'Dead' Yogurt Still Effective

Oct 20, 2004 02:36 PM EDT

Recent research has found that the benefits of “live” yogurt containing helpful strains of bacteria persist even when the bacteria it contains are dead.

Probiotic foods have been growing in popularity, and have been found to help conditions such as inflammatory bowel disease. The joint US-Israeli study’s goal was to address whether the metabolic activity of probiotics was mandatory for their protective effect.

Just as effective

In the study, the Researchers irradiated probiotics to kill the “friendly” bacteria. Scientists gave irradiated probiotics to mice with gut inflammation induced in the laboratory. The treatment reduced the inflammation in a way similar to giving “live” bacteria, and the researchers concluded that irradiated probiotics were just as effective.

Researchers believe that part of the body's immune system called the innate immune system responded to the bacteria, regardless of whether they were dead or alive.

No negative effects on products

Probiotics can be added to yogurt and a small number of other dairy-based products, as well as taken in capsule form. However, in most foods, adding bacteria would lead to fermentation within hours, changing the taste and texture of the food. The findings potentially open the door for probiotics to be added to a far wider range of foods, as dead bacteria can be added without any negative consequences to the product.


1. BBC Health