Milk, nutritional darling and subject of celebrity ad campaigns, may soon add to its long list of star qualities. In a biotech-era twist on fluoridation, scientists are a step closer to using milk to provide immunity to dental cavities. If the technique proves workable, it could offer an easy and inexpensive way to reduce tooth decay.
To many people, dental caries--better known as cavities--are little more than a nuisance, albeit a painful one. But nationwide they add substantially to the $60 billion annual cost of dental care. Ever since the developed nations adopted their sweet 20th century diets, scientists have sought a way to stop Streptococcus mutans, an acid-producing bacterium thought to be responsible for most cavities. Fluoride in drinking water and toothpaste go a long way, but about half the U.S. population still suffers from moderate to severe tooth decay, with poor people bearing the brunt.
Dental scientist Takahiko Oho and colleagues at the Kyushu University in Japan set out to see if antibodies to S. mutans could be delivered in cow's milk. They injected cows with a novel vaccine, causing them to produce antibodies to two surface proteins. One helps S. mutans attach to teeth, and the other seals in harmful acid with a sticky carbohydrate layer on teeth. For 55 days, the researchers fed one of three diets to rats infected with S. mutans. Rats that drank milk with antibodies had 4 times fewer S. mutans on their teeth compared to rats given regular milk. Rats that drank antibody milk also had one-third fewer cavities than control rats drinking distilled water, the researchers report in the May issue of Infection and Immunity. (Although rats given antibody milk had about a third fewer cavities than those given regular milk, this difference wasn't statistically significant.)
The approach has important advantages over other immunization techniques, says Howard Kuramitsu, a microbiologist at the State University of New York, Buffalo. Direct vaccination, for example, is more likely to cause adverse reactions. But even if it proves safe and effective in the complex environment of the human mouth, it may take more than souped-up moo juice to cure a nation of sugar junkies. Says Kuramitsu's colleague Michael Russell: "Interesting, but I'm not investing in it."