Diet and Osteoporosis: How to Strengthen Weak Bones
There's nothing in your refrigerator or cupboard that can cure osteoporosis. And no matter what vitamins or supplements you take, there are also no guarantees against broken bones. But if your bones have lost some of their strength, you'll need to pay extra attention to nutrition. Along with prescription medications and regular exercise, proper nutrition is a vital part of the three-pronged approach to managing osteoporosis.
How much calcium and vitamin D do I need?
Calcium and vitamin D are definitely the two most vital nutrients for healthy bones. Calcium is the mineral that gives bones their density and strength. But it's also important for many other parts of the body, including nerves, muscles, and cell membranes. If you don't get enough calcium in your diet, your body will start leaching the mineral from your bones to keep the rest of your system running smoothly. Vitamin D acts like a key to help calcium get into bone cells. So if you don't have enough D, the calcium in your diet may never have a chance to protect your bones.
Your doctor can check to see if you are deficient in vitamin D, and give you supplements to regulate your levels if they are low.
People with osteoporosis need to go above and beyond when it comes to getting enough calcium and vitamin D. Adults over 50 should aim for at least 1,200 mg of calcium, and 800 to 1,000 IU of vitamin D each day. (Because thinning bones are so common in later years, these goals make good sense for anyone over 50.) Studies have found that patients who get enough of these vital nutrients can cut their risk of broken bones by 35 percent to 50 percent.
It's possible, but difficult, to get all of the calcium that you need from diet alone. One cup of low-fat milk has a little less than 300 mg of calcium, so you'd need to drink more than four cups a day to reach your goal. Fortunately, there are plenty of nondairy sources. A cup of fortified soy milk (a good option for people who are lactose intolerant), contains about 370 mg of calcium, and a half-cup of cooked spinach contains about 120 mg. Even with so many calcium-rich options, you'd have to make a concerted effort to make sure you don't fall short on a given day.
In reality, many people don't get enough calcium from their diet. In such cases, doctors often recommend calcium supplements. Supplements are inexpensive and easy to take. Choose a supplement containing either calcium phosphate or calcium citrate. These are less likely to cause constipation, the one common complaint for people taking calcium supplements.
Likewise, it's possible to get enough vitamin D without supplements, but it's not especially easy. Whenever your skin is exposed to strong sunlight, you'll start manufacturing vitamin D. You can also get modest amounts of vitamin D in your diet. A good-sized piece of salmon will get about halfway to your daily goal. Add four cups of vitamin D fortified milk, and you're there.
Many people with osteoporosis don't get enough vitamin D from sunlight or their diets to protect their bones. Again, supplements can be an excellent insurance policy. Vitamin D can be taken on its own, or as part of a multivitamin. Some products combine vitamin D with calcium for extra convenience.
What about soy?
Over the years, soy foods and supplements have gained a reputation as an all-purpose natural remedy for postmenopausal women. Soy-based products contain compounds that are similar to estrogen, the female hormone that diminishes during menopause. In theory, women who eat a lot of these soy compounds -- called isoflavones -- could avoid some of the side effects of menopause, including thinning bones. A study published in the Annals of Internal Medicine in 2007 found that postmenopausal women who took calcium and vitamin D along with 54 mg of the phytoestrogen genistein each day for two years had denser bones than women who merely took calcium and vitamin D. However, the study was too short to know if fracture risk was affected.
Although more research is needed, it's reasonable to expect that moderate amounts of soy may be good for your bones. As with calcium and vitamin D, food sources may not be enough to get the protection you need. You'd have to eat almost one pound of tofu or drink more than three cups of soy milk each day to consume the amounts of genistein used in the Annals of Internal Medicine study. (Soy products contain other isoflavones, too, but their effect on bone density isn't clear.) In moderation, soy supplements are generally safe, but some experts believe that high doses can be dangerous to women with breast cancer; some experts have also raised concerns about supplements for women at high risk for breast cancer.
Should people with osteoporosis avoid particular foods?
People with osteoporosis don't need to completely cut out any specific foods or beverages for the sake of their bones. But some things definitely call for moderation. For example, caffeine can speed the loss of calcium in your urine, so you should try not to have too many caffeinated drinks each day. One study of more than 30,000 Swedish women found a possible association between drinking four cups of coffee each day and an increased risk of fractures. Also, the phosphoric acid found in some sodas could potentially strip calcium from bones, but you can still enjoy soda every once in a while, especially if you generally get plenty of calcium in your diet. Some nutritionists recommend going easy on salty foods, but there's not much evidence that salt makes osteoporosis worse.
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Michael Potter, MD, an attending physician and associate clinical professor at the University of California, San Francisco, who is board-certified in family practice.