Gastrointestinal Health

Teresa Doherty

The condition and function of our gastrointestinal tract (GIT) is essential to our well being. The GIT harbors a rich flora of more than 400 different bacterial species. Billions of these friendly bacteria build colonies in the small and large intestines and constitute the first line of defence against illness and disease. The health and survival of these friendly bacteria depends upon lifestyle and dietary factors.

The Gastrointestinal Tract

The GIT is self running and self healing. It is one of the largest interfaces between the outside world and the human internal environment. The nine meter tract constitutes the body’s second largest surface area, estimated to cover approximately 250 to 400m2, which is comparable to the size of a tennis court. During a normal lifetime, 60 tons of food passes through this canal. The body must be able break this food down into tiny particles so they can be absorbed through the intestinal lining and into the bloodstream where the nutrients and calories are taken and used by the cells. The waste products of digestion and metabolism must be effectively removed through the kidneys, bowels, lymphatic system and skin.

The Intestinal Flora

There are more bacteria in our intestinal tract than there are cells in our body. A total of 100 trillion bacteria live together in our digestive system, in either symbiotic or antagonistic relationships. Their total weight is about four pounds, equal to the size of the liver. The most important friendly bacteria are Lactobacillus acidophilus and Bifidobacterium bifidum. They have many functions and act like a symbiotic organ to protect our health.

The Functions of Healthy Intestinal Flora

Health intestinal flora are responsible for performing the following functions:

  1. They produce acids that keep the pH balance of the intestine. This acid environment prevents disease-producing microbes from getting a foothold.
  2. They prevent colonization of the intestine by pathogenic bacteria and yeast by protecting the integrity of the intestinal lining.
  3. They manufacture many vitamins including the B complex and vitamin K.
  4. They increase the absorption of minerals such as calcium, magnesium, iron and manganese.
  5. They increase resistance to food poisoning through their powerful antibiotic effect.
  6. They prevent the overgrowth of disease-causing microbes, such as candida, helicobacteria pylori, E. coli and salmonella.
  7. They prevent and treat antibiotic-induced diarrhoea.
  8. They inhibit the growth of bacteria that produce nitrates in the bowel. Nitrates are bowel toxins that can cause cancer and reduced activity in bacterial enzymes associated with the formation of cancer-causing compounds in the gut.
  9. They help to regulate peristalsis and bowel movement.
  10. They help prevent the production and absorption of toxins produced, which reduces toxic load to the liver.
  11. They help prevent urinary tract infections.
  12. They contribute to improved immune function and protect against development of allergic conditions.

Intestinal Flora and Dysbiosis

In the early 20th century, Dr Eli Metchnikoff popularized the theory that disease begins in the digestive tract because of imbalance of intestinal bacteria. He called this state dysbiosis, which comes from symbiosis, meaning “living together in mutual harmony,” and dys, which means “not.” The common causes of altered intestinal flora and dysbiosis include the following:

  1. Antibiotic use simultaneously kills both harmful and helpful bacteria throughout the body.
  2. The use of anti-inflammatory medication, birth control pill and steroid drugs.
  3. Psychological and physical stress.
  4. Altered gastrointestinal peristalsis. When peristaltic action slows down, a rapid overgrowth of harmful bacteria is probable.
  5. The use of laxatives.
  6. The use of antacids, which encourage an alkaline environment and favors an overgrowth of harmful bacteria.
  7. Poor dietary choices: high protein, high animal protein, high sugar and refined carbohydrate, high fat and low fibre.
  8. Undigested protein, as a result of its high consumption, can lead to an overgrowth of harmful bacteria. It has been estimated that as much a 12 grams of dietary protein per day can escape digestion in the upper GIT and reach the colon.20 This undigested protein is fermented by the harmful microflora, increasing its number and activity.

The Effects of Dysbiosis

Alterations in the bowel flora and its activities are now believed to be a contributing factor to many chronic and degenerative diseases that include: inflammatory bowel disease, rheumatoid arthritis, yeast infection (Candida Albicans) irritable bowel syndrome and ankylosing spondylitis, urinary tract infections and cancer. Digestive problems that include constipation and/or diarrhoea, abdominal pain, gas and bloating are also indicators of dysbiosis.

