Background: Because of its nutrients and anabolic hormones, cow's milk may promote height growth, which in turn has been related to breast cancer risk. We prospectively investigated associations between dairy intakes and height growth.
Methods: A cohort of 5,101 girls from throughout the United States completed annual surveys (1996-2001, 2003), providing height, weight, and past-year diet. At baseline, all were premenarchal, ages 9 years and above, with no serious medical conditions. We studied three outcomes: annual height growth, peak growth velocity, and adult height. Multivariate models estimated the effects of milk, cheese, yogurt, and energy on subsequent growth, adjusted for race/ethnicity, age, prior height, and body mass index. Other models studied fats and proteins.
Results: Premenarchal girls who drank >3 servings per day of milk grew 0.11 in. (P = 0.02) more the following year than girls consuming <1 serving per day. Yogurt (+0.13 in./cup; P = 0.02), but not cheese or total calories, predicted height growth. In a separate model, dairy protein (+0.034 in./10 g; P < 0.001) predicted height growth. Larger peak velocities were seen among girls reporting, at baseline, more milk (>3 glasses per day versus <1; +0.14 in., P = 0.01), more yogurt (+0.17 in./cup, P = 0.02), and, in a separate model, more dairy protein (+0.039 in./10 g; P = 0.003). Baseline milk and dairy protein predicted taller adults. Dairy protein was more important than dairy fat, for all outcomes. Nondairy animal protein and vegetable protein were never significant, nor were nondairy animal fat and vegetable fat.
Conclusion: Of the foods/nutrients studied, dairy protein had the strongest association with height growth. These findings suggest that a factor in the nonlipid phase of milk, but not protein itself, has growth-promoting action in girls.