Reduction in Maternal Energy Intake during Lactation Decreased Maternal Body Weight and Concentrations of Leptin, Insulin and Adiponectin in Human Milk without Affecting Milk Production, Milk Macronutrient Composition or Infant Growth

Abstract

Maternal diet has the potential to affect human milk (HM) composition, but very few studies have directly assessed the effect of maternal diets on HM composition. The primary aim of this study was to assess the effect of improving dietary quality in lactating women over 2 weeks on the concentrations of macronutrients and metabolic hormones in HM. The secondary aims were to assess the impact of the dietary intervention on 24 h milk production, maternal body composition and infant growth. Fifteen women completed a 1-week baseline period followed by a 2-week dietary intervention phase targeted towards reducing fat and sugar intake. Maternal anthropometric and body composition and infant growth measurements were performed weekly. Total 24 h milk production was measured before and after the dietary intervention, and HM samples were collected daily. Maternal intakes of energy (−33%), carbohydrate (−22%), sugar (−29%), fat (−54%) and saturated fat (−63%) were significantly reduced during the dietary intervention. HM insulin, leptin and adiponectin concentrations were 10–25% lower at the end of the dietary intervention, but HM concentrations of macronutrients were unaffected. Maternal body weight (−1.8%) and fat mass (−6.3%) were significantly reduced at the end of the dietary intervention, but there were no effects on 24 h milk production or infant growth. These results suggest that reducing maternal energy, carbohydrate, fat and sugar intake over a 2-week period is associated with significant reductions in HM insulin, leptin and adiponectin concentrations. These changes may be secondary to decreases in maternal weight and fat mass. The limited studies to date that have investigated the association between metabolic hormone concentrations in HM and infant growth raise the possibility that the changes in HM composition observed in the current study could impact infant growth and adiposity, but further studies are required to confirm this hypothesis.

Environmental determinants of human milk composition in relation to health outcomes

“…31 To date, only two interventional studies have assessed the effect of maternal diet on HM macronutrient composition. 26,32 An 8 days high-fat diet intervention resulted in increased HM total lipid concentrations. The same women then followed a low-fat diet for the same period, with no change in HM lipid content.…”

“…HM micronutrients, including vitamins (A, E, C, B1, B12), calcium and copper, have been shown to associate positively with maternal dietary intake levels 31 . To date, only two interventional studies have assessed the effect of maternal diet on HM macronutrient composition 26,32 . An 8 days high‐fat diet intervention resulted in increased HM total lipid concentrations.…”

“…Maternal adiposity has been associated with concentrations of several HM components, including hormones, proteins, carbohydrates and fat. Multiple studies report inconclusive relationships of HM insulin with maternal adiposity, negative associations with ghrelin, no associations with adiponectin, and positive associations with leptin, [24][25][26] and glucocorticoids, cortisol and cortisone. 27 Maternal adiposity is generally associated with higher HM fat content, 28 which is the most variable component, although the directions of associations vary for individual FAs.…”

“…32 In the second study, a 14 days low-fat and low-sugar dietary intervention did not result in any changes in HM macronutrient concentrations (protein, lactose and total lipid) despite a reduction in maternal adiposity; however, the concentrations of HM hormones insulin, leptin and adiponectin significantly decreased. 26 Among other components of HM, HMOs support infant health by promoting the development of the gut microbiome and immune system. Findings of previous observational studies on maternal diet and HMO composition are conflicting.…”

25 Years of Research in Human Lactation: From Discovery to Translation

“…As with leptin, there are studies reporting both presence and absence of such associations [ 170 ]. To add to the complexity further, we have shown that HM total protein concentration does not change day-to-day [ 180 ], week-to-week [ 181 ] or during a short maternal dietary intervention [ 182 ].…”