[Reading Science] Breast Milk Contains the 'Key' to Infant Heart Development

Spanish National Cardiovascular Research Institute Team
"GLA in Colostrum Plays a Key Role in Heart Development"

A key component for heart development has been discovered in the mother's breast milk that a baby consumes immediately after birth. This research suggests that breastfeeding strengthens the baby's heart.

[Photo by Getty Images Bank]

A research team from the Spanish National Cardiovascular Research Center published a paper containing these animal experiment results on the 24th (local time) in the international academic journal Nature. They found that a specific component in the mother rat's milk promotes the supply of different nutrients to the heart muscle cells of newborn rat pups, which becomes the driving force for the heart muscle cells to exert strength even into adulthood. Notably, this effect occurs within 24 hours after birth.

Typically, heart muscle is composed of cardiomyocytes that beat at a steady rhythm to create heartbeats. During the fetal stage, cardiomyocytes initially use glucose and lactic acid as energy sources, but as the cells mature, they switch to using fatty acids. Until now, the reasons and mechanisms behind this process have not been well understood.

To investigate this, the research team conducted experiments on rats. Some pups were fed milk from mothers given regular feed, while others were fed milk from mothers given fat-free feed. The pups that consumed milk lacking fat components developed heart abnormalities and most died within two days after birth.

The team continued their research to determine why this occurred. Analyzing the milk from mother rats, they identified gamma-linolenic acid (γ-linolenic acid, GLA) as the likely cause. GLA is also found in human breast milk and is a substance that cannot be synthesized by the body but must be obtained through diet. To verify this, the researchers administered GLA to mother rats fed fat-free feed and then fed their milk to the pups. Remarkably, the pups survived longer, and there was an increase in the activity of genes related to producing energy using fats.

The research team identified the retinoid X receptor (RXR) that absorbs GLA in rat cardiomyocytes and revealed that the connection between GLA and RXR promotes the switch to using fatty acids as an energy source. They also precisely identified the genes activated after RXR binds with GLA.

Professor Long Tian Mi of Washington University stated, "While it cannot be ruled out that other components such as vitamin A may also have an effect, the results from this study using RXR-deficient rats could greatly aid research on adult heart disease."

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