Probiotics are live micro-organisms designed to add or replenish friendly bacteria in the gut. They can be bought over the counter in pill or capsule form, or as powders or liquids.
Foods can be probiotic if they contain live bacteria. Live yogurt is one of the best-known probiotic foods – others include raw cheese, sauerkraut, miso soup, kefir, kombucha or any other foods that have been fermented or use live cultures.
Many people claim to benefit from pharmaceutical probiotics. It’s a billion dollar industry, despite the fact that research into this field is still at a relatively early stage – so it’s often unclear which probiotics really work, and why.
Some of the microbes that populate the gastrointestinal tract have been the subject of extensive research, while others have not even been identified yet. Some probiotics work brilliantly for some people and not so well for others.
Many factors are involved, including the individual balance of the gut bacteria, and how “live” the probiotic is. Only a small percentage of gut bacteria can survive outside the gastrointestinal tract at all, never mind in pill or capsule form.
Some probiotics will allow friendly bacteria to repopulate the gut, while others just pass through the gastrointestinal tract and out the other end.
Some probiotics work well at treating a problem, but not curing it, so they have to be taken for months, or years.
Taking probiotics can be a matter of trying different types, to see which one works.
Prebiotics are foods with an indigestible component that actually feeds the microbes in your gut and allows them to thrive. They act like fertiliser, making your digestive tract a good environment for friendly bacteria.
Foods which can act as prebiotics include Jerusalem artichokes, chicory root, leeks, onions, garlic, asparagus, bananas, dandelion root, rye bread, wholemeal bread, bran and oats.
Synbiotics are foods that combine prebiotics and probiotics. Many types of fermented foods are synbiotics.
Dr Robynne Chutkan has an excellent chapter on choosing a probiotic in her very informative book The Microbiome Solution: A Radical New Way to Heal Your Body from the Inside Out. She says that although probiotics have an excellent safety record, if you’re taking a new probiotic, it’s a good idea to start off with a quarter or half dose and build up gradually to the full amount over three or four weeks.
Among Chutkan’s recommendations:
• choose a probiotic with at least 50 billion CFU (colony-forming units)
• ensure that the product contains multiple compatible strains of bacteria designed to work together
• choose a probiotic with an enteric coating, to avoid the danger of the contents being destroyed by the stomach acid
• check the safety record – look online to see whether clinical trials or other scientific studies have been done.
If you want to find out more about which bacteria might be lacking or in low numbers in your digestive tract, you could obtain a microbiome analysis from the British or American Gut Project, or uBiome.