Exercise stimulates bones, causing them to grow stronger.
Are the following statements true or false?
• You needn’t worry about osteoporosis until you’re in your fifties.
• Calcium is the only nutrient important to bone health.
• Dairy products offer the best source of calcium.
• As long as you drink caffeine-free sodas, such beverages aren’t bad for your bones.
False. False. False. False.
Osteoporosis, which means “porous bone,” is a major public health concern, a silent epidemic. About 40 percent of postmenopausal Caucasian women (the group at highest risk) suffer a fracture due to osteoporosis during their lifetime.
Bones are dynamic. In the body’s continual biological sculpture, bone is added and removed. Several hormones, exercise and the availability of building blocks such as calcium determine whether bone is gained or lost. Osteoporosis results when the rate of bone loss exceeds bone growth.
Two factors determine an adult’s bone health at any age: (1) maximum bone mass; and (2) the rate of bone loss with advancing age. Bone mass peaks in adolescence, and bone loss can begin in your early thirties. Think of bone as money in the bank: The more you have when you’re young, the less your chances of running out in old age. Women at greatest risk for osteoporosis are those who did not attain a normal peak bone mass by the age of 20.
Although you can’t relive those prime bone-building teenage years, you can do a lot to hang on to what you’ve got. What’s bad for bones? Smoking, sedentary lifestyle and excessive intake of phosphorus, salt, caffeine and alcohol. Factors beneficial for bones are sound nutrition and exercise.
Smart Nutritional Strategies
A wide spectrum of nutrients — protein, calcium, magnesium, zinc, boron and vitamins D, K and C — maintain bones. A varied, plant-based diet provides most of these nutrients. People who eat plenty of fruits and vegetables have higher bone density scores and less evidence of bone loss. Another recent study found that generous fruit and vegetable consumption (three to five servings per day) correlated with higher bone mass in children entering puberty.
Let’s talk about protein for a minute. Bones contain a lot of it. However, when the body breaks down dietary protein, acids are released. To neutralize these acids, bones release calcium, which is lost in the urine. For this reason, experts used to think high-protein diets were bad for bones. Recent research has questioned that maxim. For instance, among women older than 50, higher protein intakes correlate with greater bone density.
Other nutrients in foods can offset the negative effects of protein. Getting enough dietary calcium makes up for losses. For example, calcium in milk helps compensate for urinary calcium losses generated by milk protein. Plants contain potassium and magnesium, which create an alkaline environment that buffers the acidity due to protein digestion, thus sparing calcium. One study found that elderly women who consumed a high ratio of animal to vegetable protein had more rapid bone loss and a greater risk of hip fracture than did those with a low ratio.
Crucial Calcium, Vital Vitamins and Minerals
Calcium is critical to bones, and most Americans don’t get enough. High calcium intake during childhood and adolescence reduces the risk of later osteoporosis. Most studies show that calcium supplementation in older people retards the loss of bone and diminishes the risk of fractures.
Recommended calcium intake per day is 800 to 1,200 mg for children; 1,200 to 1,500 mg for adolescents and young adults; and 1,000 mg for men and women. Women older than 50 and men older than 65 should bump their intake to 1,500 mg.
Dairy products are not the only sources of calcium. Other excellent choices include the dark-green leafy vegetables (such as kale, collards and mustard greens); calcium-enriched tofu, soy milk, rice milk and orange juice; and molasses, almonds, peanuts, sesame seeds, sunflower seeds, dried beans, seaweed and corn tortillas. According to herbalist Susun Weed, author of New Menopausal Years (Ash Tree, 2002) and other books, calcium-rich herbs include nettle, yellow dock, red clover, oatstraw, plantain leaf, dandelion, mint and sage. Most experts recommend calcium citrate, as it’s better absorbed than calcium carbonate, if you’re getting your calcium from supplements.
Vitamin D is needed for calcium to be absorbed from the intestines. Upon exposure to sunlight, the skin can manufacture vitamin D. The ability to do so diminishes with age. The liver, then the kidney convert this vitamin to more potent forms. Dietary sources of vitamin D include butter, egg yolks, fatty fish, liver and enriched milk. Impaired synthesis of active vitamin D, inadequate dietary intake and insufficient exposure to sunlight can lead to deficiency. And deficiency (common among the elderly) is linked to osteoporosis and an increased risk of fractures. Studies show combined supplementation of calcium and vitamin D can increase bone mineral density. Young people generally don’t need supplements. Many experts recommend people older than 50 consume 400 to 600 IU of vitamin D per day.
Vitamin K plays a role in converting a bone protein called osteocalcin into its active form. Deficiency in this vitamin has been linked to reduced bone density and an increased risk of fractures due to osteoporosis. Conversely, adequate intake and supplementation retards bone loss in postmenopausal women and prevents bone fractures. Green leafy vegetables, broccoli and cabbage are rich sources of the vitamin. So are herbs such as nettle, alfalfa and green tea.
Potassium slows loss of calcium in urine and boosts the rate of bone formation. Foods particularly rich in potassium include avocado, banana, potato, lima beans, tomatoes and dried apricots. One medium baked potato or one large banana can conserve approximately 60 mg of calcium.
Magnesium is important in skeletal metabolism. Deficiency of this mineral seems to contribute to osteoporosis, and supplementation (250 to 750 mg daily) helps reverse bone loss.
Exercise at any age stimulates bones, causing them to grow stronger. Children and teens who exercise have denser bones than their sedentary counterparts. Adults who continue to exercise reduce their rate of bone loss. Two types of exercise help: weight-bearing activities (such as running, jumping, dancing, playing tennis and climbing stairs) and resistance training (such as lifting weights). The effects of exercise are site specific. That is, if you jog, you’ll only stimulate the bones in your legs. To target your upper body, you need to do something like lift weights.
So, be good to your bones. Move them. Give up or cut back on soda consumption and quit smoking. And, eat your fruits and veggies, particularly those green leafy vegetables.
The Phosphorus Paradox
Phosphorus is a major constituent of the mineral content of bone. Too much dietary phosphorus, however, impairs calcium balance and the synthesis of active vitamin D, and promotes a hormone (called parathyroid hormone) that triggers bone loss. The net effect is to de-mineralize bone.
Americans consume too much phosphorus, chiefly in the form of carbonated soft drinks. Cola drinks are particularly high in phosphate (a phosphorus salt). Other sources include processed foods (baked goods and cheese), meat, poultry and seafood. In our culture, carbonated beverages (which lack calcium) often take the place of milk. Kids who drink sodas have lower blood calcium levels. Teenage girls who drink a lot of cola beverages are at increased risk of bone fractures.
Linda B. White, M.D. is the coauthor of Kids, Herbs, & Health (Interweave, 1998), The Herbal Drugstore (Rodale, 2000), and Healing Young Minds (Rodale, 2004).