“Cow’s Milk Fat and Child Adiposity: a Prospective Cohort Study”, 2021-08-25 (; similar):
Background: International guidelines recommend children aged 9 months to 2 years consume whole (3.25%) fat cow’s milk, and children older than age 2 years consume reduced (0.1–2%) fat cow’s milk to prevent obesity. The objective of this study was to evaluate the longitudinal relationship between cow’s milk fat (0.1–3.25%) intake and body mass index z-score (zBMI) in childhood. We hypothesized that higher cow’s milk fat intake was associated with lower zBMI.
Method: A prospective cohort study of children aged 9 months to 8 years was conducted through the TARGet Kids! primary care research network. The exposure was cow’s milk fat consumption (skim (0.1%), 1%, 2%, whole (3.25%)), measured by parental report. The outcome was zBMI. Height and weight were measured by trained research assistants and zBMI was determined according to WHO growth standards. A linear mixed effects model and logistic generalized estimating equations were used to determine the longitudinal association between cow’s milk fat intake and child zBMI.
Results: Among children aged 9 months to 8 years (n = 7467; 4699 of whom had repeated measures), each 1% increase in cow’s milk fat consumed was associated with a 0.05 lower zBMI score (95% CI −0.07 to −0.03, p < 0.0001) after adjustment for covariates including volume of milk consumed. Compared to children who consumed reduced fat (0.1–2%) milk, there was evidence that children who consumed whole milk had 16% lower odds of overweight (OR = 0.84, 95% CI 0.77 to 0.91, p < 0.0001) and 18% lower odds of obesity (OR = 0.82, 95% CI 0.68 to 1.00, p = 0.047).
Conclusion: Guidelines for reduced fat instead of whole cow’s milk during childhood may not be effective in preventing overweight or obesity.
…Findings from the present study are consistent with several other studies. A recent systematic review14 and meta-analysis13 identified observational studies which examined the relationship between cow’s milk fat and child adiposity among children aged 9 months to 18 years. An association between higher cow’s milk fat and lower adiposity was found in the majority of studies, and no study identified that reduced fat milk lowered the risk of child overweight or obesity. However, the majority of the studies were considered to have high risk of bias due to cross-sectional design or lack of adjustment for potential confounding factors such as volume of milk, prior measures of adiposity, and parent BMI.13 The current study was designed to overcome these weaknesses through a large prospective cohort study with adjustment for important potentially confounding factors. Our findings are also consistent with a RCT of children aged 4–13 years which showed no evidence of a relationship between dairy fat (including milk, cheese, and yogurt) intake and child adiposity.41
Possible mechanisms underlying the observed relationship include reverse causality, where parents of leaner children provide higher cow’s milk fat and vice versa. Another possibility is that children who consume higher cow’s milk fat may be more satiated than those who consume reduced fat cow’s milk, leading them to consume a lower quantity of cow’s milk or other energy dense foods contributing to higher energy intake.42