He intermittent fastingAlthough it has many benefits, would have some unwanted effect, such as slowing down hair growthat least in mice, as researchers at Westlake University in Zhejiang, China report in the journal ‘Cell’ from Cell Press.
According to them, the mice subjected to intermittent fasting regimens showed better metabolic health, but a slower hair regeneration compared to mice with 24/7 access to food. A similar process could occur in humansaccording to a small clinical trial the team also conducted, but it is likely less serious, since Humans have a much slower metabolic rate and different hair growth patterns compared to mice.
“We don’t want to scare people away from intermittent fasting.” because it is associated with many beneficial effects; It is only important to keep in mind that may have some unwanted effects“says lead author and stem cell biologist Bing Zhang of Westlake University in Zhejiang, China.
In addition to its metabolic benefits, previous studies have shown that fasting can improve the stress resistance of stem cells associated with blood, intestinal and muscle tissue, but Little is known about how it affects peripheral tissues such as skin and hair. Zhang’s team hypothesized that fasting might also be beneficial for skin tissue regeneration, the process by which old, damaged cells are replaced.
“We don’t want to scare people away from intermittent fasting.”
To verify this, they examined the hair growth in mice that were shaved and subjected to different intermittent fasting regimens. Some mice were fed a time-restricted feeding (TRF) schedule involving 8 hours of food access and 16 hours of fasting each day, while other mice were subjected to alternate-day feeding. (ADF, for its acronym in English).
They were surprised at discover that fasting inhibited hair regeneration. While the control mice that had unlimited access to food had regained most of their hair after 30 days, the mice that Both intermittent fasting regimens followed showed only partial hair growth after 96 days.
The team demonstrated that this Inhibition of hair growth occurs because the stem cells of the hair follicle (HFSC) cannot cope with the oxidative stress associated with the switch from glucose to fat use. HFSCs go through phases of activity and inactivity, and hair growth depends on these cells becoming activated.
While the HFSC of control mice began to activate around day 20 after shaving and remained active until their hair regrew, activated HFSCs from intermittent fasting mice underwent apoptosis (programmed cell death) during prolonged periods of fasting.
Through genetic engineering methods, the team showed that this fasting-induced apoptosis was driven by a higher concentration of free fatty acids near the hair follicles, causing an accumulation of harmful oxygen radical species within the HFSCs. Free fatty acids also caused human HFSCs to undergo apoptosis in vitro.
“During fasting, adipose tissue begins to release free fatty acidsand these fatty acids enter the HFSCs that have recently been activated, but these stem cells do not have the proper machinery to use them,” says Zhang.
In comparison, epidermal stem cells, which are responsible for maintaining the epidermal skin barrier, were not affected by intermittent fasting. The main difference between these types of stem cells is that epidermal stem cells have a greater antioxidant capacity. When the team tested whether antioxidants could mitigate the effects of fasting on hair growthshowed that both topical application of vitamin E and genetic upregulation of antioxidant capacity helped high-fructose stem cells survive fasting.
The effect of intermittent fasting was analyzed in healthy young adults
The team also conducted a small clinical trial with 49 healthy young adults to examine whether fasting similarly affects hair growth in humans. They showed that a time-restricted diet involving 18 hours of fasting per day reduced the average speed of hair growth by 18% compared to controlsbut larger studies would be needed to verify this effect given the study’s small sample size and short duration (10 days).
“The human population is very heterogeneous, so the effects can be different for different people,” Zhang clarifies. “The Mice also have a very high metabolic rate compared to humansso fasting and metabolic change have a more severe effect on mouse HFSCs. We see a milder effect in humans: there are still apoptotic stem cells, but many HFSCs survive. Therefore, there is still hair regrowth; “It’s just a little slower than usual.”
In future work, the researchers plan to collaborate with local hospitals to investigate how fasting affects other types of stem cells in the skin and other body systems.
“We plan to examine how this process affects regeneration activities in other tissues,” concludes Zhang. “We also want to find out how fasting affects skin wound healing and identify metabolites that could help the survival of high-fructose stem cells and promote hair growth during fasting.”
#effects #intermittent #fasting #hair #growth
