Nature's best just got better, "says the Citrus Hill orange juice commercial. An other company announces that their product is "made by a nutritional expert: nature."
What do the products these slogans advertise have in common with soda pop, antacids, milk, cereals, and a new whipped dessert topping? Calcium! All these products have added calcium to capitalize on the rising concern over the effects of osteoporosis.
In the past few years the concern about osteoporosis has exceeded that regarding heart disease, the leading cause of death in the United States.1 In only six years calcium supplement sales have surged from $18 million to more than $240 million, and they are still growing. 2
Osteoporosis is a disease of the bones. It involves bone calcium loss, and is the major cause of bone fractures in one third of U.S. women of middle and retirement age. A Michigan study revealed that 18 percent of women 45 to 49 years of age show signs of this disease, and in the 70 to 74 age group, the rate rises to 84 percent.3
Osteoporosis is the twelfth-leading cause of death in the United States, 4 and is estimated to cost $6 billion annually. 5 In both the United States and Great Britain incidence of this disease is increasing both in numbers and rate.6 Between 1970 and 1980 the incidence of hip fractures increased 35 percent and vertebral fractures 40 percent, whereas the number of people in this age group increased by only 30 percent.
While the United States has one of the highest rates of this disease,7 as the population of people over age 65 increases, all developed nations will see a corresponding increase in the burden the dis ease brings.
Bone mineralization and demineralization
Most people seldom think about their bones, and if they do, they don't think of them as biologically active organs. Actually bones are constantly remodeling their structure.
This remodeling is carried on by two kinds of cells—osteoclasts and osteoblasts. The dynamics between these bone cells is important. Osteoclasts dissolve old bone minerals, and osteoblasts lay down new bone minerals. If osteoclasts remove more calcium than osteoblasts replace, bone strength will gradually decline. Over time the bone weakens to the point where even simple daily activities will cause it to fracture.
The bones most affected by osteoporosis are the femoral neck (hip), the wrists, and the vertebrae. 8 Vertebral fractures slowly collapse the spine, resulting in a bent-over appearance and a hump. This degeneration of the vertebrae can become severe enough to cause the ribs to rest on the pelvic bones.
One symptom of osteoporosis is pain in the ribs or back following coughing or straining. Such pain may signal fractured vertebrae and nerve compression, but this is not always the case. Many people are unaware they have osteoporosis until a serious fracture occurs.
In 85 percent of non-osteoporotic women who suffer a fracture, the bone will heal again. Women who have osteoporosis experience only a 30 percent rate of healing. Among elderly persons who suffer a hip fracture, only 25 percent of those who were able to walk prior to the fracture are ever able to walk again. 9 And, most tragically, those requiring open surgery suffer a 20 percent mortality rate within the first year.
Factors leading to the disease
The table that accompanies this article lists the factors known to cause bone mineral loss. In the left column are those factors about which we can do little. The right column lists the factors that we can control.
Osteoporosis afflicts women at a rate double that of men: one in every three women suffer from it as compared with one in every six men. 10 The fact that men generally have 30 percent greater bone mass than do women may underlie their relative freedom from the disease. A similar factor may explain why Blacks have less osteoporosis than do Whites: Blacks have 10 percent greater bone mass. 11
As we have already noted, age is an other factor in osteoporosis. Peak bone mass is reached around age 35. Following this peak both men and women begin to lose bone mass; women experiencing loss earlier than men. The average bone loss is about 1 percent per year, although it can be higher for women.12 Ninety-seven percent of hip fractures occur in those more than 65 years old; 13 267,000 of these serious injuries occur annually, resulting in 17,191 deaths. 14
Preventing osteoporosis
The interval between the onset of bone depletion and an osteoporotic fracture depends on two factors the strength of the bone, which is related to the original extent of mineral deposits, and the rate of mineral loss once it has begun. The stronger the bones, the longer it will take to weaken them to the point of fracture. And by reducing the rate of demineralization, a person can live longer without fractures.
