WASHINGTON — The inclusion of whole grains as an option in The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) has led to increased intake of whole grains by WIC participants, according to a study on the subject published by the Economic Research Service of the U.S. Department of Agriculture. Still, whole grains intake among WIC participants remains well below levels recommended in the Dietary Guidelines for Americans.

The research was published in a 19-page report titled “U.S.D.A. Special Supplemental Nutrition Program for Women, Infants, and Children (WIC): A New Look at Key Questions 10 Years After U.S.D.A. Added Whole-Grain Bread to WIC Food Packages in 2009.”

In addition to commenting on consumption patterns, the researchers suggested a rule allowing only 16-oz loaves to qualify for redemption with WIC benefits to be overly restrictive and possibly counterproductive.

The report was written by E.R.S. economists Hayden Stewart, Jeffrey Hyman, Patrick W. McLaughlin and Diansheng Dong.

WIC is a U.S.D.A. program providing low-income, nutritionally at-risk pregnant and postpartum women, as well as infants and children up to 5 years of age, with food assistance and nutrition counseling. During the first five months of fiscal 2018, about 7 million participants per month were indicated. Foods in the program include infant formula and infant-food fruits, vegetables, and meats; fluid milk; vitamin C-rich fruit or vegetable juice; eggs, cheese, peanut butter, dried and canned beans/peas, canned fish, whole grains, and iron-fortified cereal.

The study explored the effects of 2009 changes the U.S.D.A. made to the WIC food packages, incorporating whole grains. Those changes, in turn, followed a 2005 report from the National Academies advocating adjustments to WIC food packages in line with changing Dietary Guidelines for Americans. Beginning in 2005, the dietary guidelines began advocating that at least half of grains consumed be whole grains. Additions in 2009 included a 1 lb of 100% whole wheat bread and other whole grain options, such as brown rice and whole grain tortillas, to WIC food packages for pregnant and breastfeeding women and 2 lbs to the WIC food package for children 1-4 years old.

Five years after the changes were incorporated, the U.S.D.A. asked the National Academies of Sciences, Engineering and Medicine (NASEM) to help conduct independent research looking at the WIC food packages and to make cost-neutral recommendations for changes that would better align the packages with the nutritional needs of the WIC-eligible population. In 2017, a committee formed by NASEM offered a number of recommended changes.

“These include offering 16- to 24-oz packages of 100% whole wheat bread and other whole grain options to all participants who receive this benefit, which would relax regulations that effectively require stores to stock 16-oz packages,” the E.R.S. said.

Research conducted by the E.R.S. showed that WIC households acquired significantly more whole grains in bread than did WIC-eligible households that were not participating in the program.

The research went on to show that the requirement that whole wheat bread be sold in 16-oz packages had an impact on sales of 16-oz loaves. Between 2009 and 2015, the share of whole wheat bread sales accounted for by 16-oz packages rose to 17% from 8%.

“Bread sold in 16-oz packages appears to be less economical than bread sold in larger, more standard package sizes, including both 100% whole wheat and other types,” the E.R.S. said. “For example, in 2015, a 24-oz package of 100% whole wheat bread cost $2.85, a 20-oz package cost $2.60 and a 16-oz package cost $2.76, on average. Thus, it could be cheaper to allow WIC benefits to be redeemed for a 20-oz loaf than a 1-lb loaf.”

The E.R.S. researchers said that 20-oz and 24-oz loaves of bread were far more common in the marketplace than 16 oz.

“(Bakers) seeking to produce WIC-eligible products had to adjust their production processes in order to supply whole grain bread in 16-oz packages,” the E.R.S. said. “Retailers likewise needed to create shelf space for a package of bread that was at the time not readily available on the wholesale market and not widely purchased by non-WIC participants. Concerns arose about the potential for limited availability and inflated prices.”

As suggested by NASEM, the Department recently has recommended allowing 20-oz and 24-oz packages to be included in WIC packages.

Research on whole grains intake was done using data from Information Resources, Inc. together with the National Household Food Acquisition and Purchase Survey (FoodAPS). Conducted by the U.S.D.A., FoodAPS was a survey of 4,826 demographically representative households between April 2012 and January 2013. The households were asked to report all food items they purchased.

The E.R.S. said WIC participants have been generally satisfied with the whole grain bread and other whole grain options added to their food packages since 2009.

According to the WIC guidelines, the U.S.D.A. has stipulated that whole wheat flour must be the only flour used in making the dough for 100% whole wheat bread. For all other whole grain bread, the U.S.D.A. stipulates that whole grains must be the primary ingredient by weight.

Notwithstanding the many options, “100% whole wheat bread appears to account for the bulk of bread redemptions,” the E.R.S. said

In studying whole grains purchasing decisions, the researchers examined bread buying behavior of both non-WIC households as well as WIC households during weeks when the households use and do not use benefits.

“The researchers identified an overall positive association between WIC and households’ purchases of whole grains in bread,” the U.S.D.A. said. “They also found that WIC households are less likely than other households to choose a whole grain product when paying ‘out of pocket.’”

Using its National Household Food Acquisition and Purchase Survey, the U.S.D.A. found that WIC households acquired an average of 1.33 ounce-equivalents of whole grains in bread per member, on average, versus 0.72 ounce-equivalents for the eligible, non-WIC households.

“This difference is statistically significant and can be attributed to purchases of bread through the WIC program, which must be whole grain products,” the E.R.S. said.

While a meaningful improvement from non-WIC families, the WIC families intake of whole grains remained far less than 50% of all grain intake, the E.R.S. said.

Overall intake of grain products was no higher for WIC households than non-WIC, the E.R.S. said. Total grain intake was 5.52 oz per person per week in WIC households and 5.92 oz in non-WIC households.