Maintaining health of the colon

The normal gut flora
The normal gut flora is a subject that is not well known and unheard of by most people. The theme, “Normal Gut Flora” deals with certain bacteria that are found in the intestines. They are not hostile to the intestines and are indeed friendly and play a very significant role in the colon. Indeed, these bacteria prevent the proliferation of the unfriendly and infection-causing bacteria. These bacteria can be found throughout the whole length of the gastrointestinal tract, from the mouth to the anus.

The concentration of these bacteria in the different parts of the GIT can be influenced by the pH status of the different portions of the intestine. For example, due to the high level of acidity in the stomach, the population of bacteria is lowest in the stomach. In the small intestine, the population of bacteria increases as one move further away from the stomach. Towards the caecum, (the junction between the small intestine and the large intestine), as the pH becomes more alkaline, the concentration of the bacteria concomitantly increases.

Types of bacteria in the normal gut flora
The gut flora is made up of an average of 500 species of bacteria. However, these bacteria come mainly from 30 to 40 species. These bacteria are so abundant in the colon that the composition of bacteria in the stools can be as much as 60 per cent of the dry weight of the stools. The oxygen tension in the faecal matter is very low or non-existent and with such conditions, the bacteria found in the colon are known as anaerobic bacteria. They do not need oxygen for the production of their energy.

There are mainly four bacterial phyla (phylum singular), in the human colon and these are Actinobacteria, Bacteroides, Firmicutes and Procteobacteria. Bacteroides is the most common group found in the colon. In this group are examples such as Clostridium, Eubacterium, Faecalibacterium, Bifidobacterium, Peptococcus and Peptostreptococcus. Escherichia and Lactobacillus are also found in the human colon, but in smaller concentrations.

Bacterial distribution in the gut flora
Even though the stomach is highly acidic, the following bacteria are present there: Helicobacter Pylori (the organism that causes gastritis and gastric ulcer), Staphylococcus, Streptococcus, Lactobacillus and yeast.

In the large intestine, there are over 20 different bacteria. These are such bacteria as Bacteroides, Fragilis, Bacteroides oralis, Escherichia coli, Enterobacterium species, Staphylococcus aureus, Lactobacillus etc. The largest bacterial population is found in the colon and this accounts for 60 per cent of the dry weight of the faecal matter.

Factors that affect the bacterial ecosystem of the colon
Age. Within the first two to three years of the life of a child, the microorganism flora in the GIT would have been established but not as developed as that of an adult. As the child grows, the microorganism population also increases. In an individual, the composition of the bacteria remains fairly constant throughout life. However, there are variations in the composition between different individuals.
Diet.

There is a correlation between the bacterial composition of the colon and type of diet (nutrients) commonly ingested. There are mainly three types of bacteria in the colon and these include Prevotella, Bacteroides and Ruminococcus. The predominance of bacteria in the gut will be dependent on the specific type of food eaten. For example, a diet full of carbohydrates will be accompanied by an abundance of prevotela bacteria.

On the other hand, bacteroides are seen in meals that are predominantly proteins, amino and saturated fats. It stands to reason therefore that frequent changes of diet will affect the composition of the normal gut flora. This brings us to the next factor, which has to do with ones geographical location and movement to other locations. We shall continue from here next week Thursday. The functions of these bacteria, which are an eye opener, will also be discussed.