Blueberry Compound Helps Muscle Cells Burn Stored Fat, Study Finds

Researchers in Japan have identified a natural compound found in blueberries, grapes and other berries that helps muscle cells burn stored fat instead of accumulating it, according to a study led by Associate Professor Takakazu Mitani of Shinshu University. The findings on the compound, called pterostilbene, were published in the journal Food Bioscience on September 1, 2026.

Excess fat stored inside skeletal muscle is different from fat stored under the skin. It can interfere with normal muscle function and reduce the body's ability to use glucose and fatty acids efficiently, which over time can contribute to insulin resistance. High-fat diets, physical inactivity and aging can all encourage this buildup, known as myosteatosis, for which no approved treatment currently exists.

To search for a natural intervention, the team tested a range of food-derived compounds on cultured mouse skeletal muscle cells. Pterostilbene produced the strongest reduction in fat buildup inside the cells without disrupting their normal growth. The treated cells released more glycerol, a sign that stored fat was being broken down, and showed higher activity of genes involved in fatty acid oxidation.

The researchers traced this effect to a protein called peroxisome proliferator-activated receptor delta, or PPAR, which promotes fat breakdown when it is active. Unlike most experimental compounds that activate PPAR by binding directly to it, pterostilbene worked by blocking the protein's breakdown inside the cell, through the ubiquitin-proteasome pathway that normally clears it out. That allowed more PPAR to accumulate and remain active.

Mitani said the results provide a framework for developing functional foods and supplements targeting muscle fat metabolism, and for finding other natural compounds that stabilize PPAR the same way. The findings are limited to experiments in cultured mouse muscle cells and do not yet show that the compound works in living animals or humans; further research will need to test its effectiveness and safety in vivo.