While there may be a number of ways individuals can get more vitamin D, any one on its own is likely to be inadequate. This is part of the reason why many experts recommend that individuals consider taking nutritional supplements.

Mary Ann Giacona, who operates the Center for Wellness in Auburn, New York, wrote in the Auburn Citizen that there are many different ways people can get vitamin D. The most obvious source is food. However, only a few foods, including fish, mushrooms and fortified products, have the nutrient.

The skin naturally produces vitamin D following exposure to UV radiation from the sun or tanning beds. However, these sources may have unintended consequences, such as poor skin health.

"The other option is supplementing through cod liver oil, which is a great source of vitamin D," Giacona wrote.

Alternatively, people can take multivitamins, which contain most of the 600 to 800 international units of vitamin D that an individual should get on a daily basis. For those who think even this level is inadequate, there are also specialty supplements that contain larger doses.