Herein lies hope! Like many other chronic diseases of the twentieth century, osteoporosis can be prevented by lifestyle changes. While we cannot control such factors as our race, sex, or age, we can, by lifestyle changes, slow the rate of demineralization. Among the controllable factors:
1. Cigarette smoking. Mayo Clinic investigations have found that smokers more than double their risk of developing osteoporosis. This finding has been con firmed by other studies. Slender women who smoke are affected most.15
2. Sedentary lifestyle. That lack of exercise leads to the thinning of the bones is also well known. Early in the U.S. space program and in Skylab studies, medical scientists recognized that weightlessness increased calcium excretion in the urine and brought on bonemineral loss. 16 As a result of this observation, astronauts in space are now given time to do exercises that increase stress on the bones, thus decreasing or halting bone-mineral loss.
Therapeutic bed rest in which the patient is not allowed to get up and about decreases the physical stress needed to stimulate bone formation. Measurements taken in studies of short-term bed rest indicate a bone mineral loss of 1.2 percent per week.17
Exercise helps in a number of ways. First, it increases the flow of blood to the bone, thereby increasing mineral avail ability. Second, exercise changes the hormonal balance favoring bone growth.
Third, bone stress strengthens and maintains bones. Exercise also generates small electrical currents within the bone that stimulate bone growth. 18 Studies of exercise in female nursing home patients have shown that bone mass can be increased. Over a three-year period, patients on an exercise program increased bone mass 4.2 percent, whereas patients who didn't exercise through that time experienced a 2 percent loss of bone minerals.19
3. Alcohol consumption. Alcoholics have a greater incidence of hip and rib fractures and compression of vertebrae than do the rest of the population. Alcohol is toxic to bone cells. When given to rats, it rapidly decreases the blood calcium level and prevents its rise, even when parathyroid hormone (which in creases blood calcium) is administered.
Mayo Clinic researchers studying the risk factors of osteoporosis in men found that the social use of alcohol does not appear to have an effect until after the age of 60. But from age 60 to 69, the risk of bone fracture is nearly double for a nonsmoking drinker. When alcohol use is coupled with smoking, the risk triples.
In men 70 years or older, a nonsmoking drinker's risk rises to 6.5 times that of the nondrinker, and when smoking is added, the risk increases to more than 20 times that of the abstainer.
Autopsies performed on young alcoholic men show thinner bones than nonalcoholics of similar age have. Re searchers conclude that smoking and alcohol consumption increases bone calcium loss above that which age incurs.
4. Excess phosphorus. Scientists have found that phosphorus inhibits the body's absorption of dietary calcium. A diet containing twice as much calcium as phosphorus is ideal for bone health. But the average American diet, which contains large amounts of meat and carbonated soft drinks, inhibits calcium absorption since these foods contain 15 to 45 times more phosphorus than calcium. 21
5. Excess protein. Meats are also high in protein, which has been shown to in crease calcium elimination through the kidneys. Bones are one source of replenishment for the calcium excreted.22
Researchers have found that subjects who consume meat in quantities characteristic of the average American diet have less bone mass than do vegetarians.23 In fact, vegetarian men in their 70's had bone mass equal to that of nonvegetarian men 11 to 20 years younger. 24 Since protein consumption by Americans is nearly double the recommended dietary allowance set by the National Academy of Science Food and Nutrition Board, most people could cut their meat consumption by about half and still be within recommended levels.
University of Wisconsin researchers found that, at the level protein is consumed in the typical American diet, a daily intake of 800 milligrams of calcium was insufficient. In fact, calcium intakes nearly double, 1,400 milligrams, were insufficient or only marginally successful in balancing daily calcium absorption with daily losses.25
U.S. recommended dietary calcium levels have been set at 800 milligrams per day. At a recent NIH consensus meeting on osteoporosis, however, it was recommended that women past 40 years of age should take 1,000 to 1,500 milligrams daily. 26 But, although some evidence indicates a partial slowing of postmenopausal osteoporosis by dietary compensation, the most recent studies look grim. 27 Presently it is viewed as an irreversible condition, though high daily calcium supplements of 1,500 milligrams daily appear to slow its advance.
