Growing up in Singapore, you might at some point have been told by your grandmother as she picks up a fishball that has fallen on the floor, blows on it, and pops it into your mouth – lak sup jiak, lak sup tua.

It’s a piece of Hokkien wisdom that roughly translates “eat dirty, grow up dirty”, meaning that consuming a bit of filth has a fortifying effect on one’s growth.

It now appears that there is science to back up what our grandmothers have known all along. An article in the International Herald Tribune reviews ongoing research into the hypothesis that the bacteria, viruses and worms that come along with a dose of dirt, help to develop the body’s immune system.

An excerpt:

“What a child is doing when he puts things in his mouth is allowing his immune response to explore his environment,” Mary Ruebush, a microbiology and immunology instructor, wrote in her new book, “Why Dirt Is Good” (Kaplan). “Not only does this allow for ‘practice’ of immune responses, which will be necessary for protection, but it also plays a critical role in teaching the immature immune response what is best ignored.”

One leading researcher, Dr. Joel Weinstock, the director of gastroenterology and hepatology at Tufts Medical Center in Boston, said in an interview that the immune system at birth “is like an unprogrammed computer. It needs instruction.”

He said that public health measures like cleaning up contaminated water and food have saved the lives of countless children, but they “also eliminated exposure to many organisms that are probably good for us.”

“Children raised in an ultra-clean environment,” he added, “are not being exposed to organisms that help them develop appropriate immune regulatory circuits.”

Read the full article here.