The Science of Probiotics

Glenn Gibson explains to Chris Smith how probiotics can be beneficial to intestinal health...

Glenn - I work on bacteria in the gut and look at what they do for our diet, why they are there and how they can affect our health.

Chris - Why do you want to build an artificial gut?

Glenn - We've made about 25 artificial guts so far! They cover lots of different age ranges and a range of different gut diseases. We use these to test the effect of diet on the bacteria that grow in them. Diet can stimulate the growth of both beneficial and harmful bacteria. The benefit of building an artificial gut is that it avoids the expensive and long term studies on human volunteers, and is of course an alternative to animal testing.

The gut itself contains a huge number of bacteria; enough to weigh about 1kg! These huge numbers can be reached because the gut is a very favourable environment for bacterial growth. Bacteria reproduce about million times faster than us. Human babies are born sterile, that is, they have no bacteria on or in them. Bacteria are first given to us during the birth process, such as from mum or from the hand of the midwife. Babies born by Caesarean section have slightly different micro-organisms to babies born in the normal manner, but this is not the most important factor to picking up important bacteria. The key issue is whether you are breast or bottle fed.

Chris - What makes a bacterium friendly or hostile?

Glenn - Lactobacillus is friendly and is anaerobic, meaning it doesn't use oxygen. A less friendly bacterium would produce toxins and might have effects in other parts of the body.

Chris - Why should you notice a difference when you drink a probiotic drink?

Glenn - You are drinking millions of micro-organisms but whether they survive your stomach acid is a big point of debate. You should possibly notice a difference if it can get through to your large intestine, but about half the products don't. Only the more robust strains of micro-organisms make it. The other way to increase the amount of bacteria in your gut is to grow more of what you already have. This is known as pre-biotics. Extracts of chicory, onion and garlic can have a positive pre-biotic effect.

Kat - At home I have a hand soap that claims it can tell the difference between good and bad bacteria. Is it rubbish?

Glenn - It might have some mild disinfectant against a certain bad bacteria, but there are many types of bacteria on your hand, so it is unlikely it can accurately tell which is which.