Sunscreen is considered key when it comes to protecting against skin damage. A new study, however, suggests that there may be a significant drawback to using sunscreen: it could lead to vitamin D deficiency.

Share on Pinterest Researchers say that sunscreen can reduce the body’s production of vitamin D-3 by 99 percent.

The research suggests that sunscreen use and chronic diseases – such as diabetes, celiac disease, and other conditions that affect the body’s ability to absorb nutrients from food – contribute to nearly 1 million cases of vitamin D deficiency across the globe.

Study co-author Dr. Kim Pfotenhauer, from the College of Osteopathic Medicine at Touro University California, and colleagues recently reported their findings in The Journal of the American Osteopathic Association.

Vitamin D is important for bone health, as it helps the gut to absorb calcium. The vitamin also aids muscle and nerve function, and it helps the immune system to stave off infection.

Vitamin D deficiency – generally defined as having a serum 25(OH)D concentration lower than 20 nanograms per milliliter – may lead to loss of bone density, which can increase the risk of bone fractures and osteoporosis.

According to recommendations from the Food and Nutrition Board, adults should aim to get between 600 and 800 International Units of vitamin D every day.

While some foods contain vitamin D – including fatty fish, beef liver, and fortified breakfast cereals – these are usually in low amounts. Exposure to sunlight is considered one of the best sources of vitamin D; sunlight penetrates the skin and converts a vitamin D precursor, called 7-dehydrocholesterol, to the active form of vitamin D-3.

However, the risks that come with sunlight exposure – such as sunburn and skin cancer – cannot be ignored, and sunscreen is considered one of the best ways to protect against such harms.

In their new review, however, Dr. Pfotenhauer and team suggest that individuals should avoid sunscreen use when exposed to midday sun for up to 30 minutes twice weekly, in order to increase and maintain normal vitamin D levels.