Osteoporosis and Nutrition

            Osteoporosis is a weakening of the bones, which usually occurs in middle-aged and older women. It is a serious problem that can dramatically affect the quality of life for someone, especially if they end up with bone fractures. The health cost of fractures alone in older people was almost $15 billion per year in the 1990’s (1). There are three types of osteoporosis. Type I is hormonal-related (ex. estrogen deficiency). Type II is diet-related (ex. calcium deficiency). Type III is drug treatment-related (ex. corticosteroid therapy for an unrelated condition) (2). As of 1999, an estimated 10 million people in the USA had osteoporosis (2). About one out of three women end up with osteoporosis after menopause (3).

            A woman’s menstrual cycles that stop in mid-life is known as menopause. The bone-maintaining hormone estrogen falls in concentration after menopause. Estrogen helps maintain healthy bone density. The lowering of estrogen levels then results in bone loss over time, although the loss is highly variable between people. Ten years after menopause, bone mass losses can range from 5-40% (4). In the past, doctors would simply prescribe estrogen as a replacement therapy. Later, John Lee, MD discovered that the hormone progesterone is equally important as estrogen to bone health. Estrogen therapy may slow bone loss, but progesterone therapy can reverse bone loss (5). Unfortunately, both estrogen and progesterone hormone replacement can have serious side effects, including: heart attack, stroke, endometrial cancer, breast cancer, gallbladder disease, and vision problems (6). There are other causes of osteoporosis besides hormonal changes after menopause. They include: drug use, old age (after age 70), other illnesses of organs, non-sex hormone gland problems, malnutrition, and physical inactivity (4). The use of drugs for ailments unrelated to osteoporosis can be a major factor in their unwanted contribution to bone thinning. There are many different medications that may contribute to osteoporosis, including: antibiotics, corticosteroids, diuretics (water pills), thyroid medications, and antacids that contain aluminum (7). Since drug use can have such a powerful effect on bone health, there has been a large amount of research on how to maintain bone health through several different means, including nutrition.

            There are two main nutrients that have been examined when looking at the relationship between nutrition and bone health: protein and calcium. The reason is that one third of bone is protein (collagen matrix), and two-thirds of bone is composed of calcium phosphate, with some small amounts of sodium and magnesium. When protein (especially animal protein) is digested and assimilated, there is a release of acids in the body. The excess acid is then excreted by the kidneys. However, acid is positively charged, and there always has to be an equal amount of positively and negatively charged molecules in any solution. The molecules that release the positively charged acid into the body (for example, sulfate) are now negatively charged. The body cannot simply get rid of the positively charged acid by itself, it needs negatively charged molecules to soak up, or buffer the acid. With otherwise healthy people, this is easy to do, because the body has different molecules to bind to the acid and later excrete it.

            Similarly, the body cannot get rid of the sulfate molecules alone that recently released the acid. The kidneys need to balance the negatively charged sulfate molecules with positively charged minerals, such as sodium, potassium, calcium, and magnesium. This is where minerals are lost from the body: balancing the charges of molecules that were once acidic. There are minerals in the bloodstream that can initially buffer the protein-derived molecules, but they are eventually depleted. This is when the minerals in bone are recruited to help balance diet-related acid production.

            The first compounds in the bone to help buffer an excess acid load from the diet are sodium bicarbonate and potassium bicarbonate. Later, calcium is leached from the bones as calcium carbonate and calcium phosphate (8). High-protein diets do result in increased calcium excretion (9). Additional evidence for protein leaching calcium from the bones comes from a study showing that there is an elevated risk of bone fracture in women that have a high protein intake and low calcium intake (10). However, there is some evidence that increasing protein intake does not necessarily use up buffering minerals from bone for two reasons. First, if the diet is balanced with adequate amounts of calcium, magnesium, sodium, and potassium, then there does not have to be an acid neutralization of the protein from bone minerals. Second, excess acid generated by digestion stimulates ammonia production, which can accept excess acid, becoming the ammonium ion, which is then excreted (11). Whatever the cause, there is bone loss from mineral leaching, which happens over long periods of time.

