Food that beckons from the organic aisles of grocery stores may not be any better for you than what lines the rest of supermarket shelves.

According to a British review of studies done over the past 50 years, organic and conventionally produced foods have about the same nutrient content, suggesting that neither is better in terms of health benefits.

"We did not find any important differences in nutrient content between organically and conventionally produced foods," said study author Alan Dangour, a registered public health nutritionist with the London School of Hygiene and Tropical Medicine.

Nonetheless, the researchers noted, organic foods continue to grow in popularity. In the United Kingdom, the market share for organic foods increased 22 percent from 2005 to 2007, they said.

Likewise, the market for organic foods in the United States has grown at about a 20 percent rate each year since 1990, reaching $13.8 billion in consumer sales in 2005, according to the Organic Trade Association. That represents 2.5 percent of total food sales in the country, the trade group noted.

"As a registered dietitian, it is good to see that a systematic review of the literature supports what has long been believed -- that the nutritional content of traditionally grown foods and organic foods are comparable," said Connie Diekman, director of university nutrition at Washington University in St. Louis and past president of the American Dietetic Association. "This report provides confirmation for consumers that if they choose conventionally grown foods or organic foods they will be meeting their nutritional needs."

The review zeroed in on 162 studies that dealt with the nutrient content of foods. Only 55 were of what the researchers considered to be "satisfactory quality" -- a strong indicator that, overall, the science on the subject is not up to snuff.

They found no noted differences between conventional and organic crops with regard to vitamin C, magnesium, calcium, potassium, zinc and copper content. Organic crops did have higher levels of phosphorus, and conventionally produced crops had higher levels of nitrogen.