Preweaning diet programs postweaning plasma thyroxine concentrations in baboons

Duration of breast-feeding and adiposity in adult life

Few studies have examined whether the duration of breast-feeding is associated with BMI in adult life. In the past, the heights and weights of infants and the duration of breast-feeding were routinely recorded at infant welfare clinics in Helsinki, Finland. Most infants in the city were taken to these free clinics. The Helsinki Birth Cohort comprises 13,345 people born in the city during 1934-1944; 84% were breast-fed. In 2001, a questionnaire was sent to members of the cohort asking about their weight and height. A random sample of 2003 men and women attended a clinic at which height, weight, and body composition were measured. We studied sibships that included 2 or more people from the cohort. There were 1823 subjects: 831 had completed the questionnaire; 129 had attended the clinic. We grouped the subjects according to duration of breast-feeding: 0-2 mo, 3-4 mo, 5-7 mo, and 8 mo or more. We compared siblings who were discordant for duration of breast-feeding. We found that a longer period of breast-feeding was associated with lower BMI at 1 y of age (P = 0.04 for a linear trend). This relation disappeared by the age of 7 y. People breast-fed for 5-7 mo had the lowest reported BMI at age 60 y, although this was not statistically significant; 8.8% more people breast-fed for 8 mo or more had reported BMIs that were overweight (25 to 30 kg/m(2)) compared with those breast-fed for shorter periods (P = 0.06). Breast-feeding for <2 mo or 8 mo or more was associated with an increased BMI and percentage body fat in later life, measured at the clinic (P = 0.08 and P = 0.03 for quadratic trends). We conclude that breast-feeding for <2 mo may be deleterious, possibly because of lack of exposure to protective factors in breast milk. Breast-feeding beyond 8 mo may be deleterious because mother's hormones in breast milk reset the infant's hypothalamic-pituitary-thyroid axis.

Breast feeding in infancy and arterial endothelial function later in life. The Cardiovascular Risk in Young Finns Study

BACKGROUND/OBJECTIVES

Breast feeding in infancy may be associated with reduced cardiovascular morbidity in adulthood. We examined the association between breast feeding in infancy and arterial function and structure in adulthood in a population-based cohort of Finnish adults.

SUBJECTS/METHODS

Noninvasive ultrasound was used to measure brachial artery flow-mediated dilatation (FMD), carotid artery intima-media thickness (IMT) and carotid artery compliance (CAC) in 1667 young adults participating in the Cardiovascular Risk in Young Finns Study with data on early nutrition.

RESULTS

Maximal FMD was higher in breast-fed men compared to formula-fed men (7.2+/-4.0 vs 5.9+/-3.4%, P=0.029) while no differences were seen between breast-fed and formula-fed women (8.9+/-4.5 vs 8.8+/-5.0%, P=0.84). In men, the multivariable correlates of FMD included the group variable for breast feeding (P=0.014), birth weight (P=0.043), waist circumference (P<0.001) and baseline brachial artery diameter (P<0.001). In women, the multivariable correlates of FMD were birth weight (P=0.02), waist circumference (P<0.001) and brachial artery baseline diameter (P<0.001). Breast feeding was not significantly associated with IMT or CAC in multivariable models.

CONCLUSIONS

Adult men who have been breast fed have better brachial endothelial function compared to men who have been formula fed.

Breastmilk feeding and lipoprotein profile in adolescents born preterm: follow-up of a prospective randomised study

BACKGROUND

Breastfeeding is associated with reduced cholesterol concentration later in life, but previous studies have not used random assignment of infant diet with prospective follow-up. We tested the hypothesis that breastmilk feeding benefits the lipoprotein profile in adolescents born preterm, in whom randomisation to different diets at birth is feasible.

METHODS

926 infants born preterm were randomly assigned in two parallel trials to receive (trial 1) donated banked breastmilk or preterm formula, or (trial 2) standard term formula or preterm formula, as sole diet or as supplements to mother's milk in both trials. We followed up 216 participants at age 13-16 years and measured ratio of low-density to high-density lipoprotein cholesterol (LDL to HDL), ratio of apolipoprotein B to apolipoprotein A-1 (apoB to apoA-1), and concentration of C-reactive protein (CRP; a measure of the inflammatory process associated with atherosclerosis).

RESULTS

Adolescents who had been randomised to banked breastmilk had a lower CRP concentration (p=0.006) and LDL to HDL ratio (mean difference 0.34 [14% lower], 95% CI -0.67 to -0.01; p=0.04) than those given preterm formula. A greater proportion of human milk intake in infancy was associated with lower ratios of LDL to HDL (p=0.03) and apoB to apoA-1 (p=0.004)--independent of gestation and potential confounding factors--and with lower CRP concentration (p=0.03). CRP concentration correlated with the two lipoprotein ratios (p<0.0001 and p=0.003, respectively).

INTERPRETATION

Our data provide experimental evidence for the long-term benefits of breastmilk feeding on the risk of atherosclerosis.

Programming of initial steps in bile acid synthesis by breat-feeding vs. Formula-feeding in the baboon

We tested the hypothesis that breast- vs. formula-feeding differentially affects the enzymatic activity of three sterol hydroxylases critical in the initial steps of bile acid formation. Thirty baboons were either breast-fed or formula-fed for the first 14 wk of life before weaning to baboon chow. At 14 and 34 wk of age, liver biopsies were assayed for cholesterol 7alpha-hydroxylase (CYP7A1), 27-hydroxycholesterol-7alpha-hydroxylase (CYP7B1), and cholesterol 27-hydroxylase (CYP27A1). We also determined the kinetics of 3H-27-hydroxycholesterol (27-OHC) turnover in vivo at both ages. At 14 wk of age, hepatic CYP7A1 activity was low but sevenfold higher among formula-fed vs. breast-fed baboons. By 34 wk, CYP7A1 activity had increased nearly 10-fold in both infant diet groups, and the sevenfold difference in CYP7A1 between previously breast- and formula-fed animals persisted. There were no differences in CYP7B1 activities between infant diet groups at either 14 or 34 wk of age although the activity increased in both groups by about 50% from 14 to 34 wk. CYP27A1 activity also increased between 14 and 34 wk of age, and, compared with CYP7A1, relatively small differences in CYP27A1 activity due to infant diet were observed at each age. Plasma 27-OHC turnover had a half-time of 2-4 min. We had previously reported that after weaning, the total bile acid synthesis rate was higher among baboons that were formula-fed than among breast-fed animals. The present results suggest that this difference is most likely due to significantly higher CYP7A1 activity among formula-fed vs. breast-fed animals.