FEATURE STORY
Healthy Holiday Eating

IN THE NEWS
Beat the Winter Blues with Light Therapy

CHECKLIST
Useful Herbs & Supplements

COOKING CORNER
Sweet Potato Switch

VITAMINS & MINERALS
Vitamin D in the Winter

HERBAL REMEDIES
Root Out Anxiety with Valerian

EVERYDAY ANSWERS
Are There Natural Ways to Keep My Skin Healthy?

More Health Info & Answers

Vitamin D in Winter

Vitamin D deficiency causes abnormal bone formation. It occurs more commonly following winter, owing to restricted sunlight exposure. Living in an area with a lot of atmospheric pollution, which can block the sun's ultraviolet rays, also appears to increase the risk of vitamin D deficiency.

Vitamin D deficiency is more common in strict vegetarians, elderly people, dark-skinned people, alcoholics, people with liver or kidney disease, people suffering from intestinal malabsorption, people with insufficient pancreatic function, and men with advanced prostate cancer. Vitamin D deficiency is also common in individuals with hyperthyroidism, particularly women, and in people with hyperparathyroidism, a condition in which the parathyroid gland is overactive. In children, vitamin D deficiency is called rickets and causes a bowing of bones.

Vitamin D’s most important role is maintaining blood levels of calcium, which it accomplishes by increasing absorption of calcium from food and reducing urinary calcium loss. When necessary, vitamin D transfers calcium from the bone into the bloodstream, which does not benefit bones. Although the overall effect of vitamin D on the bones is complicated, some vitamin D is necessary for healthy bones and teeth.

How much is usually taken?
People who get plenty of sun exposure do not require supplemental vitamin D. Although the recommended dietary allowance for vitamin D is 200 IU per day for adults, there is some evidence that elderly people need 800 to 1,000 IU per day for maximum effects on preserving bone density and preventing fractures. Sun-deprived people should take no less than 600 IU per day and ideally around 1,000 IU per day

Where is it found?
Cod liver oil is an excellent dietary source of vitamin D, as are vitamin D-fortified foods. Traces of vitamin D are found in egg yolks and butter. However, the majority of vitamin D in the body is created during a chemical reaction that starts with sunlight exposure to the skin.

Are there any side effects or interactions?
People with hyperparathyroidism or sarcoidosis should not take vitamin D without consulting a physician. Too much vitamin D taken for long periods of time may lead to headaches, weight loss, and kidney stones. Rarely, excessive vitamin D may even lead to deafness, blindness, increased thirst, increased urination, diarrhea, irritability, children’s failure to gain weight, or death.

vitamin D increases both calcium and phosphorus absorption and has also been reported to increase aluminum absorption. Increased blood levels of calcium (which may be a marker for vitamin D status) have been linked to heart disease. Some research suggests that vitamin D may slightly raise blood levels of cholesterol.

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