Probiotics is the term is used to describe dietary supplements or foods that contain good bacteria similar to those found naturally in our bodies. We have billions of microorganisms in our bodies, including bacteria in our guts that can be good or bad for us. The bad can cause diseases and make us ill. But good ones are important for our health, helping to:

• Protect against bad bacteria
• Digest and absorb food and nutrients
• Develop the immune system properly

Levels of good and bad bacteria can be thrown out of kilter by a poor diet and use of antibiotics (when used to treat bacterial infections, antibiotics can kill off good bacteria as well as the bad ones that are making you sick).

The World Health Organisation has recognised that probiotics may have health benefits, while probiotics advocates say we should eat foods containing them every day.

What can probiotics do?

Research into the benefits of probiotics is still at a fairly early stage but several trials have had some positive outcomes. These have shown that probiotics may help in:

• Treating diarrhoea
• Preventing and treating urinary tract infections
• Treating irritable bowel syndrome
• Preventing and managing eczema
• Reducing the recurrence of bladder cancer

After some initial encouraging results, probiotics are now also being further investigated as a possible way of:

• Lowering cholesterol
• Improving your immune system
• Managing lactose intolerance
• Lowering blood pressure
• Preventing colon cancer
• Managing weight
• Treating the bacterial infection that causes peptic ulcers

Are there any side effects?

So far, it appears that most of the side effects noted after probiotics have been used tend to be mild, such as bloating or gas. But there have also been instances of probiotics apparently making people who are already sick more susceptible to certain infections. Doctors are cautious about how safe they are for babies, young children, the elderly and people with weakened immune systems. Those with any kind of health condition should always check with their doctor before taking supplements.

How do you take probiotics?

• Food containing probiotics include:
• Yoghurt
• Fermented and unfermented milk
• Japanese food like miso and tempeh
• Some soy drinks

They are also found in supplements, such as drinks, capsules and tablets. The trouble is knowing what to take or eat. There are different strains of good bacteria and the mixture we have in our bodies varies from person to person. Most good bacteria come from two groups – lactobacillus or bifidobacterium – so taking probiotics that contain high doses of these may be the most beneficial.

Can probiotics replace drugs?

Researchers say their studies suggest probiotics may one day be able to replace antibiotics. Scientists from University College in Ireland found that probiotics were as effective as the best available antibiotics in fighting off infections in animals. They say the probiotics not only work by killing off harmful bugs, but also prevent bacteria from establishing themselves in the gut.

Meanwhile, Swedish researchers reported a certain type of probiotic was as effective as antiseptic in preventing patients on ventilators developing pneumonia. Another study found workers who were given a probiotic supplement missed less work due to respiratory or stomach conditions than colleagues who were not given the probiotic.

Can probiotics keep your weight down?

Taking probiotics is being studied as a way of maintaining a healthy weight after scientists noticed some interesting links between bacteria and how much weight people gain.

Researchers in Finland found that children who had larger amounts of a type of probiotic, called bifidobacteria, when they were babies were more likely to be a normal weight by the time they were seven than children who had low levels of it.

The same scientists have also discovered that women who took a supplement of commonly used probiotics while pregnant had less belly fat. The women took part in a controlled trial that found 25% of the mums-to-be who took the probiotics and received dietary counselling developed belly fat, compared to 43% who only had nutritional advice.

It’s not known exactly how bacteria affects your weight, although scientists have a theory that two types of “fat-inducing” bacteria may have something to do with it. These bacteria are found in people who are obese but not in those who are a normal weight. It’s thought that they may cause certain people to absorb more calories and store more fat, thereby causing obesity. The researchers are looking at whether probiotics can prevent these particular bacteria from doing that.