Good Bacteria
Do They Survive The Trip Through The Stomach?

Good bacteria could be defined as any bacteria that do not harm us. Probiotic bacteria are ones that actively do us good.

Most members of the Lactoabacillus and Bifidobacterium families are good bacteria.

Mankind has used good bacteria for thousands of years to help preserve our foods from harmful pathogens.

We should be eating foods that are full of good lactic acid bacteria.

But not only do we need to buy foods full of lactic acid bacteria for optimum health, we need to ensure that these bacteria do survive our treatment of them before consumption.

For instance, let's look at the good bacteria that should be in yogurt.

First the bacteria have to survive the yogurt making process where, if they close their eyes for a moment, there are manufacturers ready to pasteurize them. Then they have to survive lengthy days in a chiller unit and being left in an overheated car whilst you wanders off window shopping.

good bacteria

Finally, the yogurt makes it home. You spoon it onto a plate and eat it. All should be well.

But no - that brings us to the next danger for good bacteria!


Survival of yogurt bacteria in the human gut

People often debate as to whether the good bacteria in yogurt or supplements can survive the trip through the human digestive system. The following research clearly shows that they can.

Researchers decided to see if they could recover the two classic yogurt starter bacteria from the feces of 20 healthy volunteers.

These two yogurt starters, Lactobacillus delbrueckii subspecies bulgaricus and Streptococcus thermophilus, do not originate from humans. This does not lessen there desirability - their role is to ferment milk into yogurt and they do this superbly well. Lactobacillus delbrueckii subspecies bulgaricus is found in green plants and Streptococcus thermophilus comes from milk.

These two good bacteria are useful for anyone who is lactose intolerant.

Shepherds in the Rodopi mountains of Bulgaria took plants such as Christ's thorn (Paliurus aculeatus) and Barberry (Berberis vulgaris), softened their roots, and then inoculated milk with the juice.1 This is how the first yogurt starters were developed and these two have been an unbeatable tag-team for centuries.

Test-tube studies show that these two good bacteria, Lactobacillus delbrueckii subspecies bulgaricus and Streptococcus thermophilus do not like the high acidity in the stomach and the bile salts in the duodenum and so SHOULD have only a limited survivability after being eaten.2

However, food acts as a buffer by moderating both the acidity in the stomach and the time for emptying the stomach so that results obtained during in vitro studies do not always show the whole picture

The tolerance of probiotic lactic acid bacteria can be greatly increased due to the protective effect of milk. Yogurt is the ideal food source to assist these two to complete their dangerous journey.


Two good bacteria put to the test

Twenty people (10 men and 10 women) ate 125g of commercial yogurt twice a day for 1 week. They had not eaten any yogurt or fresh dairy products in the two weeks prior to the trial.

They were divided into two groups of ten, and after one week of the trial 6 out of 10 volunteers had viable L delbrueckii subsp bulgaricus bacteria in their feces.

The second group were tested at two days when once again 6 out of the 10 had viable L delbrueckii subsp bulgaricus bacteria in their feces. They were retested at day 7 and now 7 out of the 10 were passing viable bacteria.

Streptococcus thermophilus was detected in only one of the subjects.

However, a 2005 study where the subjects ate a larger amount of yogurt over a longer time period (12 days), produced 32 viable Streptococcus thermophilus samples from 13 people.3

Yogurt, or any of the fermented milk products, is the perfect vehicle for getting probiotic good bacteria into your gastrointestinal tract.


1. Nikolov Z, Stefanova?Kondratenko M. The Bulgarian Starters for Yogurt. Paper presented at the 2005 International Symposium on Original Bulgarian Yogurt

2. Conway PL, Gorbach SL, Goldin BR. Survival of lactic acid bacteria in the human stomach and adhesion to intestinal cells. Journal of Dairy Science 1987 70, 1-2

3. Mater DDG, Bretigny L, Firmesse O, Flores M-J, Mogenet A, Bresson J-L, Corthier G. Streptococcus thermophilus and Lactobacillus delbrueckii subsp bulgaricus survive gastrointestinal transit of healthy volunteers consuming yogurt. FEMS Microbiology Letters vol 250 issue 2 pp185-187 2005