Although the terms "prebiotics" and "probiotics" sound similar, they are in fact quite different. In this article we will explore these differences, and how they may benefit your overall health. Before we dive in, it is important to know that our large intestine is home to trillions of bacteria made up from over 500 different species some of which are beneficial to our health. Bacteria such as lactobacillus, bifidus, and acidophilus have a range of functions from improving immunity to synthesising some vitamins.
What are Prebiotics and Probiotics?
Prebiotics are forms of dietary fibre and are unable to be digested by your gut. Instead, they are digested by the bacteria that reside in your large intestines. In doing so, prebiotics provide a source of nutrition to encourage the growth of these good bacteria. Probiotics on the other hand, are actual live bacteria that are eaten to help top up your natural levels of bacteria already present in your gut.
Where do Prebiotics and Probiotics Come From?
Considering that prebiotics are forms of fibre, foods such as garlic, leek, onions, asparagus, and whole wheat are high in prebiotic contents. The best well known sources of probiotics are in fermented dairy products such as yoghurt. However, live probiotics can be added to many foods and supplements.
Benefits of Prebiotics and Probiotics
Both prebiotics and probiotics help to increase the numbers and health of the good bacteria that live in your gut. This results in a few potential health effects, the best well known of such is boosting immunity. By increasing the number of good bacteria in your gut, it leaves less room for disease causing bacteria to set up residence in your colon. Other benefits of probiotics are that it may prevent a range of illnesses and even cancer. It has been theorised that increasing the number of good bacteria can reduce the number of bacteria that may be a contributing factor to the cause of bowel cancer (Ouwehand et al, 2002). A clinical trial has shown that the consumption of probiotics was able to reduce the likelihood of children contracting, and decreasing the severity of respiratory tract infections including colds and flus (Hatakka et al, 2001).
Another benefit worth mentioning is the ability of probiotics to reduce the severity and duration of diarrhoea. It has been repeatedly shown that supplementation with probiotics reduces the length of diarrhoea caused by the Rotavirus. Likewise, probiotics are recommended for those using antibiotics, as it restores the microbial balance of the gut to prevent diarrhoea caused by the antibiotics (Ouwehand et al, 2002). It probably goes without say, that a healthy immune system means less down time as a result of illness, and thus allows you to stay in the gym for more days of the year.
Negatives of Prebiotics and Probiotics and Side Effects
The side effects of prebiotic consumption are the same as those of high fibre diets. Not everyone tolerates a rapid large increase in fibre well. Diarrhoea, flatulence, and other stomach upsets may occur. So it is important to gradually increase prebiotic intake and avoid shocking your digestive system. Probiotics are well tolerated among most people. Think of how many people enjoy frequent yoghurt consumption. It is therefore very safe to eat probiotics, under normal circumstances. However, there are small groups of people who may suffer side effects from probiotics. Severely immune-compromised people may develop septicaemia (bacteria finding its way into the blood) from using probiotics. However, this is extremely unlikely to occur with healthy people.
Prebiotics and Probiotics Recommended Doses and Ingredient Timing
The amount of dietary fibre (and hence prebiotics) you should be aiming for is around 30 g/day, in total, from all food sources. However, remember to increase dietary fibre content slowly to avoid digestive upsets. More detail about this can be found in our dietary fibre article. The recommended dose for probiotics is a little more complicated. Hatakka et al (2001) found that 100 million Lactobacillus bacteria/day were helpful for preventing infections. However, the number of bacteria you are actually eating may not be so easy to determine, because manufacturers sometimes do not give this on the label. Timing for taking prebiotics and probiotics is not particularly important.
Prebiotics and Probiotics Supplements
Many supplements contain prebiotics, but their presence may not always be apparent. Very rarely do supplement manufacturers actually list "prebiotics" as an ingredient. Rather, it is common practice for manufacturers to list the exact prebiotic they are using (eg. inulin, fructo-oligosaccharides or FOS). So if you are looking for a prebiotic, look for hints that there is soluble fibre present in the product. Quite often, Greens supplements contain prebiotics.
Fortunately, probiotics are a little easier to find. Manufacturers quite often advertise the presence of probiotics, as well as the type of bacteria included (eg. lactobacillus, bifidus, etc). Generally, bacteria names end with "-us". So if you see an ingredient with "-us" at the end, chances are, it contains a probiotic. Again, Greens supplements are a good source of probiotics. However, they can also sometimes be found in a variety of protein powders.
Stacking Prebiotics and Probiotics
Prebiotics and probiotics should be included in any balanced diet, regardless of stage of training or goals. They are therefore, good additions to any other supplement.
Hatakka et al (2001), Effect of long term consumption of probiotic milk on infections in children attending day care centres: double blind, randomised trial. BMJ, 7298: 1327
Ouwehand et al (2002), Probiotics: an overview of beneficial effects. Antonie van Leeuwenhoek, 82: 279-289