Deficiency of vitamins A and C increases asthma risk

Saturday April 18, 2009 (foodconsumer.org) -- More evidence linking dietary deficiencies to asthma emerged yesterday after British researchers revealed an increased risk for asthma in people who do not have adequate intake of vitamin A and vitamin C. 

The researchers at the University of Nottingham conducted a meta-analysis of 40 studies conducted between 1980 and 2007 before arriving at this conclusion. 

The usual recommended intake for vitamin C is 75 milligrams per day for adult women and 90 milligrams per day for men. However, the present review found that the average intake among those with asthma was just 182 micrograms a day. 

Furthermore, the researchers also found a 12 percent increased risk of asthma among people whose intake of vitamin C-rich foods was low. These patients also had a low level of vitamin A and consumed lesser amounts of vitamin A-rich foods.

The report, which was published in the current issue of Thorax, did not find any association between vitamin E intake and an increased risk for asthma. However in patients who had severe asthma the blood levels of vitamin E were very low as compared to those whose asthma was diagnosed as mild. 

In the United States, more than 22 million people are known to have asthma. Nearly 6 million of these people are children. Earlier studies have shown that the Mediterranean diet, which advocates a high intake of fruits and vegetables, lowers the risk of asthma. It is a known fact that fruits and vegetables are rich in antioxidants. 

The above study highlights the importance of dietary antioxidants in preventing asthma. Consumers must be aware of the sources of vitamin A and vitamin C so they can incorporate adequate amounts into their daily diets. 

Sources of vitamin A - dark green and yellow vegetables and fruits, such as broccoli, spinach, turnip greens, carrots, squash, sweet potatoes, pumpkin, cantaloupe, and apricots. Animal sources include liver, milk, butter, cheese and whole eggs.

Sources of vitamin C - broccoli, bell peppers, cauliflower, strawberries, lemons, turnip greens, Brussels sprouts, papaya, cabbage, spinach, kiwifruit, snow peas, cantaloupe, oranges, grapefruit, limes and tomatoes.

(Written by Kathy Jones and edited by Heather Kelley)