WASHINGTON — The dramatic increase in availability of whole grain foods in recent years may offer hope that changes in labeling requirements for food service establishment could have the desired effects of improved eating.

The connection between whole grains and healthier eating at restaurants was proposed in a study, “Will Calorie Labeling in Restaurants Make a Difference?” published recently in Amber Waves magazine by the Economic Research Service of the U.S Department of Agriculture.

Authors of the article were Rosanna Mentzer Morrison, Lisa Mancino and Jayachandran N. Variyam, all with the E.R.S.

The article, asking whether calorie labeling in restaurants matters, was prompted by a provision in the Patient Protection and Affordable Care Act of 2010 requiring chain restaurants to post the number of calories in each standard menu item.

While many restaurants already offer such information, the study estimated that 55% of U.S. restaurants will be affected by the new law. The rule exempts restaurants with fewer than 20 locations.

In addition to exploring the degree to which labeling will affect customer behavior (and serious doubts are raised by the authors about this issue), the study raised the possibility restaurants may adjust their menus in response to the new law.

“Changing food choices is not the only way to shift aggregate consumption patterns and nutrient intake,” the U.S.D.A. said. “In an effort to compete for health-conscious customers, manufacturers often introduce new products or reformulate existing ones to capitalize on the latest health concerns. Such changes can offer secondary benefits. Even consumers not looking for better nutrition may reap dietary benefits from healthier versions of their favorite foods and beverages. Calcium-fortified juices and breads are examples of such product reformations.”

The authors went on to say bakers were “quick to respond” to recommendations in the 2005 Dietary Guidelines for Americans that at least half of grains consumption should be from whole grains. They cited other E.R.S. researchers noting the average of new whole grain product introductions jumped to 16 per month in 2006 from 4 in 2001.

“For whole grain products, these reformulations have translated into increased sales of healthier foods,” the E.R.S. said. “Using Nielsen Homescan data, E.R.S. researchers found that in 2001, whole grain products accounted for 11.1% of all pounds of packaged grain products purchased in grocery stores (excluding flours, mixes and frozen or ready-to-cook products). By 2006, whole grains’ share of total grain product purchases was 17.9%. E.R.S. researchers found whole grain bread accounted for 6% of all pounds of bread purchases in 2001 and close to 20% by 2007. Over this same period, whole grain cereals jumped from 30% of all cereals purchased to 46%.”

A more direct reformulation example cited by the authors was what has happened with trans fatty acids.

“The F.D.A. issued a final regulation for mandatory trans fat labeling in 2003, which went into effect on Jan. 1, 2006,” the authors said. “Manufacturers reacted to media attention and mandatory trans fat labeling by reformulating many of their products. The number of new products stating ‘no trans fats’ on the label increased from 64 in 2003 to 733 in 2007, then fell to 642 in 2008.”

Bolstering the connection with restaurants, the authors said public health advocates are hopeful that calorie labeling will encourage restaurants to reformulate many calorie-dense products and lead to the introduction of lighter, healthier options.

“The question is, will customers buy the lower calorie entrees and side dishes?” the study asked. “Some observers are dubious, since past attempts to offer healthier menu items have not always been successful, especially when reformulating ingredients that influence taste perceptions.”

The possibility that consumers may not respond to restaurant nutrition labeling in the same way they do at supermarkets was raised by the authors. On a more optimistic note, they raised the possibility consumers could be even more attentive since they will be looking at calories for an entire dish versus a single ingredient that will be part of a meal.

Back to a more wary perspective, they noted a study of New York’s calorie labeling law. The requirement “did not appear to have an effect on the quantity of calories consumers purchased,” they said.

Researchers in the New York study found that 27.7% of New York customers indicated their choices were influenced by the labeling, resulting in the purchase of fewer calories.

“Their receipts showed otherwise, however,” they said. “Survey participants in New York City purchased about the same number of calories both before and after the labeling law took effect, and about the same amount as the New York participants. “

The U.S.D.A. said a different study, though, showed labeling has had the desired effect of reducing caloric intake at Starbucks.

The second study, conducted by Stanford University researchers, found that calorie posting caused average calories to fall by 6%, to 232 calories per transaction.

“Almost all of the effect was related to food purchases,” the U.S.D.A. said. “There was almost no change in purchases of beverage calories.”