Do You Know Nutrition: Vitamin D protects against disease

April 20, 2010 at midnight
Updated April 19, 2010 at 11:20 p.m.

by Phylis B. Canion

Q: I keep hearing and reading about vitamin D and its importance. How much do we need daily? What are the benefits? What are the best food sources of vitamin D?

A: Studies continue to flood the news about the benefits of vitamin D. These studies indicate it is essential for the heart, bones and almost everything in between.

Vitamin D also protects against diseases such as cancer and diabetes. Current dietary guidelines recommend 400 IU of vitamin D daily. Stephen Sinatra, a cardiologist, recommends 2,000-5,000 IU a day.

Sinatra states that because the average person doesn't spend enough time in the sunlight to produce serum D levels linked to better health, supplementation is more important than ever.

According to the Mayo Clinic, the major biological function of vitamin D is to maintain normal blood levels of calcium and phosphorous. Recent research also suggests that vitamin D may provide protection from osteoporosis, high blood pressure, cancer and several autoimmune diseases.

While vitamin D intake is important, if you suffer from adenoma of the parathyroid gland, granulomatous diseases, lymphoma, sarcoidosis and tuberculosis, these conditions may cause your body to produce too much vitamin D, increasing your risk of developing an elevated calcium level.

As always, I recommend you talk with your physician before starting a vitamin D supplementation program or, for that matter, any supplements.

The best food sources of vitamin D include salmon (cooked-not farm raised), which contains 360 IU for a 3-ounce serving. Mackerel (cooked-not farm raised) has 345 IU for a 3-ounce serving and sardines, canned in oil and drained, contains 270 IU for a 3-ounce serving. An egg has 25 IU and cod liver oil tops the chart with 450 IU for 1 teaspoon.

Q: You recently mentioned in your column a few comments about onions. Can you elaborate a bit more about onions? You previously listed nuts in order of nutrient value, so I wonder if there is one onion variety that is better than another.

A: Onions do have a ranking order with some being better than others based on their antioxidant level. If you can't remember the names, just remember that the sweeter or milder tasting the onion is, the fewer antioxidants it contains. The order, starting with No. 1: shallots (which are related to onions), western white, western yellow, Imperial Valley sweet, northern red and vidalia.

It is best to not store onions in the fridge or near potatoes. Potatoes give off moisture and a gas that causes onions to spoil faster. If you eat onions raw, be sure to wash them thoroughly. Because they grow underground, they can harbor nasty bacteria.

Onion is great for bee stings and removing rust from knife blades. Rub onion on your skin for repelling mosquitoes and biting insects. It worked great for us in Africa.

Phylis B. Canion is a doctor of naturopathic medicine and is a certified nutritional consultant, e-mail her at This column is for nutritional information only and is not intended to treat, diagnose or cure.



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