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The Evidence for Probiotics

by Sandra Goodman PhD(more info)

listed in colon health, originally published in issue 9 - January 1996

Ecology Vital for Optimal Health

Just as we have learned, to our peril, about the grave consequences to us of upsetting nature's ecological balance – decimating the rainforests, slaughtering species to extinction, polluting and contaminating the food chain through the use of chemicals and drugs – so has research revealed the importance to our health of maintaining the integrity of our own body's intricate and complex inner ecological balance.
Moreover, just as certain animals, plants, birds and insects are exquisitely adapted to live in certain environmental terrains with particular climates, in balance with competitors and predators for food, water and space, so it is within our own bodies. Various micro-organisms, most notably beneficial bacteria, have evolved and adapted to live in symbiotic association within most regions of our bodies, including the skin and most of the gastro-intestinal tract, including mouth, small and large intestines, vagina and rectum. The study and therapeutic use of various beneficial bacteria for health purposes for humans and animals is termed Probiotics, literally "for life". We provide a home for these beneficial micro-organisms which, unbeknown to us most of the time, live and grow in their particularly well-adapted ecological niche within our bodies, which provide them with their particular requirements:
  • Nutrients – probiotic bacteria thrive on complex carbohydrates, low sugar, low fat diet; a diet high in meat, sugar and fat
  • predispose the growth of harmful bacteria and yeasts;
  • pH (degree of acidity or alkalinity); – probiotic bacteria prefer an acidic pH;
  • Oxygen – probiotic bacteria are either anaerobic (require no oxygen) or can live in the presence or absence of oxygen (facultative anaerobes).
In return, these friendly bacteria have a highly significant role to play, which is becoming more widely recognised amongst health professionals, in influencing our health within the complex metabolic, biochemical and nutritional cycles of the human body. Therapeutic Action of Probiotics Extensive biomedical research has documented considerable evidence for the wide-ranging therapeutic properties of probiotic organisms and has established their role in maintaining optimal health. The major areas of their therapeutic clinical action includes:

Competition against harmful micro-organisms including Candida, preventing colonisation of pathogens through the production of inhibitory substances including acids and hydrogen peroxide and natural antibiotics;
  • Enhancement of digestion of lactose (milk sugar);
  • Reduction in blood cholesterol levels;
  • Immune enhancement, including enhanced macrophage activity;
  • Reduction in the levels of and deactivation of potential cancer causing chemicals, particularly in the colon and direct anti-tumour activity of certain strains;
  • Reduction in liver toxicity;
  • Enhancement of peristalsis, digestion, regularity and re-absorption of nutrients, In infants, promotion of healthy digestive tract colonisation;
  • Enhancement and balance of oestrogen levels, prevention of osteoporosis through increased calcium uptake;
  • Protection against food poisoning, travellers' diarrhoea, allergies, skin problems;
  • Enhancement of vitamin status (B, K), digestion of proteins, fats, carbohydrates.
Dysbiosis – Out of Ecological Balance The ecological balance within our internal organs may be disrupted by numerous external influences:
  • Diet, particularly if high in fat, sugar and meat. People who eat a varied diet with high proportions of vegetables and fruits have higher numbers of beneficial organisms in their colons than do heavy meat and sweet eaters;
  • Drugs such as antibiotics, steroids, hormones including the Pill;
  • Environmental pollution;
  • Spermicides including Nonoxynol, household cleaning chemicals;
  • Stress, which may cause profound changes to the mucosal lining of the colon;
  • Depressed immunity including illnesses such as AIDS and treatments such as chemotherapy and radiation;
  • Natural ageing which results in a decline of acidic gastric juices and a consequent drop in the numbers of probiotic inhabitants.
All of the above may change the conditions within the inner environment of parts of our body and encourage the entry and colonisation by pathogenic bacteria. When our previously healthy ecological balance is shifted, harmful micro-organisms – E. coli, Klebsiella, Bacteroides, Streptococci and Staphylococci species and yeasts such as Candida species – invade, colonise and take over. Following the disruption of our internal intestinal ecology, our health may suffer fairly dramatic and far-reaching negative consequences, including bacterial overgrowth, lowered immunity, increased risk of cancer, allergies, impaired digestion and toxic overload.

