To build and maintain strong bones, eating the right foods makes all the difference. By the same token, certain foods can actually sap bone strength by leaching minerals right out of the bone, or they block the bone's ability to regrow. Surprisingly, some of these are foods we eat lots of every day. Here, the six biggest bone-sappers:
Soft drinks pose a double-whammy danger to bones. The fizziness in carbonated drinks often comes from phosphoric acid, which ups the rate at which calcium is excreted in the urine. Meanwhile, of course, soft drinks fill you up and satisfy your thirst without providing any of the nutrients you might get from milk or juice.
What to do: When you're tempted to reach for a cola, instead substitute milk, calcium- and vitamin D-fortified orange juice, or a fruit smoothie made with yogurt. Or just drink water when you're thirsty, and eat a diet high in bone-building nutrients.
Salt saps calcium from the bones, weakening them over time. For every 2,300 milligrams of sodium you take in, you lose about 40 milligrams of calcium, dietitians say. One study compared postmenopausal women who ate a high-salt diet with those who didn't, and the ones who ate a lot of salt lost more bone minerals. Our American diet is unusually salt-heavy; many of us ingest double the 2,300 milligrams of salt we should get in a day, according to the 2005 federal dietary guidelines.
What to do: The quickest, most efficient way to cut salt intake is to avoid processed foods. Research shows that most Americans get 75 percent of their sodium not from table salt but from processed food. Key foods to avoid include processed and deli meats, frozen meals, canned soup, pizza, fast food such as burgers and fries, and canned vegetables.
The numbers for caffeine aren't as bad as for salt, but caffeine's action is similar, leaching calcium from bones. For every 100 milligrams of caffeine (the amount in a small to medium-sized cup of coffee), you lose 6 milligrams of calcium. That's not a lot, but it can become a problem if you tend to substitute caffeine-containing drinks like iced tea and coffee for beverages that are healthy for bones, like milk and fortified juice.
What to do: Limit yourself to one or two cups of coffee in the morning, then switch to other drinks that don't have caffeine's bone-sapping action. Adding milk to your coffee helps to offset the problem, of course.
In the case of vitamin A, recent research is proving that you really can get too much of a good thing. Found in eggs, full-fat dairy products, liver, and vitamin-fortified foods, vitamin A is important for vision and the immune system. But the American diet is naturally high in vitamin A, and most multivitamins also contain vitamin A. So it's possible to get much more than the recommended allotment of 5,000 IUs (international units) a day -- which many experts think is too high anyway.
Postmenopausal women, in particular, seem to be susceptible to vitamin A overload. Studies show that women whose intake was higher than 5,000 IUs had more than double the fracture rate of women whose intake was less than 1,600 IUs a day.
What to do: Switch to low-fat or nonfat dairy products only, and eat egg whites rather than whole eggs (all the vitamin A is in the yolk). Also check your multivitamin, and if it's high in vitamin A, consider switching to one that isn't.
Think of alcohol as a calcium-blocker; it prevents the bone-building minerals you eat from being absorbed. And heavy drinking disrupts the bone remodeling process by preventing osteoblasts, the bone-building cells, from doing their job. So not only do bones become weaker, but when you do suffer a fracture, alcohol can interfere with healing.
What to do: Limit your drinking to one drink a day, whether it's wine, beer, or hard alcohol.
6. Hydrogenated oils
For a number of years now, we've known from studies that the process of hydrogenation, which turns liquid vegetable oil into the solid oils used in commercial baking, destroys the vitamin K naturally found in the oils. Vitamin K is essential for strong bones, and vegetable oils such as canola and olive oil are the second-best dietary source of this key nutrient, after green leafy vegetables. However, the amounts of vitamin K we're talking about are tiny here -- one tablespoon of canola oil has 20 micrograms of K, and one tablespoon of olive oil has 6 micrograms, as compared with 120 micrograms in a serving of spinach.
What to do: If you're eating your greens, you don't need to worry about this too much. If you're a big lover of baked goods like muffins and cookies, bake at home using canola oil when possible, and read labels to avoid hydrogenated oils (which many manufacturers of processed foods have eliminated in recent years).