            The key to slowing osteoporosis is to ensure that there are adequate minerals to balance molecules like sulfate, especially the mineral calcium. Estrogen helps the body absorb calcium (12). Soybeans have chemicals that mimic estrogen; therefore the eating of soybeans may be safer than direct estrogen-replacement therapy. Since the serious side effects of estrogen and progesterone replacement have been recognized, there have been some relatively safer drugs put out on the market. Bisphosphonate, or Alendronate (Fosamax) is generally well-tolerated (6). Calcitonin nasal spray is safer than calcionin injection, which has resulted in at least one fatality in the past, due to an allergic reaction (13). Raloxifene (Evista) has a relatively low side-effect profile. Potassium bicarbonate has been experimentally used to treat osteoporosis. However, there can be serious side effects form overuse of oral bicarbonate solutions (14).

            There are two ways to get more calcium in the body: food and supplements. Foods that have a good amount of calcium include beans and green leafy vegetables. However, the calcium in spinach is poorly absorbed. People who tend to do better with a protein and fat-based diet need a greater calcium intake. These are probably the same people who would benefit from supplementing with calcium for the treatment and/or prevention of osteoporosis. People who tend to do better on carbohydrates instead of protein and fat should add magnesium to their osteoporosis-fighting regimen (5). Additionally, it appears that there are highly variable calcium requirements between ethnic groups for maintaining bone mass (7). Since both protein and minerals are lost in osteoporosis, it would make sense to replace both protein and minerals at the same time, through a supplemented meal, for example.

            Although the recommended daily allowance of calcium is 1000-1200 mg, the National Osteoporosis Foundation claims that the average adult American has a calcium intake of only 500-700 mg/day (3). Calcium intake by drinking milk may not be the best method. Women who drank at least two glasses of milk a day actually had a 50% higher chance of hip fractures (15). The reasons for this strange outcome are unknown. There probably is not enough protein in the milk to leach calcium from the bones, especially when there is calcium in the milk to begin with. It has been known for a long time, though, that most adults are at least partially lactose intolerant, and that dairy product use can contribute to a number of different illnesses, including allergies and certain infections.

            If you supplement with high doses of calcium (more than 1000 mg/day), try to also supplement with some magnesium, manganese, and zinc. High calcium intake can inhibit the actions of these three other minerals (12). Do not supplement with more than 500 mg/day of magnesium, 10 mg/day of manganese, or 50 mg/day of zinc. Do not take calcium supplements at the same time as eating whole grains---they can inhibit calcium absorption (2). Also do not take calcium supplements at the same time as any fiber supplements, or when eating leafy greens such as spinach.

            Calcium supplements, if taken with food (not with whole grains or spinach) are generally well-tolerated. People with kidney stones, a family history of kidney stones, or low stomach acid (achlorhydria) should notify their physician before taking any supplements. Calcium supplements may be somewhat more effective when taken in the evening (16). Calcium citrate and calcium phosphate are supposedly the best absorbed forms. Calcium gluconate and calcium lactate are decently absorbed, and calcium carbonate is poorly absorbed (2).

            Vitamin D supplementation may be even more important for middle-aged women than calcium supplementation. Vitamin D helps absorb and regulate calcium in the body. Whether to supplement with vitamin D or not may depend on how much sunlight someone gets. Ultraviolet (UV) light from the sun helps to produce vitamin D internally. There is some controversy about the maximal amount of vitamin D supplementation that is still safe to take. A conservative level would be a maximal amount of 1000 IU/day. Some practitioners claim that much greater amounts of vitamin D are safe. Too much vitamin D supplementation can cause dangerously high calcium levels (hypercalcemia), which can sometimes lead to heart problems.

