Tuesday, June 10, 2008

Vitamin D Minimum To Be Increased

In addition to vitamin D's well-known function of increasing calcium absorption and thereby helping encourage healthy bone growth, it has shown promise in helping to prevent certain cancers, heart disease, diabetes, and osteoarthritis.

Foods naturally rich in vitamin D are scarce. However, while many in the scientific community are excited about its promise, they have yet to agree on how much you need and where to obtain it.

Vitamin D behaves like a hormone in the body, relaying chemical messages -- something no other vitamin does. For example, vitamin D signals the intestines to absorb calcium from foods and to regulate its uptake by bone cells.

"Vitamin D is a key component in helping the body respond to many different kinds of assaults and stimuli," says Robert Heaney, Ph.D., professor of medicine at Creighton University in Omaha, Nebraska. "In the absence of it, you're asking the body to defend itself with one hand tied behind its back."

How much do you need?

The Institute of Medicine, a group that uses scientific research to formulate public health policies, currently recommends an Adequate Intake, or AI, rather than a specific daily amount of vitamin D. The AI for vitamin D is 200 International Units for adults under age 50, 400 IU for those 51 to 70, and 600 IU for those age 71 and above.

A group of leading scientists are calling for an "urgent need" to increase the AI for vitamin D. Among them was Walter Willett, M.D., the widely respected chairperson of the Harvard School of Public Health's department of nutrition. "The range we are talking about -- 1,000 IU per day -- is still a small dose," Willett says.

A fair-skinned person can manufacture 15,000 IU or more of vitamin D in as little as 30 minutes of optimal sun exposure.

Patsy M. Brannon, Ph.D., professor of nutrition at Cornell University, says "The current recommendation is a decade old. There's been a lot of research in the last 10 years. Whether there is sufficient strength of evidence to increase recommendations is where scientists disagree."

Until they reach a consensus, you have three options for obtaining vitamin D: food, sunlight, or supplements.

Source 1: Food

Foods naturally rich in vitamin D are scarce. Seafood options top the list -- cod liver oil, salmon, mackerel and tuna. (Bonus: they also contain heart-healthy omega-3 fatty acids.) After that, fortified foods help fill the gap. Milk is fortified with 100 IU per 8-ounce serving. Some yogurts and cheeses also contain vitamin D, as do breakfast cereals and juices.

Source 2: Sunlight

Every time sunlight warms our skin, your body produces vitamin D. However, sunlight is unreliable and several factors influence its ability to induce vitamin D production, including: the angle of the sun, the latitude in which you live, you skin pigmentation, age, and use of skin-care products containing sun-protection factor (SPF). Also, there's the not-small matter of skin cancer risk, which is heightened by exposure to sunlight.

Source 3: Supplements

Supplements are a reliable -- and safe -- source of vitamin D. The key is buying the right type of supplement. Most multivitamins are fortified with the current AI for vitamin D; 400 IU. Check the label to make sure the vitamin you choose is made with the D3 form (it may be listed as cholecalciferol).

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