The analysis -- based on data from 17 studies with about 17,000 participants, some breastfed and some formula-fed -- provides support that early exposure to human milk may be linked to lower blood cholesterol concentrations in adult life.
In adulthood, the participants from seven of the studies who had been exclusively breastfed had slightly lower blood cholesterol concentrations than those who had been exclusively formula-fed.
In their previous review, the researchers found blood cholesterol concentrations were higher in breastfed babies than in formula-fed babies. By childhood, levels were similar for both groups.
The study is based on data from 17 published observational studies that recorded whether participants were breastfed or formula fed and that also measured blood cholesterol concentrations in adulthood. Data were extracted from more than 17,000 participants -- 12,890 breastfed, 4,608 formula fed -- and adjusted for socioeconomic position, body mass index, age, and smoking status.
The reason breastfeeding may result in lower cholesterol is that the high cholesterol content of human milk may exert physiologic changes that influence cholesterol synthesis, according to the researchers. However, they also point out that other factors, such as differing lifestyles between adults who were initially breastfed or formula-fed, may play a role.