The Long-Term Effects of Early Nutrition: The Role of Breastfeeding on Cholesterol Levels

Over the past 2 decades, there have been several investigations examining the influence of early nutrition on chronic disease in adulthood. In 1991, Alan Lucas proposed the term nutritional programming for describing the concept of early nutritional stimulus, applied during a critical or sensitive period, having long-term effects on health and disease. As described by Lucas, nutritional programming may influence health outcomes in adulthood by either (1) “induction, deletion or impaired development of a somatic structure resulting from a stimulus or insult during a critical period or (2) physiological setting by an early stimulus or insult at a critical period, with long-term consequences for function. ” Considerable differences in the nutritional intake of breast and formula-fed infants have led researchers to examine the extent to which infant-feeding mode influences nutritional programming. Several investigations have explored the effect of breast versus artificial baby milk on subsequent cardiovascular disease risk, especially cholesterol status. Unfortunately, the evidence has been inconclusive. The research spotlighted here, by Owen et al, combines a large cross-sectional study of cholesterol status in contemporary adolescents with a systematic review of 37 other reports (encompassing 52 studies, each serving as a separate observation) of cholesterol status during infancy, childhood, adolescence, and adulthood. The report is unique in that the researchers hypothesized that the effect of infant feeding on total cholesterol (TC) may vary with age. Thus, the data were examined separately by infancy (< 1 y of age; 26 observations), childhood and adolescence (1-16 y; 17 observations), and adulthood (≥ 17 y; 9 observations). For each meta-analysis, the mean difference (breastfed vs. artificial baby milk fed) and 95% confidence interval (95% CI) of the difference in TC and low-density lipoprotein cholesterol (LDL, when available) were analyzed. Since the studies used data from subjects with a wide range of birth years (1920-1994), observations were examined for publication bias. In addition, the effect of excluding studies in which the breastfed group included subjects that were not exclusively breastfed was examined. When the observations were analyzed separately by age group, it was shown that the effects of feeding mode depended on life cycle stage (Table 1). Among infants, 25 of the 26 observations found that serum TC was higher among those breastfed than among those receiving artificial baby milk. The mean difference, based on meta-analysis, was 0.64 mmol/L (95% CI, 0.49-0.79). Six of 7 observations also found that LDL was higher among breastfed infants compared to nonbreastfed infants (mean difference, 0.57 mmol/L). In contrast, there was no mean difference by feeding group in TC or LDL during childhood or adolescence. Sixteen of the 17 observations had confidence intervals that crossed the line of no difference for TC, and all 4 observations for LDL crossed the line of no difference. Older children showed a similar pattern to the younger children. However, among the 9 observations conducted during adulthood, 7 showed TC to be lower for the breastfed group than the nonbreastfed group. The mean difference was – 0.18 mmol/L (95% CI, –0.06 to –0.30). Among the 4 studies examining LDL during adulthood, all showed levels to be lower among the breastfed group than the nonbreastfed group. Meta-analysis results were affected neither by exclusion of the 11 observations in which the breastfeeding group included mixed feeding