Short report

Milk consumption and the prepubertal somatotropic axis

Janet W Rich-Edwards^{* 1,2,3} , Davaasambuu Ganmaa^{* 4} , Michael N Pollak⁵ , Erika K Nakamoto² , Ken Kleinman² , Uush Tserendolgor⁶ , Walter C Willett^3,4,7 and A Lindsay Frazier^7,8

¹Connors Center for Women's Health and Gender Biology, Brigham and Women's Hospital, Boston, USA

²Department of Ambulatory Care and Prevention, Harvard Medical School and Harvard Pilgrim Health Care, Boston, USA

³Department of Epidemiology, Harvard School of Public Health, Boston, USA

⁴Department of Nutrition, Harvard School of Public Health, Boston, USA

⁵Division of Cancer Prevention, Department of Oncology, McGill University, Montreal, Canada

⁶Public Health Institute, Ulaanbaatar, Mongolia

⁷Channing Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston, USA

⁸Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, USA

author email corresponding author email* Contributed equally

Nutrition Journal 2007, 6:28doi:10.1186/1475-2891-6-28

Published:	27 September 2007

Abstract

Background

Nutrients, hormones and growth factors in dairy foods may stimulate growth hormone (GH), insulin-like growth factor I (IGF-I), and raise the ratio of IGF-I to its binding protein, IGFBP-3. We conducted pilot studies in Mongolia and Massachusetts to test the extent to which milk intake raised somatotropic hormone concentrations in prepubertal children.

Methods

In Ulaanbaatar, we compared plasma levels before and after introducing 710 ml daily whole milk for a month among 46 10–11 year old schoolchildren. In a randomized cross-over study in Boston, we compared plasma hormone levels of 28 6–8 year old girls after one week of drinking 710 ml lowfat (2%) milk with their hormone levels after one week of consuming a macronutrient substitute for milk.

Results

After a month of drinking whole milk, Mongolian children had higher mean plasma levels of IGF-I (p < 0.0001), IGF-I/IGFBP-3 (p < 0.0001), and 75^th percentile of GH levels (p = 0.005). After a week of drinking lowfat milk, Boston girls had small and non-significant increases in IGF-1, IGF-1/IGFBP-3 and GH.

Conclusion

Milk drinking may cause increases in somatotropic hormone levels of prepubertal girls and boys. The finding that milk intake may raise GH levels is novel, and suggests that nutrients or bioactive factors in milk may stimulate endogenous GH production.