Vitamin D plays a major role in the body's regulation of calcium and phosphorous levels in the blood. It also helps absorb calcium, which is needed for strong bones. According to the Mayo Clinic, vitamin D may protect against osteoporosis, cancer, high blood pressure and some autoimmune diseases. Vitamin D is found in a variety of foods.
Normal Lab Values
Normal levels of vitamin D in blood tests are 20 ng/mL to 50 ng/mL. At this level, vitamin D stores are adequate for bone and overall health in most healthy adults. Levels less than 12 ng/mL are considered deficient and can cause rickets in infants and children and osteomalacia in adults. Levels from 12 ng/mL to 19 ng/mL are considered inadequate for bone and overall health. At levels greater than 50, toxicity and adverse effects can occur.
Vitamin D and Calcium
More than 40 million adults in the U.S. have or are at risk of developing osteoporosis. This is a condition in which low bone mass greatly increases the risk of bone fractures. Vitamin D is vital in preventing osteopororis because it helps the body absorb calcium. Older individuals, people who do not exercise enough, postmenopausal women, and those on chronic steroid therapy are at risk of inadequate vitamin D levels.
Sources of Vitamin D
Vitamin D is found naturally only in a very few foods -- primarily fatty fish such as tuna, salmon, and mackerel and in fish liver oils. Cheese, egg yolks and beef liver contain small amounts of vitamin D. Most Americans get their vitamin D from fortified foods such as milk, orange juice, cereals, and yogurt. Some margarines are also fortified. Other sources of vitamin D include exposure to sunlight and vitamin supplements. The U.S. Food and Drug Administration currently recommends 400 IU, or international units, for most children and adults.
Toxicity and Deficiency
While toxicity is very rare, taking too much vitamin D can cause severe damage to the body, including the kidneys, bones and soft tissues. Signs and symptoms of vitamin D overdose include constipation, fatigue, irritability, muscle weakness and high blood pressure.
Having insufficient vitamin D is more likely. According to the U.S. News, people with lower levels of vitamin D are at greater risk for respiratory infections, such as colds and the flu. Those with a history of asthma or chronic obstructive pulmonary disease are more likely to have vitamin D deficiencies. Nearly half of American adults are vitamin-D deficient and may be at increased risk for strokes and heart attacks.
Member Comments