The association between maternal body mass index and breast milk composition: a systematic review

CONTEXT

Breast milk composition is influenced by many factors, ranging from maternal nutritional status to infant sex. Previous studies have explored the relationship between maternal body mass index (BMI) and breast milk composition; however, the findings have been inconsistent and controversial.

OBJECTIVE

To systematically review the evidence on the association of maternal weight and BMI with breast milk composition.

DATA SOURCES

The PubMed and Scopus databases were searched up to May 3, 2023, using the following search strategy: ("maternal weight" OR "maternal BMI" OR "mother's weight" OR "mother's BMI") AND ("maternal milk" OR "human milk" OR "breast milk").

DATA EXTRACTION

A total of 83 publications, involving data from more than 11 310 lactating women, were identified. All extracted data were compiled, compared, and critically analyzed.

DATA ANALYSIS

Overall, maternal BMI was associated with higher levels of leptin and insulin, and the ratio of omega-6 to omega-3 polyunsaturated fatty acids in breast milk. However, no conclusive associations were found between maternal BMI and the levels of energy, macronutrients, micronutrients, and other components of breast milk.

CONCLUSIONS

This systematic review provides robust evidence supporting a positive correlation between maternal BMI and breast milk concentrations of leptin, insulin, and the omega-6 to omega-3 polyunsaturated fatty acid ratio. Nevertheless, disparities in findings are noticeable for other constituents of breast milk. To comprehensively grasp the influence of maternal weight and BMI on breast milk composition, further research endeavors are imperative.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42023458667.

Development, validity and reproducibility of a dish-based semi-quantitative food frequency questionnaire in Iran

BACKGROUND: The food frequency questionnaire (FFQ) is the method of choice for dietary assessment in epidemiological studies. FFQs focusing on mixed-dishes and simple food items are useful where mixed-dishes are an essential part of food consumption. OBJECTIVE: Regarding the fact that the nature of the Iranian diet is mixed-dish, the present study aimed to design and assess the validity and reproducibility of a dish-based semi-quantitative FFQ in the Iranian adult population. METHODS: A list of 302 food items was collected from four geographical areas around Iran. The validation study was conducted on 97 healthy adults. The FFQ was introduced at the beginning of the study and 10 months after; two three-day food records were collected during the study. Also, biomarkers including 24-hour urinary potassium and nitrogen, serum retinol, and alpha-tocopherol were measured. RESULTS: A 142-food-item FFQ was concluded. The correlation coefficient between the second FFQ and the second three-day food record ranged from 0.225 to 0.323 for macronutrients and 0.128 to 0.476 for micronutrients. The percentile agreements (same or adjacent quartile) between the two methods were more than 60% for all nutrients. The intraclass correlation coefficient between FFQs (except for vitamin E) ranged from 0.363 to 0.578. The correlation coefficient between the second FFQ and the second biomarker assessment was 0.241 for protein.