Low levels of vitamin D are a definite red flag that your good bill of health is being threatened. Vitamin D deficiency is an underlying cause of many poor health conditions, as well as a major factor contributing to the exacerbation of symptoms of other diseases. The causes of low vitamin D can be very complex, but ensuring you get enough may be easier than you think.

Vitamin D

Vitamin D is a fat-soluble vitamin that supports a multitude of functions in the body. These functions include supporting pathways that promote bone growth and maintenance, moderating cell growth, neuromuscular function and immune response. The most common source is exposure to UVB rays from the sun, which initiates vitamin D synthesis by the body. A small number of foods provide vitamin D naturally; however, fortification of milk and other dairy products improve intake levels. Supplementation is often necessary to achieve the RDA of 600 IU.

Sunlight and Vitamin D

Low levels of vitamin D can be attributed to a number of behaviors and conditions. Insufficient exposure to sunlight is among the top reasons vitamin D levels are low. Many parts of the world do not see sunlight for a majority of the year, limiting the opportunity for adequate exposure. In other areas, certain cultures require individuals to wear clothing that inhibits sun exposure. Individuals with dark skin do not absorb as much vitamin D as light skin, making adequate exposure times longer for these individuals.

Dietary Causes

Many causes of vitamin D deficiency can be attributed to your dietary and lifestyle choices. Vegetarianism, veganism, obesity, gastric bypass surgery and for children, breast-feeding without supplementation, can all be root causes of low vitamin D. Including fortified dairy products, certain fatty fish, eggs and specially-treated UV exposed mushrooms in your diet can improve vitamin D levels. Supplementation may also be necessary to ensure adequate intake. It is important to consult your doctor to assess your physical condition and lifestyle factors that may be contributing to low levels of vitamin D.

Diseases and Conditions

Some diseases inhibit the body's ability to properly synthesize or absorb vitamin D. Individuals who suffer from fat malabsorption as associated with liver disease, Crohn's disease and cystic fibrosis will struggle to maintain sufficient levels of vitamin D. Kidney and liver diseases can inhibit the body's ability to convert vitamin D to the usable form making absorption minimal to impossible.