Probiotics: The Friendly Bacteria

Inside each of us live vast numbers of bacteria without which we could not stay alive in good health.

Before looking at the amazing things they do for us we should reflect on just how many of them we house.

There are several thousand billion in each of us (more than all the cells in your body!) divided into over 400 species, most of them living in your digestive tract.

If they were all placed together the total weight of the of friendly bacteria would come to nearly four pounds weight and in fact about a third of the faecal matter (water removed) which you pass consists of dead or viable bacteria.1

What Do They Do?

These bacteria are not parasites. They do not just take up residence and do nothing in return…indeed they pay their way handsomely. We live in true symbiosis with them.

As long as you are providing them with a reasonable diet (and the foods that are good for you are the ones that are good for them) and as long as they remain in good health they provide excellent service in return.

However not all of the friendly bacteria do the same things, some being far more useful and plentiful than others and it is on these that we will concentrate.

Among the most important of their proven roles are some functions which help maintain our good health while others have a definite value in helping us regain health once this has been upset.

These dual roles (protective and therapeutic) help explain why the word ‘probiotics’ was coined since it means ‘for life’.

  1. They manufacture some of the B-vitamins including niacin (B3), pyridoxine (B6), folic acid and biotin.2

  2. They manufacture the milk-digesting enzyme lactase which helps you digest calcium-rich dairy products.3

  3. They actively produce anti-bacterial substances which kill or deactivate hostile disease-causing bacteria. They do this by changing the local levels of acidity or by depriving pathogenic bacteria of their nutrients or by actually producing their own antibiotic substances which can kill invading bacteria, viruses and yeasts.4,5

    Naturally enough they are doing this to preserve ‘their’ territory, not because they love you!

  4. Some (such as the bifidobacteria and acidophilus) have been shown to have powerful anti-carcinogenic features which are active against certain tumours.6

  5. They improve the efficiency of the digestive tract and when they are weakened bowel function is poor.7

  6. They effectively help to reduce cholesterol levels when this is high.8

  7. They play an important part of the development of a baby’s digestive function and immune system. Bifidobacteria infantis is acquired from breast-milk and when it is in poor supply allergies and malabsorption problems are more common.9

  8. They help protect against radiation damage as well as deactivating many toxic pollutants.10

  9. They help to recycle oestrogen (one of the female hormones) which reduces the likelihood of menopausal symptoms and osteoporosis.11

  10. Therapeutically they have been shown to be useful in treatment of acne, psoriasis, eczema, allergies, migraine, gout (by reducing uric acid levels), rheumatic and arthritic conditions, cystitis, candidiasis, colitis and irritable bowel syndrome and some forms of cancer!12

Meet the Cast

Some of the friendly bacteria which help you most are residents, others are transient visitors, staying in your digestive tract for a few weeks before passing on.

The key players in this drama of life and death, territorial demands and ferocious battles involving villains of great power and heroes with surprising weapon systems, are as follows:13

  • Lactobacillus acidophilus: This is the main inhabitant of your small intestine in humans and animals. It is also found in the mouth and vagina.

    Acidophilus manufactures lactase to digest milk sugar and produces lactic acid which suppresses undesirable bacteria and yeasts. Some strains produce natural antibiotics. They also lower cholesterol levels and kill Candida yeasts.

    They are very susceptible to poor diet and stress conditions (pollution, antibiotics such as penicillin).

  • Lactobacillus bulgaricus: This is a transient but very important bacteria. Together with Streptococcus thermophilus it makes yogurt. Some strains of bulgaricus and thermophilus also produce antibiotics which kill harmful bacteria.

    By manufacturing lactic acid these encourage a good environment for the resident bacteria such as acidophilus and the Bifidobacteria.

  • Bifidobacterium bifidum and B.longum: These is a the main inhabitants of your large intestine. Bifidum is also found in the vagina and the lower part of the small intestine.

    In breast-fed infants and adolescents these make up 99% of the entire flora of the bowel. There is strong evidence that the numbers and efficient working of these bacteria decline as we age and with any decline in our health status.

    They produce a number of specialised acids and use these to prevent colonization of the large intestine by invading bacteria, yeasts and some viruses.(see Box)

    They help infants retain nitrogen thus increasing their weight and they prevent potential toxicity from nitrites in your food; manufacture B vitamins for you as well as helping detoxify bile from which they recycle oestrogen in women.

  • Bifidobacteria infantis: This is the main inhabitant of every infant’s intestines and is found in small amounts in the vagina. Its functions are very much the same as the other Bifidobacteria.In a freeze-dried form it is the only probiotic product which should be supplemented to infants without professional guidance (see Box)

What Damages the Friendly Bacteria?

