Nutrient - Probiotics: what are they?
Probiotic bacteria are essentially helpful, live micro organisms that, when present in adequate amounts, are beneficial to our health. Micro organisms are tiny living organisms which include bacteria, yeasts and viruses that can only be seen under a microscope. They are usually eaten as part of our food, but can be introduced into our bodies in a number of other ways including breathing in. To be termed a ‘probiotic’, an organism must be ‘live’, beneficial to health and safe.
Billions of bacteria and other microbes live in and on our bodies. They can be found on our skin, in our mouths, in our intestines and other parts of the body. The gut micro flora is complex and dynamic. There is a population of approximately 400 different microbial species in the gut alone which together weigh somewhere in the vicinity of six pounds!
Bacterial flora in the gut lumen plays an important role in normal human physiology. The mix of bacteria in a person’s body varies between individuals. How these micro organisms interact between themselves and the person’s body can be crucial to their health and wellbeing. We live quite happily alongside these microbes, giving them space to live and eat whilst in return they protect us in a number of ways.
A life-long intestinal microflora is established in the first few weeks after a baby is born. Lactobacilli and bifidobacteria will establish themselves in newborns that are breast fed due to the presence of oligosaccharides and prebiotic factors in breast milk. In addition bifidus factor, lactoferrin, casein and nucleotides will promote an increase in the colonisation of these bacteria.
On the other hand, babies fed with cow’s milk formula, will develop mainly enterobacteria and gram-negative organisms. This is because of the absence of the prebiotics contained in human milk and the alkaline surroundings. Following weaning the microflora of a baby’s intestines resembles that of the adult’s flora.
Probiotics are different from prebiotics. Compared with probiotics, which introduce external bacteria into the human colon, prebiotics are non digestible food ingredients that stimulate the preferential growth of a limited number of health-promoting flora already living in the colon; especially, but not exclusively, lactobacilli and bifidobacteria. Combinations of probiotics and prebiotics are called synbiotics.
The whole concept of helpful or ‘friendly’ bacteria may seem confusing since bacteria are usually associated with diseases and illnesses. But this is not the only role that bacteria play in our bodies. Some types of bacteria can be quite helpful and without them we would become ill. These microbes are thought to have several functions:
They produce cytochrome p450 such as enzymes and may help with detoxification
They have been shown to help produce vitamin K and some B vitamins within the gut
They aid digestion, enhancing absorption of nutrients and also support the immune system and digestive tract
Help produce the lactase enzyme which digests lactose
They may also manage the leakiness of the gut
They may counteract the colonisation of the gut by pathogenic organisms, which can cause an imbalance and produce gastrointestinal symptoms
They promote urinary and genital health as well as intestinal health
SOURCES OF PROBIOTICS
Probiotics can be found in yoghurt, fermented and unfermented milk, tempeh, miso and some soy beverages. Some foods have probiotics added during the preparation. Other foods have probiotics that are naturally present. They are also available as dietary supplements in the form of capsules, powders and tablet.
CHOOSING A PROBIOTIC
The efficacy of probiotics is dependant on the ability of the bacteria to survive the digestive process and the type of probiotic used. Often the manufacturing process and shipping times of foods like yoghurt mean that by the time it is consumed there is little or no probiotic activity left. There are also many different strains and species of probiotics, the majority of which have not been researched to prove whether or not they are effective. It is important to choose a strain of probiotic that can establish itself and survive the stomach acid and digestive juices found in the intestinal tract. One should also be aware that the health benefits conferred are usually strain specific.