BACTERIA described as “life-giving” and “favourable to life”? That is the meaning of probiotics, a combination of a Latin and a Greek word to define the healthy flora of the human gut.
The health benefits of probiotics were known thousands of years ago in countries of the Middle East where fermented milk was consumed for digestive upsets. Eli Metchnikoff, the 1908 Nobel Prize winner for his work on the immune system, suggested that people should consume sour milk to slow down the process of ageing. The suggestion was based on his observation of Bulgarian farmers’ daily consumption of yoghurt and their longevity. Since Metchnikoff, there has been a dramatic increase in scientific work supporting the concept that there are clinical benefits to ingesting probiotics.
Bacteria in our body
We have more bacteria than cells in our body. There are about 400 to 500 types of bacteria of different strains and the overwhelming majority of the bacteria reside in our large intestine – the colon. Common ones found in our body are Bifidobacteria, Lactobacillus, Rheumanococccus, Bacteriodes, Eubacterium, Fusobacteria, Peptococcaceae and Streptococcus.
Every day, we are producing about a hundred grams of these bacteria and eliminating about the same amount in our stool. Different strains and types affect our health in different ways. Some bacteria can cause acute or chronic illness while probiotics offer us protective and nutritive benefits.
The most important resident bacteria for continued good health and the integrity of the gastrointestinal tract are the Lactobacilli genus found mainly in the small intestines and the Bifidobacteria genus which is common in the large intestines. These bacteria are rather territorial and would latch on strongly to the lining of the gut. In doing so, they put a stop to harmful bacteria, fungi and microbes from settling in our gut, thus preventing them from creating mischief.
Some beneficial bacteria do not remain long in our system and they are referred to as transient visitors. As they pass through, they help resident bacteria flourish, and the best known and most beneficial are Lactobacillus bulgaricus and Streptococcus thermophilus.
Where do these bacteria come from
We are born with a sterile digestive tract and once out in the world, we are exposed to bacteria in breast milk or milk formula. With every breath and touch, bacteria enter our body to colonise the skin and mucous membranes. In breast-fed babies, the friendly microflora is mainly Bifidobacteria until the child is weaned, where a different microflora develops and this is mainly Lactobacilli. Human beings have developed a symbiotic relationship with these beneficial bacteria that has become a miniature ecosystem in our body.
Benefits of probiotics· Digestive health
The bacteria that line our gut help in improving digestion of our food and enhance absorption and assimilation of nutrients. It is known that when the ecosystem in our gut is affected, digestive problems such as diarrhoea, constipation, excessive wind or flatulence, heartburn, gastritis, indigestion and irritable bowel syndrome result.
The use of probiotics in diarrhoea is well-documented. Antibiotics can severely disrupt gut microbial ecology and give rise to antibiotic-associated diarrhoea. Clostridium difficile is one of the bacteria that causes diarrhoea commonly seen in hospitals due to the prolonged use of antibiotics. Probiotic supplement is generally advised to be taken when one is on a course of antibiotics as it prevents the overgrowth of pathogenic bacteria, which in turn results in changes to stool consistency and frequency.
Probiotics are found to be effective in the prevention of traveller’s diarrhoea. Parasitic and bacterial infections such as the harmful E.coli can cause diarrhoea in travellers to foreign countries where sanitation and food preparation may expose travellers to pathogens, particularly those who have no immunity. Diarrhoea due to infections is usually contracted through food, water, or faecal/oral transmission from food handlers; from consumption of spoiled food; and from close contact with an infected person.
The best-established benefit of using probiotic agents has been in the management of acute paediatric diarrhoeal disease. The use of probiotics shortens episodes of diarrhoea and results in quicker recovery of health. It has also been shown that regular consumption of probiotics decrease the incidence of diarrhoeal disease in chronically hospitalised children.
· Food sensitivities and allergies
The foods that most often trigger allergic response in children and adults are eggs, cow’s milk, soy, wheat, nuts, shellfish and white fish. The approach to such sensitivities is to eliminate them from the diet. This approach admittedly is difficult to implement as the symptoms may take several hours or days to manifest, thus making it very difficult to identify the food culprits.
