If anyone knows a thing or two about healthy aging, it's the Japanese. They live longer and better than anyone else on the planet, nearly five years longer than Americans on average.

So what's the secret?

Aside from good genes, a low obesity rate and a diet rich in fatty fish, the Japanese have one habit that never quite caught on here: They drink green tea by the gallon.

Nearly every home and workplace has an electric kettle, always on and ready to brew some green tea -- and new research out of Japan confirms again that those who drink the most, age the best.

The study of 14,000 Japanese seniors finds that the heaviest tea drinkers -- those who gulp down five or more cups a day -- are less likely to need help with everyday activities like getting dressed and bathing.

These tea-loving seniors are 33 percent less likely to suffer from "functional disabilities" than those who drink little to no tea.

People with more moderate tea consumption -- two or three cups a day -- can still get most of the benefit: They're 25 percent less likely to suffer from functional disability than non-drinkers, according to the study in the American Journal of Clinical Nutrition.

The study didn't look at why green tea drinkers are healthier and more independent, but this one's a no-brainer: Green tea's famous antioxidants have been shown to fight and even repair the DNA damage that comes from aging and disease.

One small study a couple of years ago found a 20 percent reduction in DNA damage after just a month of regular green tea consumption.

It's practically a miracle in a mug, boosting your health from head to toe -- and along with slashing your risk of functional disability, green tea can also help cut your odds of cancer, dementia, diabetes, depression, heart disease, osteoporosis and more.

Green tea drinkers even live longer, too (as the Japanese can testify).

There are lots of products that claim to have green tea -- or green tea extract -- in them, but skip all that and get yours the old-fashioned way: brew a cup fresh whenever you want some.