Characteristics of the Predominant Probiotic Organisms

The two main groups of micro-organism which have been shown to be therapeutically beneficial as probiotics are the lactobacilli and the bifidobacteria.
The microbiological properties of two of the most important probiotic lactobacillus strains, L. acidophilus and L. bulgaricus are summarised briefly, followed by the two major bifidobacteria strains B. bifidum and B. infantis:

L. acidophilus

Inhabits the human small and large intestine, also found in the mouth and vagina; Able to grow either in the presence or absence of oxygen (facultative anaerobe); Produces lactic acid as the main by-product of carbohydrates, thereby maintaining the vaginal pH at 4 – 4.5; Optimum growth temperature 35° – 38°C; Suppress hostile invaders, including Candida albicans through production of natural antibiotics and other inhibitory substances such as lactic acid, and H2O2;

L. bulgaricus

Found in yoghurt and cheese; Facultative anaerobe; optimum temperature 40° – 43°C A transient bacterial inhabitant in human ecology which can encourage a more acidic environment by producing H2O2 and antibiotic substances to inhibit harmful bacteria;

B. bifidum

The major bacterial component in the human large intestine, but also found in small intestine and vagina; Grows without oxygen (anaerobic); Optimum temperature; 37° – 41°C; usual pH range – 5.5 – 7; Produces acetic and lactic acid, increasing the intestinal acidity, making it less desirable for harmful bacteria; Competes with and control populations of pathogenic intestinal bacteria and yeasts; Produces B vitamins;
B. infantis Predominant bacterial inhabitant of human infants' large intestine; Produces lactic, acetic,and formic acids from carbohydrates; Optimum temperature 37° – 41°C; Protects against dysentery caused by Shigella species.

Quality Control in Cultivating Superior Probiotic Strains

Every aspect involved in the selection, growth, preparation, shipment and storage of micro-organisms is of vital importance to the quality obtained of the final product. Thus, attention to scrupulous quality control throughout the entire production of probiotics cannot be over-emphasised. The following points regarding microbiological techniques and procedures are essential in the manufacture of quality probiotic products:
  • Superior strains of micro-organisms should be selected on the basis of their superior microbiological and clinical properties in humans;
  • In selecting the chosen strains and individual biotypes of particular organisms, the following microbiological properties need to be experimentally determined, assayed and monitored: Adherence to the human gastrointestinal tract; Colonisation ability; Competitive against other micro-organisms;
  • The purity of the culture, absence of mixed cultures, and absence of pathogens must be assayed, preferably by independent laboratory analysis;
  • To ensure the highest possible numbers of living, intact cells, the cells should be refrigerated at every stage of manufacture and shipping;
  • To ensure against damage to living cells, cultures should not be subjected to centrifugation or other procedures which may damage cell walls;
  • In order to ensure the maximum life span and nutrient supply to the micro-organisms, the nutrient medium contained in the culture's supernatant, should be preserved;
  • The carrier used, whether powder, capsule or oil matrix delivery, should be of the highest quality substances, and hypoallergenic.

