Blueberry compound may help muscles burn stored fat, study finds
Japanese researchers found that pterostilbene, a polyphenol found in blueberries and grapes, can reduce fat buildup in cultured muscle cells by stabilizing a key metabolic protein. The findings are still limited to lab experiments in mouse muscle cells.
Excess fat accumulating inside skeletal muscle is considered a growing metabolic health concern, driven by high-fat diets, inactivity, and aging. Unlike fat stored under the skin, lipid droplets inside muscle cells can impair muscle function and reduce the body's ability to efficiently use glucose and fatty acids, potentially contributing to insulin resistance over time.
A research team at Shinshu University in Japan, led by Associate Professor Takakazu Mitani, has identified pterostilbene, a naturally occurring polyphenol found in blueberries, grapes and other berries, as a compound that can influence fat metabolism inside muscle cells. Earlier studies had linked pterostilbene to beneficial effects in the liver and fat tissue, but its impact on skeletal muscle was largely unknown.
How the discovery was made
The researchers screened a range of food-derived phytochemicals using cultured mouse skeletal muscle cells, looking for compounds that could reduce abnormal fat buildup without disrupting normal muscle growth. Pterostilbene produced the strongest reduction in intracellular fat, while treated cells continued developing normally.
Further tests showed the compound did not block fatty acids from entering the cells. Instead, it promoted the breakdown of already-stored fat, evidenced by increased glycerol release and higher activity of genes linked to fatty acid oxidation.
Examining the underlying mechanism, the team found that pterostilbene boosts signaling of a protein called PPARδ, which drives fat breakdown. Unlike many compounds that directly activate this protein, pterostilbene instead stabilizes it by slowing its degradation inside the cell, allowing it to remain active longer.
What comes next
According to the researchers, the findings could serve as a starting point for developing functional foods or supplements targeting muscle fat metabolism, and also offer a framework for identifying other natural compounds with similar effects. However, the results so far are limited to molecular experiments in cultured mouse cells and do not yet prove that pterostilbene can prevent or treat metabolic disease in living animals or humans. Further research is needed to confirm effectiveness, safety and selectivity before any practical applications can be developed.
