Intermittent Fasting Reduces Hair Regeneration

Summary: By affecting hair follicle stem cells (HFSCs), intermittent fasting may slow hair regrowth even though it is good for metabolic health. In mice, prolonged fasting led to oxidative stress and the accumulation of free fatty acids, which caused HFSCs to undergo apoptosis.

On a time-restricted diet, a small clinical trial found that the effect was milder in humans, reducing hair growth speed by 18 percent. Antioxidants, such as vitamin E, lessened the adverse effects on HFSCs, suggesting possible ways to lessen these unexpected consequences.

Key Facts.

Stem cell stress: HFSC apoptosis is triggered by fasting, which raises free fatty acids close to hair follicles.

Impact on Humans: Fasting was found to reduce human hair growth by 18%.

Antioxidant Role: HFSCs are shielded from damage caused by fasting by vitamin E and their enhanced antioxidant capacity.

Cell Press.

Although intermittent fasting has been shown to improve metabolic health, a recent study suggests that it may also inhibit hair growth, at least in mice.

In contrast to mice that had constant access to food, mice that were subjected to intermittent fasting regimens displayed better metabolic health but slower hair regeneration, according to research published December 13 in the Cell Press journal Cell.

Based on a small clinical trial that the team also carried out, a similar process might occur in humans, though it’s probably less severe because humans have a much slower metabolic rate and different hair growth patterns than mice.

Bing Zhang, a stem cell biologist and senior author at Westlake University in Zhejiang, China, says, “We don’t want to scare people away from practicing intermittent fasting because it is associated with a lot of beneficial effects—it’s just important to be aware that it might have some unintended effects.”.

Few studies have examined the effects of fasting on peripheral tissues like skin and hair, but prior research has demonstrated that it can enhance the stress resistance of stem cells linked to blood, intestinal, and muscle tissue in addition to its metabolic advantages. Zhang’s group postulated that fasting might also help with skin tissue regeneration, which is the process of replacing damaged and aged cells.

They tested this by looking at the regrowth of hair in mice that had been shaved and then made to fast intermittently under various conditions. Some mice were given alternate-day feeding (ADF), while others were fed on a time-restricted feeding (TRF) schedule that included 16 hours of fasting and 8 hours of food access daily.

They discovered, to their surprise, that fasting prevented the growth of new hair. Mice on both intermittent fasting regimens displayed only partial hair regrowth after 96 days, whereas control mice with unrestricted access to food had regrown the majority of their hair after 30 days.

The group demonstrated that hair follicle stem cells (HFSCs) are unable to handle the oxidative stress brought on by the switch from using glucose to fat, which results in inhibited hair growth. Hair regrowth is contingent upon the activation of HFSCs, which undergo periods of dormancy and activity.

During prolonged fasting periods, the activated HFSCs in the intermittent fasting mice experienced apoptosis, or programmed cell death, whereas the HFSCs in the control mice became active around day 20 after shaving and stayed active until their hair had grown back.

By using genetic engineering techniques, the team demonstrated that the growth of dangerous radical oxygen species within the HFSCs was caused by an elevated concentration of free fatty acids close to the hair follicles, which in turn triggered the fasting-induced apoptosis. In vitro apoptosis of human HFSCs was also induced by free fatty acids.

“Adipose tissue begins to release free fatty acids during fasting, and these fatty acids enter the recently activated HFSCs, but these stem cells lack the necessary machinery to utilize them,” Zhang explains.

The epidermal skin barrier-maintaining epidermal stem cells, on the other hand, were not impacted by intermittent fasting. The primary distinction between these stem cell types is the increased antioxidant capacity of epidermal stem cells.

Both topical application of vitamin E and genetic upregulation of antioxidant capacity helped HFSCs survive fasting, according to the team’s test of whether antioxidants could lessen the effects of fasting on hair growth.

To see if fasting has a similar effect on human hair regrowth, the team also carried out a small clinical trial with 49 young adults in good health. Larger studies would be required to confirm this effect given the study’s small sample size and short duration (10 days), but they demonstrated that a time-restricted diet involving 18 hours of fasting per day decreased the average speed of hair growth by 18 percent when compared to controls.

Zhang states, “The effects might be different for different people because the human population is very heterogeneous.”.

Fasting and metabolic switching have a more severe effect on mouse HFSCs because mice also have a much higher metabolic rate than humans. Although many HFSCs survive, the effect is less pronounced in humans, where apoptotic stem cells still exist. Thus, hair regrowth is still occurring, albeit a little more slowly than normal. “”.

In subsequent research, the scientists intend to work with nearby medical facilities to examine the effects of fasting on different kinds of stem cells found in the skin and other bodily systems.

Zhang says, “We intend to investigate the impact of this process on the regeneration activities in other tissues.”.

Additionally, we look for metabolites that may support HFSC survival and encourage hair growth while fasting, as well as how fasting affects skin wound healing. “”.

Funding:.

The National Natural Science Foundation of China, the Key RandD Program of Zhejiang, the Research Center for Industries of the Future (RCIF), the Westlake Laboratory of Life Sciences and Biomedicine, and the Center of Synthetic Biology and Integrated Bioengineering at Westlake University provided funding for this study.

About the news of genetics research and intermittent fasting.

The author is Kristopher Benke.

Cell Press is cited.

Get in touch with Cell Press’s Kristopher Benke.

Image: Neuroscience News is the source of the image.

Original Study: Publicly available.

By Bing Zhang and colleagues, “Intermittent Fasting Induces Interorgan Communication to Suppress Hair Follicle Regeneration.”. Cell.

abstract.

Inter-organ communication is triggered by intermittent fasting, which inhibits the regeneration of hair follicles.

Despite its unclear effects on somatic stem cells and tissue biology, intermittent fasting has become increasingly popular worldwide due to its possible health benefits.

Here, we show that popular intermittent fasting regimens cause activated hair follicle stem cells (HFSCs) to undergo selective apoptosis, which inhibits hair follicle regeneration.

Calorie restriction, changes in the circadian rhythm, or the mTORC1 cellular nutrient-sensing mechanism have no bearing on this effect.

Instead, fasting causes the skin’s dermal adipocytes and adrenal glands to interact, causing a rapid release of free fatty acids into the niche. This disrupts the HFSCs’ regular metabolism and raises their levels of reactive oxygen species, which leads to oxidative damage and apoptosis.

According to a randomized clinical trial (NCT05800730), human hair growth is inhibited by intermittent fasting.

During times of unstable nutrient supply, our study reveals that intermittent fasting inhibits tissue regeneration and identifies interorgan communication that eliminates activated HFSCs and stops tissue regeneration.