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theses

In recent years, there has been a population-level trend toward earlier puberty, which presents psychological and clinical risks to girls. Body fatness and earlier puberty are also risk factors for problems including adult obesity and breast cancer. Diet is a primary and modifiable factor that can influence puberty and growth. Current research on a Mediterranean-like dietary pattern in regard to these outcomes is limited; no studies have examined its role in puberty outcomes or longitudinal growth, and only one study has examined a Mediterranean-like diet (MD) and body mass index (BMI) in a healthy U.S. pediatric population. We aimed to address these gaps in the literature by evaluating the role of MD adherence in puberty, growth, and body fatness in The Jersey Girl Study. We developed an index for assessing adherence to a Mediterranean-like diet and evaluated its relationship with cross-sectional and longitudinal outcomes. Our sample was a cohort of 202 girls who resided in New Jersey and were 9 or 10 years old at baseline. Data were collected from a baseline study visit and physical examination, a 3-day dietary recall, a general baseline questionnaire filled out by girls’ mothers, and annual follow-up questionnaires on growth and puberty outcomes.

Multivariable Poisson regression models showed that high adherence (score 6-9) was significantly associated with lower prevalence of thelarche at baseline compared to girls with low adherence (score 0-3) (Prevalence Ratio: 0.65, 95% confidence interval (CI): 0.48-0.90 in the fully adjusted model). Further analysis suggested that this may have been driven by consumption of fish and reduced/low/non-fat dairy. Multivariable linear regression models to examine mean age at thelarche also suggested a nonsignificant trend of later age at thelarche with higher MD adherence. Multivariable Cox proportional hazards models found that girls with higher MD adherence had significantly longer time to menarche (Hazard Ratio: 0.45, 95% CI: 0.28-0.71 in the fully adjusted model for girls with high vs. low MD adherence). Further analysis suggested that this relationship was driven by vegetable and reduced/low/non-fat dairy consumption. Multivariable proportional odds models for being overweight or obese at baseline, and multivariable linear regression models comparing mean BMI z-score, percent body fat, waist circumference, waist-to-hip ratio, waist-to-height ratio, height at baseline, and height at menarche, did not show a significant relationship with MD adherence in this study. Multivariable linear mixed-effects growth models also did not show a difference in pubertal growth rate based on MD adherence.

The results of our study were consistent with previous findings that certain components of a Mediterranean-like diet were associated with a later age at menarche and thelarche. To our knowledge, this is the first study to demonstrate an association between an overall MD pattern and puberty outcomes. Our results suggest that consuming a more Mediterranean-like diet (high in plant-based foods, unsaturated fats, reduced/low/non-fat dairy, and fish, and low in red and processed meats), may decrease girls’ risk of earlier puberty. Later age at puberty onset, in turn, could lead to decreased risk of adverse psychological, behavioral, and clinical outcomes in these girls, including low self-esteem, drug abuse, polycystic ovarian syndrome, and cancer risk. Further research is necessary to confirm our findings in other U.S. pediatric populations, and to elucidate the mechanism through which Mediterranean-like diet may influence puberty.

ETD_9244

Ph.D.

Includes bibliographical references

by Elizabeth A. Szamreta

doi:10.7282/t3-0a28-5t15

ETD doctoral

The author owns the copyright to this work.