“Babies who are breastfed have lower cholesterol levels in later life”, the Daily Express reports. It says that researchers who reviewed the histories of 4,608 children given formula milk and 12,890 breastfed children found that in adulthood, those who were breastfed had a lower overall level of cholesterol.
This story was based on a review that combined the results of several studies on infant feeding practices and cholesterol levels in adult life. Although the results did show a very small reduction in cholesterol in adults who had ever been breastfed compared to those formula-fed, it cannot prove that this was caused by breastfeeding. This is not the due to the quality of the review, which was well conducted, but due to limitations that are inherent when combining data from several studies that have different designs and methods. However, despite offering no conclusions on whether breastfeeding reduces cholesterol in later life, this review provides another indication that breast may be best.
Dr Christopher Owen and colleagues from the University of London, University of Bristol, Umea University, Sweden, and several other institutions across the UK and worldwide, carried out the research. The study was funded by the British Heart Foundation and was published in the peer-reviewed medical journal: American Society for Nutrition.
In this systematic review, the researchers looked at the current published evidence on whether breastfeeding is associated with lower blood cholesterol in adult life.
A literature search was carried out in a number of electronic databases to look for published observational studies, review articles or letters that had recorded infant feeding practices and measured blood cholesterol levels at some point in adult life. Following the exclusion of studies that had not collected the necessary data, the researchers were left with 18 publications of 17 studies (mostly North European) that involved 17,498 participants.
Where possible, the researchers contacted the authors of the primary research (13 studies) to obtain the original study data. Where this was not possible, they used the data from the published reports (four studies). They were looking for data on groups of exclusively breastfeeding and exclusively bottle feeding mothers. They were also interested in the duration that the child was breast fed or bottle fed, or the duration that they were given both.
All but four of the studies had measured cholesterol after the subjects had fasted. The data was analysed to look for differences in total cholesterol levels in adults who had been characterised as being breastfed compared to those characterised as formula-fed. The analyses took into account various potential confounders such as age, sex, BMI, smoking and socioeconomic variables. Attempts were also made to consider the type of formula the child was given and its year of birth.
It was possible to compare exclusively breastfed babies with exclusively bottle-fed babies in seven of the studies. In the other 10 studies, it was not known whether the type of feeding was exclusive. When the researchers combined all 17 studies, they found that there was marginally significant reduction in total cholesterol among adults who had been breastfed compared to those formula-fed (reduction of 0.04mmol/L; 95% confidence interval -0.08 to 0.00mmol/L). The studies had different designs and methods, and there were significant differences in the results.
When the researchers combined the data from just the seven studies that could determine exclusive feeding patterns, they found the reduction in cholesterol in those people exclusively breastfed compared to those exclusively bottle-fed was greater (reduction of -0.15mmol/L; 95% confidence interval -0.23 to -0.06mmol/L). In addition, the results of these seven studies did not differ significantly.
A separate analysis of the 10 studies that could not say for certain whether feeding patterns were exclusive, did not show any significant difference in cholesterol levels between the two groups. There was little effect upon the results when confounding factors were taken into account.
The researchers concluded that breastfeeding, ‘particularly when exclusive’, may be linked to lower blood cholesterol concentrations in later life.
This was a well-designed and carefully conducted review; however, there are unavoidable complications which limit interpretation of its results.
Although the question of whether breastfeeding reduces cholesterol in later life cannot be conclusively answered by this review, the study does present another indicator that breast may be best.