Many factors influence just how healthy the flora are. While the type of friendly bacteria living in a region may seem much the same in health and disease, the tasks they perform change according to circumstances.

For example when Bifidobacteria are in a good state of health they will detoxify pollutants and carcinogens as well as manufacturing the various B vitamins as listed above. When in a poor state of health however they just cannot do these jobs as well or at all.

So what makes them function less efficiently?

  • The level of local acidity is one major influence and this is affected by your diet and digestive function and most importantly by any stress you are under.14

  • Another important influence is the wave-like contraction of the intestines (called peristalsis) which moves food along the intestines.

    If it is too rapid (as in diarrhoea or irritable bowel syndrome or colitis) this severely reduces the efficiency of the flora.

    If it is too slow (as in atonic or spastic constipation) this too causes changes in their function.

  • The type of diet you eat is a major influence on bacterial health.

    They are healthier on a diet rich in complex carbohydrates (vegetables, whole grains, pulses) and low in animal fats, fatty meat and sugars. They also love cultured dairy products (especially ‘live’ yogurt and cottage cheese).15

    So not surprisingly the diet which is good for you is also ideal for them!

  • They are also influenced to a major extent by the degree of infection by yeasts and bacteria to which ‘their’ territory (your bowels) are subjected.

  • And they are severely upset by certain drugs especially antibiotics (penicillin will kill a friendly bacteria just as efficiently as it will kill a disease-causing bacteria).16

Steroids (hormonal drugs such as cortisone, ACTH, prednisilone and ‘the Pill’) also cause great damage to the bowel flora.

How can they regain health and efficiency once damaged?

By dealing with any of the factors listed above which you can, especially your diet and by stress reduction, and by supplementing with good quality freeze-dried bacteria.

How can you be sure of the quality of supplemental friendly bacteria?

There are many undesirable products on the market, and it is only by insisting on the best that these can be eliminated.

  • For example we have seen what the main inhabitants of the intestines are, and which transient bacteria are most helpful to them and these are the ones which should be supplemented (bifido, acidophilus and bulgaricus).

  • Some products carry ‘cocktails’ of bacteria which should not be together in a container and which are only minutely a part of the total flora picture, such as Bacillus laterosporus and Streptococcus faecium.
    These should be avoided.

  • Even cocktails of the best friendly bacteria should not be found in the same container since they are destined to inhabit different regions of the digestive tract and will damage each other if confined together.

The way products are made is very important:

  • When being separated from the ‘soup’ (supernatent) in which they are cultured some manufacturers spin the bacteria (in a centrifuge). This damages the delicate chains of bacteria, something which does not happen when a slower (and therefore more expensive) filtration process is used.
    This information should be on the container.

  • Similar damage can occur if the bacteria are encapsulated or tableted, which means they are best found as a powder in a dark glass (never plastic) container.

  • Viable cultures of strains of the particular bacteria you want, which are capable of re-colonising the intestines need as a rule to be refrigerated after the opening of their container and should be taken away from meal times so avoiding the extreme acidity of the stomach when it has food in it.

  • All good products should carry guarantee of numbers of viable colonising bacteria up to a specific expiry date.

  • If you look for such information on the container of friendly bacteria you will find that very few meet all the requirements listed. One manufacturer which does guarantee ALL the above is Natren of California and these are recommended.

When to Use Probiotic Products:

    Under professional guidance if their are chronic bowel problems or on-going infections such as Candidiasis.

    As a preventive against food poisoning when travelling (Bifidobacteria and Acidophilus kill most food-poisoning bacteria)

    After (and during) any period when antibiotics are taken.

    B.infantis should be given to all babies.

    By all premenopausal and menopausal women to reduce chances of osteoporosis.

    By anyone with high cholesterol problems

    By anyone with chronic health problems (acne, skin problems, allergies, arthritis, cancer, etc) under professional guidance.

    By anyone receiving radiation treatment.

    By anyone having recurrent vaginal or bladder infections (thrush or cystitis)


Two major health problems, Rheumatoid arthritis (Rh.A) and Ankylosing spondylitis (A.K.) have been found to be associated with overgrowth in the intestines of particular harmful bacteria, proteus and klebsiella respectively.17

Both of these can be controlled by healthy bowel flora. The natural antibiotics manufactured by L.bulgaricus, L.acidophilus and the bifidobacteria ALL kill both of these bacteria.18

British research has shown benefits to people with A.K. if they go onto a diet low in fat and sugar and high in complex carbohydrates – the very diet the friendly bacteria enjoy and which allows them to do their job efficiently.
Rh.A patients have been shown to benefit in recent Norwegian trials, from a vegetarian diet, something which also dramatically improves the health and function of the friendly bacteria.