Estrogen replacement is considered more effective than calcium supplementation, but it also may increase a woman's risk of endometrial cancer. To help counter this risk, estrogen is given for 25 days per month, and a progesterone is added the last 10 days of the cycle.
Those individuals who decide to take a calcium supplement should be aware that such supplements come in various forms with varying amounts of usable calcium available. Some of these supplements include calcium gluconate (9 percent calcium), calcium lactate (13 percent), dolomite (22 percent), bone meal (31 percent), calcium chloride (36 percent), tricalcium phosphate (38 percent), and calcium carbonate (40 percent). 28 Tricalcium phosphate, bone meal, and dolomite are not good supplements. Tricalcium phosphate is thought to be poorly absorbed, and the other two substances may contain heavy metals such as mercury, lead, and arsenic, and other toxic substances as well. 29
Although it has been stressed that postmenopausal women need 1,500 milligrams of calcium, it is still fair to say that this is not the key. The problem with this approach is that Americans, Europeans, and the people of other industrial nations eat luxurious diets and are ailing from excesses in calories, protein, refined carbohydrates, and fats, resulting in hypertriglyceridemia, hypercholesterolemia, hyperinsulinemia, hyperglucemia, and hypertension. The solution to the problem of osteoporosis, created by excesses in diet, is not to be found in adding an excess of calcium.
The human body can survive on considerably less calcium than what has been proposed. Many nations, and the World Health Organization as well, recognize 400 to 500 milligrams of calcium per day as sufficient for good bone health, 30 while some people in less affluent countries survive on as little as 50 milligrams per day and still maintain good bone health. 31 We must recognize that it is not poor calcium nutrition that is costing such a heavy toll in lives and suffering. Rather, it is our socially acceptable drug addictions such as coffee, tea, alcohol, and caffeine-containing soft drinks; our poor diet choices in excess meats, soft drinks, and sugar; and our sedentary lifestyles.
Dr. Myron Winick, director of the Institute of Nutrition at Columbia University, says, "A well-balanced, vegetarian diet that allows milk and milk products is probably the best diet for the prevention of osteoporosis. The closer we all come to eating such a diet, the better."32
By instituting good nutritional practices and eliminating the lifestyle habits that prepare the way for osteoporosis— even as early as adolescence—we can prevent the onset of this disease.
1. C. I. Waslien, "New and Old Calcium Sources," Cereal Foods World 31, No. 5 (1986): 426.
2. G. Breu, "The Calcium Controversy: An Expert Warns That Supplements Are Not the Cureall for Dowager's Hump," People Weekly 27, No. 15 (1987): 69-71.
3. J. L. Kelsey, "Prevalence and Incidence in Osteoporosis," Osteoporosis (Bethesda, Md.: National Institutes of Health, 1984), pp. 25-28.
4. M. Winick, "Osteoporosis," Nutrition and Health 6, No. 1, 6 (1984): 1-6; "Exercising for Bone Health," Calcium Currents 2 (1986): 1, 4.
5. S. R. Cummings, J. L. Kelsey, M.C. Nevitt, K. J. O'Dowd, in Epidemiologzcal Reviews 7 (1985): 178-208.
6. A. S. and], Dixon, "Osteoporosis An Unheeded Epidemic," The Practitioner 230, No. 144 (1986): 363-371; Cummings.
7. Kelsey.
8. Cummings.
9. H. R. Fish and R. F. Dons, "Primary Osteoporosis," American Family Practitioner 31, No. 1 (1985): 216-223.
10. G. S. Gordon, "Prevention of Bone Loss and Fractures in Women," Maturitas 6, No. 3 (1984): 225-242.
11. A. M. Parfitt, "Definition of Osteoporosis: Age-related Loss of Bone and Its Relationship to Increased Fracture Risk," Osteoporosis (Bethesda, Md.: National Institutes of Health, 1984), pp. 15-19.
