Would you like a dose of bacteria? If someone presented you with this offer, you’d probably decline, politely, as we strongly associate ‘bacteria’ with disease. But in fact you already carry around a vast population of intestinal bacteria that are actually helping you stay healthy. You can influence the robustness of your own bacteria population, and as a result, your overall health, by providing the good bugs with food that they like.
At the time of birth your intestines are actually sterile. You pick up your first dose of bacteria as you pass through the birth canal, and also through exposure to the environment. Mum’s breast milk provides the materials that commensal (good) bacteria like to feed and breed on – prebiotics. Your good bacteria population then begin populating your intestines, providing the initial spark for your immune system development. So having these bacteria in residence does you good.
Your helpful bacteria need to be fed well to perform well; their populations will grow and decline rapidly, depending on how well they’re nourished and the state of their environment (kind of like people, don’t you think?). When you eat a meal including fibre and complex carbohydrates, good bacteria pounce upon it, using their enzymes to break down the food, ferment it, and prepare it for absorption by bowel cells. They even create some vitamins while they’re working. Without these bacteria your food wouldn’t be digested properly, and you’ll be short on nutrients.
If you ever wonder what it’s like to live without commensal (good) bacteria, spare a thought for the special laboratory mice that have been selectively bred to be germ-free. They don’t grow normally, and need extra nutrition just to survive, because the bacteria aren’t there to help out. They’re also more susceptible to infection.
There are also some unwanted bacteria in your intestines that can cause disease. They’re opportunistic creatures. What keeps their populations under control is the right pH in your bowel environment, and also the presence of good bacteria, which compete with them for space and food. If the food you’re eating doesn’t support your good bacteria, if you’re stressed, or taking antibiotics, their population will diminish. The bad bacteria numbers will begin to grow, and your bowel cells will start to suffer. You might experience some unpleasant symptoms too, like bloating and flatulence. If you happen to pick up a parasite or bowel infection when this is happening, your population of good bacteria can be almost wiped out. Your bowel wall can become chronically inflamed, or even ulcerated, which means reduced nutrients for you.
Probiotics in a capsule are a great short term therapy to help rebuild populations of good bacteria. If you’re also eating the right diet for you then the introduced population will happily take up residence and you’ll feel better. But if you are still eating foods that irritate your gut, or if the parasite remains, then your symptoms will return soon after you stop taking the probiotics.