May 9, 2001 -- We all know that milk helps build strong bones and teeth. Now, new research suggests it may offer a surprising additional benefit. According to Dutch scientists, that glass of 'moo juice' just might protect you from some nasty bacteria -- the kind that cause food poisoning.
"There was some evidence that milk may protect against bacterial infections," researcher R. Corinne Sprong, PhD, tells WebMD. She's with the department of nutrition, quality and safety at NIZO Food Research, in Ede, the Netherlands. "And it's already known that some kinds of fatty acids can kill bacteria. So, we wanted to look at the positive effects of milk fats."
For more information on this topic, or others like it, go to WebMD's Food and Nutrition board moderated by Martha McKittrick, RD, CDE.
Her team isolated the critical components -- fatty acids and sphingolipids -- from regular cow's milk, and tested them on a few of our most menacing bacterial foes: Campylobacter, Salmonella, E. coli 0157H7, and Listeria. These are the dreaded, foodborne bugs that wreak havoc on the gut. They cause most people a few days of miserable diarrhea and vomiting, but they can be deadly for the very young, very old, and those with weakened immune systems.
"We didn't test the whole spectrum of bugs that can induce gastrointestinal infection, because we didn't look at viruses," says Sprong, "but we did look at the most important bacteria that cause the majority of foodborne illnesses here in the Netherlands and in the United States."
The researchers prepared special petri dishes to mimic the highly acidic environment of the human stomach. Then, to ensure that any findings would reflect the actions of the milk, and not just the specially prepared dishes, they did a test run on all the bacteria, without the milk. Just about all the bugs survived.
Next, they grew bacterial colonies on the special petri dishes, and watched what happened when they added the milk components. Although it worked better on some than others, the overall effect was fairly dramatic. The bugs died. "Listeriaand Campylobacter were most sensitive [to the isolated milk products], while E. coli and salmonellawere less sensitive." says Sprong.
Because it contains higher concentrations of the key components, "full fat milk may be more protective than skim milk," says Sprong. "But the message is not just to drink more high-fat milk."
Instead, it's likely that continued research will lead to low-fat products, and maybe drugs, being enriched with these pathogen-killing isolates, she tells WebMD.
"That's certainly one approach that will be taken on as we look to the future of 'functional foods'," says Greg Miller, PhD, senior vice president of nutrition and scientific affairs at the National Dairy Council. "It's a realistic scenario."
But then again, he tells WebMD, "these researchers were looking at the same isolate levels that you'd get from drinking a glass of whole milk." So, he says, given the potential benefits, if you're looking to maintain a low-fat diet, you might want to cut the excess from an area other than milk.
Still, says Sprong, it's best that adults stick to low-fat and nonfat dairy, for now. It's just not clear yet whether milk digestion, in the human body, actually releases enough of these components to produce the same bactericidal effect seen in the laboratory. "That still needs to be established," she says.
"We are going to look further into this and measure the effect in rats, because [in live animals] all sorts of digestive factors are involved," she says. Later on, she says, they'll test the isolates in humans. Since few folks are likely to sign up for a dose of Salmonella, "we'll test it in people who are already infected," she says.