Low-income Sonoma County residents miss out on 47 million meals a year, according to a first-ever calculation of the county's "meal gap" by food, health and human services officials.

Released three days before Thanksgiving, the 2013 Hunger Index report indicates a nutritional shortfall affecting about 40 percent of the county's households, defined as those with an income of $50,000 or less.

The calculation of missing meals was based on food standards set by the U.S. Department of Agriculture, subtracting the number of meals that about 200,000 members of low-income families purchase on their own and leaving a total of 91 million meals a year those families cannot afford.

With food stamps, the Redwood Empire Food Bank and other sources providing 44 million meals a year, the "meal gap" is 47 million meals, the report said.

David Rabbitt, chairman of the Sonoma County Board of Supervisors, said the report underscores an often overlooked reality in a county "known for its rich agriculture and resources."

Thousands of residents, many of them children, are "going to bed hungry each day," Rabbitt said in a written statement accompanying the report.

The food gap report was produced by the Sonoma County Departments of Health Services and Human Services, the food bank, Community Action Partnership and the Redwood Community Health Coalition.

George Malachowski, a Human Services Department analyst, said it was modeled after a Hunger Index developed by the Second Harvest Food Bank of Santa Clara and San Mateo counties and Santa Clara University.

The size of Sonoma County's food gap "didn't surprise me," said Oscar Chavez, Human Services Department assistant director.

Chavez, who joined the county agency six months ago, previously served as executive director of the anti-poverty Community Action Partnership.

"The next step is to figure out what we are going to do about it," he said, acknowledging that food insecurity is "not a problem any one agency can solve alone."

The most immediate step, Chavez said, will be to "maximize existing programs," including food stamps, officially known as CalFresh.

Food stamps, with nearly 35,000 recipients in the county, provide the largest portion (28 percent) of the meals low-income households cannot afford on their own, the Hunger Index report said.

About 29,000 more people, mostly low-wage workers who "don't earn enough to make ends meet," Chavez said, are eligible for food stamps.

Grocery stores, which would benefit from additional food purchases, will be part of a multi-pronged effort to get more people registered for food stamps, he said.

Another effort will be a "bundled services program" initiated in January at five of the United Way of Wine Country's income tax assistance centers, which provide free tax preparation for families earning less than $50,000.

Enabling these families to claim an earned income tax credit can boost their income by $2,000 to $4,000, and signing them up for food stamps can give them an additional financial lift, Chavez said.

The Redwood Empire Food Bank, which feeds 78,000 county residents a month, accounts for 12 percent of the food people can't afford on their own, according to the Hunger Index.

The Women, Infants and Children program, school meals and other programs collectively fill an additional 8 percent of the food gap.

For information on the Sonoma County Hunger Index, go to www.refb.org/hunger_index. For food assistance, call the food bank at 523-7900, or dial 2-1-1 or 565-2108 for the information and referral center.