of vitamin D on the label of supplements. One last stop at the kidneys activates it into calcitriol which regulates calcium absorption. Calcitriol is in some osteoporosis medications.
Problems in any of these conversion pathways can cause low vitamin D levels. Environmental factors, such as increased air pollution that blocks UVB rays, as well as lifestyle factors such as decreased outdoor activities or a diet lacking in vitamin D-rich foods, can contribute.
The New England Journal of Medicine states that nearly half of the world’s population has vitamin D insufficiency, and around 1 billion people have frank vitamin D deficiency. This holds true across ethnicity and age groups. This finding is important for public health because large studies of populations around the world have shown that people with lower levels of vitamin D have higher mortality risk overall, regardless of health status or pre-existing conditions.
Supplementation with vitamin D has shown promising results for several conditions. One of these is uterine fibroids. Vitamin D helps by inhibiting cell division of the fibroid (benign) tumor. Other journals suggest that vitamin D can be helpful in chronic diseases such as osteoporosis, cancer, cardiovascular diseases, dementia, multiple sclerosis, autism, type 1 and type 2 diabetes mellitus and male and female fertility.
An article from JAMA suggests optimal baby birth weight is helped by vitamin D. Despite this research, some current trends are steering away from vitamin D testing and supplementation unless a person has one of the following chronic diseases: osteoporosis, inflammatory bowel disease, celiac disease, kidney or liver disease or pancreatitis.
Foods that naturally help with vitamin D conversions are fatty fish such as eel, mackerel or salmon, fish liver oils (think cod liver oil…yum!), malted drinks and egg yolks. Some vitamin D fortified foods may include fruit juices and fruit juice drinks, energy bars, soy milk, cheeses, cereals, milk, flour and infant formula.
So how can we ensure that our vitamin D levels are optimal? Maintaining optimal vitamin D levels are a combination of building blocks such as the sun, supportive foods and functioning conversion organs. Ask your health care provider if you are at risk, if you need to include vitamin D activities into your lifestyle or foods into your diet, or if you should have your vitamin D levels checked.