Breaking the habits that break bones
April 27, 2011
The first line of defense in preventing and reversing osteoporosis is to break the habits that deplete the body of vitamins and minerals required for bone health. Excess intake of salt, sugar, caffeine, alcohol and soda are such habits.
The calcium-losing effect of sodium on the bones has been known since the 1980s. Two studies published in 1995 compared sodium intake and bone mineral density. The first was carried out in young female subjects aged 8 to 13 years and found that urinary calcium losses caused by high dietary sodium intake reduced calcium retention in the skeleton. This could reduce peak bone mass, a major predictor of future osteoporosis.
The second study was done on subjects at the other end of the age range, postmenopausal women, over a period of two years. This study found that the rate of bone loss in these women was significantly reduced by halving their sodium intake and that this reduction in bone loss was equivalent to that achieved by almost doubling their calcium intake.
How much salt should we be eating? According to a report issued in February 2004 by the Institute of Medicine, an organization that provides scientific advice to federal policy makers, the desirable level is 3.8 grams of salt daily (about two-thirds of a teaspoon, or 1,500 milligrams of sodium.) How much do we eat? The average American takes in more than 4,000 milligrams a day, more than three-fourths of it from prepared and processed foods like spaghetti sauce, frozen dinners, snack foods and restaurant meals. Interestingly, processed table salt has more sodium than unprocessed sea salt: 2,200 mg per teaspoon compared to 1,320 mg per teaspoon, respectively.
Sugar may also deplete our bodies of calcium. Administering 100 grams (about 25 teaspoons) of sugar to healthy volunteers caused a significant increase in the urinary excretion of calcium. The average American ingests about 41 teaspoons of sugar per day!
Ingesting large amounts of sugar also causes a significant increase in serum cortisol levels. Cortisol is the primary corticosteroid (a hormone) secreted by the adrenal glands. An excess of corticosteroids can cause osteoporosis. Eating too much sugar is comparable to taking a small amount of cortisone (a synthetic corticosteroid), which could cause bone to become thinner. This possibility is supported by a study on hamsters, in which feeding a diet containing 56 percent sugar caused osteoporosis, despite adequate intake of calcium.
Many studies on caffeine suggest that it, too, contributes to bone loss. In one of these, 84,484 American women aged 34 to 59 completed a questionnaire pertaining to their intake of various foods and beverages. During the ensuing six years, the risk of hip fracture in these women increased with increasing levels of caffeine intake. Women with a high consumption of coffee (greater than four cups per day) had a three-fold increase in the risk of hip fractures compared to women who rarely drank coffee.
Hard Liquor and Soft Drinks
In this same study, alcohol intake was independently associated with increased risk of both hip and forearm fractures. Compared to nondrinkers, women consuming 25 grams (less than an ounce) or more of alcohol per day had more than twice the risk of hip fractures and 38 percent greater risk of forearm fractures. In a study of 96 male alcoholics ages 24 to 62, 47 percent had osteoporosis.
Hard liquor is bad for the bones, but soft drinks are no better. The phosphorus in the form of phosphoric acid, is used as a preservative in most commercial canned sodas and is required for dissolving the sugar and contributing to the taste. When phosphorus levels exceed calcium levels in the blood, the body responds by stimulating bone breakdown to release calcium into the blood stream. The United States ranks first among countries in soft drink consumption. The per capita consumption is greater than 150 quarts per year, or about three quarts per week.
Salt, sugar, caffeine, alcohol, soda - these are the habits to break. The habits to make for healthy bones will be the subject of subsequent articles in this series.
Mary Lou Williams, M. Ed., is a lecturer and writer in the field of nutrition. She welcomes inquiries. She can be reached at 267-6480.