Sensitivities or allergic reactions occur when certain groups of antibodies called immunoglobulins are triggered in response to foods, chemicals and bacterial toxins. The antibodies’ response to these foreign substances (antigens) manifest symptoms that include migraine, running or stuffy nose, asthma-like symptoms, eczema, skin rashes, joint aches, fatigue, poor concentration and mood swings.
Probiotics can contribute to the processing of food antigens in the gut and modify the structure of potential antigens, thus reducing the antibodies’ response. Clinical studies show significant improvement of atopic eczema in children and the reduction of allergic response in children and adults with the use of Lactobacilli and Bifidobacteria.
· Immune support
Among the possible mechanisms of probiotic therapy is the support of a barrier in the gut lining against the penetration of foreign invaders into the blood stream. The Lactobacillus strain produces natural antibiotic substances that deter the growth of potentially harmful organisms, whereas the Bifidobacteria binds excess iron, thus making it unavailable to pathogenic bacteria that need the mineral for its activity. Both strains are acid-producing and create a hostile environment for harmful microbes that are not able to survive in acidic conditions. Lactobacillus casei and Lactobacillus bulgaricus activates the production of macrophages, which are large white blood cells that are active in destroying and devouring bacteria or foreign matter that has entered the body. Apart from modulating the immune system against foreign invaders, researchers found that probiotics protect against cancer by reducing enzymes secreted by harmful microbes that convert nitrates into cancer-causing nitrosamines.
Maintaining the ecosystem
Just like any ecosystem, our gut ecology can be easily disturbed by stress, poor diet, drugs such as antibiotics and hormonal preparations and surgery. Stress slows down digestion and the elimination of waste material, and allows colonisation of different and harmful microbes.
Research indicates a diet high in fat, sugar and processed foods is low in essential nutrients to nourish, repair and maintain gut health. Such a diet has also been linked to an increase in harmful bacteria and a decline in the beneficial Bifidobacteria.
Rampant use of antibiotics is the main cause of upset in the gut flora. The action of antibiotics is not usually specific, so the bad ones along with the good bacteria are also destroyed. Candida, a yeast found commonly in gut usually controlled by the friendly bacteria, rises to the occasion and starts to proliferate and cause vaginal infection, thrush, nail and skin infections.
Ensuring the right probiotics
Current research confirms that probiotics have an important role in health. Since the beneficial microflora do not stay permanently in our gut, we have to ensure that we get them from our foods or resort to daily probiotic supplements.
The European Commission coordinated by the International Life Sciences Institute, redefined probiotics as “A live microbial food ingredient that is beneficial to health.”
The criteria for choosing a probiotics supplement include that the strain be of human origin, is safe for human consumption, stable in acid and bile, and adhere to the intestinal mucosa. The strains most commonly used are Lactobacillus and Bifidobacteria.
A high quality probiotic supplement should contain at least four billion live units in each capsule and comprises strains of Lactobacillus and Bifidobacteria. Probiotics are stable and dormant at 40C and to ensure their viability, they should be stored in the refrigerator and carry an expiry date.
If you have just completed a course of antibiotics, take one to two probiotic capsules three times a day for one month. If you are currently taking antibiotics, take probiotic supplements two hours before or after medication. Probiotics may be weakened by the hydrochloric acid our stomachs produce to digest foods. To avoid that, take probiotic supplements half an hour before food.
References: Lipski E., Digestive Wellness. Keats Publishing 2000
Nichols TW and Fass N., Optimal Digestion, New Strategies for Achieving Digestive Health. Quill 2000
Saavedra J., Clinical applications of probiotic agents. The American Journal of Clinical Nutrition, Vol 73, No.6, 1147S-1151S, June 2001
Isolauri E., Probiotics in human disease. The American Journal of Clinical Nutrition, Vol 73, No.6, 1142S-1146S, June 2001
Isolauri E et al., Probiotics: effects on immunity. The American Journal of Clinical Nutrition, Vol 73, No.2, 444S-450S, February 2001