Milk-Tot Study: Impact of Whole Versus Low-fat Milk on Child Health

In the U.S. it is recommended that children consume whole cow's milk (3.5% fat) from ages 1 to 2 years to support rapid early growth and brain development, and then at age 2 years transition to low-fat (1%) or non-fat milk to reduce saturated fat and calorie intake. To date, few studies have examined the optimal milk type for children to prevent obesity. This randomized controlled trial will evaluate the effect of consumption of whole versus 1% milk on child adiposity.

The prevalence of child obesity in the U.S. has tripled since the 1970s and excess weight gain - even in young children - is a precursor to adult obesity and associated co-morbidities. In the U.S. it is recommended that children consume whole cow's milk (3.5% fat) from ages 1 to 2 years to support rapid early growth and brain development, and then at age 2 years transition to low-fat (1%) or non-fat milk to reduce saturated fat and calorie intake. However, surprisingly few rigorous trials to support recommendations on optimal milk type have been conducted and existing observational studies paradoxically suggest that lower fat milk consumption is associated with increased adiposity in children. The effects of the types of fat found in milk on cardiometabolic disease risk have also been questioned. This randomized controlled trial will evaluate the effect of consumption of whole versus 1% milk on child adiposity and other health and developmental outcomes beginning after toddlers have successfully transitioned from breastmilk and/or formula to cow's milk at 2 years of age. Investigators will recruit 625 parents of toddlers and randomly assign 625 toddlers to either whole or 1% milk groups for 1 year (with estimated final sample size of 500). Our primary aim is to determine how milk fat type (whole versus 1%) consumed from age 2 to 3 years affects change in adiposity as measured by waist-to-height ratio (primary outcome), body mass index, tri-ponderal mass index, and waist circumference. Secondary aims are to evaluate how milk type consumed from age 2 to 3 years affects changes in milk, total and saturated fat, added sugars, and total energy intake and overall diet quality, as well as blood lipids and vitamin D status, and neurocognitive development. Results from the Milk-TOT Study can help pediatric health care providers give evidence-based dietary recommendations to improve child weight and health, and can inform the types of milk provided to participants in the federal nutrition programs which collectively provide milk to over half of all young children in the U.S.