Osteoporosis, which means 'porous bones', describes any condition that reduces bone mass. Symptoms include leg and foot cramps; height loss; lower-back pain; hip, wrist and spine fractures; and 'dowager's hump' (upper spine curvature). Some bone loss is natural in both women and men with age - it's only when bones are thin and brittle that osteoporosis occurs. The good news is that there are many things you can do to prevent this disturbing condition.
* Calcium may help. Higher calcium intake hasn't reduced the risk of osteoporosis in women just entering menopause (Clin Ther, 1998; 20: 933-44) or in men (J Nutr, 1997; 127: 1782-7). But three years or so into menopause, calcium supplementation does appear to be protective in women (Am J Ther, 1999; 6: 303-11). Nevertheless, even the most positive trials show that calcium on its own is not enough (see box, upper right).
* Choose dietary sources of calcium. Different dairy products have different effects on bone density and fractures (Am J Clin Nutr, 2000; 72: 681-9). Milk, especially non-fat milk, is a good choice because it is relatively low in protein and salt, and higher in calcium. But cottage cheese and some hard cheeses may be high in salt and low in calcium. Younger women may benefit from including non-fat milk and yoghurt in their diets.
* Exercise helps in two ways. Load-bearing exercise helps keep bones strong and increases muscle mass which, in turn, helps strengthen bones. Aim for at least 20-60 minutes three times a week. Good choices include walking, aerobics, jogging, using weights, racquet sports and cycling; Kenneth Cooper, the American aerobics guru, maintains that 'strike' exercises (where your feet hit the ground or floor) are best.
* Cut out coffee. Caffeine increases urinary loss of calcium (J Am Coll Nutr, 1994; 13: 467-72) and hip-fracture risk (Am J Clin Nutr, 1991; 54: 157-63) and leads to lower bone mass in women who don't consume enough calcium (Am J Clin Nutr, 1994; 60: 573-8).
* Tea may be protective. While caffeine-containing tea consumption has been linked to osteoporosis (Osteoporos Int, 1999; 9: 45-54), tea drinkers appear to have a lower risk of osteoporosis than people who don't drink tea (Am J Clin Nutr, 2000; 71: 1003-7). The calcium-losing effect of caffeine in tea may be compensated for by its other constituents, such as flavonoids.
* Increase dietary isoflavones. Soya foods such as tofu, soya milk, roasted soybeans and soya protein powders may help to prevent osteoporosis. Postmenopausal women who took 40 g/day of soya protein powder (containing 90 mg of isoflavones) were protected against bone mineral loss in the spine, though lower amounts were not protective (Am J Clin Nutr, 1998; 68 [Suppl]: 1375-9S).
* Consider ipriflavone supplements, a synthetic flavonoid derived from daidzein. Studies show that it helps bones absorb and maintain healthy levels of calcium, and increases bone density (Alt Med Rev, 1999; 4: 10-22) and decreases fracture rates. Trials show that 600 mg/day of ipriflavone with 1000 mg of supplemental calcium is both safe and effective in halting bone loss in postmenopausal women or women who have had ovaries removed.
* Protect your adrenals. These glands go on producing a form of oestrogen after menopause. This may help to keep bones strong.
* Lower stress wherever possible.
* Avoid soft drinks. These contain phosphoric acid, which leaches calcium from the body
(J Pediatr, 1995; 126: 940-2). While the occasional soda is unlikely to pose a risk, overconsumption may increase the risk of bone fractures (J Adolesc Health, 1994; 15: 210-5).
* Fish oil (4 g/day) can improve calcium absorption and help the body form new bone (Nutr Res, 1995; 15: 325-34). Evening primrose oil may confer extra benefits. In one trial, 6 g of EPO and fish oil plus 600 mg/day of calcium for three years prevented spinal bone loss in the first 18 months and significantly increased spin-al bone mineral density during the last 18 months (Aging, 1998; 10: 385-94).
* Put that cigarette out! Smoking eats away at your bones (N Engl J Med, 1994; 330: 387-92).
* Maintain a healthy weight. Losing weight may also lose bone mass (Am J Clin Nutr, 1999; 70: 97-103).
* Cut back on salt. Over time, too much salt may cause bone loss (Am J Clin Nutr, 1989; 50: 1088-94) in postmenopausal women (Eur J Clin Nutr, 1997; 51: 394-9). Although a link between salt intake and osteoporosis is not definite, many doctors recommend using less salt, and eating fewer processed and restaurant meals, which tend to be highly salted.