Study: Water from Japan hot spring soothes capybaras’ skin

By Hayato Goto / Yomiuri Shimbun Staff Writer

12:27 JST, December 16, 2021

YAMAGUCHI — The rough skin of capybaras turned clear and smooth after the animals bathed for a few weeks in water from the Yuda hot spring in Yamaguchi City, a scientific study has shown.

Yuda hot spring water is said to produce beautiful skin, but it is rare for the efficacy of a hot spring to be proved scientifically through animal experiments. The research was conducted by Kengo Inaka, 29, a third-year student at Yamaguchi University’s Joint Graduate School of Veterinary Medicine, and his instructor Prof. Toru Kimura.

The two said they would keep studying to prove further effects.

Experiments were conducted over five occasions, starting in the winter of 2016. A paper summarizing the results was published this month in the British journal Scientific Reports.

The Yuda hot spring is a simple alkaline hot spring known for its abundant waters — about 2,000 tons gush out every day. According to legend, an injured white fox healed itself in the hot water. Capybaras usually live in hot, humid South American bogs, and Japan’s cold, dry winters tend to make their skin dry and rough.

The experiments were conducted at Akiyoshidai Safari Land in Mine in the prefecture. Nine capybaras were bathed in water from the hot spring for 15 minutes a day for three weeks, and the scientists checked their skin’s average moisture level and melanin value. Over the course of the experiment, the moisture level in their skin tripled, while the melanin decreased by about 10%.

The researchers also observed how much the animals relaxed as a result of bathing, based on their eyelids and ears drooping. Research is also being conducted to compare the effects of capybaras bathing in heated tap water versus hot spring water.

“We want to clarify the efficacy of the Yuda hot spring through various experiments,” Inaka said.