The American Public Health Association (APHA) has set out to raise awareness of vitamin D deficiency among children and adults alike, a phenomenon that it sees as a top public health issue in the U.S.
According to the association, 30-40 percent of American children and 40-50 percent of adults are at risk of the deficiency which stems mainly from low sunlight exposure, age-related decreases in vitamin D formation through the skin and a diet low in vitamin D.
"Maximal vitamin D production occurs in the summer months, and depending on the latitude, little or no vitamin D may be generated in winter months," says an APHA informational paper.
It adds that clothes can also play a big role, and gives an example of Saudi women who suffer from rampant vitamin D deficiency because traditional clothes completely cover their skin.
Vitamin D is essential for bone health, especially in children and older people, and various studies have linked it to lower risks of cancer and heart disease.
In addition to direct sunlight, other natural sources of the nutrient include butter, eggs, orange juice, and fish liver oils as well as milk and cereal.
Consumers who might be at risk of vitamin D deficiency may consider enriching their diet with supplements.