Okay, so he sates:
So they eat root vegetables, fish and low iron foods. This diet helps these people retain HA (the root vegetables themselves provide no HA).
Is it the fish? Wonder what low iron foods they consume.
Also found this to support the above:
Question: What foods contain hyaluronic acid?"
Answer: I have found very little information on this myself, though I am aware of two possible sources. The first was mentioned in a segment from ABC news about a hyaluronic acid consumption in a village in Japan . In the 20/20 segment, "The Village of Long Life: Could Hyaluronic Acid Be an Anti-Aging Remedy?" the town doctor attributed the villager's long lives to "starchy root vegetables"-- satsumaimo, a type of sweet potato; satoimo, a sticky white potato; konyaku, a gelatinous root vegetable concoction; and imoji, a potato root. The doctor believes "these locally grown starches help stimulate the body’s natural creation of a substance called hyaluronic acid, or HA, which aging bodies typically lose. This may ward off the aging process by helping the cells of the body thrive and retain moisture, keeping joints lubricated, protecting the retina in eyes and keeping skin smooth and elastic. 'I have never seen anyone suffer from skin cancer here, ' he says. 'I have seen a woman in her 90s with spotless skin.' ”