by Thomas Incledon, MS, RD, LD/N, CSCS
In this article, author Thomas Incledon explores treatment and nutritional strategies for preventing and reversing osteoporosis caused by amenorrhea.
Osteoporosis
Osteoporosis is the most common human bone disease and is characterized by low bone mass or bone mineral density (BMD) and loss of bone tissue [1]. Bone is living tissue and it is constantly undergoing remodeling where old bone is replaced by new bone. Osteoporosis develops when the bone that is lost is not replaced by new bone. This results in a decreased bone mass and the increased risk for fractures. The many common causes of osteoporosis range from lack of physical stress (exercise) on the bones, malnutrition, lack of estrogen, and old age [2]. Osteoporosis is seen as a disease that primarily concerns women as they enter their postmenopausal years because of their decreasing levels of estrogen. Estrogen causes increased osteoblastic (bone formation) activity and after menopause, no estrogen is secreted from the ovaries [2]. But since the recognition of the development of The Female Athlete Triad, osteoporosis, osteopenia, and stress fractures are now a concern for much younger women.
Total Energy Intake
The best treatment for the osteoporosis that can develop from amenorrhea is to have normal menses. Studies have shown that women who were previously amenorrheic were able to increase bone mineral density when their menses returned [3, 4]. One theory about the amenorrhea seen in athletes involves energy deficit states. The energy drain theory suggests that the decrease in reproductive hormones stems from an inadequate calorie intake to match high calorie needs during intense training [5]. Athletes have large exercise energy expenditures that result in a calorie requirement that is more than sedentary people. When athletes consume fewer calories than their exercising bodies need, either consciously or inadvertently, an energy deficit results. Therefore, female athletes need to ensure that they are eating enough calories to match their energy expenditure [6]. Athletes in general need to eat more than the U.S.R.D.A., which for women is 2000 calories [7]. Exactly how many calories are needed depends on a variety of factors including age, body composition and weight, intensity and duration of training, and type of training.
You Are What You Eat
Even more important than the adequate amount of calories, may be the type of calories. Studies have shown that amenorrheic athletes consumed less dietary fat, less red meat, and more dietary fiber than eumenorrheic (normally menstruating) athletes [8, 9]. This points to the fact that adequate nutrient intake is important to menstrual health and, in turn, may be important to bone health. A sound nutritional program for female athletes involves ingesting enough protein to support the demands of their active lifestyle, enough fat to support hormone production and other physiological needs, and sufficient carbohydrates to fuel their activities and assist in recovery from strenuous activity. The types of ranges that can fulfill these requirements amount to a protein intake of approximately 13-20% of calories (supplying up to 1 gram of protein per pound of body weight), fat 20-30% of calories, and carbohydrate 50-67% of calories. Of course, the actual percentages will vary according to the amount of calories the athlete needs to ingest.
Get Your Vitamins and Minerals
A well-rounded diet with the appropriate amount of calories should include all of the vitamins and minerals needed for menstrual and bone health. Although increased calcium intake cannot directly compensate for bone lost due to osteoporosis or not gained during the crucial peak bone mass years, calcium supplementation can be recommended if proper requirements are not being met. Healthcare providers may prescribe 1500 mg. of calcium and 400 to 800 IU of vitamin D for bone health [10]. Calcium-rich foods include all dairy foods and spinach, broccoli, shrimp, almonds, peanuts, and soybeans. In addition, some athletes train and compete indoors and may not be exposed to sufficient sunlight. These athletes may want to supplement their calcium with vitamin D [11]. Rat studies in vitro have shown that the essential trace mineral zinc is important for bone growth because it can stimulate bone formation and it can prevent bone resorption [12]. In a related study, the effect of zinc supplementation on strenuously training (treadmill running) rats showed that zinc can preserve bone mass during intense exercise [13]. The researchers confirmed that strenuous exercise can have an adverse effect on bone tissue in rats and that zinc can prevent it. Since a previous study proved that zinc could prevent bone loss in rats without ovaries, it has been speculated that zinc may help prevent osteoporosis in amenorrheic athletes. More direct evidence on female athletes is required to support or refute this notion. Irregardless, because athletes lose zinc in sweat and so many have poor diets that lack the necessary vitamins and minerals, eating a diet that contains zinc-rich foods seems prudent. Good sources of zinc in foods include red meat, dark meat chicken, pork, oysters, crabmeat, eggs, and oatmeal.
