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"I discovered your work and it's really awesome! I'm a dentistry student but the more I learn the more I ask myself 'Is there anything really left in that mainstream field that isn't a hoax?' As an individual I know what to do, what to eat and what to take, but I don't see these things being prescribed as a dentist to a patient. I'm so confused!"
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Illustration of bacteria

Fermented foods

The current popularity of probiotic supplements and functional foods have their origins in more traditional fermented foods when, prior to the advent of refrigeration, many cultures fermented foods to improve holding and storing properties.

Yoghurts, for example, are first thought to have been made when milks were put in goat skin bags on the backs of camels in the hot desert sun.

However, it was not until 1910 that the famous Nobel prize-winning Russian bacteriologist, Elie Metchnikoff, first considered the possible health benefits of fermented foods.

At the time Metchnikoff was a professor at the Pasteur Institute in Paris, and he formulated the notion that the ageing process was the result of the activity of putrefactive (proteolytic) microbes in the bowel.

Bacteria such as clostridia, a normal inhabitant of the gut, digested proteins and produced toxic substances including phenols, indols and ammonia. It was these noxious substances that were then absorbed into the body in a process of auto-intoxification that he believed caused the degenerative processes associated with ageing. 

Metchnikoff also observed that all the longest lived and most vital people in the world including the Hunzas of Kashmir and the Georgians in Eastern Europe ate some form of fermented food regularly. In particular he studied the Bulgarians who in the early twentieth century had an exceptional average life-span of 87 years and who consumed large amounts of fermented milks.

At that time milk fermented with lactic-acid bacteria was known to inhibit the growth of proteolytic bacteria because of the low pH produced by the fermentation of lactose. So based upon these facts, Metchnikoff proposed that consumption of fermented milk would 'seed' the intestine with harmless lactic-acid bacteria and decrease the intestinal pH and that this would suppress the growth of the proteolytic bacteria and counter ageing.

He started consuming sour milk fermented with the bacteria used in Bulgaria that he called 'Bulgarian Bacillus' and which we now know as Lactobacillus bulgaricus into his diet. Noticing personal health benefits, friends in Paris soon started to follow his lead and physicians began prescribing the Sour Milk diet for their patients.

This grew in popularity for many years before another researcher, Retteger demonstrated that Lactobacillus bulgaricus, could not live in the human intestine, and the Sour Milk movement petered out although Lactobacillus bulgaricus is still commonly used to make yoghurt. 

Later research in 1935, reignited interest and research in this field when it was found that certain strains of Lactobacillus acidophilus were very active in the human digestive tract. 

Many cultures throughout the world have their own local version of fermented foods the most common of which are:

  • Live yoghurt and/or buttermilk
  • Miso which is a traditional Japanese seasoning that is added to soups and sauces and is produced by fermenting various beans or grains
  • Tempeh which is a fermented whole soybean product that has the chewy texture of meat
  • Kefir - a sour drink made of milk fermented with kefir grains
  • Sauerkraut which is cabbage fermented or pickled in brine 


There is still value in including these foods in your diet regularly (intolerances permitting). However, for most people these days the majority of their probiotic bacteria are more likely to come in the form of food supplements or functional foods. 


The development of healthy gut flora

In the womb, our intestines are sterile and it is during vaginal delivery that the emerging baby is first exposed to the mother's bacterial flora which will become the infant's commensal or 'friendly' bacteria and colonise the intestines. The colic many infants experience may be a symptom of the colonisation of the intestines by such microorganisms.

Of course, many mothers now have Caesarian deliveries for a variety of reasons which short circuit this natural process. This means that the first bacteria that the baby is exposed to in the operating theatre will become their future bacterial flora - for good or ill.

These days too the majority of mothers may have a bacterial flora which has been greatly altered from that which nature intended by taking repeated courses of antibiotics, steroid drugs and the contraceptive pill to the point where the flora the baby is exposed to may not be entirely beneficial.

Feeding the baby breastmilk as opposed to formula also further promotes growth of a type of beneficial bacterial flora that provides natural protection against many diseases.

