Vitamin D Therapy
Vitamin D, calciferol, is a fat-soluble vitamin. It is found in food, but can be made in your body after exposure to ultraviolet rays from the sun. Vitamin D exists in several forms, but some forms are relatively inactive in the body and have limited ability to function as a vitamin. The liver and kidney help convert vitamin D to its active hormone form. It aids in the absorption of calcium and promotes bone mineralization (the process where a substance is changed from an organic substance to an inorganic substance) together with a number of other vitamins, minerals, and hormones.
Fortified foods are the major dietary sources of vitamin D. Milk in the United States is fortified with 400 IU of vitamin D per quart. Dairy products made from milk like cheese, yogurt, and ice cream are generally not fortified with vitamin D. Only a few foods naturally contain significant amounts of vitamin D, including fatty fish and fish oils:
Cod Liver Oil, 1 tbs: 1,360 IU
Salmon, cooked, 3 1/2 oz: 360 IU
Mackerel, cooked, 3 1/2 oz: 345 IU
Sardines, canned in oil, drained, 3 1/2 oz: 270 IU
Exposure to sunlight is an important source of vitamin D. Ultraviolet (UV) rays from sunlight cause vitamin D production in the skin. Season, latitude, time of day, cloud cover, smog, and sunscreens affect UV ray exposure. For example, in Boston the average amount of sunlight is insufficient to produce significant vitamin D production in the skin from November through February. Sunscreens with a sun protection factor of 8 or greater will block UV rays that produce vitamin D, so it is still important to routinely use sunscreen whenever sun exposure is longer than 10 to 15 minutes. It is especially important for individuals with limited sun exposure to include good sources of vitamin D in their diet. Try my favorite
Swanson Premium BrandDouble-Strength Cod Liver Oil.
A deficiency of vitamin D can occur when dietary intake of vitamin D is inadequate, when there is limited exposure to sunlight, when the kidney cannot convert vitamin D to its active form, or when someone cannot adequately absorb vitamin D from the gastrointestinal tract.
Americans over fifty are thought to have a higher risk of developing a vitamin D deficiency. The ability of skin to convert vitamin D to its active form decreases as we age. The kidneys, which help convert vitamin D to its active form, sometimes do not work as well when people age.
Wake up gently to the rising sun, the way we were meant to.....
Housebound individuals, people living in northern latitudes such as in New England and Alaska, women who cover their body for religious reasons, and individuals working in occupations that prevent exposure to sunlight are at risk of deficiency and should supplement their diet.
People who have reduced ability to absorb dietary fat, pancreatic enzyme deficiency, Crohn's disease, cystic fibrosis, liver disease, surgical removal of part or all of the stomach, and small bowel disease may need extra vitamin D. Symptoms of fat malabsorption include diarrhea and greasy stools.
It is estimated that over twenty-five million adults in the United States have or are at risk of developing osteoporosis. Osteoporosis is a disease characterized by fragile bones. It results in increased risk of bone fractures. Having normal storage levels of vitamin D in your body helps keep your bones strong and may help prevent osteoporosis. Researchers know that normal bone is constantly being broken down and rebuilt. During menopause, the balance between these two systems is upset, resulting in more bone being broken down than rebuilt.
Laboratory, animal, and the study of epidemic diseases suggest that vitamin D may be protective against some cancers. Some dietary surveys have associated increased intake of dairy foods with decreased incidence of colon cancer. Another dietary survey associated a higher calcium and vitamin D intake with a lower incidence of colon cancer.
Alzheimer's patients have an increased risk of hip fractures because many are housebound and frequently sunlight deprived. Alzheimer's disease is more prevalent in older populations, so the fact that the ability of skin to convert vitamin D to its active form decreases as we age, also may contribute to increased risk of hip fractures in this group. One study of women with Alzheimer's disease found that decreased bone mineral density was associated with a low intake of vitamin D and inadequate sunlight exposure. Physicians evaluate the need for vitamin D supplementation as part of an overall treatment plan for adults with Alzheimer's disease.
Consuming too much vitamin D through diet alone is not likely unless you routinely consume large amounts of cod liver oil. It is much more likely to occur from high intakes of vitamin D in supplements. The Food and Nutrition Board of the Institute of Medicine considers an intake of 1,000 IU for infants up to 12 months of age and 2,000 IU for children, adults, pregnant, and lactating women to be the tolerable upper intake level.
Toxicity can cause nausea, vomiting, poor appetite, constipation, weakness, and weight loss. It can also raise blood levels of calcium, causing mental status changes such as confusion. High blood levels of calcium also can cause heart rhythm abnormalities.
Information provided by the National Institutes of Health, Article Updated: 2001-02-14.