| Vitamin D, a fat-soluble vitamin, is required
for the absorption and utilization of calcium
and phosphorus by the intestinal tract. It is necessary
for growth, and is especially important for the normal growth
and development of bones and teeth in children. It protects
against muscle weakness and is involved in regulation of the
heartbeat. It is also important in the prevention and treatment
of osteoporosis and hypocalcaemia, enhances immunity, and
is necessary for thyroid function and normal blood clotting.
The form of vitamin
D that we get from food or supplements is not fully active.
It requires conversion by the liver, and then by the kidneys,
before it becomes fully active. This is why people with liver
or kidney disorders are at a higher risk for osteoporosis.
When the skin is exposed to the sun’s ultraviolet rays,
a cholesterol compound in the skin is transformed into a precursor
of vitamin
D. Exposing the face and arms to the sun for fifteen minutes
three times a week is an effective way to ensure adequate
amounts of vitamin
D in the body.
Severe deficiency of vitamin
D can cause rickets in children and osteomalacia, a similar
disorder, in adults. Lesser degrees of deficiency may be characterized
by loss of appetite, a burning sensation in the mouth and
throat, diarrhea, insomnia, visual problems, and weight loss.
Sources
Fish liver oils, fatty saltwater fish, dairy products,
and eggs all contain vitamin D. It is found in butter, cod
liver oil, dandelion greens, egg yolks, halibut, liver, milk,
oatmeal, salmon, sardines, sweet potatoes, tuna, and vegetable
oils. Vitamin D is also formed by the body in response to
the action of sunlight on the skin. Herbs that contain vitamin
D include alfalfa, horsetail, nettle, and parsley.
Comments
Intestinal disorders, liver problems, and gallbladder
malfunctions interfere with the absorption of vitamin D. Some
cholesterol-lowering drugs, antacids, mineral oil, and steroid
hormones also interfere with absorption.
Cautions
Do not take vitamin D without calcium. Toxicity may
result from taking amounts over 65,000 international units
over a period of years.
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Vitamins and Minerals > Vitamin D
