Intestinal flora form a major part of our physiology and play a pivotal role in our health – some friend, and some foe.
There are more bacteria in our intestinal tract than cells in our entire body. One hundred trillion bacteria live in the human digestive system. The majority are found in the colon, followed by the small intestine and then the mouth.
HOW DO BACTERIA GET INTO OUR GUT?
Up until birth, humans have a sterile digestive tract. The infant first encounters bacteria during its passage down the birth canal. Thereafter exposure occurs everywhere – through breath and touch, breast or bottle milk, sucking on nipples, and from fingers and toes. It does not take long for the ingested bacteria to fully colonise the colon and the rest of the digestive tract. The type of bacteria to take hold in the neonate’s gut will play a major role in its current and future health.
WHAT ROLE DO THEY PLAY IN THE BODY?
In return for a warm and protected environment in which to live, our gut flora reciprocate by carrying out some very important functions in the body. Beneficial bacteria, such as Bifidobacterium and Lactobacillus, offer the following health benefits.
- Control of potentially disease-causing bugs. Gut flora literally crowd out disease-causing organisms preventing them from taking hold and proliferating in the body. An example is vaginal candidiasis (yeast) which is carried asymptomatically by many women. Vaginal thrush becomes symptomatic in many women after a course of antibiotics as a direct result of the beneficial flora being eradicated, allowing yeast to proliferate.
- Nutrient production:
- B vitamins (B1, B2, B3, B5, B6, B12), biotin, vitamin A and vitamin K.
- Short-chain fatty acids which feed the cells lining our colon.
- Enzymes that enable the breakdown of foods, e.g. lactase which digests milk sugars.
- They help to release the beneficial isoflavones from soya products.
- Useful metabolites:
- Antibiotics and anti-fungals which help to keep disease-causing organisms out of the gut.
- They play a role in the reduction of cholesterol.
- Manufacture essential fatty acids.
- Have anti-cancer and anti-tumour effects.
- Produce lactic acid which provides the correct pH balance in the colon and the vagina.
- Function in the beakdown and rebuilding of hormones.
- Removal of toxins from the gut. They can remove or destroy carcinogens, mutagens and cancer-causing nitrosamines.
- Stimulation of the intestinal immune system. Gut flora assist in the development and maturation of a competent immune system, thereby offering protection against allergy and disease formation.
GETTING THE RIGHT BALANCE OF FLORA
Many factors can disturb the fine balance of our gut flora. These include diet and lifestyle, chronic stress, exposure to manufactured chemicals, oral contraceptives, faulty ileocaecal valve function, surgery, use of antibiotics and pain killers (non-steroidal anti-inflammatory drugs). An imbalance in gut flora is known as dysbiosis, and can lead to numerous unpleasant symptoms.
Our dietary and lifestyle choices determine the type of flora we cultivate in our digestive system and whether we create disease or support health. It starts in infancy. Breast milk is very rich in substances called oligosaccharides which feed the right type of gut flora providing protection against the formation of an overreactive immune system and allergy formation. Cow’s milk, on the other hand, does not contain these substances, which may result in an altered intestinal flora composition in bottle-fed babies. This is one of the hypotheses proposed for the increasing prevalence of allergy over the past three decades.
Fermented foods containing bacterial cultures include: kefir, yoghurt, sauerkraut, kimchi and kombucha.
Some foods contain prebiotic substances such as FOS and inulin which feed beneficial gut flora. These include: artichoke, garlic, shallot, onion, chive, leek, asparagus, salsify, chicory, dandelion, soya, tomato, banana, burdock, potato, beer-root, rye, barley, wheat
A diet high in carbohydrates (sugar, fruit, beer, wine, grains and fibre) can lead to a proliferation of gut flora that causes fermentation. This is called fermentation dysbiosis and is characterised by bloating, constipation, diarrhoea, fatigue and gas, and an overgrowth of Candida yeast. A high-fat, high animal protein and low-fibre diet predisposes people to putrefaction dysbiosis where an overgrowth of putrefactive bacteria cause our food to rot inside us leading to bloating, discomfort and indigestion. Research has implicated this type of dysbiosis with breast and colon cancer.
A course of broad-spectrum antibiotics can eradicate up to 95% of our entire normal flora. This can lead to a microbial imbalance which will result in an explosion in growth of disease-causing organisms. This imbalance can persist for up to 6 months after a 7-day course of antibiotics and can result in symptoms of irritable bowel syndrome, increased susceptibility to allergy development (asthma, eczema, hay fever) due to leaky gut formation, overgrowth of yeast, antibiotic-associated diarrhoea and more. Three times more asthma, hay fever and eczema has been shown to develop with the use of antibiotic treatment in the first year of life.Not only do antibiotics disturb our natural gut flora, they are leading to the emergence of antibiotic-resistant strains of disease-causing organisms, such as Methicillin-resistant Staphylococcus aureus (MRSA). In an interview with CAM (the Magazine for Complementary and Alternative Professionals), Dr Nigel Plummer, technical director of the UK’s Biocare range of supplements states that: ‘We are moving towards a point where antibiotics are going to be of limited use – due to an increasing resistance to their effects’.
