TOKYO, Japan — Obesity can bring on a number of life-changing and potentially fatal conditions in humans. While heart disease, diabetes, and cancer are among the top concerns for people who are overweight, a recent study reveals that too much fat in your diet can also be bad for your hair. Researchers from Tokyo Medical and Dental University have discovered that a high-fat diet accelerates hair thinning and hair loss as we age.
Specifically, study authors found that both high-fat diets and obesity caused by genetics can contribute to the depletion of hair follicle stem cells (HFSCs). In studies using mice, obesity introduces certain inflammatory signals to the body, blocking hair follicle regeneration and eventually leading to the loss of the follicles.
In a healthy person, HFSCs renew themselves during every hair follicle cycle. This is how your hair continues to grow back and get longer over time. As we get older however, these stem cells start to falter and don’t replenish themselves as well. When there are fewer HFSCs, hair starts to thin and fall out.
“High-fat diet feeding accelerates hair thinning by depleting HFSCs that replenish mature cells that grow hair, especially in old mice,” says lead author of the study Hironobu Morinaga in a university release. “We compared the gene expression in HFSCs between HFD-fed mice and standard diet-fed mice and traced the fate of those HFSCs after their activation. “We found that those HFSCs in HFD-fed obesed mice change their fate into the skin surface corneocytes or sebocytes that secrete sebum upon their activation. Those mice show faster hair loss and smaller hair follicles along with depletion of HFSCs.”
Even a few days of high-fat eating can hurt your hair
“Even with HFD feeding in four consecutive days, HFSCs shows increased oxidative stress and the signs of epidermal differentiation,” Morinaga continues.
Importantly, the team discovered a specific genetic path which replenishes the hair stem cells.
“The gene expression in HFSCs from the high-fat–fed mice indicated the activation of inflammatory cytokine signaling within HFSCs,” adds senior author Emi K. Nishimura. “The inflammatory signals in HFSCs strikingly repress Sonic hedgehog signaling that plays crucial role in hair follicle regeneration in HFSCs.”
The study confirmed that the “Sonic hedgehog” signaling pathway does activate during the hair regrowth process and can protect against the depletion of hair follicle stem cells. Nishimura adds the new insights into obesity may lead to treatments which repair tissue dysfunction due to a high-fat diet.
The study appears in the journal Nature.