Which Bacteria can the Friendly Flora Control?

Many studies prove the antibiotic effects of the friendly bacteria.

In 19 cases of non-specific infection of the vagina treated with acidophilus (Doderlein bacillus strain) 95% were cured.

In 25 cases of Monilia vaginitis 88% were cured and 12% relieved of symptoms.

In 444 cases of Trichomonas vaginitis 92% were cured and remained infection free up to a year later.19

The acidophilin antibiotic which L.acidophilus produces will kill 50% of 27 different disease causing bacteria.20

16 Children with salmonella poisoning and 15 with shigella infections were cleared of all symptoms using acidophilus. B.bifidum effectively kills or controls E.coli, S.aureus (cause of toxic shock syndrome) and shigella. Acidophilus can also control viruses such as herpes.21


German research has shown that the state of the intestinal flora (measuring both numbers and quality of colonies) of most breast-fed babies today is similar to that of formula (bottle) fed babies 40 years ago, leading to malabsorption and food sensitivity problems as well as increase in allergies and susceptibility to infection.22

Further research has pointed to contamination of breast milk, world-wide, with pollutants such as DDT and dioxin.23

This suggests that supplementation of all babies with Bifidobacteria infantis would be a helpful strategy (available as Life-start from Natren of California)


1. Leon Chaitow Natasha Trenev: Probiotics; Thomas Harper Collins 1990

2. Alm L. et al: Effect of Fermentation on B Vitamin Content of Milk in Sweden; Journal of Dairy Sciences 65:353-359

3. Alm L.: Journal of Dairy Sciences; 64(4)509-514

4. Friend B. Shahani, K.: Nutritional and Therapeutic Aspects of Lactobacilli; Journal of Applied Nutrition 36, 125-153

5. Hamdan I.: Acidolin and Antibiotic Produced by Acidophilus; Journal of Antibiotics 8, 631-636

6. Reddy G.: Antitumour Activity of Yogurt Components; Journal of Food Protection 46, 8-11 1983

7. Shehani K.: Role of Dietary Lactobacilli in Gastointestinal Microecology; American Journal of Clinical Nutrition 33, 2248-2257

8. Mott G.: Lowering of Serum Cholesterol by Intestinal Bacteria Lipids 8,428-431 1973

9. Rasic J.: Bifidobacteria and There Role; Birkhauser Verlag Boston 1983

10. Simon G.: Intestinal Flora in Health and Disease Physiology of the Intestinal Tract (ED.Johnson L) pp1361-1380 Raven Press New York 1981

11. Speck M.: Interactions Among Lactobaccilli and Man; Journal of Dairy Sciences 59,338-343

12. Chaitow L. Trenev N.: Probiotics; Thorsons/Harper Collins 1990

13. Microbial Ecology of Intestinal Tract; Old Herborn Universty, Herborn, Germany as Seminar Monograph 1987

14. Giannella R. et al: Gastric Acid Barrier T Ingested Microorganisms in Man; Gut 13,251-256

15. Henteges D.: Effect of High-Beef Diet on Bacterial Flora of Humans; Cancer Research 37,568-571

16. Finegold S.: Effect or Broad Spectrum Antibiotics on Normal Bowel Flora; Annals of New York Academy of Sciences 145, 269-281

17. Chaitow L. Trenev N.: Probiotics; Thorsons/Harper Collins 1990

18. Shahani K.: Natural Antibiotic Activity of L.acidophilus and Bulgaricus; Cultured Dairy Products Journal 12(2)8-11

19. Butler B.: Bacterial Flora in Vaginitis; American Journal of Obstetrics and Gynaecology 79, 432-440

20. Fernandes C. et al: Control of Diarrhoea by Lactobacilli; Journal of Applied Nutrition 40,32-42 1988

21. Weekes D.: Management of Herpes Simplex with Virostatic Bacterial Agent; EENT Digest 25 1983

22. Grutte F.: Human Gastrointestinal Microflora pp39-44 J. Barth Verlag Leipzig 1980

23. Scecter A. Health Hazard Assessment of Chlorinated Dioxin and Dibenzflurans in Human Milk; Chemosphere 16,2147-2154

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Written by Leon Chaitow ND DO MRO

Explore Wellness in 2021