Hormone Replacement Therapy (HRT)
If nutritional interventions and a decrease in exercise do not promote menses, estrogen replacement may be prescribed to prevent osteoporosis and other problems associated with estrogen deprivation [10]. Birth control pills are the method of choice for women in the reproductive age group who are not interested in conception. Unfortunately, there are no large, prospective, longitudinal studies that demonstrate increased bone mineral density when amenorrheic athletes are given HRT [14]. However, this treatment regimen is based on the benefits of HRT in postmenopausal women and while it is thought that amenorrheic athletes should respond in a similar fashion, more research is required to support this notion.
A Multidiscipline Approach to a Multifactorial Problem
The Female Athlete Triad contains components where one leads to another and the symptoms and diseases that develop overlap in many ways. The causes are multifactorial, and the treatment must include many disciplines of health care workers. An internist may be the primary healthcare provider, but a gynecologist should be consulted when amenorrhea and osteoporosis are involved. A licensed, registered dietician can help develop sound eating programs and a psychologist can address behavioral problems. The athlete’s coaches, trainers, parents, and peers make a strong support system and should be closely involved. It is possible that in addition to adequately maintaining calorie needs, decreasing psychological stress and the stress from training intensity and the pressure to perform, amenorrhea and the resulting osteoporotic condition can be resolved. Education is an important tool. Female athletes need to be presented with nutrition information, proper training programs, and the consequences that The Female Athlete Triad may have on her present and future health.
References
1. National Osteoporosis Foundation Physician’s Guide To Prevention and Treatment of Osteoporosis. 1998: http://www.nof.org.
2. Guyton, A.C. and J.E. Hall, Textbook of Medical Physiology. Nineth ed. 1996, Philadelphia: W.B. Saunders Company.
3. Bullen, B.A., et al., Induction of menstrual disorders by strenuous exercise in untrained women. N Engl J Med, 1985. 312(21): p. 1349-1353.
4. Drinkwater, B.L., et al., Bone mineral density after resumption of menses in amenorrheic athletes. Jama, 1986. 256(3): p. 380-382.
5. Warren, M.P., The effects of exercise on pubertal progression and reproductive function in girls. J Clin Endocrinol Metab, 1980. 51(5): p. 1150-1157.
6. Otis, C.L., et al., American College of Sports Medicine position stand. The Female Athlete Triad [see comments]. Med Sci Sports Exerc, 1997. 29(5): p. i-ix.
7. Kleiner, S.M., Power Eating. 1998, Champaign, IL: Human Kinetics. 1-216.
8. Kaiserauer, S., et al., Nutritional, physiological, and menstrual status of distance runners. Med Sci Sports Exerc, 1989. 21(2): p. 120-125.
9. Snow, R.C., J.L. Schneider, and R.L. Barbieri, High dietary fiber and low saturated fat intake among oligomenorrheic undergraduates. Fertil Steril, 1990. 54(4): p. 632-637.
10. Wiggins, D.L. and M.E. Wiggins, The female athlete. Clin Sports Med, 1997. 16(4): p. 593-612.
11. Warren, M.P., Health issues for women athletes: exercise-induced amenorrhea. J Clin Endocrinol Metab, 1999. 84(6): p. 1892-1896.
12. Moonga, B.S. and D.W. Dempster, Zinc is a potent inhibitor of osteoclastic bone resorption in vitro. J Bone Miner Res, 1995. 10(3): p. 453-457.
13. Seco, C., et al., Effects of zinc supplementation on vertebral and femoral bone mass in rats on strenuous treadmill training exercise. J Bone Miner Res, 1998. 13(3): p. 508-512.
14. Fagan, K.M., Pharmacologic management of athletic amenorrhea. Clin Sports Med, 1998. 17(2): p. 327-341.
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