You’ve decided to be good to your stomach, so you start taking probiotic supplements. Maybe you’ve been prescribed an antibiotic and want to protect yourself from stomach upset. Perhaps you’ve already experienced a bout of diarrhea from a stomach “bug” and want to get right again. Or you just want to give your gastrointestinal tract a healthy new start.

So you buy a 30-day supply of probiotic supplements, and start to take them each day with a glass of water. So far, so good. But what if there were a way for the probiotic to work better…and faster?

The trick isn’t to change the probiotic itself but to wash it down with something else—milk. The research is new, and the study was done on animals rather than humans, but it suggests that we should not only choose our probiotic supplements wisely, but also pay careful attention to how our diets affect their ability to help us. Here’s how…


Researchers at the University of California, Davis examined one of the most studied probiotic species, Lactobacillus casei (L. casei), often used to ferment dairy products such as yogurt and kefir. Strains of L. casei in supplements have been shown to help with many gastrointestinal conditions including constipation, antibiotic-caused diarrhea and even more serious inflammatory bowel diseases such as Crohn’s disease and irritable bowel disease (IBD). Popular brands that contain L. casei include Yakult and DanActive.

The Davis scientists looked at the effectiveness of a specific strain of L.casei called BL23, which has been shown to improve ulcerative colitis in animal studies and is almost identical to the kind used in the manufacture of many fermented dairy foods. Ulcerative colitis is a disease that causes disabling pain and increases risk for colon cancer for more than 500,000 people in the US.

In the study, one group of mice got L.casei in milk, while a second got it in water and a third, just milk (no L. casei). The amount of milk or water was equivalent to about six ounces for humans—what’s in a typical juice glass. Then the mice were given a solution that impaired the lining of their colons, induced inflammation and mimicked ulcerative colitis.

The mice that got the probiotic in milk did best, showing…

• Superior survival of the L. casei bacteria in the intestines—five times greater than the mice that got the probiotic in water

• Less diarrhea and rectal bleeding than the other two groups

• Less weight loss (a good outcome in this context)

• The lowest disease score. On a scale of 0 (no disease) to 18 (the worst disease), the milk/probiotic group scored 6, while the water/probiotic group scored 11 and the milk-only group scored 9. That means much less inflammation in the intestines.

In short, taking the probiotic in milk rather than water led to more beneficial bacteria surviving and thus greater protection of the lining of the intestines against the inflammatory disease. It didn’t cure the disease, but it did protect the mice from its worst effects.


It makes sense that a beneficial bacteria that thrives in dairy foods would do better in your gut when you take it as a supplement along with dairy. That doesn’t mean that all probiotics would do better with a glass of milk. We need more studies—this is one of the very first to look at the dietary “matrix” in which probiotics are consumed.

But it’s smart to hedge your bets. If you’re generally healthy, choose your probiotic wisely. If you have a specific medical condition, such as IBD or Crohn’s disease, be sure to work with an educated health-care provider to select the right probiotic for your needs and to make any changes in your diet.

And here’s good general advice for ways to make your probiotic work better…

• Even though you are taking a supplement, make sure you are eating probiotic-rich foods such as yogurt and kefir as well as sauerkraut, miso and kimchi. That way, you’ll be working to improve your population of healthy gut bacteria from several directions.

• Eat plenty of prebiotics, too—fiber compounds that “good bugs” thrive on. These include onions, leeks, garlic, asparagus, Jerusalem artichokes, bananas, whole wheat, yams and sweet potatoes. (Again, these foods may not agree with you if you have IBD or even the less severe irritable bowel syndrome/IBS.)

If the probiotic you’re taking with water every day doesn’t seem to be helping you, try taking it with a small glass of milk to see if that makes a difference. If milk doesn’t agree with you, try cheese, yogurt or kefir. You may even want to add your probiotic supplement to a fermented dairy food, such as yogurt or kefir.