Gut health and probiotics are no new buzz words when it comes to holistic health; it’s been said for years that all diseases begins in the gut. However, it has come to light recently that our microbiome is much larger than we first thought. This significant insight only affirms that our gut health and the balance of the good and bad bacteria needs to take a centre seat. To better understand the influence of probiotics we talk to nutritional therapist Tracy Tredoux (@TracyTredoux)

Did you know?

It used to be said that there are 10x more bacteria in our bodies than human cells. More recently, however, a study out of the Weizmann Institute in Israel states that the number of bacterial cells may actually be very similar to the number of human cells in the body, estimating the number to be about 39 trillion. While this study does not take into account viruses, fungi and archaea (which all make up the human microbiome), the often-stated ratio of 10:1 for bacterial cells to human cells is most likely not accurate. This does not, however, take away from the importance of bacterial cells in human health.

Our microbiome – another organ of the human body?

Our human body is inhabited by huge numbers of micro-creatures, making up one eco-system and living together in harmony in our digestive system, skin, eyes, respiratory and excretory organs. It is a symbiotic relationship meaning they cannot live without us and we cannot live without them. The number of functions they fulfil in our bodies are so vital to us that if we sterilised our guts completely, we would most likely not survive. Recent studies have even connected our microbiome to our genetic expression, weight gain and loss, immune function (the important beneficial bacteria keeping the ‘bad bacteria’ in check), mental health and memory and risk factors for chronic disease. In fact, our microbiome is so important to our overall health that it is more recently being considered our newest (or perhaps our forgotten) organ. Improving patients’ gut bacteria is proving to be an important factor in diabetes, cardiovascular disease prevention, neuroscience, obesity, depression, anxiety, inflammatory bowel diseases and autoimmune disorders.

Three main groups making up our gut flora

Essential or beneficial flora: This is the most important group and in healthy individuals, the most numerous. They are often referred to as our indigenous friendly bacteria and include Bifidobacteria, Lactobacteria, Propionobacteria, physiological strains of E.coli, Enterococci etc.

  • Opportunistic flora: This is a large group of various microbes (around 500 different species). In a healthy person their numbers are normally limited and tightly controlled by the beneficial flora. Each of these microbes is capable of causing various health problems if they get out of control, hence the importance of looking after our beneficial flora.
  • Transitional flora: These are numerous microbes which we swallow on a daily basis with food and drink. When our gut is well protected by the beneficial bacteria, this group of microbes simply pass through our digestive tract without doing any harm. But if the population of the beneficial bacteria is damaged and not functioning well, this group of microbes can cause disease.

Yoghurt has long been a source of helping good bacteria

What can damage our gut flora?

  • Antibiotics: One of the most prescribed medications in the world today, these have a devastating effect on beneficial bacteria, not only in the gut but in other organs and tissues. Antibiotics change bacteria, viruses and fungi from benign to pathogenic, enabling them to invade tissues and cause disease. They make bacteria resistant to antibiotics and they kill the ‘good’ with the ‘bad,’ often making space for the colonisation of the more pathogenic bacteria.
  • Diet: What we eat has a direct effect on the composition of our gut flora. Too many sugary foods and processed carbohydrates increase the numbers of different fungi (such as Candida species, Clostridia species and Staphylococci). Processed and sugary carbohydrates (white bread, cakes, biscuits, pastries and pasta) also promote population of the gut with worms and other parasites. A diet high in fibre from grains (bran and breakfast cereals in particular) has a profound negative effect on gut flora predisposing a person to IBS and other problems. Fruit and vegetables provide a much better-quality fibre for gut health.
  • Disease: Infectious diseases such as salmonella and some viral infections can cause lasting damage to the gut flora. Repopulating the gut with beneficial bacteria is always an important part of treating patients with these serious infections.
  • Stress: Stress can have a detrimental effect on gut flora, but it usually recovers well after the stressful situation is over. However long term, chronic ongoing physical or psychological stress can do permanent damage to our indigenous flora.
  • Other factors: Old age, pollution, exposure to toxic substances, pharmaceutical drugs, radiation, chemotherapy, surgery, hormone therapy etc all have a detrimental effect on our gut flora.

From mother to child

The best gift a mother can give to her child is a healthy microbiome. The transition from womb to world is when the baby ingests some of the first bacteria that will colonise his/her gut. Breast milk continues to contribute significantly to babies’ bacteria. In fact, a recent study found that 30 percent of the beneficial bacteria in a baby’s intestinal tract comes directly from mother’s milk, and an additional 10 percent comes from skin on the mother’s breast. As a damaged gut flora gets passed down from generation to generation, it gets deeper and deeper with numerous concomitant health issues. Unfortunately, in today’s world, C-section babies are becoming more common and with the stress of many mothers’ needing to return to work asap, breast feeding is becoming more of a challenge. It is important to know that the human microbiome is largely a product of lifestyle and environment and most malleable in infancy and childhood. By school age, however, the general makeup of a child’s microbiome has been established and will remain with them for years, decades and possibly their entire life. Nurturing your child’s microbiome in the early years is therefore important and includes:

  • Feeding the good bacteria: They thrive on complex carbohydrates such as fruits, vegetables, nuts, legumes etc (carrots with hummus).
  • Trying not to over sanitize.
  • Avoiding unnecessary antibiotics.
  • Allowing your kids play in the garden and snuggle with pets.

