WEDNESDAY, Oct. 5, 2005 (HealthDay News) -- Higher prices for fruits and vegetables may lead to increased weight gain in school-age children, particularly those who live in low-income areas.
By contrast, new research finds, children who live in neighborhoods where fruits and vegetables are more affordable gain less weight in the years from kindergarten to third grade.
While previous studies have linked the availability of food with diet, this one, conducted by the Rand Corp. and published in the current issue of Public Health, is the first to look at the relationship between children's weight gain and the price of food, said lead author Roland Sturm, a Rand senior economist.
"It's a very important study," said Dr. Tom Farley, a professor of community health sciences at Tulane University School of Public Health and Tropical Medicine in New Orleans. "It's the first that I'm aware of that does link the price of fruits and vegetables or any food item with obesity in kids and maybe even obesity in any age population."
The findings may help explain the current epidemic of overweight and obesity in the United States and other developed nations. During the same period that the study participants gained extra weight, the price of fruits and vegetables rose faster than other food prices and faster than the cost of living, the authors stated.
Experts have postulated that the availability and affordability of different foods might be contributing to the current obesity epidemic. Poor people, who have a higher rate of overweight and obesity, for instance, tend to live in neighborhoods with fewer large supermarkets and more small convenience stores. These smaller stores often carry higher prices.
"Nobody really knows why we're having such a problem with obesity. But it's a severe problem, and it's occurring when nobody wants to be overweight and when everyone understands the basic biology of how you become overweight," said Farley, who is co-author of Prescription for a Healthy Nation. "Many people are interested in trying to understand the environmental influences, and the availability and price of healthy and unhealthy items. There's not much information out there in terms of hard studies."
For this study, the authors looked at weight gain in a nationally representative sample of 6,918 children from 59 metropolitan areas around the United States. The children were followed from kindergarten through third grade. Their weight gain was then cross-referenced with the relative price of fruits and vegetables in each geographic area, as well as with the number of restaurants, grocery stores and convenience stores.
"Usually, because of confidentiality, you don't know where the people live but here we have the zip code and school," Sturm said.
According to growth charts, children should gain about 22 pounds between kindergarten and third grade. The children in this study gained an average of 29 pounds.
Children living in metropolitan areas with higher priced fruits and vegetables gained significantly more weight than children living in areas where these items were more affordable.
For instance, children in Mobile, Ala., the region with the highest relative price for fruits and vegetables, gained 50 percent more excess weight (measured in terms of body mass index) than children nationally. But for children in Visalia, Calif., which had the lowest cost for these items, excess body mass index gain was about half the national average.
Lower meat prices had the opposite effect, although the effect was not statistically significant. There were also no effects for dairy or fast-food prices, the researchers said.
There was again no association between excess weight gain and an overabundance of convenience stores, restaurants (including fast-food ones) and grocery stores in their neighborhood.
That finding, Sturm acknowledged, was "surprising."
But it may not rule out an association, Farley pointed out. "They were looking at levels of entire cities, large geographical areas, so it could be that the influence is more important at small geographical neighborhoods," he said. "The effect could still be there."
This study included no information on what children were actually eating. A different study out this week found, however, that the number and frequency of American children eating restaurant-served fried food more than doubled between 1996 and 1999.
The question then becomes: What can be done? Previous research has found that a 10 percent reduction in the price for fruits and vegetables increased consumption by 7.2 percent.
"You cannot change large-scale prices but there are USDA [U.S. Department of Agriculture] pilot programs in some schools to give kids access to fruits and vegetables," Sturm said. "If we were to roll this program out nationwide, it would cost $4.5 billion, which is not exactly small change."
Food taxes on calorie-dense foods might help ease the problem, Farley said. "It may be the relative pricing that's particularly important," he said. "Working with low-income people in what was New Orleans, we found that the pricing of Twinkies vs. the pricing of an apple can make a big difference."
The U.S. Department of Agriculture has information on nutrition for children and the new kids' food pyramid.