Asthma linked to lack of vitamins A and C in the diet

A review of published scientific studies carried out by British researchers has revealed that people with low levels of the vitamins A and C were more likely to suffer from asthma.

The review of 40 studies by researchers at the University of Nottingham, found that a diet low in vitamins A and C increases the risk of developing asthma and the increased risk was independently linked to each vitamin - people with the lowest levels of vitamin A tended to have more severe asthma than other sufferers.

The researchers analysed the data from the studies and found no link for vitamin E, but said the associations for A and C were significant, and on average, men with asthma were lacking 26% of their daily requirements of vitamin A, while women with asthma were lacking 30%.

The findings of this latest research contradict the results of a large-scale study published last year which found no link between levels of antioxidants in the diet and asthma and the Nottingham team say their study is more robust.

According to health experts a healthy diet should provide people with their daily supply of vitamins A and C - good sources of vitamin A include cheese, eggs, oily fish, milk, fortified margarine and yoghurt and good sources of vitamin C are a wide variety of fruit and vegetables, including broccoli, Brussels sprouts, sweet potatoes, oranges and kiwis.

The review included studies carried out over the last three decades, that measured dietary intake of the vitamins, or levels of vitamins in the blood - 13 of the studies related to children while the rest were in adults or were unspecified.

Lead researcher Dr. Jo Leonardi-Bee says their findings indicate that low levels of vitamin C intake and - to a lesser extent - vitamin A are consistently associated with asthma risk to a degree that, if causal, would be sufficient to be clinically relevant.

Dr. Leonardi-Bee says it is now important that larger-scale studies are carried out in order to clarify the link and to see if there was a direct cause between vitamin intake and asthma.

The review is published in the journal Thorax.