So some people may get off to a bad start with regards to colonisation of their intestines with 'friendly' bacteria for reasons dating back to their first weeks of life!  

Any course of antibiotics will eliminate the natural beneficial bacteria along with any pathogenic species and the intestinal flora may never fully recover or may take many months or years to do so. This is particularly critical in the infant and young child.

For this reason it is best to use antibiotics only as a last resort and only where the infectious agent is known to be bacterial and not viral or fungal. Antibiotics may also favour the overgrowth of pathogenic species such as Clostridium difficile and may also turn the immune system 'off'.

For anyone having to take antibiotics a course of probiotic supplements and/or live fermented foods is highly recommended to reseed the gut flora and consuming prebiotics to help the friendly bacteria to establish is also a good idea (see below). The probiotics are also thought to turn the processes of the immune system back 'on'.

In addition, our intestinal flora can be adversely affected by one or more of the following factors over time:

  • The use of any steroid medications and the contraceptive pill and/or HRT
  • Water chlorination which destroys good gut bacteria along with the pathogens it seeks to control in the water supply
  • Constipation which promotes the overgrowth of yeasts
  • Some diseases such as having an underactive thyroid, anaemia and diabetes which cause the immune system to become compromised and where the normal control of bacterial flora may be lost allowing the overgrowth of pathogenic species
  • The swallowing of mercury from dental amalgam fillings along with food causes suppression of the normal flora as bacteria convert the elemental mercury to organic mercury making it much more toxic and also promoting the overgrowth of yeasts
  • A diet deficient in vitamins and minerals and high in sugars, refined carbohydrates and yeast-containing foods also favours the overgrowth of pathogenic species 
  • Finally, the excess cortisol of chronic stress destroys friendly bacteria and promotes the growth of pathogens and yeasts. 


What are probiotics?

The term probiotic comes from the words 'pro' meaning 'for' and 'bios' meaning 'life' and the current definition developed by the World Health Organisation and the Food and Agriculture Organisation of the United Nations, is that probiotics are "live microorganisms, which, when administered in adequate amounts, confer a health benefit on the host."

Probiotics are also referred to as 'friendly' or 'good' bacteria although some yeasts such as Saccharomyces boulardii, are also regarded as being probiotics. 

Friendly bacteria are vital to:

  • The proper development of the immune system
  • Inhibiting the growth of pathogenic bacteria such as salmonella, Staphylococcus aureus, Escherichia coli, listeria, genitourinary and other species
  • The digestion and absorption of food and nutrients
  • Reducing bowel inflammation and diarrhoea 
  • Reducing allergic responses 
  • Reducing the severity of Helicobacter pylori infections of the stomach 


Probiotics are available in capsule, tablet and powder form as food supplements, in fermented foods where the bacteria are naturally occurring and in functional foods where they may have been added during preparation. The whole area of functional foods currently represents a huge growth area with spending in the US on probiotic supplements alone tripling in the decade to 2003.

Danone Activia Yogurt is probably the best known probiotic functional food which, in addition to being a dairy product (if that is an issue for you) also contains added sugar, fructose syrup and modified corn starch. The colouring in the red and purple coloured yoghurts also comes from carmine, which whilst natural, is made from boiled and ground beetles!   

Probiotics have been shown to help in the following conditions:

  • Infectious diarrhoea
  • Irritable bowel syndrome (especially Bacillus infantis and Lactobacillus plantarum)
  • Inflammatory bowel diseases such as ulcerative colitis (especially VSL#3, Bifidobacterium animalis DN-173 010 and the species in Mutaflor), Crohn's disease and in the prevention of bowel cancer
  • Infection with Helicobacter pylori, a bacterium that causes most ulcers and many types of chronic stomach inflammation
  • Tooth decay and periodontal disease
  • Compromised immune function - reduces the number of respiratory and genitourinary tract infections
  • Reduces inflammation 
  • Eczema and other skin conditions
  • Reduces lactose intolerance
  • Improves mineral absorption in people with high phytate content diets ie: grains and legumes
  • Lowers blood cholesterol and produces modest reductions in blood pressure 
  • Prevents harmful bacterial overgrowth during times of stress 


Side-effects of probiotics tend to be mild and most typically involve flatulence or bloating. 


