A new report from the U.S. Surgeon General underscores why it's important not to skimp on dairy products or seafood when trying to whittle your waistline. It turns out that Americans, most of whom eat too much, often don't get enough calcium, vitamin D or activity to keep their bones healthy.

As a result of these deficiencies, the report, "Bone Health and Osteoporosis," concludes that by 2020 one in two Americans over age 50 will be at risk for fractures or low bone mass related to osteoporosis. This chronic, debilitating bone condition already afflicts 10 million Americans; 34 million more are at risk, according to the report.

Nor is this just a problem for older generations. In May, Janet Rubin, professor of medicine at Emory University, testified before Congress that military recruits are frequently deficient in both calcium and vitamin D. Due in part to poor bone health, as many as 5 percent of male recruits and up to 20 percent of female recruits suffer from stress fractures, Rubin said.

The good news: There are simple food choices and smart physical moves that can help build and preserve bone. It's no surprise, of course, that dairy foods and calcium supplements can help. But here are some additional tips:

Breakfast on yogurt and fortified, ready-to-eat cereal. Doing so will get you at least halfway to the 1,000 daily milligrams of calcium considered adequate for those aged 19 to 50. (Youngsters, teens and pregnant or lactating women need 1,300 milligrams daily; adults 51 and older need 1,200 milligrams.)

In addition, cereal and nonfat, plain yogurt are caloric bargains. An ounce of fortified cereal provides 350 to 1,000 milligrams of calcium but just 74 to 120 calories, according to the 2005 U.S. Dietary Guidelines Committee. A cup of plain nonfat yogurt provides 452 milligrams of calcium for just 127 calories. Add some fruit or a dab of honey for extra flavor. (See below why fruit is also good for bones.)

Move it. "You can't make bone without exercise or calcium," said Robert P. Heaney, a physician with the Creighton University Osteoporosis Research Center in Omaha. "You need both." Any activity that keeps you upright helps build and preserve bone. So walk, take the stairs or just stand up frequently throughout the day. Jogging, step aerobics and weight training also help improve bone health.

Snack on . . . herring? It's a rich source of vitamin D, which helps regulate blood levels of calcium and phosphorus. The higher the levels, the better the bone. An ounce of herring has 193 International Units (IU) of vitamin D -- about the daily intake considered adequate by the National Academy of Sciences for healthy people aged 9 through 50. Older adults need twice that amount. But a growing number of experts say that vitamin D recommendations are likely too low.

Most fish and seafood are rich in vitamin D (plus healthy omega-3 fatty acids, which are good for the heart, the brain and the joints). Women of childbearing ages, as well as children, need to balance concerns about mercury and other contaminants. So choose light tuna and limit consumption to no more than twice per week. Find more information at www.cfsan.fda.gov/~dms/admehg3.html.

Drink milk and other vitamin-D-fortified beverages. Other dairy products, including yogurt and cheese, don't have vitamin D. The Dietary Guidelines Committee recommends three servings of milk or other dairy products for those eating 1,600 calories or more per day, two servings for those eating less. Skim milk packs more calcium than either low-fat or whole milk. Can't stomach milk because of lactose intolerance? Choose soy milk or fruit juices fortified with calcium and vitamin D.

Color your plate -- with more fruit and vegetables, that is. Studies presented at the latest annual meeting of the American Society for Bone and Mineral Research suggest that fruit and vegetables alter blood acidity, which in turn helps minimize bone loss -- yet another reason to get those minimum seven servings per day of fruit and vegetables for women, nine for men.

Reach for leafy green vegetables. They're loaded with vitamin K. (Yes, spinach, kale and broccoli also contain calcium, but in a form that is unavailable to the body.) New research hints that vitamin K may boost production of a substance that helps preserve bone density.

Toss some sesame seeds on your salad. An ounce of sesame seeds contains nearly the amount of calcium found in a glass of skim milk. But it packs about 160 calories -- almost double that found in the milk. So go easy.

Easy on the caffeine. "In excess, it's a minor risk factor for bone loss, because it promotes calcium excretion," said Bess Dawson-Hughes, director of the Bone Metabolism Laboratory at the USDA Nutrition Research Center at Tufts University.

Hedge your bets with dietary supplements. "Dairy products remain the best source of calcium, but the American public is not getting anywhere near what they need," said Heaney. Dawson-Hughes routinely recommends both calcium and vitamin D supplements to her patients. Her advice: a multivitamin or a single tablet with 400 IU of vitamin D, plus a calcium tablet or antacid with 500 milligrams or less of calcium -- the most the body can absorb at any one time. Calcium carbonate requires a little food for absorption; calcium citrate or malate can be taken on an empty stomach. Take a calcium tablet before bedtime to help reduce nighttime bone loss.

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