Age of cow milk introduction and growth among 3-5-year-old children

Beneficial effects of short-term breastfeeding versus non-breastfeeding in early life against childhood obesity: findings from the US-based population study NHANES

BACKGROUND

Breastfeeding is widely recognized for its potential to reduce childhood obesity. However, research investigating these benefits in children breastfed for a short duration (up to 6 months) remains limited despite this being a common practice globally.

METHODS

This study focused on a population breastfed for 6 months or less to determine the potential benefits of short-term breastfeeding for preventing childhood obesity. Data were collected from five survey cycles of an US-based population study (the National Health and Nutrition Examination Survey (NHANES)), spanning 2009-2020. A sample of 3,211 children aged 2-6 years was selected, including 1,373 never breastfed and 1,838 ever breastfed. Logistic regression analysis examined the direct association between short-term breastfeeding and childhood obesity. Subsequent subgroup analyses were conducted. Additionally, stratified logistic regression explored the relationship between childhood obesity and the introduction of other early nutrition in both ever-breastfed and never-breastfed children.

RESULTS

Overall, breastfeeding for 6 months or less did not directly prevent childhood obesity. However, among participants with older mothers (aged 35 or above), short-term breastfeeding was associated with a lower risk of childhood obesity compared to never being breastfed (OR 0.31, 95% CI: 0.17, 0.59). Similarly, children aged 3-4 years who were breastfed for > 3 ~ 6 months exhibited a lower obesity risk (OR 0.56, 95% CI: 0.35, 0.89). In ever-breastfed children, delayed infant formula introduction was linked to a lower risk of obesity (P-trend < 0.05: introduction at age ≤ 1 vs. >1 ~ 3 vs. >3 months). Conversely, for non-breastfed children, introducing milk (other than breast milk or formula) later (≥ 12 versus < 12 months) and introducing alternatives to whole cow's milk were associated with lower obesity risks (OR 0.54, 95% CI: 0.37, 0.78; OR 0.21, 95% CI: 0.08, 0.60, respectively). Notably, these trends were not observed in ever-breastfed children.

CONCLUSIONS

Short-term breastfeeding may offer some benefits in preventing childhood obesity for specific populations. Additionally, it could potentially mitigate risks associated with the introduction of formula and cow's milk at inappropriate times.

Milk and dairy consumption is positively associated with height in adolescents: results from the Israeli National Youth Health and Nutrition Survey

PURPOSE

Milk consumption is associated with increased height primarily in early childhood. However, in adolescents, data are scarce with inconsistent results. Since height is a proxy for overall health and well-being, this study evaluated the association of dairy intake with height in adolescents.

METHODS

Students in 7th-12th grades, participating in the 2015-2016 Israeli Health and Nutrition Youth Survey, a school-based cross-sectional study, completed self-administered questionnaires, including a semi-quantitative food frequency questionnaire (n = 3529, 48% males, 15.2 ± 1.6 years). Anthropometric measurements were also performed. Dairy servings were calculated as the calcium equivalent of 1 cup of milk, and consumption was divided into four categories from very low (< 1 serving/day) to high (3 + servings/day). BMI- and Height-for-age z scores (HAZs) were calculated according to WHO growth standard; relatively short stature (RSS) was defined as HAZ < - 0.7 SD (< 25th percentile). Multivariable linear and logistic regression analyses were performed to evaluate the association of dairy intake with HAZ and prevalence of RSS, respectively.

RESULTS

Median consumption of dairy products was 2 servings/day, 1.4 from unsweetened products (milk, cheese and yogurt). Controlling for age, sex, BMI-z-score and socioeconomic status, each increment of unsweetened dairy intake was associated with on average 0.04 higher HAZ (equivalent to 0.3-0.4 cm, p < 0.05), and with reduced risk for RSS: OR 0.90, 95%CI: 0.84, 0.97, p < 0.01. No such associations were found with sweetened dairy products.

CONCLUSION

Consumption of unsweetened dairy products (3-4 servings/day) appears to contribute to achieving growth potential in adolescents. Intervention studies are necessary to determine the causal relationship between dairy intake and linear growth.