Probiotics are well publicised. In the media there are frequent adverts for yoghurt drinks that are literally alive with various bacteria said to be beneficial for our health.
When examining the claims of the probiotic suppliers a number of questions arise: are probiotics good for our health: if so in what ways? And how do they work?
Probiotics and Health
Probiotics contain one or more species of bacteria found in the colon. When ingested they colonise the colon along with the other thousands of bacterial species that live there. Two common species are Bifidobacteria and Lactobacilli.
The evidence for the health benefits of probiotics is still coming in. Some reports, for example that in Current Opinion in Gastroenterology, suggest that they can help reduce bowel inflammation.
A study reported by the Cochrane Collaboration suggests that probiotics may be helpful in treating antibiotic-associated diarrhoea in children.
Evidence for beneficial probiotic effects on the general immune system and therefore useful in such things as otitis media and chest infections is less certain.
Bacteria and Humans
Humans have a symbiotic relationship with very many species of bacteria. This means that they live on various bits of us and obtain somewhere to obtain food and reproduce and we gain something in return. The essence of a symbiotic relationship is that both partners benefit.
Many bacteria live on our skin and mucous membranes (mouth, genitals etc). This benefits us because whilst they are there it leaves very little room for other bacteria that might be less friendly – so they help keep away infections.
Bacteria and the Colon
This relationship also applies to the colon but here the bacteria do a great deal more. Some of the species in our gut break down plant material that we can’t – cellulose from plants for example. Others make vitamin K which is vital in blood clotting processes.
Another benefit that has recently been recognised is that gut bacteria play a vital role in developing our immune system. Newborn babies pick up bacteria from the vagina or faeces during birth. These then quickly colonise the gut. It seems that this early colonisation stimulates the baby’s immune system to develop in such away as to tolerate beneficial bacteria but not disease causing types.
Having the right mix of species of bacteria in the colon is important for the prevention of some diseases. Crohn’s disease, ulcerative colitis and colon cancer have all been linked to disturbance of the normal bowel symbiosis.
Colon Bacteria and Antibiotics
One of the drawbacks of antibiotic therapy is that in trying to kill disease-causing germs in one part of the body it’s likely to knock off large numbers of those normally living in the gut. With many of the beneficial species out of the way, disease-causing bacteria like Clostridium difficile can take hold causing serious illness.
Drawbacks of Probiotics
There seem to be very few. One study in the Netherlands, reported on the BBC’s Case Notes program on patients seriously ill with pancreatitis, found that those given probiotics were less likely to recover than those given placebo.
However these patients were in intensive care units and extremely unwell. For the vast majority of people probiotics may well offer benefits in terms of better bowel function, especially if taken during antibiotic therapy, and improved immunity.
This article is for information only, if you have any health concerns you should consult your doctor.
Resources
Case Notes, BBC Radio 4, 7th January 2009
Current Opinion in Gastroenterology November 2007
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