Previous research suggests the existence of a self-regulatory mechanism that determines milk intake from feed to feed in breastfed infants, allowing them to feed according to appetite. It has been noted that milk intake is not restricted by maternal milk supply and is determined according to infant demand. Data regarding the association between breastmilk composition and infant feeding patterns (frequency and amount of breastmilk taken) would help in understanding the regulation of food intake in breastfed infants.

A study was undertaken in Australia to examine the relationship between breastmilk macronutrient concentration and patterns of milk intake in breastfeeding infants over a 24-hour breastfeeding period. Pre and post breastfeed samples, from each breast, over a 24-hour period were collected by mothers of exclusively breastfed babies (n=15). Breastmilk samples were analysed for fat, lactose, total protein, casein, and whey protein content and the energy content for each feed was calculated.

The researchers noted that breastfeeding patterns and milk composition varied greatly between individuals. The fat content of milk significantly differed over 24 hours whereas the concentration of lactose and protein content remained the same. A significant negative relationship was found between the 24-hour total protein intake and frequency of breastfeeds (P = .01). Thus, a higher 24-hour protein intake was significantly associated with fewer feeds per day. Lactose concentration changed little throughout the day and the average lactose concentration was not associated with the intervals between feeds. No relationship was seen either between fat or energy content and feeding patterns.

Whilst the authors acknowledge that data was taken at one time point in a mother’s breastfeeding experience, they suggest that the association between milk protein intake and the breastfeeding frequency suggests that protein intake may play a role in infant appetite control.

Khan S, Hepworth AR, Prime DK et al (2012). Variation in Fat, Lactose, and Protein Composition in Breast Milk over 24 Hours: Associations with Infant Feeding Patterns. J Hum Lact. published 13 July 2012, 10.1177/0890334412448841