            Vitamin C helps in the formation of collagen, a connective tissue protein that is essential for bone stability. Also, Vitamin C improves calcium absorption up to 2-fold (17). There are other minerals besides calcium that can be helpful for osteoporosis. Magnesium helps calcium incorporation into bone. Zinc may be useful to supplement with if someone has osteoporosis, since both blood and bone levels of zinc are lower in osteoporotic women (18). Boron is a good supplement for middle-aged women to consider taking. Boron slows calcium and magnesium loss from the body (7). Also, boron can raise estrogen levels significantly. Therefore, women who have had breast or endometrial cancer, or a family history of the above cancers, may not want to supplement with boron.

            As you have read, there are many different ways to deal with both the prevention and treatment of osteoporosis, including more non-invasive natural ones. However, one needs to be careful in the way they approach any natural therapy for preventing or treating osteoporosis. Simply drinking milk or taking calcium supplements may not help anything by themselves. It would be a good idea to discuss strategies for dealing with osteoporosis with both your physician and a nutritional consultant.

References:

1. Katzung, B. Basic and Clinical Pharmacology, 7th Ed. New York, NY: Lange Medical Books/McGraw-Hill Health Professions Division, 1998.

2. Balch, P. Prescription for Nutritional Healing, 3rd Ed. Avery Books/Penguin Putnam Inc., 2000.

3. Reavley, N. The New Encyclopedia of Vitamins, Minerals, Supplements, and Herbs. New York, NY: M. Evan & Co., 1998.

4. Colbin, A. Food and Our Bones. New York, NY: Penguin Putnam Inc., 1998.

5. Wolcott, W., & Fahey, T. The Metabolic Typing Diet. New York, NY: Random House, 2000.

6. Physician’s Desk Reference, 59th Ed. Montvale, NJ: Thomson PDR, 2005.

7. Brown, S. Better Bones, Better Body. Los Angeles, CA: Penguin Putnam Inc, 2000.

8. Lemann, J Jr., & Lennon, E. (1972). Role of diet, gastrointestinal tract and bone in acid-base homeostasis. Kidney Int, 1: 275-279.

9. Hu, JF, Zhao, XH, Parpia, B, & Campbell, TC (1993). Dietary intakes and urinary excretion of calcium and acids: a cross-sectional study of women in china. American Journal of Clinical Nutrition, 58: 398-406

10. Meyer, H., Pederson, J., Loken, E., & Tverdal, A. (1997). Dietary factors and the incidence of hip fracture in middle-aged Norwegians. A prospective study. Am J Epidemiology, 145(2): 117-123.

11. Remer, T. (2001). Influence of nutrition on acid-base balance—metabolic aspects. European Journal of Nutrition. Oct, 40(15): 214-220.

12. The Healing Power of Vitamins, Minerals, and Herbs. Pleasantville, NY: Reader’s Digest Association, 1999.

13. PDR Generics, 3rd Ed. Montvale, NJ: Medical Economics Company, Inc., 1997.

14. Sebastian, A., et. al. (1994). Improved mineral balance and skeletal metabolism in postmenopausal women treated with potassium bicarbonate. New England Journal of Medicine, 330(25): 1776-1781.

15. Feskanich, D., Willet, W., Stampfer, M., & Colditz, G. (1997). Milk, dietary calcium, and bone fracture risk in women: a 12-year prospective study. American Journal of Public Health, 87(6): 992-997

16. Horowitz, M., et. al. (1988) Biochemical effects of calcium supplementation in postmenopausal osteoporosis. European Journal of Clinical Nutrition, 42: 775-778.

17. Leichsenring, J., Norris, L., & Halbert, M. (1957) Effect of ascorbic acid and of orange juice on calcium and phosphorus metabolism in women. Journal of Nutrition, 63: 425-435.

18. Atik, S. (1983). Zinc and senile osteoporosis. J Am Geriatric Soc, 31: 790-791