12. Ibid.
13. G. S. Gordon and H. K. Genant, "The Aging Skeleton," Clinical Geriatric Medicine 1, No. 1 (1985): 95-118.
14. B. L. RiggsandL. J. Melton III, "Involutional Osteoporosis," New England Journal of Medicine 314, No. 26 (1986): 1676-1684; Gordon, "Prevention."
15. Riggs.
16. A. E. Nicogossian and]. F. Parker, Jr., Space Physiology and Medicine (National Aeronautics and Space Administration, 1982); A. C. Santora II, "Role of Nutrition and Exercise in Osteoporosis," The American Journal of Medicine 82, Supp. IB (1987): 73-79.
17. Santora.
18. E. L. Smith and D. M. Raab, "Osteoporosis and Physical Activity," Acta Medica Scandinavica: Supplementum 711 (1986): 149-156; Winick.
19. R. D. Lindsay and W. Dempster, "Osteoporosis: Current Concepts," Bulletin of the New York Academy of Medicine 61, No. 4 (1985): 307-322.
20. E. Seeman, L. J. Melton III, W. M. O'Fallon, B. L. Riggs, "Risk Factors for Spinal Osteoporosis in Men," American Journal of Medicine 75, No. 6 (1983): 977-983.
21. Winick.
22. R. M. Walker and H. M. Linkswiler, "Calcium Retention in the Adult Human Male as Affected by Protein Intake," Journal of Nutrition 102, No. 10 (1972): 1297-1302; Winick.
23. A. G. Marsh, T. V. Sanchez, F. L. Chaffee, G. H. Mayor, O. Michelsen, "Bone Mineral Mass in Adult Lacto-Ovovegetarian and Omnivorous Males," The American Journal of Clinical Nutrition 37, No. 3 (1983): 453-456; A. G. Marsh, T. V. Sanchez, O. Michelsen, ]. Keiser, G. Mayor, "Cortical Bone Density of Adult Lacto-Ovovegetarian and Omnivorous Women," Journal of the American Dietetics Association 76, No. 2 (1980): 148-151.
24. F. R. Ellis, S. Holesh, J. W. Ellis, "Incidence of Osteoporosis in Vegetarians and Omnivores," The American Journal of Clinical Nutrition 25, No. 6 (1972): 555-558.
25. L. H. Alien, "Protein-induced Calciuria: A Long-Term Study," American Journal of Clinical Nutrition 32, No. 4 (1979): 741-749.
26. Parfitt.
27. "Calcium: Oversold," Harvard Medical School Health Letter 12, No. 6 (1987): 1, 2; "No Calcium Fix, "Scientific American 256, No. 4 (1987): 72; B. Riis, K. Thomsen, C. Christiansen, "Does Calcium Supplementation Prevent Postmenopausal Bone Loss? A Double-blind, Controlled Clinical Study," The New England Journal of Medicine 316, No. 4 (1987): 173-177.
28. "The Role of Calcium in Health," Dairy Council Digest 55, No. 1 (1984): 1-8; L. H. Alien, "Calcium and Osteoporosis," Nutrition Today 21, No. 3 (1986): 6-10.
29. "Role of Calcium."
30. R. Passmore, B. M. Nicol, M. N. Rao, G. H. Beaton, E. M. Demayer, Handbook of Human Nutritional Requirements (World Health Organization, 1974) pp. 49-52.
31. Gordon, "Prevention"; A. R. P. Walker and B. F. Walker, "Recommended Dietary Allowances and Third World Populations," The American Journal of Clinical Nutrition 34, No. 10 (1981): 2319-2321.
32. Winick.
