If your bones, muscles or joints ache for no apparent reason, you could be suffering from vitamin D deficiency. This silent epidemic is spreading throughout the United States, because as Americans, we’re increasingly avoiding sun exposure and consuming fewer milk products.

Vitamin D is very important to our health. It helps the body absorb calcium and phosphorus, responsible for bone growth and density. Vitamin D also suppresses the release of a hormone that causes bone breakdown.

Vitamin D can also boost our immune systems and act as an anti-inflammatory. For this reason, it may help treat inflammatory diseases such as certain types of arthritis, dermatologic conditions, osteoporosis, cancers, autoimmune diseases and central nervous system diseases. It may also help prevent organ transplant rejection. Studies show that vitamin D may even play a role in cardiovascular health and the prevention of gum disease.

Vitamin D deficiency can affect anyone and is usually caused by poor diet, insufficient sun exposure or certain diseases that limit the body’s ability to absorb vitamin D. In rare cases, a person’s body absorbs vitamin D but is unable to process it.

Infants, children, the elderly and postmenopausal women are at the highest risk for vitamin D deficiency. Infants are at risk because human breast milk contains low levels of vitamin D, and most infant formulas do not contain adequate vitamin D. The elderly are at risk because they consume fewer vitamin D-rich foods, and their bodies are less able to absorb and store Vitamin D. Postmenopausal women with osteoporosis frequently have unrecognized vitamin D deficiency.

A recent study showed that more than 30 percent of healthy adults ages 18 to 29 had vitamin D insufficiency at the end of winter, falling to 4 percent by the end of summer. The amount of sun needed to synthesize vitamin D varies and depends on the person’s age, skin color, sun exposure and underlying medical problems.

Complications of vitamin D deficiency include low blood calcium, low blood phosphate, rickets (bone softening seen in childhood) and osteomalacia (bone softening seen in adults). Vitamin D insufficiency is also common and may or may not have visible signs or symptoms, but it can still lead to reduced bone density, mildly decreased blood calcium, and an increased risk of falls and fractures. Osteomalacia puts adults at a higher risk for pain and fractures. For these reasons, identifying and treating vitamin D deficiency or insufficiency is important to maintaining bone strength.
 
The daily vitamin D recommendation for infants and children is 400 international units (IU) per day. For adults, the recommendation is at least 800 IU per day. You can increase your vitamin D intake through diet, vitamin supplements and some exposure to ultraviolet (UV) light. However, using sun exposure or tanning beds as the primary source of vitamin D is not recommended due to the risk of skin cancer.

Sources of vitamin D include fortified dairy products such as milk (100 IU per cup), fatty fish such as tuna (200-400 IU per serving) or salmon (800 IU per serving), and cod liver oil (1,300 IU per tablespoon). Other good sources are green leafy vegetables and sundried food productsÑincluding mushrooms, peppers and tomatoes.

If you are diagnosed with vitamin D deficiency or insufficiency, you may also benefit from prescription vitamin D preparations.

Vitamin D deficiency is a commonly unrecognized and undiagnosed condition. If you experience unexplained aches and pains and believe you don’t get enough dietary vitamin D or sun exposure, ask your doctor to check your levels today to get the information or treatment you need to lead a healthier, longer and more comfortable life.

— By Sung Hui Knueppel, M.D.

— The Palo Alto Medical Foundation and column editor Arian Dasmalchi provide this monthly column.