Prescription for Bone Health in AN: Better Nutrition and Return of Menses

Reprinted from Eating Disorders Review
September/October 2007 Volume 18, Number 5
©2007 Gürze Books

Anorexia nervosa (AN) usually occurs at the same time that peak bone mass is being formed. Since AN often has a chronic course and a high relapse rate, the disease can have a profound effect on bone, leading to increased fractures and osteoporosis at menopause. Nutritional rehabilitation and return of menses are two of the essential ele-ments needed to restore bone mineral density (BMD) in women with AN, according to a team of researchers at ColumbiaUniversity, New York City (Am J Clin Nutr 2007;86:92).

The mechanisms that lead to osteo-penia are still not well understood but are thought to be nutritionally mediated, according to Dr. Jennifer Dominguez and colleagues. And, according to the authors, the fact that the role of nutrition in the recovery of bone has been underestimated might explain the disappointing failure of therapy with oral contraceptives or estrogen replacement therapy (J Pediatr 2002; 141:64; Clin Endocrinol (Oxf) 2000; 52:113).

Two study groups

The Columbia researchers studied bone mineral density and markers for bone formation (osteocalcin) and resorption (N-teleopeptide, or NTX) in 28 patients hospitalized with AN who were following a behavioral weight-gain protocol, and 12 control patients. In addition, they compared their data with those from 30 reference control patients.

Patients with AN were evaluated with a battery of blood tests and thorough medical histories when they were first hospitalized. Venous blood and urine were collected for hormone profile analysis. Each healthy control subject completed a medical questionnaire to assess her general medical and menstrual history and had a brief physical examination. The healthy controls were also were given take-home ovulation test kits to confirm ovulatory cycles and asked to keep a record of their menstrual periods. Total body dual energy x-ray absorptiometry (DXA) was used in both groups of women to measure bone mass and bone density.

Anorexic patients who regained menses had the best results

Of the original 37 patients and 12 healthy control subjects, 28 patients and 11 controls completed the study. Among the 28 patients, 8 regained normal menstrual periods when they reached 90% of ideal body weight (IBW). The 28 patients were divided into two subgroups according to menstrual status at the time of treatment after 90% IBW testing. No significant differences were noted in age, weight, body mass index, lean body mass, or percentage body fat between those who regained menses and the amenorrheic group at admission or after weight gain.

Nutritional rehabilitation is critical
to bone recovery; estrogen therapy
alone has not been effective.

The anorexic patients who regained menses had significant increases in BMD. As the authors reported, these women regained bone in the following areas: (4.38 ±7.48% for the spine; 3.77 ±8.8% for the hip; P <0.05 for both) from the time of admission to recovery of 90% IBW, achieved over a little more than two months. NTX concentrations, asign of bone resorption or bone loss, were significantly higher among patients with AN than among healthy controls at admission. In weight-recovered subjects with AN, os-teocalcin levels increased significantly, from 8.0±3.05 ng/ml to 11.2±6.54 ng/mL. A decrease in NTX occurred only in the subgroup of women who regained normal menses as they recovered their weight.

The benefits of nutritional rehabilitation

Thus, nutritional rehabilitation induces a powerful anabolic effect on bone. However, a fall in NTX levels and a shift from bone resorption, which they postulate means a full recovery, may involve hormonal mechanisms and require the return of menses.

The fact that nutritional rehabilitation seems to be critical to bone recovery among AN patients may explain the disappointing ineffectiveness of estrogen therapy alone on BMD among such patients.

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