An examination of breastmilk composition among high altitude Peruvian women.

Objective: Relatively little is known about sources of variation in human breastmilk composition. Previous research posits that composition may be affected by the low oxygen environment found at high altitude (HA). Our objective is to compare the milk composition of a sample of HA Andeans to previously published data on HA Tibetans and low altitude (LA) Peruvians.

Methods: Mid-feed milk samples were collected from 22 women and tested for lipid, carbohydrate and protein content in addition to dietary surveys and anthropometric measures. We examined relationships between maternal and infant characteristics (maternal BMI, adiposity, age, skinfold thickness, infant age) and milk composition using multiple regression analyses. A Welch-Satterthause t-test was used to compare summary measures from Andean sample and Tibetan samples.

Results: Milk fat, sugar, and true protein content were correlated with different maternal and infant characteristics, with only waist to hip ratio negatively affecting fat and positively affecting sugar content in full models. Nuñoan and LA Peruvian milk exhibited significantly lower lactose levels (6.01 ± .89 g/100 mL and 6.38 ± 0.03 g/100 mL) than Tibetans (7.25 ± 0.35 g/100 mL). Fat content among Nuñoans was similar to that of Tibetans (4.5 ± 0.78 g/100 mL and 4.6 ± 1.51 g/100 mL, respectively), and higher than those of LA Peruvians.

Conclusions: Both HA populations demonstrate relatively high fat content and both Peruvian samples exhibited relatively higher protein and lower lactose than Tibetan samples, suggesting that both population-based differences in feeding behavior and climatic differences may influence composition.