WASHINGTON — Virtually all American adults — not just women — should eat and drink more calcium-rich foods such as milk, cheese and yogurt to slow an “alarming” increase in the brittle-bone disease osteoporosis, a panel of experts said Wednesday.

Protecting against brittle bones requires 1,000 to 1,300 milligrams of calcium a day, the report by the Institute of Medicine concludes. But most Americans get far less than that.

“Most age groups are not at 75 percent — especially women,” said Dr. Connie M. Weaver, a Purdue University nutrition expert on the panel. “Among elderly Americans, only about 10 percent are getting anywhere close to the requirements needed to protect against losing bone.”

One cup, or 8 ounces, of skim milk contains about 300 milligrams of total calcium. Thus, drinking 3.3 cups, about 26.5 ounces, would put 1,000 mg of calcium into the diet. About a third of this is absorbed by the body.

But worries about the fat content in whole-milk products has frightened a generation of Americans away from these foods, Weaver said. High-fat diets have been linked to heart disease and obesity. Although fat-free or low-fat milk products are now common, many people still avoid the dairy case, she said.

“That is why one out of four women will have hip fractures within their lifetime,” said Weaver.

In Bangor, at the Maine Center for Osteoporosis Research and Education, nationally known researcher Dr. Cliff Rosen was pleased to hear about the new recommendations. He said calcium intake from age 9 to 18 is critical, as lifetime bone mass is then being formed. The panel Wednesday recommended 1,300 mg daily for the 9-to-18 age group.

But most people, including most pediatricians, don’t think of osteoporosis as a problem that begins in childhood.

“It’s really an adolescent disease,” he said. “It begins with genes that determine bone mass, but the genes can be modified.”

Hip fractures are on the increase among men as well. They now account for about 20 percent of such injuries. Rosen is about to embark on the first major study of osteoporosis in men. He said it takes four to five times longer for men to be diagnosed with the condition.

“The increase in osteoporosis is becoming alarming,” said Weaver. “It now costs the nation about $13.8 billion annually in health care expense.”

New research into calcium and its effect on bones and general health caused the panel to change the way the nutrient’s value is calculated.

Instead of setting a Recommended Dietary Allowance for calcium, the panel established what it calls Adequate Intake. RDAs have been used since 1941 as the measure of “nutritional adequacy,” but the committee said the AI measure is for nutrient levels needed for “optimizing health.”

The new system also establishes more age categories for preferred nutrient levels.

For children ages 1 to 3, the board recommends 500 milligrams of calcium daily. The level jumps to 800 mg for ages 4 through 8, and to 1,300 mg for ages 9 through 18.

The AI for ages 19 to 50 is 1,000 mg. For those aged 51 and older, the board called for dietary calcium levels of 1,200 mg daily.

The new levels are 25 percent to 50 percent higher for adults than RDAs previously used.

“The need is greater than we previously thought, so the requirements went up some,” said Weaver. The most serious deficiency is among females ages 11 and older.

Dr. Rosen said the local study center is seeking funding from the National Institutes of Health for a study of college women at the University of Maine to determine if bone mass can be built after 18 with calcium supplements.

A first-time collaboration with the Maine Dairy Council this fall will bring calcium education to Bangor schools, Rosen said.

“I think this report will push the agenda,” he said. “It’s long overdue.”

With 25 million more Americans expected to suffer from low bone mass down the road, the problem is already closing in on an epidemic, Rosen said. “We’re swamped with calls.”

Calcium intake is best accomplished by eating foods rich in the nutrient, but some people also may require fortified foods or pills, the panel said.

“The panel recommends food first because there are a lot of nutrients other than calcium that are helpful in building bone,” Weaver said. “But taking supplements is better than not getting calcium at all.”

Although dairy foods are the most common source of calcium, food such as tofu, spinach, almonds, mustard greens, pinto beans and broccoli are also rich in it.

The panel also set new dietary levels for phosphorus, magnesium, vitamin D and fluoride. Weaver said these are not significantly different from earlier recommendations.

“Calcium is the most serious issue,” she said.