Direct evidence of hydrogen absorption from the skin – a pig study

hot water in an 80-litre bathtub. Two hairless mini pigs (14.2 ±1.4 kg, 60 days old, 1 male and 1 female) were first placed in the H 2 -dissolved bath. After a washout period, one pig was bathed in an H 2 -dissolved bath and the other in a bath containing no H 2 for 20 min. During the experiment, blood was collected from the pigs’ jugular vein, carotid artery, inferior vena cava (IVCs), and portal vein to measure the blood H 2 concentration. Results: The H 2 concentration at the IVC of the pig in the H 2 -dissolved bath increased from 0.733 ±0.636 ppb (w/w) to 16.9 ±4.46 ppb (w/w) after 2 min, 37.2 ±13.8 ppb (w/w) after 10 min, and 45.7 ±7.73 ppb (w/w) (H 2 saturation level: 3%) after 20 min. The blood H 2 concentration levels of the pig in the non-H 2 bath remained below the detection limit of 0.3 ppb. Conclusions: Bathing in water with a high concentration of dissolved hydrogen was considered an effective means of supplying H 2 to skin tissues and beyond.