This is where probiotics are of particular benefit, not only in the maintenance of health through the restoration of the correct balance of gut flora, but in preventing the formation of drug-resistant strains of bacteria.
WHAT ARE PROBIOTICS?
‘Probiotic’ is derived from the Greek word meaning ‘for life’. The term ‘probiotic’ commonly refers to supplemental use of bacteria in capsule or powder form and is routinely prescribed by many health care professionals such as holistic practitioners, naturopaths, nutritional therapists, chiropractors, and herbalists to assist in the re-establishment of the correct balance of gut flora.
Scientific interest in probiotics is still growing. The Food and Agricultural Organization (FAO) of the United Nations and the World Health Organization (WHO) have stated that there is adequate scientific evidence to indicate a potential for probiotic foods to provide health benefits and that specific strains are safe for human use.
In a review of the potential uses of probiotics in clinical practice, Reid et al.7 highlight that the surging levels of drug-resistant strains of bacteria, the increasing consumer demand for natural substitutes for drugs, and the emergence of scientific and clinical evidence showing the efficacy and effectiveness of some probiotic strains, are leading many physicians to examine probiotics and other alternatives to pharmaceutical remedies.
Probiotics taken with, and following, a course of antibiotics can stunt the overgrowth of disease-causing organisms and antibiotic-resistant strains. A suitable probiotic should be taken during the course of antibiotic treatment, but not at the same time because the antibiotic has a negative effect on the probiotic, e.g. if the antibiotic is taken in the morning and evening, the probiotic supplement should be taken at lunch time.
What to look for in a probiotic supplement
- The efficiency of the probiotic is determined by the type of strain and the number of organisms present in the product.
- Look for the two well-known beneficial bacteria, namely Lactobacillus acidophilus and Bifidobacterium bifidum, because they have the best-established safety record.
- A higher number of bacteria produce a more potent effect. Look for numbers in the billions.
- As a preventive measure, take a billion of each species a day. For therapeutic doses this amount can be taken three times a day.
- Refrigeration is advised. As temperature increases, shelf-life decreases.
- Choose an age-appropriate product e.g. Bifidobacterium infantis is suitable for infants.
- Many manufacturers include prebiotics, fructo-oligosaccharides (FOS) or inulin, to feed the bacteria. Note that some people bloat when they take FOS.
- NOTE: Taking large quantities of probiotic supplements can result in sudden bloating, diarrhoea, gas or worsening of symptoms, as a result of chemicals released when disease-producing bacteria and fungi are killed.
INDICATIONS FOR PROBIOTIC USE
- Antibiotic-induced infant diarrhoea
- Infant colic
- Infant infections (diarrhoea) in childcare centres
- Acute, viral induced diarrhoea in young children (mainly caused by rotavirus)
- Mild gastroenteritis
- Persistent diarrhoea in children
- Paediatric Crohn’s disease
- Necrotising enterocolitis
- Prevention of allergy formation in infants
- Infant allergy to cow’s milk
- Gastritis and peptic ulcers as a result of H. pylori infection
- Irritable Bowel Disease such as Crohn’s disease and pouchitis
- Ulcerative colitis
- Traveller’s diarrhoea
- Urinary tract infections, bacterial vaginosis, and yeast vaginitis
- Immune modulation
- Surgical infections
- Harmsen HJ, et al. Analysis of intestinal flora development in breast-fed and formula-fed infants by using molecular identification and detection methods. J Paediatr Gastroeneterol Nutr 2000; 30(1): 61-67.
- Tannock GW. The bowel microflora: an important source of urinary tract pathogens. World J Urol 1999; 17: 339-344.
- Mouton G. Lecture: Probiotics Against Antibiotics. British College of Nutrition and Health, 2003-2004.
- Fermented Foods and Healthy Digestive Functions. Nutrition and Health Collection. Danone Vitapole Research, 2001.
- Levy J. The effects of antibiotic use on gastrointestinal function. Am J Gastroenterol 2000; 95: S8-10.
- Plummer N. Superbugs to the rescue. Magazine for Complementary and Alternative Practitioners (CAM) 2004; Vol 3, Issue 7.
- Reid G, et al. Potential uses of probiotics in clinical practice. Clin Microbiol Rev 2003; 16: 658-672.
- Lipski E. Digestive Wellness. 2nd ed. USA: Keats Publishing, 2000.
- Sanders ME, et al. Sporeformers as human probiotics: Bacillus, Sporolactobacillus,and Brevibacillus. Comprehensive Reviews in Food and Science and Food Safety 2003: Vol 2.