Diet and Osteoporosis

According to the International Osteoporosis Foundation, the lifetime risk of a hip fracture in women is greater than the risk of breast, endometrial and ovarian cancer combined. Osteoporosis weakens bones to the point where even a small trauma can cause a fracture. A 5-year study in Australia found that all people who suffered a major fracture had an increased risk of mortality.1

In addition to exercise, which is very important for prevention of osteoporosis, there are a number of dietary factors, which affect bone density (BD). Some we need to reduce or avoid, while others need increased. Cut Back on SaltSalt is one of the most important factors contributing to an increased loss of calcium in the urine and the development of osteoporosis. One must increase the intake of dietary calcium by approximately 1000 mg daily to prevent bone loss in postmenopausal women who are ingesting an extra 2000 mg of sodium as salt daily.2 It should be noted that the problem with increased urinary excretion of calcium with increased dietary salt is not due to sodium alone. Even 5500 mg of sodium given as sodium citrate or sodium carbonate does not increase calcium excretion as does sodium chloride.3 Cut Back on Coffee and Soft DrinksA heavy consumption of caffeine may also contribute to an increased loss of calcium from the body and thus contribute to bone loss over time. Moderate intake of caffeine is certainly not a major factor in the development of osteoporosis. However, the lifetime intake of the amount of caffeine in as little as 2 cups of coffee per day, is associated with decreased BD in older women. The negative impact of caffeine on BD was greatest in those women who did not consume milk on a daily basis.4Soft drinks, often high in phosphoric acid and caffeine, are becoming an increasingly popular beverage for girls and young women. Consuming a diet high in phosphorus and low in calcium reduces BD.5 Avoid Excess Vitamin A SupplementationThe highest rates of osteoporosis and hip fractures in the world are in Norway and Sweden.6 These two countries also have a very high intake of dairy products. Sweden fortifies all low and NF dairy products with retinol (vitamin A) at twice the level found in whole milk. In addition, retinol is added to margarine and there is also a lot of retinol in cod liver oil, a commonly used supplement in these countries. Retinol intake is 6 times higher here than in most European countries.7Based on current evidence, it seems prudent to advise people at risk of osteoporosis to limit their intake of retinol to the RDA level of 800 RE or 0.8 mg per day. This means fortified foods with retinol or palmitate should be avoided, as should liver, retinol-fortified foods and cod liver oil. Other Items to AvoidHeavy drinking contributes to bone loss and fractures. Limit alcohol to less than 2 drinks per day.Smoking decreases body mass and increases the rate of fractures.Excess protein intake, especially from animal sources, increases the loss of calcium in the urine. Get Plenty of Calcium The most obvious and well-publicized of dietary factors associated with a lower BD is a lack of calcium. While skim milk is fairly high in sulfur-containing amino acids, claims that it may increase the risk of osteoporosis do not appear accurate. Indeed, previous milk consumption in young women has been associated with greater BD.8 A study of 843 Chinese women found that BD was positively associated with calcium from dairy products. The connection between dairy product calcium and stronger bones was even stronger than for calcium from other sources.9Other good non-dairy food sources of calcium include kale, broccoli, sardines with bones, salmon with bones, and calcium-fortified foods such as soy milk, grain products and fruit juices. Get Enough Vitamin DPeople who live in high northern latitudes and do not drink vitamin-D fortified milk, should be encouraged to take a vitamin D supplement during the winter months. Daily supplements of 500 mg of calcium and 700 I.U. of vitamin D have been shown to reduce bone loss and fractures in older men and women.10 Increase Fruits & VegetablesThe metabolism of the typical American diet, with its high intake of meat and low intake of fruits and vegetables, tends to yield an excess of endogenous acid. The human skeleton serves as a reservoir of calcium that can be mobilized to prevent the blood from becoming too acidic. An increased consumption of fruits and vegetables (which are excellent sources of potassium, vitamin K, magnesium and other trace minerals involved in bone metabolism in older men and women) was shown to contribute to the maintenance of BD in a 4-year longitudinal study.11 It is clear that people at risk for osteoporosis should consume more fruits and vegetables. The Bottom LineA diet low in salt and meat and high in skim milk and skim milk products such as yogurt or ricotta cheese, fruits and vegetables, coupled with an active lifestyle is probably best for preventing osteoporosis and bone fractures. For individuals who don’t like to drink skim milk, today’s grocery store offers other choices such as calcium fortified soyfoods, grains and fruit juices and calcium supplements. Dr. James J. Kenney, PhD, RD, FACN, is the Director of Research for the Pritikin Longevity Center. He is Board Certified as a Specialist in Human Nutrition by the American Board of Nutrition. See the insert to receive a full text article with CPE course and resources for teaching diet and osteoporosis or see www.foodandhealth.com/continuingeducation.htm References:1. Lancet 1999;353:878-822. Res 1996;11:731-63. Kidney Int 1989;35:688-954. JAMA 1994;271:280-35. J Clin Endocrinol Metab 1990;70:1334-406. Osteoporos Int 1991; 1:232-417. Ann Intern Med 1998;129:770-88. Am J Clin Nutr 1999;69:1014-79. Am J Clin Nutr 1993;58:219-2710. Nutr Rev 1998;56:148-5811. Am J Clin Nutr 1999; 69:727-36.