Researchers in Japan have identified pterostilbene, a natural compound found in blueberries and grapes, as a substance that stabilizes the PPARδ protein to help skeletal muscle cells break down excess fat in laboratory experiments published on September 1, 2026. The new findings were published in Volume 83 of the Food Bioscience journal on September 1, 2026.
Excess fat stored inside skeletal muscle has become an important metabolic health concern. This type of fat buildup can be encouraged by high-fat diets, physical inactivity, and aging. Unlike fat stored under the skin, lipid droplets that accumulate within muscle cells can interfere with normal muscle function and make it harder for the body to efficiently use glucose and fatty acids. Over time, this reduced metabolic flexibility can contribute to insulin resistance. Finding ways to limit excess fat inside skeletal muscle could therefore be important for supporting healthy aging and reducing the risk of lifestyle-related disease. Most fat in the body is stored as subcutaneous fat, or under the skin. But people can also build up deposits of ectopic fat, which literally means fat ‘in an abnormal place.’ These deposits can build-up in the liver, heart, pancreas and muscles, and raise the risk of multiple complications. Doctors say those who are obese or severely obese or have larger waistlines are at higher risks, but warn that the fat can also build up in people with flat stomachs. Ectopic fat can only be detected using a detailed body scan. To reduce these deposits, doctors normally recommend exercise. But scientists are now investigating whether a compound could also help.
One pathway that plays an important role in this process involves peroxisome proliferator-activated receptor δ (PPARδ). When PPARδ signaling is active, it promotes fatty acid oxidation and helps limit the accumulation of lipids inside cells. Researchers have become increasingly interested in food-derived bioactive compounds that may influence this pathway, but exactly how these substances affect PPARδ has remained unclear.
Compound in blueberries may help muscle cells burn excess
Screening Plant Compounds in Cultured Muscle Cells
A research team in Japan led by Associate Professor Takakazu Mitani of Shinshu University has now identified pterostilbene as a natural dietary compound that can stabilize PPARδ and influence fat metabolism inside muscle cells. Pterostilbene is a naturally occurring polyphenol found in blueberries, grapes, and other berries. Previous research has linked the compound to beneficial metabolic effects in the liver and adipose tissue, but scientists knew much less about how it might affect skeletal muscle. We currently lack approved treatments specifically targeting myosteatosis,
says Dr. Mitani. This critical gap led our team to screen food-derived compounds for natural, dietary interventions. During the screening, we identified pterostilbene and focused our investigation.
A natural antioxidant found in blueberries and grapes helps cultured mouse muscle cells break down stored fat, according to laboratory experiments conducted by researchers in Japan and published in the journal Food Bioscience on Sept. 1. Researchers discovered that the compound, known as pterostilbene, significantly decreased abnormal fat accumulation in skeletal muscle cells without interfering with muscle growth. Excess fat inside muscle tissues often stems from high-fat diets, physical inactivity, and aging, which can ultimately disrupt glucose processing and contribute to insulin resistance.
Natural Compound in Berries Reduces Fat Buildup in Muscle
In a lab test, researchers exposed the compound to muscle cells from mice. They found that it caused the cells to start breaking down ectopic fat, a type of fat more common in people who are obese or severely obese that raises the risk of conditions such as type two diabetes and high blood pressure. Researchers said this happened because the compound triggered a pathway in cells that causes them to begin to break down more fats.
Stabilizing the PPARδ Protein Pathway
The study showed that pterostilbene stimulated cells to clear out existing fat reserves while preserving PPAR-delta, a vital protein responsible for regulating cellular fat processing. Scientists screened several food-derived compounds before identifying pterostilbene as the most effective agent for clearing fat buildup while protecting key cell proteins. The research also provides an 'experimental framework' for identifying other natural compounds that protect PPAR-delta,
Mitani added.
Blueberries can 'switch on fat-burning mode' in muscle cells
Translating Cellular Science to Human Health
Our findings establish a scientific framework for developing functional foods and nutritional supplements that target muscle fat metabolism,
lead researcher Takakazu Mitani, an associate professor at Shinshu University, said in a statement. ‘Our findings establish a scientific framework for developing functional foods and nutritional supplements that target muscle fat metabolism,’ Dr Takakazu Mitani, lead study author, said. ‘However, beyond the potential of pterostilbene itself, this work provides an experimental framework for identifying other natural compounds [for weight loss].’
The preliminary findings offer a starting point for potential dietary interventions targeting obesity, type 2 diabetes, and age-related metabolic decline. However, health experts emphasize that isolated cell models differ significantly from human biological systems. In people, pterostilbene has to be digested, absorbed, metabolized, circulated and actually reach muscle tissue at an effective dose,
Johannah Katz, a registered dietitian from Florida, told Fox News Digital, noting that using a cell model removes the natural complexity of human biology.