Most people are familiar with probiotics, the healthy bacteria that should be found in your gut. Some shoppers choose food products such as yogurt or health drinks that contain probiotics. But are those probiotic-enriched foods really making as much of a difference as they could be?
Nobody denies that having a healthy digestive system, with beneficial micro-organisms such as lactic acid bacteria or bifidobacteria, can make a huge difference to your general health. But does eating or drinking the food-based probiotic bacteria guarantee that they’ll make it through your stomach and take up residence in your colon? Nutritionists agree now that the best way to stimulate healthy gut flora is to consume probiotics AND prebiotics.
A prebiotic is a substance that passes through the upper part of your intestinal tract and isn’t destroyed by the acid in your stomach. Once it gets to your colon, it naturally leads to the growth of healthy bacteria. Prebiotics vary in chemical composition, but generally are all forms of insoluble fibre. Two of the prebiotics that have been studied for their positive health effects are galacto-oligosaccharide (GOS) and fructo-oligosaccharide (FOS).
FOS is found naturally in a variety of foods, including chicory, Jerusalem artichoke, garlic, leek and onion, as well as whole wheat flour. The level of FOS in these vegetables is reduced by cooking, so it’s best to eat them raw in salads. Less than half an ounce of raw chicory or about two and a half ounces of raw onion will provide a healthy dose of FOS. But you don’t have to live on salads: double the amount of cooked onion will provide the same dose, as will five ounces of cooked whole wheat flour.
GOS is fermented from lactose, and is usually found as an additive. You may find it listed as an ingredient in infant formula, because it’s chemically very similar to the natural prebiotics found in breast milk. The use of GOS in foods varies around the world; Japan leads the way with several food manufacturers using it. It’s less popular in Europe and at present is infrequently found as a food additive in the USA.
Several studies have shown that prebiotics (FOS and GOS) can help with constipation. In the modern world, where many people have a semi-sedentary lifestyle, constipation is a growing problem. As well as being uncomfortable, chronic constipation is also linked to increased likelihood of colorectal cancer (ncbi.nlm.nih.gov/pubmed/24832002). Using prebiotics has been shown to reduce constipation in adults who have a history of this problem, as well as infants and the elderly.
Prebiotics also seem to strengthen the body’s natural defenses. A 2009 review (ncbi.nlm.nih.gov/pubmed/18814803) concluded that prebiotics helped to support the immune system and reduced inflammation. There is also evidence that FOS and GOS not only encourage the growth of healthy bacteria, but they can reduce levels of harmful bacteria too.
Prebiotics have also been shown to have wider benefits to your well being. A 2015 study measured the levels of cortisol, a stress hormone, in a group of healthy people taking a FOS supplement. Compared with a placebo group, those taking FOS were less stressed, and in a psychometric test were more likely to focus on positives than negatives. Further research is needed, but there is now the possibility of treating mood disorders with natural, food-based remedies or prebiotic + probiotic daily supplements aimed at improving your mood.
As the scientific evidence accumulates for the benefits of prebiotics, you can expect to see more and more food manufacturers adding GOS and FOS to products, and of course you can boost your own levels of FOS through food. So do your body and your mind a favor by making sure that you are always getting your daily prebiotic.