A compound found in blueberries and grapes may reduce fat in muscles, a Japanese study suggests

Fat does not accumulate solely in adipose tissue — it also builds up inside muscle cells, and when the amount becomes excessive, it can impair their function and the body's ability to efficiently utilise glucose and fatty acids. For this reason, researchers are looking for dietary compounds that might limit this process.

According to ScienceDaily, a team from Shinshu University in Japan, led by associate professor Takakazu Mitani, tested several natural substances to determine whether any of them could reduce excessive fat accumulation in muscle cells.

Pterostilbene, the compound with the most potent effect

The substance that caught the researchers' attention is called pterostilbene, a polyphenol — that is, a natural compound produced by plants — found in small quantities in blueberries, grapes, and other berries.

Of all the compounds analysed, pterostilbene had the most potent effect in reducing fat accumulated inside the cells, without inhibiting the normal growth and development of muscle cells.

Experiments showed that the substance does not prevent fatty acids from entering muscle cells. Instead, it appears to stimulate the breakdown of already-stored fat and the processes by which fatty acids are used to produce energy.

The mechanism behind the effect

The researchers focused on a protein called PPAR delta (peroxisome proliferator-activated receptor delta), which is involved in controlling genes that regulate how cells utilise fats. When this protein is more active, the oxidation of fatty acids is stimulated — the process by which they are broken down for energy — and fat accumulation within cells may decrease.

Unlike other experimental substances that directly activate this protein, pterostilbene protects it from natural degradation within the cell. As a result, a greater quantity of the protein remains available, capable of activating the genes involved in fat metabolism.

What this study does not yet tell us

This finding does not mean that eating more blueberries or grapes will automatically lead to fat burning or weight loss. The experiments were conducted exclusively on mouse muscle cells grown in a laboratory setting, not on live animals or humans.

The researchers note that further studies are needed to establish whether the observed effects also occur in a living organism, what quantity of pterostilbene would be required, and whether its use is safe and effective. The authors nonetheless believe that the results open a promising line of research for the development of functional foods or other products related to metabolic health.

The study, entitled "Pterostilbene suppresses intracellular lipid accumulation in C2C12 myocytes via PPARδ stabilization", was published in the scientific journal Food Bioscience.