What to Look for in a Probiotic Supplements

The best micro-organism in the world does no good sitting in the supplement bottle. For probiotic products to carry out their therapeutic functions, they must survive their manufacture, transport, delivery to the consumer and finally arrive at their final destination – the customer's gastrointestinal tract. To ensure that the probiotic strain in the bottle is alive and intact, the individual should confirm the following data regarding the product's manufacture, shipment and storage procedures:
  • Strain specificity – the strain should be listed and be specific for human;
  • Pure rather than mixed cultures, except in the oil matrix delivery system, where Vitamin E and wheat germ oil encapsulate individual strains;
  • High numbers of organisms, at least 1 billion (109) organisms per gram;
  • Independent laboratory assays for potency and contaminants;
  • Guarantees for viability of cultures for stated shelf life;
  • Refrigerated products at each stage of production, shipment and delivery;
  • Not centrifuged – retention of supernatant with vital nutrients;
  • Assurances that the strains produce natural antibiotic and antimicrobial products, i.e. H2O2, lactic acid, formic acid, etc;
  • Storage in amber-coloured glass containers which maximally preserves the integrity of the organisms.
In Conclusion Knowledge, information and understanding go a long way toward ensuring optimal health. As with every health product and lifestyle practice, the best result is likely to be obtained through a lively and open relationship between you the individual and your health professional practitioner(s). Find out as much as possible about your condition, different approaches which suit you, and, in considered consultation with your health and personal advisors, select the best quality products available. In addition, always be open to modify your programme in the light of results achieved in your particular case. In this way, you can use beneficial probiotic products to your best advantage.

References and Further Reading

Chaitow L and Trenev N. Probiotics – How to use "friendly bacteria" to restore total health and vitality. Thorsons. 1990.
Bocci V. The neglected organ: bacterial flora has a crucial immunostimulatory role. Perspectives in Biology and Medicine. 35(2): 251-60. 1992.
Gorbach SL. Lactic acid bacteria and human health. Ann Med. 22: 37-41. 1990.
Mitsuoka T. Intestinal flora and aging. Nutrition Reviews. 50(12): 438 -46. 1992.
Black FT et al. Prophylactic efficacy of lactobacilli on traveller's diarrhoea. Travel Medicine S: 333-35. Springer-Verlag Berlin 1989.
Kirsch M. Bacterial overgrowth. Amer J of Gastroenterology. 85(3): 231-7. 1990.
Hood SK and Zottola EA. An electron microscopic study of the adherence of Lactobacillus acidophilus to human intestinal cells in vitro. Food Microstructure. 8: 91-7. 1989.
Rasic JL and Kurmann JA. Bifidobacteria and their Role: Microbiological, Nutritional-Physiological, Medical and Technological Aspects and Bibliography.
Poupard JA, Husain I and Norris RF. Biology of the Bifidobacteria. Bacteriological Reviews. 37(2): 136-65. 1973.
Clemmesen J. Antitumor effect of lactobacilli substances: "L. bulgaricus effect". Mol Biother. 1: 279-82. 1989.

Originally commissioned by Nutri (Imports & Exports) Ltd and reprinted here with their permission.


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About Sandra Goodman PhD

Sandra Goodman PhD, Co-founder and Editor of Positive Health, trained as a Molecular Biology scientist in Agricultural Biotechnology in Canada and the US, focusing upon health issues since the 1980s in the UK. Author of 4 books, including Nutrition and Cancer: State-of-the-Art, Vitamin C – The Master Nutrient, Germanium: The Health and Life Enhancer and numerous articles, Dr Goodman was the lead author of the Consensus Document Nutritional and LifeStyle Guidelines for People with Cancer and compiled the Cancer and Nutrition Database for the Bristol Cancer Help Centre in 1993. Dr Goodman is passionate about making available to all people, particularly those with cancer, clinical expertise in Nutrition and Complementary Therapies. Dr Goodman was recently featured as Doctor of the Fortnight in ThinkWellness360.

Dr Goodman and long-term partner Mike Howell seek individuals with vision, resources, and organization to continue and expand the Positive Health PH Online legacy beyond the first 30 years, with facilities for training, to fund alternative cancer research, and promote holistic organizations internationally. Read about Dr Goodman and purchase Nutrition and Cancer: State-of-the-Art.  She may be contacted privately for Research, Lectures and Editorial services via:   and

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