Diet Affects Lung Health

September 05, 2000

New York (MedscapeWire) Sept 5 — Breathing and eating are known to interact with each other, for better and for worse, and the food people choose to eat may lastingly affect respiratory function. At the World Congress on Lung Diseases in Florence, Italy, many scientific communications have attempted to unravel the complex relations between respiratory disorders and food.

Asthma is of course one of the prime concerns. Dr. Michael Abramson, associate professor at the Department of Epidemiology and Preventive Medicine, Monash Medical School in Melbourne, Australia, has studied the eating habits of 81 patients suffering from asthma, which he compared with those of a group of 338 healthy individuals. He paid special attention to the effect of tinned oily fish on the disease. He found that eating this food increases the risk of asthma one and a half times. On the other hand, dietary sodium (common salt) appeared to have a preventive effect, reducing the risk 30 times.

This result is in line with previous studies which indicate that some foods or food ingredients can be beneficial to breathing. A recent large-scale survey conducted on 3000 men in Italy, Finland, and the Netherlands found that regular consumption of fruit and green vegetables improved respiratory capacity.

In Italy, this benefit is believed to be due to the vitamin C contained in fresh fruit, whereas in Finland the effect would stem from the vitamin E found in abundance in vegetable oils. In the Netherlands, the scientists concluded that the protective effect was due to the beta-carotene contained in berries or yellow pulp fruit and in vegetables.

A British team reported, after analyzing the lung capacity of 2500 Welshmen, that eating apples was a good way to ward off respiratory diseases. The expiratory volume of subjects who ate 5 apples a week was 140 mL greater on average than that of persons who ate none.

These examples show clearly how food can affect breathing. But the reverse is also true, as was noted at the World Congress on Lung Diseases, and some disorders classified at first sight as respiratory diseases may affect the nutritional condition of patients.

This was found by Dr. Christophe Pison, based in Grenoble, France, and his colleagues of the IRAD network, a group studying persons who are suffering from respiratory failure and receive respiratory assistance at home. As they explained in Florence, the team surveyed more than 700 patients suffering from chronic respiratory failure (CRF), owing either to neuromuscular disorders of the thoracic pump, or to chronic obstructive pulmonary disease (COPD). They found a significant reduction in fat-free mass in 40% of CRF patients and in 80% of patients suffering from either bronchiectasis or neuromuscular disorders.

"CRF was long considered as a chiefly respiratory phenomenon," adds Christophe Pison. "But its effects on the organism as a whole clearly indicates that it should be treated as a systemic disorder, in which denutrition is a preponderant factor." The calorie and protein intake of these patients must therefore be increased, since they have to spend more energy because of their breathing difficulties and chronic inflammatory condition.

This point was highlighted in one of the oral presentations by Dr. Annemie Schols, of the Department de Lung Disease, University of Maastricht, in the Netherlands. "With oral liquid supplements or enteral nutrition," said the Dutch doctor, "a significant increase in body weight and respiratory muscle function may be achieved in COPD patients after only two or three weeks." An even better result is obtained by supplementing the treatment with physical exercise, which has the advantage of increasing fat-free mass, and avoiding an excessive intake of fat, as a precondition of any improvement in breathing.

For this type of patient, breathing difficulties are associated with weight loss; for others, and especially asthmatics, the main problem is weight gain and obesity.

Dr. Mohammed Shamssain, of the Department of Physiology of the University of Sunderland in the United Kingdom, told the congress that many more obese children suffered from asthma. Compared with a general population with no weight problem, where 1 person in 4 is asthmatic, the proportion rises to almost 1 in 5 among obese children. This result, which the author considered "significant," was based on a study of 7000 schoolchildren in northeast England, with similar values for girls and boys.

This link between asthma and obesity was confirmed in Florence by Dr. Isabella Annesi-Maesano, respiratory epidemiologist at the Santé et de la Recherche Médicale (INSERM) in Villejuif, France, who reported even more alarming figures. After an official French National Adolescents' Health Survey, she showed that the risk of asthma was 30% greater on average among obese adolescents, and more so among girls than boys.

In light of these figures, the INSERM epidemiologist decided to analyze the eating habits of French adolescents. Her research brought an unknown fact to light: there are more asthmatics among boys and girls who skip the odd meal or who hide to eat. This means that bad eating habits have harmful effects on the respiratory function.

The answer might lie then in giving the patients back some of the pleasure of eating a good meal. "It is interesting to note that there are fewer asthmatics among young people who regularly enjoy their food," adds Dr. Annesi-Maesan.

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