We've been told all our lives to drink milk for strong bones. Many of us even feel guilty when we don't get the recommended three servings of dairy each day. In fact, we've been led to believe that we have a "calcium crisis" in the United States because so many of us don't get enough dairy. The proposed solution? Drink more milk, eat more yogurt and cheese, and take calcium supplements.

So why are we convinced that milk, dairy foods, and calcium supplements prevent the fractures osteoporosis can cause? Because teachers, doctors, and advertisers have told us we need calcium - and lots of it - to keep our bones strong as we age. Because every major US health agency endorses daily consumption of milk and dairy: the Surgeon General, the Centers for Disease Control and Prevention, the National Institutes of Health, and the National Osteoporosis Foundation.

But consider this: The most industrially advanced countries - the US, Australia, New Zealand, and most Western European nations - have the highest fracture rates, yet consume more dairy than anywhere else in the world. Meanwhile, the people in much of Asia and Africa consume little or no milk (after weaning), few dairy foods, and next to no calcium supplements, and their fracture rates are 50 to 70 percent lower than ours. What's going on?

The latest research shows that our bones need more than just calcium. It turns out the way we eat - along with our lifestyle choices and stress levels - can actually contribute to bone depletion, no matter how many calcium supplements we take or glasses of milk we drink. Amy Lanou, PhD, an assistant professor of health and wellness at the University of North Carolina Asheville, and I came to this realization after reviewing 1,200 studies on the dietary risk factors for osteoporosis. Our rather radical conclusion: The calcium theory is bankrupt. The better solution? Eating a low-acid diet, which strengthens bones much more effectively and, as a growing number of bone-health researchers agree, holds the key to preventing osteoporosis.

Why calcium isn't all bad

We have nothing against calcium. It's an essential mineral necessary for good health. But bone health doesn't depend on taking lots of calcium. Just look at these studies:

Four worldwide epidemiological surveys show that the nations that consume the most calcium have the highest rates of hip fracture.

One epidemiological study correlated hip fractures with the amount of animal and vegetable protein various countries consume. As animal food consumption increases, so do hip fractures.

Since 1975, 136 trials have explored calcium's effects on osteoporotic fracture risk. Two-thirds of these studies show that high calcium intake yields no reduction in the number of fractures - even if people begin taking calcium (with vitamin D) during childhood.

In one study, Harvard researchers surveyed diet and hip fractures among 72,337 older women for 18 years. They concluded, "Neither milk nor a high-calcium diet appears to reduce [fracture] risk."

Another Harvard team analyzed seven trials that followed 170,991 women for several years and found "no association between total calcium intake and hip fracture risk."

So why the almost monomaniacal emphasis on calcium? Because your body needs it. Calcium supports the structure and function of your bones and your teeth. So, the logic goes, since your body needs a lot of calcium, you should consume lots of dairy, which is high in calcium. But here's where that theory breaks down: Think of calcium as the bricks in a brick wall of bones. Bricks are essential, for sure, but without enough mortar - which comes in the form of about 16 other nutrients - the wall can't hold itself up. (See "Beyond Calcium," page 60.) So, yes, you do need calcium, but you must supply the body with the right kind of calcium - which does not come from dairy products - along with plenty of other vitamins and minerals.

A better bone-health diet

In order to get the right balance of bricks and mortar, so to speak, you need a diet that's packed with fruits and vegetables and includes few (if any) high-protein foods such as meat, poultry, fish, milk, and dairy. Why? Strange as it may sound, good bone health begins in the bloodstream - and a high-protein diet acidifies the blood. For the body to function properly, the blood must maintain a pH (relative acidity or alkalinity) that's slightly alkaline.

Protein is composed of amino acids. As the body digests high-protein foods, amino acids flood the bloodstream. The body must then neutralize these acids to avoid life-threatening problems, including osteoporosis. To do so, the body draws from its own reservoir of alkaline material, such as the calcium compounds stored in bone. The bones release their calcium, which eventually gets excreted in urine. Unfortunately, as many studies suggest, the more dietary protein we consume, the more acidic the blood becomes and the more calcium the body must leach from the bones to bring the blood's pH back into balance.

While dairy does contain ample calcium, it's also highly acidic. So if you drink milk (or eat a lot of animal protein) and don't include plenty of alkalizing foods, your diet will - ironically - suck more calcium from bone than it provides, and eventually cause osteoporosis.

What about vegetable proteins?

Many Americans believe they can't get adequate protein if they don't eat animal foods. This is not true. Nutritionists agree that vegetarians can get more than enough protein for good health. In fact, the diseases that kill most Americans (heart disease, cancer, stroke, diabetes) are all closely linked to diets too high in animal foods. That's why a low-acid diet not only helps prevent osteoporosis, it can also reduce your risk of Western society's major killers.

Although fruits and vegetables do contain enough protein to keep you healthy, their protein counts are much lower than those of animal foods. But when you eat fruits and veggies, only a small amount of acid enters the bloodstream, along with a great deal of alkaline material that immediately neutralizes the acid. As a result, the body doesn't need to draw calcium compounds from bone, resulting in healthier bones.

Meat, fish, poultry, and dairy, on the other hand, contain five to 10 times more protein per serving than fruits and veggies - and very little alkaline material - which means the blood's acidity level skyrockets and the body must look to bone for additional calcium to neutralize it.

Healthy bones: the whole picture

Although fracture studies show that increasing calcium doesn't prevent breaks, research on bone-mineral density (BMD) - which measures the amounts of calcium and other minerals in your bones - says otherwise. By a slim majority, studies found that calcium improves BMD. So how do we explain this apparent contradiction? By remembering that bones are more than calcium and that strong, fracture-resistant bones require a balance of calcium and at least 16 other nutrients (see page 60). Once again, consuming lots of calcium but not enough of the other nutrients is like building a brick wall without enough mortar. The wall may look strong, but it isn't.

In fact, more than 100 studies have explored the effects of fruits and vegetables on BMD. Although calcium improved BMD in 52 percent of studies focused on the mineral, fruits and vegetables improved BMD in 85 percent of more than 100 studies on these foods. That's no surprise, since fruits and veggies contain not only calcium but plenty of other bone-building nutrients as well.

Remember, how you live your life is up to you. If you want to eat the American-standard 220 pounds of meat a year and only two to three servings of fruits and vegetables a day, go for it. But this type of diet carries a high price - substantial risk of osteoporosis and other top causes of death, including heart disease, cancer, and stroke. Low-acid eating is the key to healthier bones and decreasing your risk of osteoporosis. It's a safe, effective, low-cost prescription for health, vitality, and longevity.