Serum cholesterol and lipoprotein concentrations in mothers during and after prolonged exclusive lactation

Abstract

The effect of exclusive lactation on lipid levels was investigated by evaluating serum concentrations of total and lipoprotein cholesterol, triglyceride (TG), and apoprotein (apo) B in mothers during and after exclusive, prolonged lactation. Serum total cholesterol concentrations were measured at delivery (n = 195), at 2 (n = 165), 6 (n = 119), 9 (n = 74), and 12 months (n = 32) of lactation, and 2 months (n = 27) after ending this exclusive lactation. In a subgroup of 34 mothers, serum levels of very-low-density lipoprotein (VLDL), low-density lipoprotein (LDL), high-density lipoprotein 2 (HDL 2), HDL 3, and LDL apo B were determined at 2, 6, 9, and 12 months of lactation. The mean value of serum total cholesterol concentrations decreased from 6.2 ± 0.12 (SEM; n = 195) at delivery to 4.8 ± 0.1 mmol/L (n = 116) at 6 months of exclusive lactation ( P < .001). The average decrement in total cholesterol level was 0.80 mmol/L ( P < .001) from delivery to 2 months of lactation and 0.55 mmol/L ( P < .001) from 2 to 6 months of lactation, and levels were stable thereafter. In the 27 mothers who were exclusively breast-feeding their infants at 9 months of lactation and whose serum cholesterol levels were measured 2 months after the end of lactation, cholesterol levels increased rapidly to 5.7 ± 0.21 mmol/L ( P = .001). In the subgroup of 34 mothers who were examined more closely, the course just described was also true for serum TG, LDL and VLDL cholesterol, and LDL apo B levels. HDL 3 cholesterol levels were high at 2 and 6 months of exclusive lactation and decreased thereafter; in contrast, HDL 2 cholesterol levels were low at 2 months of lactation and slowly increased throughout the lactation period. We found that prolonged exclusive lactation reduced mothers' serum concentrations of total, LDL, HDL 2, and VLDL cholesterol and TG, which returned to their normal levels after the end of lactation.