The association of body size in early to mid-life with adult urinary 6-sulfatoxymelatonin levels among night shift health care workers

摘要

Background Adult body mass index (BMI) has been associated with urinary melatonin levels in humans; however, whether earlier-life body size is associated with melatonin, particularly among night shift workers, remains unknown. Methods We evaluated associations of birth weight, body shape (or somatotype) at ages 5 and 10, BMI at age 18 and adulthood, weight change since age 18, waist circumference, waist to hip ratio, and height with creatinine-adjusted morning urinary melatonin (6-sulfatoxymelatonin, aMT6s) levels among 1,343 healthy women (aged 32–53 at urine collection, 1996–1999) in the Nurses’ Health Study (NHS) II cohort. Using multivariable linear regression, we computed least-square mean aMT6s levels across categories of body size, and evaluated whether these associations were modified by night shift work. Results Adult BMI was inversely associated with aMT6s levels (mean aMT6s levels?=?34 vs. 50?ng/mg creatinine, comparing adult BMI ≥30 vs. 2; P_trend interaction?=?0.72 for night shifts worked within two weeks of urine collection). Conclusions Our results suggest that adult BMI, but not earlier measures of body size, is associated with urinary aMT6s levels in adulthood. These observations did not vary by night shift work status, and suggest that adult BMI may be an important mechanism by which melatonin levels are altered and subsequently influence chronic disease risk.