Healing Options

Maintaining or attaining a healthy colon is uncomplicated. Adhere to the following guidelines:

  • • Use a good probiotic supplement to restore healthy flora
  • • Consume foods that stimulate the growth and activity of the healthy flora in the GIT. A form of natural prebiotic is obtained from the indigestible starch found in banana, onions, leeks, asparagus and Jerusalem artichokes
  • • Increase fiber intake
  • • Reduce the intake of protein, in particular animal protein, refined carbohydrates and sugar and saturated fats
  • • Maintain good levels of omega 3 fatty acids
  • • Reduce levels of wheat and rye
  • • Drink adequate levels of water

Probiotic Supplement vs Commercialized Yogurt

In order to have any benefit, products that contain Lactobacillus acidophilus and Bifidobacterium bifidum must provide these organisms in a manner in which they can survive. Typically, a high quality commercial preparation (probiotic supplement) produces greater colonization than eating yogurt. Yogurt is usually made with Lactobacillus bulgaricus or Streptococcus themophilus. While these two bacteria are beneficial and possess some health benefits, they are transient visitors to the GIT and do not colonize the colon. Proper manufacturing, packaging, storing of the product with the correct amount of moisture and freedom from contamination and the need for refrigeration is also necessary to provide maximum benefit. Some yogurts are pasteurized. This process destroys both harmful and beneficial bacteria. When fruit is added to yogurts, the culturing agents nibble on the fruit sugars rather than ferment the milk. Chemical additives are added to fruit yogurts to prevent the live bacteria from coming into contact with the fruit sugars. The fruit added to commercialized yogurt is processed. Many commercial types of yogurt contain refined sugars, additives and preservatives.

To conclude, proper digestion is essential for optimum health. Incomplete or disordered digestion can be a major contributor to the development of many diseases. Good health begins within the body and particularly within the colon. Without proper elimination of waste products, there are serious repercussions to our health.

Maintaining or attaining a healthy colon is straightforward: eat a nutrient rich diet that is high in fibre, drink water, moderate amounts of protein, seed and maintain the health-promoting microflora and take appropriate actions when there are problems.

Changes in food habits


  1. Bengmark S, Ecological control of the gastrointestinal tract, The role of probiotic flora.Gut, (1998) 42:1-5.
  2. Bland J et al, Clinical Nutrition: A Functional Approach, Gig Harbor, Wash, Functional Medicine Institute, (1999).
  3. Shahani KM and Friend BA, Nutritional and Therapeutic aspects of Lactobacilli, Journal of Applied Nutrition, (1984) 36: 125-152.
  4. Roberfroid M, Prebiotics and Probiotics: are they functional foods? American Journal of Clinical Nutrition, (2000), 71 (suppl): 16825S-7S.
  5. Anad SK et al, Antibacterial activity associated with Bifidobacterium bifidum. Cultured Dairy Products Journal, (1984) 19:6-8.
  6. Murray ND and Pizzorno J, Encyclopedia of Natural Medicine, Prima Publishing (1997).
  7. Reddy et al, Natural antibiotic activity of Lactobacilli acidophilus and bulgaricus, Cultured Dairy Products, (1983) 18(2):15-19.
  8. Shahani KM and Ayebo AD, Role of dietary Lactobacilli in gastrointestinal microecology, American Journal of Clinical Nutrition, (1980) 33:2448-2457.
  9. Ayebo et al, Effect of feeding Lactobacillus acidophilus milk upon faecal flora and enzyme activity in humans, Journal of Dairy Science, (1979) 62 (Suppl.1): 44.
  10. Bogdanov IG et al, Antitumor action of glycopeptides from cell wall of Lactobacillus bulgaricus, Bulletin of Experimental Biology, (1977) 84:1750
  11. Plaskett Dr L (2004), Distance Learning Course in Nutrition (2004) London: Thames Valley University.
  12. Jameson RM, The prevention of recurrent urinary tract infection in women, The Practitioner, (1976) 216:178-181.
  13. Metchnikoff E, The Prolongation of Life, Optimistic Studies, London: William Heinemann. (1907) 161-183.
  14. Gismondo MR, Antibiotic impact on intestinal microflora, Gastrointestinal Int, (1998) 11:29-30.
  15. Bjarnason I et al, Side Effects of Non-Steroidal Anti-Inflammatory Drugs on the Small and Large Intestines in Humans, Gastroenterology, (1993) 104 (6): 1832-47.
  16. Lenz HJ and Druge G, Neurohormonal pathways mediating stress-induced inhibition of gastric acid secretion in rats, Gastroenterology, (1990) 98:1490-1492.
  17. Moore WE et al, Some current concepts in intestinal bacteriology, American Journal of Clinical Nutrition, (1978) 31:S33-S42.
  18. Trenev N, Probiotics, Nature’s Internal Healers, Avery. (1998).
  19. Hawrelak J and Myers S, The Causes of Intestinal Dysbiosis: A Review, Alternative Medicine Review, (2004) 9(2):180-197.
  20. Linder MC, Nutrition and metabolism of proteins, in: Linder MC, ed, Nutritional Biochemistry and Metabolism, 2nd ed, Norwalk, CT: Appleton and Lange. (1991) 87-110