What to look for in a probiotic supplement

The bacteria used in probiotic supplements mostly belong to two main groups: Lactobacillus or Bifidobacterium. Within each group, there are different species so that there are Lactobacillus acidophilus and Bifidobacterium bifidus, and within each species there are different strains.  

In the same way as an Alsatian dog is a good guard dog, but a Yorkshire terrier is probably not, the benefits offered by one strain of bacteria do not necessarily transfer to other strains

Of the Lactobacilli bacteria that have been researched most intensively, the focus has largely been on L. acidophilus, L. caseii, L. rhamnosus and L. johnsonii. 

Bifidobacteria were found to predominate in the intestines of breast-fed babies and it was also found that infants with diarrhoea could be effectively treated using bifidobacteria. The Bifidobacteria demonstrated to have therapeutic effects include B. lactis and B. bifidus.

These lactobacilli and bifidobacteria species have been shown to adhere well to the intestinal mucosa, survive the conditions in the gastro-intestinal tract, utilise prebiotics to aid colonisation and to control pathogenic species.

Because probiotic supplements contain live microorganisms, unless freeze dried or treated in some other way it is best to refrigerate them and certainly to use them before the expiry date. 

The number of live organisms in a supplement is measured in terms of colony forming units or CFU with products typically being in the order of 15-60 billion CFU or viable bacteria per dose.

Some probiotics are also derived from dairy products and if sensitive to milk and its products you may want to look for a dairy-free alternative. Some products also contain other synergistic substances such as immunoglobulins to support mucosal health and fructooligosaccharides which act as prebiotics supporting the growth of the probiotic bacteria. 

Finally, the yeast Saccharomyces boulardii, has been shown to aid many digestive disorders including IBS, but short courses have been shown to be of particular value in preventing and treating bouts of traveller's diarrhoea and also in restoring normal bowel flora when taken during or after a course of antibiotics.  


What are prebiotics?

Probiotics are not to be confused with prebiotics which are nondigestible food ingredients that selectively stimulate the growth and/or activity of the beneficial microorganisms already in people's colons.

Prebiotics include:

  • Chicory root
  • Jerusalem artichoke
  • Garlic, leek and onions
  • Asparagus
  • Banana
  • Whole wheat
  • Honey
  • Fruit
  • Raw apple cider vinegar
  • Sprouted wheat
  • Tomato and
  • Fructooligosaccharides (FOS)


It is worth routinely including these foodstuffs in your diet to encourage growth of friendly bacteria in the colon and also to make a point of eating these foods after a course of antibiotics to help reestablish a healthy gut flora. 


Further resources

You might also be interested in the following: 

Read button

How Bacteria Communicate

Antibiotics: Use and Abuse

The Health Benefits of Colonic Hydrotherapy

Parasitic Worms

Candida Albicans: The Enemy Within

Coeliac Disease: The Undiagnosed Epidemic

The Large Intestine and Guilt

For a step-by-step approach to recovering your health after chronic illness, please refer to The Natural Recovery Plan book

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Dr Watson on Probiotics listed in Supplements & Nutrition

Understanding IBS, Controlling Yeast Levels and Why Do I Keep Getting Sick? and Fermented Foods listed in Fatigue Syndromes & Toxicity in the Audio Hub

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Why You Need Probiotic Supplements


Restoring the Good Bacteria


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Probiotics: Article summary

This article looks at the history of the use of fermented foods and probiotic supplements. The specific health benefits of probiotics, the role of prebiotics and the ways in which gut flora can become unbalanced are examined.


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The Natural Recovery Plan Ezine February 2011 Issue 15. Copyright Alison Adams 2011. All rights reserved
Dr Alison Adams Dentist, Naturopath, Author and Online Health Coach

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