The easiest way to get vitamin D is from sunlight. The ultraviolet rays react with skin cells to produce the vitamin. But many people worry about skin cancer and skin damage from the sun.
Also, darker skinned people produce less vitamin D than lighter skinned people. Production also decreases in older people and those living in northern areas that get less sunlight. Vitamin D helps bones and muscles grow strong and healthy. Low levels of vitamin D can lead to problems like rickets and osteoporosis. Rickets is a deformity mainly found in children. Osteoporosis is the thinning of bone, a common problem as people, especially women, get older.
Studies in recent years have suggested that vitamin D may also have other uses. Studies have shown that low levels of D may increase the risk of heart attacks in men and deaths from some cancers. Other studies have shown that people with rheumatic diseases often have low levels of D.
Not many foods naturally contain vitamin D. Foods with high levels include oily fish such as salmon, tuna and mackerel, and fish liver oils. Boston University researchers reported in two thousand seven that farmed salmon had a lot less vitamin D than wild salmon.