Diet can have a significant effect on asthma, according to research reported in the current issue of California Agriculture journal. The evidence suggests that the risk of asthma and the severity of its symptoms may be increased by low intake of magnesium and overweight.

The research, by postdoctoral researcher Alexandra Kazaks and nutrition professor Judith Stern of UC Davis, also indicates that people who are overweight get less magnesium in their diets.

"Replacing low-magnesium foods with high-magnesium foods may be a practical, low-cost way to reduce asthma symptoms," Kazaks says. "It may also improve overall health."

Inside everyone's bodies, there is an ongoing interplay of damaging reactive molecules and antioxidants that neutralize them. The body's defense systems and the person's diet provide antioxidants that protect cells from damage, such as inflammation related to asthma. In foods, there are more than 4,000 compounds that act as antioxidants, including vitamins C, E and magnesium. The relative importance of individual nutrients in asthma control is unclear, the scientists write, but magnesium appears to be significant.

Asthma is a major cause of illness and disability in the United States. Numerous studies show a relationship between low magnesium intake and asthma symptoms, and studies show that intake of magnesium in the general population does not reach recommended levels. In fact, the scientists report, less than half of American adults consume the recommended daily allowance of magnesium, even though it is found in a variety of foods, including whole grains, green leafy vegetables, legumes and nuts.

The researchers studied a group of Sacramento volunteers, 54 with mild to moderate asthma and 47 who do not suffer from the disease. The subject's weight and height, dietary habits and magnesium levels were documented.

"When the subjects were broken down according to their weight and height ratios, it was very clear that the more overweight the subjects were, the more likely they were not eating foods that provide the recommended levels of magnesium," Stern says. "Further, the asthma subjects who were overweight and obese had significantly lower magnesium than the normal-weight asthma subjects."

The findings led the researchers to the conclusion that increasing magnesium intake and losing weight will help control asthma.

"As a bonus, the foods with magnesium are also part of a diet that supports general good health and healthy weight management," Stern says.

The research report is part of a series of articles on obesity that appear in the July-September issue of California Agriculture journal, http://californiaagriculture.ucop.edu.

California Agriculture is the University of California's peer-reviewed journal of research in agricultural, human and natural resources. For a free subscription, go to: http://californiaagriculture.ucop.edu, write to calag@ucop.edu or call (510) 642-2431 x33.