Doctors say they are seeing health issues arise in adults and children who do not get the recommended amount of vitamin D.

They say when people don't get enough of the vitamin, it can have significant impact.

"Skeletal issues, muscle function issues, immune system compromise, potential links to chronic diseases and mental health effects," says Matthew Goldman of The Cleveland Clinic.

Doctors also say during the winter, when there is less sun exposure, people are at a higher risk of vitamin D deficiency. Symptoms include fatigue, bone or joint pain, muscle weakness, muscle cramping and mood changes.

If people are concerned that they might be deficient, they should speak to their doctor about diagnosis and treatment options.

Ways to get more vitamin D include eating foods that naturally contain the vitamin or have been fortified with it. Exposure to the sun, specifically UVB rays, can help our bodies, specifically the liver and kidneys, make vitamin D.

People can also take a supplement to increase their vitamin D intake.

"The recommended daily allowance for most adults is 600 to 800 international units. But some individuals may require higher doses especially if they're deficient. It's important to follow your health care providers recommendations and guidance because high doses of vitamin D can lead to toxicity," says Goldman.

A study in the American Journal of Lifestyle Medicine shows people do best with five to 20 minutes of sun exposure each day.