Vitamin D: what to know when sunlight is not enough

Vitamin D is often called the sunshine vitamin because the body can make it when skin is exposed to sunlight. Food and supplements can also contribute, especially when sun exposure is limited.

Its best-known role is helping the body absorb calcium and maintain normal bone health. It also plays a role in muscle function and normal immune function.

A low vitamin D result can happen for many reasons: winter, indoor routines, darker skin, covered clothing, sunscreen habits, older age, digestive conditions, or a diet with few vitamin D-rich foods.

Useful food sources include fatty fish, eggs, fortified dairy or plant milks, and fortified cereals. For some people, food alone may not provide enough.

More is not automatically better. Vitamin D is fat-soluble, and high intakes can become unsafe, especially when combined with high calcium intake or certain health conditions.

If you have low sun exposure, bone concerns, kidney disease, pregnancy, medication use, or a previous low blood test, ask a healthcare professional about testing and the right dose.

Only Health products that include vitamin D should be treated as routine support, not a replacement for testing or medical care when deficiency is suspected.