A Window into Understanding the Lasting Impact of the Nutritional Milieu in Adolescents: Anorexia Nervosa as a Model

Linear growth and pubertal development are complex processes requiring the integration of genetic, nutritional, medical, and hormonal factors (1). The pubertal growth spurt accounts for approximately 20% of final adult height. Nutritional and hormonal deficiencies or chronic disease may blunt the pubertal growth spurt and negatively impact final adult height. Anorexia nervosa (AN) provides a model for the understanding of the influence of nutrition on pubertal growth spurt because it typically manifests around the time of puberty. This timing has the potential to decrease the pubertal growth spurt and final adult height. However, studies evaluating final adult height in patients with AN have yielded mixed results, and many studies have not followed adolescents to final adult height (2).

In this issue of the Journal of Clinical Endocrinology & Metabolism, Modan-Moses, et al report the impact of AN on final adult height in female adolescents (3). They tracked growth at admission to an inpatient treatment center (average age of 15.4 years) through final adult height. Subjects had menarche at an average 12.7 years of age and average disease duration of 2 years. Their population of female adolescents with AN were not shorter than average prior to the development of AN but reached a final adult height that is shorter than average. The magnitude of the impact on growth was not trivial, with an average decrease in final adult height of 0.3 standard deviations, equivalent to approximately 2 cm. Factors associated with increased height with treatment included younger age and bone age at admission.

The impact on final height in these patients is somewhat surprising, given the fact that the female pubertal growth spurt occurs prior to menarche and the subjects in this cohort developed AN after menarche. The impact of AN on final adult height depended upon the timing of disease and treatment in relationship to the pubertal growth spurt. Younger adolescents in this study who received treatment for AN had a better response in linear growth, suggesting that the impact on growth can be mitigated with early identification and treatment. These observations imply that growth in female adolescents, even after menarche, is impacted by health status, and lead to the hypothesis that the impact on growth may be even greater if younger adolescents develop AN and are not treated adequately during this critical period of growth. These findings have implications for other causes of nutritional deprivation in adolescents, including excessive exercise, undiagnosed or inadequately treated inflammatory bowel disease, celiac disease, or other chronic illnesses. Early identification and treatment of these disorders may allow time for weight gain and recovery from inflammation and nutritional deficiency, and result in improved linear growth.

In addition to its influence on growth, malnutrition in childhood and adolescence is associated with an increased risk for a host of social, intellectual, economic, and medical issues in adulthood (4). The observation of decreased adult height in older female adolescents opens the door to the possibility that patients with AN may be at risk for additional morbidity. Certainly, it is known that bone health is impacted by AN. Other chronic illnesses, such as metabolic syndrome and type 2 diabetes, appear to be less common in patients with AN, but may in fact be increased in other types of eating disorders (5).

These findings are not generalizable to the entire population of patients with eating disorders. The subjects of this study were older female adolescents with AN severe enough to require hospitalization. The impact of AN in younger patients, male patients, and patients with less severe AN cannot be determined by these findings. Disordered eating not severe enough to meet diagnostic criteria for an eating disorder is common in adolescents, impacting up to 50% of the population. These disordered eating habits may impact weight (either excessive or inadequate), and adolescents with disordered eating have lower health-related quality of life compared to those without disordered eating (6). Thus, further studies of patients with disordered eating are required to determine the impact of these factors on all aspects of health.

The impact of body composition on long-term morbidity and mortality can also be explored from the standpoint of overnutrition. Obesity in adolescence and childhood is associated with risk for the metabolic syndrome and type 2 diabetes. Disordered eating is common in patients with metabolic syndrome and type 2 diabetes; approximately 20% to 50% of adolescents with type 2 diabetes exhibit eating disordered behaviors (7). It is well known that adolescents with metabolic syndrome and type 2 diabetes are at a very high risk for continued disease into adulthood, manifesting as early heart disease and associated with increased risk for early mortality. Maintaining a healthy relationship with food, appetite regulation, and access to healthy foods in childhood are important factors for health as adults. Therefore, attention to access to health foods, healthy eating habits, and opportunity for exercise throughout childhood and adolescence may be a modifiable risk factor to prevent morbidity and mortality in adulthood.

Disordered eating is common in children and adolescents. This disordered eating results in abnormalities of body composition, including obesity and malnutrition. These factors influence health risk as an adult and have lasting impact on height. Studies such as that published by Modan-Moses, et al (3) provide a window into the link between childhood nutrition height in adulthood. Further studies are required to more fully understand the impact of alteration of nutrition on the risk for chronic diseases in adults, including for patients with eating disorders. Understanding these influences may allow for the identification of modifiable factors to prevent the development of significant morbidity and even mortality in adulthood.

Glossary

Abbreviation

AN

anorexia nervosa

Additional Information

Disclosure Summary: The authors have nothing to disclose.

Data Availability

Data sharing is not applicable to this article as no datasets were generated or analyzed during the current study.