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SAN FRANCISCO (FRONTLINE MEDICAL NEWS) – Consumption of non-cow’s milk in early childhood is associated with decreased height, compared with consumption of cow’s milk by children in the same stage of life, a study has shown. The results call into question perceived health benefits of the consumption of non-cow’s milk in childhood.
“These findings are important for health care workers and parents in terms of optimal growth of children and the kind of milk needed to achieve that,” presenter Marie-Elssa Morency explained at the meeting of the Pediatric Academic Societies. Ms. Morency is a master’s student in the department of nutritional sciences at the University of Toronto.
Whether cow’s milk is a better source than non-cow’s milk of nutritional and caloric energy to a growing body has not been studied with rigor. Perceived health benefits of non-cow’s milk have led some parents to substitute cow’s milk with other types of milk for their children, Ms. Morency said.
To gain some clarity, the researchers looked at data from the TARGetKids! longitudinal cohort of children. The cohort is being followed into adolescence to link early life exposures to various physiological and developmental health problems. The present study looked at more than 5,000 healthy children aged 24-72 months. Any conditions that could affect growth were grounds for exclusion.
The primary exposure was the daily consumption of cow’s milk in 4,632 children or non-cow’s milk in 643 children. The typical number of 250-mL glasses of milk consumed per day was gleaned by a questionnaire completed by the parents. The primary outcome was height-for-age z score.
The two groups were similar at baseline in age, sex (slightly more than half were male), body mass index, and maternal height. Those who predominantly consumed cow’s milk averaged 2 cups per day. Some also consumed non-cow’s milk (about one glass per day). Those in the non-cow’s milk group consumed on average 1.4 cups per day, with cow’s milk consumption being rare.
The overall z-score was 0.1 (95% confidence interval [CI], –0.6 to 0.8). The groups differed in z-score, with a score of 0.2 (95% CI, –0.6 to 0.8) in the cow’s milk group and –0.04 (95% CI, –0.8 to 0.7) in the non-cow’s milk group. The resulting shorter height in those consuming non-cow’s milk was 0.42 cm (95% CI, –0.61 to –0.19) in a univariate analysis (P less than .001). A multivariate analysis that adjusted for age, sex, maternal ethnicity, maternal height, z-score, and neighborhood income revealed a significant difference in the same group of 0.31 cm (95% CI, –0.50 to –0.11; P less than .001).
The reduced consumption of cow’s milk in the non-cow’s milk group was identified as a partial mediator of the association between non-cow’s milk consumption and height. Putting the results into context, Ms. Morency explained that a 3-year-old child typically drinking 3 cups of non-cow’s milk each day would be 1.5 cm shorter than a similar child drinking the same amount of cow’s milk each day.
The literature shows that height children achieve during childhood is an important benchmark of growth and development, adequate nutrition, and pending obesity. Shorter-than average children can often be shorter than average in height as adults, which has been linked with increased risk of type 2 diabetes, gestational diabetes, coronary heart disease, and hypertension.
Diet influences height: Reduced calories and nutrients in an inadequate diet hinder growth, Ms. Morency noted. Cow’s milk delivers more protein, fat, vitamins, minerals, and calories than do non-cow’s milk formulations, such as almond milk and soy milk. Moreover, non-cow’s milks contains added sugar in an already sugar-laden diet of many children in North America and elsewhere, she said.
“While non-cow’s milk consumption in childhood may have other health benefits, increased height does not appear to be one of them,” said Ms. Morency.
Study strengths include the relatively large sample size, statistical rigor, and consistent findings with prior studies. Limitations include the cross-sectional design that rules out any conclusions about direct cause, and the use of questionnaire data, which inherently comes with problems of report and recall bias.
A causal connection awaits randomized controlled trials. For now, the researchers suggest that standard labeling of non-cow’s milk beverages concerning the nutritional contents could be helpful in guiding parental choice.
The University of Toronto sponsored the study, which was funded by the Canadian Institutes for Health Research. Ms. Morency reported having no financial disclosures.