The need to supplement?

More than ever, today it is crucial for most people to supplement with a good quality probiotic on a daily basis. The toxic environment we live in, depleted soils worldwide (from overuse of pesticides, herbicides, fungicides), processed foods, GMO’s, pharmaceutical drugs etc have put our microbiome under constant attack and taking a probiotic daily can have a big impact on microbiome health and thus our health.

What are probiotics?

Probiotics are the ‘friendly’ bacteria lining our gut and helping it to fight infection, synthesise various vitamins, digest certain foods and absorb nutrients. The concept of probiotics has been around for quite a long time now. They were first identified in 1907, when Russian zoologist, Ilya Illyich Mechnikov observed that Bulgarian peasants who had a high concentration of microorganism-rich yoghurt in their diet tended to live longer. Mechnicov theorised that this was due to the useful microbes taking up residence in the intestine and replacing the harmful kind. But it wasn’t until the 1980’s that probiotics began to gain attention in the mainstream media and complementary health world. Research into the health effects of probiotics has flourished in the past decade with many studies and meta-analyses showing a growing range of potential benefits.

Benefits of probiotics

It is a well-established principle that ‘good health begins in the gut’. The flip side of this is that bad health begins here too. Dysbiosis occurs when the balance between ‘good’ and ‘bad’ bacteria is disrupted. As mentioned, numerous conditions have been associated with poor gut health, including autoimmune disorders, joint pain, thyroid issues, chronic fatigue, skin conditions and many more. It therefore makes sense that you would want to take good care of this essential part of your body. Probiotics help to address dysbiosis by restoring a healthy ratio between ‘good’ and ‘bad’ bacteria, which is currently thought to be around 85%:15%. Benefits of probiotics include:

  • Better digestive health
  • Decrease in antibiotic resistance
  • Improved mental health
  • Immunity boost and decreased inflammation
  • Healthier skin
  • Better weight management

Starting with prebiotics

The best place to start is to feed your own indigenous beneficial bacteria. Prebiotics are food ingredients that induce the growth or activity of beneficial microorganisms. The best natural sources of prebiotics to try including in your diet are:

  • Raw asparagus
  • Raw chicory root
  • Raw leeks
  • Raw Jerusalem artichokes
  • Raw or cooked onions
  • Under-ripe bananas
  • Yacon syrup
  • Raw garlic
  • Raw dandelion greens
  • Acacia gum


Prebiotics feed the bacteria already in your gut. However, the need to take probiotics is to increase the number and variety of your beneficial bacteria.

As with most areas of health and nutrition, the best place to start is your food. Fermented foods contain probiotics and also help to support and nourish the probiotic bacteria already living in your gut. Some of the best fermented foods include:

  • organic natural yoghurt;
  • kefir;
  • sauerkraut;
  • kimchi;
  • miso (as in the Japanese soup).

Another option, that I make part of my morning breakfast routine, is to drink a cup of warm water with a tablespoon of raw apple-cider vinegar (always make sure that the brand you select contains ‘extract of the mother’) and a tablespoon of lemon juice.

Many people now take a daily probiotic supplement to support proper gut health, usually in the form of a capsule or a tasteless powder than can be dissolved in liquid. This can be an excellent option, especially when recovering from illness. However, probiotic supplements vary hugely in quality and effect, so some further advice on selection may be helpful. An important point to remember about the term ‘probiotic’ is that it refers to a wide variety of different bacteria and yeasts. Therefore, the fact that a certain strain is helpful in treating the symptoms of IBS does not mean that a different strain will have the same benefit (although this different strain could well help prevent certain cases of inflammation or reduce symptoms of diarrhoea). More research is still needed into the effects of individual strains of probiotics and so the most effective method of consumption is currently to look for a supplement that contains at least 10 strains, but preferably 20-30. Similarly, the number of CFU’s (Colony Forming Units) should be at least 15 billion, with some brands offering up to 450 billion CFU’s.

When shopping for a probiotic supplement, always take note of the storage instructions. If a supplement needs to be refrigerated, this means that it will have to have been kept cool all through the manufacture and transport process, as well as just when you get it home. If you want to play it safe, look for a brand that is ‘shelf-safe’ or ‘shelf-stable’, then you know that the bacteria will not have been killed off by heat before you even get them home.

If you are taking a probiotic and believe this is aggravating your symptoms, this could be due to a condition called SIBO (bacterial overgrowth of the small intestine). Today SIBO is believed to be the root cause of up to 84% of IBS cases and taking certain types of probiotics are known to aggravate SIBO symptoms. This is due to the fact that SIBO does not necessarily involve ‘bad’ bacteria but rather an overgrowth of bacteria in the wrong place (i.e. the small intestine). It is important therefore to get this overgrowth under control before putting more bacteria into your body.


Humans have not evolved alone. Trillions of microbes have accompanied us on our journey from prehistoric ape, evolving with us. As a result of the Human Microbiome Project launched in 2008 and ongoing studies, we have a much better understanding today of the fundamental role our microbiome play in our overall health. As Hippocrates said, “All disease begins in the gut.” Being healthy, therefore, means we do not only have to take care of ourselves, but also our microbiome.

Tracy Tredoux is a fully qualified Nutritional Therapist, living and working in London. When not giving talks or consulting with clients, she writes health and nutrition articles, tips and recipes which you can find at @TracyTredoux

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