I don't know about you, but here is something I have often wondered.

How does changing a breastfeeding mum's diet affect the contents of her breast milk?

Now a new small study of 9 breastfeeding women provides a fascinating insight into exactly how diet may affect the composition of a mother's breast milk.

In particular, the study offers some insight into how the maternal diet can change the macronutrient concentrations in breast milk.

For example, one of the main findings was that if if a mum increased her sugar and fat intake even just for a day, this will affect the composition of her breast milk.

The study:

Ward E. at el. (3 March, 2021) looked at the impact of increased consumption of sugar and fat on breast milk protein, lactose and lipids (fats).

  • The study included 9 women who were exclusively breastfeeding.
  • Each of the 9 were provided with a control, higher fat (+28 g fat) and higher sugar (+66 g sugar) diet.
  • These diets were eaten over three separate days, with each day being at least 1 week apart.
  • Breast milk samples were collected hourly and analysed for triglycerides, cholesterol, protein, and lactose concentrations

A simple explanation of triglycerides:

Triglycerides are a type of fat. When you eat, any calories that are not needed straight away are converted into triglycerides and stored in fat cells. Later, triglycerides are released for energy between meals.

The results:

The study found the composition of breast milk had the following changes:

  • Triglycerides in breast milk increased significantly with both the higher fat and sugar diets, but there was a greater response in the higher sugar diet compared to the control.
  • Cholesterol in breast milk increased most in response to the higher sugar diet, compared to the control and the higher fat diet.
  • Triglyceride and lactose concentrations in breast milk increased, whereas protein in breast milk decreased in response to the higher fat diet compared to the control

And outside of the impact of diet, the researched noted additional changes to the composition of the breast milk.

  • The composition of breast milk changed over the day.
  • At the end of a day, concentations of triglycerides and cholestero were higher.
  • And interestingly, protein and lactose concentrations peaked at hour 10.

"Independent of diet, there were significant variations in breast milk composition over the day; triglycerides and cholesterol concentrations were higher at end of day, whereas protein and lactose concentrations peaked at Hour 10 (of 12)."

The conclusion:

To quote from the abstract:

"In conclusion, controlled short‐term feeding to increase daily sugar/fat consumption altered breast milk triglycerides, cholesterol, protein and lactose. The variations observed in breast milk protein and lactose across the 12 h period is suggestive of a circadian rhythm."

Key messages of the research (quoting from the paper)"

  • "Increasing sugar and fat intake in a controlled short‐term feeding study acutely affected breast milk composition.

  • Increasing sugar intake significantly increased breast milk triglycerides and to a greater extent than increasing fat intake.

  • Breast milk protein and lactose concentrations exhibited significant changes across the 12 h period independent of dietary intake, suggestive of circadian variation in concentrations."

Science reference:

Ward E, Yang N, Muhlhausler BS, et al. Acute changes to breast milk composition following consumption of high‐fat and high‐sugar meals. Matern Child Nutr. 2021;e13168. https://doi.org/10.1111/mcn.13168



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