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The Honolulu Advertiser

Posted on: Saturday, December 28, 2002

You may not really need extra vitamin D

By Laurie Steelsmith

Q. As a resident of Hawai'i, do I really need to take vitamin D for healthy bones?

A. You may need to take vitamin D, or you may not. It depends on your sun exposure, dietary intake and age.

Vitamin D is a nutrient that is critical for healthy bones, because it signals your intestines to absorb calcium from your food when your calcium levels are low.

Vitamin D is made by your body after your skin has been exposed to ultraviolet rays from sunlight. The good news is that through living in the Aloha State, you have excellent sun exposure, allowing you to make vitamin D throughout the year. If you lived in Seattle, you wouldn't be able to make vitamin D during the winter months because of the low angle of the sun.

How much sunlight do you need to make enough vitamin Dr. Michael F. Holick, a leading researcher on sunlight exposure and bone health, recommends you expose your hands, face and arms to sunlight for about 15 minutes two to three times per week. Be sure that your sun exposure is after 8 a.m. and before 4 p.m., and be aware that sunscreens with an SPF greater than 8 block ultraviolet rays, resulting in less vitamin D production.

You can also ingest vitamin D in your food. Milk has been fortified with vitamin D since the 1930s, but a cup of milk contains only about one fourth of your daily need. Foods that contain vitamin D include salmon, mackerel, sardines and eggs. Most multiple vitamins contain vitamin D, although often not enough to provide the recommended daily intake.

How much vitamin D do you need? During different stages of your life, you require different amounts. The recommended amount for everyone 50 or younger is 200 international units per day. For those 51 to 69, 400 IU per day is recommended, and for those 70 or older, the recommended amount is 600 IU per day.

Elders have a greater need for vitamin D; studies have found they make less of it even if they are exposed to the same amount of sunlight as younger people.

Can you get too much vitamin D? Yes, but not from sun exposure or diet. Too much vitamin D from supplements is a concern when daily intake for a prolonged period exceeds 2,000 IU for adults and 1,000 IU for children.

Laurie Steelsmith is a naturopathic physician and licensed acupuncturist in Honolulu.

Send questions to: Prescriptions, Island Life, The Advertiser, P.O. Box 3110, Honolulu, HI 96802; e-mail ohana@honoluluadvertiser.com; fax 535-8170. This column is for information only. Consult your health provider for medical advice.