Probiotics & Friendly Bacteria
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How friendly are friendly bacteria?
If you ask the average person to explain what bacteria do, most would probably say something along the lines of "make you ill" or "decay things". Both are indeed valid points, however in the case of bacteria that live in the human gut there is so much more that these tiny organisms do. The health and balance of the different bacteria types can easily mean the difference between good and bad health of their host - you!
Staggeringly, there are approximately 100,000 billion bacteria living in our intestine, which is TEN TIMES the number of cells in the human body! This figure does not include the bacteria that live on our skin, in our nose, mouth, lungs and urinary tract. We are quite literally a mobile home for billions upon billions of bacteria. Fortunately for us not all these bacteria are freeloaders looking for a nice place to live. Most pay rent in a number of beneficial ways, which in turn is good for the bacteria themselves. As long as we are alive and healthy they all continue to have an ideal place to live and breed.
Our intestines contain between 400 and 500 different species of bacteria. Some are resident and attach themselves to our gut wall, whilst others pass through us without anchoring themselves. The majority of such bacteria (or Gut Flora to give them their proper biological name) are found towards the end of our intestinal tract, as the movement of matter through the gut is slower and ensures they don't get swept along too quickly.
The main species of gut flora are Lactobacilli and Bifidobacteria families, the "good" guys. The so-called "bad" guys could be considered to be any bacteria that fail to provide health benefits to the host. These are the squatters who turn up and live in your intestines, making a nuisance of themselves by producing toxic material, and occupying valuable living space that could be occupied by better tenants. The main culprits are E. coli, Staphylococci and Bacteroides. It would be nearly impossible to have none of the bad bacteria in your gut, although fortunately if their numbers remain small they don't cause us many problems.
So how do Bacteria get inside us in the first place?
At birth our intestines are totally sterile. The first bacteria to make contact with us are from our mothers skin and vaginal tract. Breast milk contains many beneficial nutrients that are in the perfect ratio for the growing baby, two of which are Galacto-oligosaccharides and Lacto Ferrin. These help feed the good bacteria and encourage them to proliferate, which in so doing helps keep the bad bacteria at bay.
Every time you eat you will be introducing bacteria from your food and the surrounding air into your stomach. Our stomach acid (at a pH of around 2) is extremely effective at sterilising the food we eat and killing off large numbers of bacteria. This helps prevent the gut from being overrun, however some do get through and, if the conditions are right, will colonise the lining of the gut.
What are the benefits that the bacteria bring?
Good gut flora provides a number of functions that are beneficial to the host, such as;
- They produce Vitamin K & many B Vitamins, which are absorbed via the digestive tract and used for various functions in the body.
- In a process that is still not fully understood, your bacteria help prime the immune system of an infant and continue to help provide support to the immune system of an adult. As the bacteria are on the surface of the gut lining and not actually in the body itself they do not provoke an immune response in the host.
- They are territorial in the respect that they occupy sites on the gut lining that the pathogenic (bad) bacteria would otherwise occupy.
- They produce chemicals & acids that kill the pathogenic bacteria but not you. Like it or not there is a huge bacterial war going on in your digestive tract right now!
- They provide food for the cells of the digestive tract lining. These cells are worn away and need to reproduce quickly, a process which takes a lot of energy. The main source of this energy is a short-chain fatty acid called Butyrate, which our good bacteria produce as a by-product of their metabolic activity.
- They help digestion by breaking down plant cells we have eaten, helping to release the nutrients stored within. For example they help the release of Quercitin (a powerful anti-oxidant) which helps defend the body against free radicals.
- Reduction of cholesterol is also reliant on gut flora. As our bacteria metabolise the fibre in fruit and vegetables they produce lactic acid. This reduces the pH of our intestinal tract (making it more acidic) and as a result this causes the bile acid in our gut to become less soluble. We are then unable to reabsorb it and it is removed in our faeces. As cholesterol is a major component of bile acid the liver has to remove cholesterol from our blood to manufacture more.
What kills the beneficial gut flora and what do the bad guys like?
Probably the biggest culprit is anti-biotics. Whilst they are very efficient at killing infections and without doubt have saved countless lives since they were invented they are not specific to a certain type of organism and can easily wipe out a majority of your gut flora - both good and bad. If you're prescribed anti-biotics it is well worth taking a pro-biotic supplement to replace your gut flora.
Suffering from diarrhoea can also deplete your levels of gut flora as they are all literally washed away from the intestine wall.
Certain bacteria (such as Bacteroides) thrive if our diet is high in meat. The by-products of their metabolism can be toxic to humans and have been linked to increased incidences of colon cancer. This is particularly the case if the diet is low in fruit and vegetables, as the lack of fibre means that bacteria (and their food) remain in the gut for longer. To limit the damage that these bacteria can do it is best to go easy on red meat and eat a diet high in fruit, vegetables and wholegrains (such as brown rice, oats and wholemeal bread.)
Nowadays there are a number of reputable companies producing food supplements that allow us to replace and care for our beneficial gut flora. Probiotic yoghurts (pictured) are readily available, however many contain a large amount of sugar to make them taste sweet - read the labels! Compared to the supplements available from health product manufacturers they also don't contain that many live organisms. For example a certain very popular probiotic drink contains 6.5 billion organisms, which sounds like a lot. However when you compare this to dedicated health food supplements (from companies such as Biocare - see sidebar) who start at around 8 billion per capsule with a recommended dose of two capsules per day, then 6.5 billion is not a huge number. However it's a lot better than nothing at all!
- Author: Stuart Cornock
- Sources: Patrick Holford 'The Optimum Nutrition Bible', Udo Erasmus 'Fats that Heal, Fats that Kill', Internet sources.
