A healthy gastrointestinal tract is something we often take for granted. But to keep this intricate system firing on all cylinders, it needs a bit of maintenance.  This doesn't involve a sudden, massive overhaul; instead, it requires a gradual process in which you boost the numbers of friendly bacteria in your gut - something which can easily be done with the help of probiotic-rich foods such as yoghurt, or through the use of an increasing number of powerful probiotic supplements.

Research shows that friendly bacteria, or "probiotics", boost immunity, treat diarrhoea, help those with lactose intolerance and possibly prevent allergies and inflammatory bowel disease.

But the friendly bacteria in your GI tract also need fuel to function optimally: by ensuring you have an adequate fibre intake, you can make sure that the probiotics you're ingesting work more effectively towards protecting you from disease. At the same time, you'll also be giving the good bacteria that are already present in your colon a boost.

How does it work?

Food components that help probiotics to do their job are called "prebiotics". Simply put, prebiotics are non-digestible components that stimulate the growth of good bacteria in the colon. In other words, prebiotics act as food for probiotics.

Two fructo-oligosaccharide compounds have emerged in recent years as having very important prebiotic properties. These compounds, called inulin and oligofructose, contain substrates that nourish the beneficial micro-organisms in the gut.

Both inulin and oligofructose are generally classified as dietary fibre. This is because they both simply pass through the GI tract without being absorbed (like other types of dietary fibre). Both also have definite health benefits.

These two fructo-oligosaccharides occur naturally in over 36 000 plants and vegetables. These include chicory, artichokes, asparagus, salsify, leeks, onions and garlic. Chicory is a particularly useful source.

What are the health benefits?

Unlike most other dietary fibres, inulin and oligofructose are selectively fermented by the intestinal flora, i.e. it benefits very specific bacteria in the colon.

Research has shown that these two fructo-oligosaccharides are selective growth media and energy substrates for the Bifidobacteria, which act as good bacteria in terms of human health. By boosting the growth of these good bacteria, the prebiotics help to increase the bacteria's efficiency. The Bifidobacteria group:

    • Has an antibacterial effect on pathogens ("harmful" bacteria)

    • Helps with the production of the B-vitamins

    • Promotes immunological attack against malignant cells, which cuts the risk for colon cancer

Interestingly, preliminary studies are also showing that inulin and oligofructose could have a positive effect on calcium absorption, thereby increasing bone-mineral density.

The fact that the fructo-oligosaccharides have a very low energy value is an added bonus.

How is it applied?

More and more manufacturers of food products and probiotic supplements are starting to recognise the potential of prebiotics. As a result, a trend is starting to emerge in which food and supplement manufacturers are making a point of adding inulin and/or oligofructose to their probiotic products. With many of these supplements containing much higher levels of probiotics than you can get from food, plus prebiotics, they are worth a look for maintaining a healthy digestive tract.

Even international companies that aren't specialising in probiotic foods or supplements are recognising the need for more products that have prebiotic qualities. Examples of other types of food to which the addition of prebiotics have been successfully applied include fruit juice, cereals, baby foods, ice cream, biscuits and even chocolate.

A few yoghurt products that contain both pre- and probiotics are already available on shop shelves. Be on the lookout for the following terms on yoghurt labels: "prebiotics", "soluble dietary fibre", "inulin", "chicory" and/or "oligofructose". If you buy a product that contains both pre- and probiotics, the benefits are just enhanced.

It also can't hurt to get more fibre from your diet. Fruit, vegetables, wholegrain foods and oat bran are good sources of dietary fibre. Make a point of combining these foods with probiotic-rich foods to make the most of their beneficial properties.