Probiotics are a culture of ‘good’ bacteria. Probiotics can found in

  • A supplement (a pill or powder) of beneficial bacteria
  • In some foods – anything fermented and not pasteurized, as pasteurization will kill the bacteria. This includes sauerkraut, kimchi, lacto-fermented fruits and vegetables, non-pasteurized yoghurt, kefir, cheese and non-pasteurized meats like salami and some sausages.

Where do I start with probiotic supplements?

Any probiotic supplement has a either a single or different mix of different strains of healthy probiotic bacteria.

Regardless of claims, no one brand has the entire mix exactly as it occurs intestinally. It is not possible to manufacture certain strains of probiotics found in the gut. If dealing with a specific gut health issue then look for a strain of bacteria that is scientifically and clinically proven to contribute to improving that condition. If you are looking to treat a specific health issue with a probiotic, look at the available research and talk to your clinician about whether probiotic supplementation is necessary.

What should I look out for?

  • A probiotic supplement containing the right genus e.g. Lactobacillus, the right species e.g. Rhamnosus and the specific strain of the species e.g. LGG. Each genus and species can address different health concerns.
  • Be aware that whilst you may read research on the benefits of say Lactobacillus rhamnosus LGG, this does not mean the same benefits apply to all Lactobacillus probiotic supplements, and it does not even apply to other types of Lactobacillus rhamnosus. For example, L. rhamnosus Rosell-11 has been shown in some clinical trials to maintain gut health when taking antibiotics, and to reduce the risk of antibiotic-associated diarrhoea. However, L. rhamnosus GR-1 has not been shown to directly aid digestive health but has been shown to colonise in the vaginal tract and to help maintain vaginal microflora balance.
  • Look for CFUs or “colony forming units” on the side of the bottle. That’s how many bacteria you will receive per dose. Some of these bacteria are bound to die during transit to your intestines. Be aware that some probiotics may also be effective at dosages of 1–2 billion CFU per day, while others may require at least 20 billion CFU to achieve the desired effects.
  • What’s the shelf life of the CFUs? You don’t want just the CFUs at ‘time of manufacture.’ You also need to know how long the CFUs will retain their viability.

Look for valuable strains, including species of Lactobacillus and Bifidobacteria such as Lactobacillus acidophilus and Lactobacillus plantarum that reside in the small intestine or the upper gastro intestinal tract among your immune cells. Bifidobacterium lactis, Bifidobacterium longum, and Bifidobacterium bifidum reside in the large intestine or the lower bowel, which are also critical areas for health

Read more about the specific strains of probiotics and the claims around their health properties in this evidence review paper published in the International Journal of Environmental Research & Public Health.

Above all, if taking a probiotic in tablet form, check to see that the probiotic does reach the gut. Remember that any research published by manufacturers will be biased to benefit their product and sales.

When should I take probiotics?

There is no science to support taking probiotics either at night or in the morning. Taking them with or without food is the more important decision. The digestive tract can be hostile to probiotics due to the acidity of the gut rather than the time of day you take them.

It’s more important to take probiotics with food, not on an empty stomach. The reason is the pH balance. Stomach acidity is described in terms of pH – the lower the pH, the higher the acidity, whereas higher pH is more neutral.

On an empty stomach, the low pH (more acidic) is too harsh for bacterial survival. After a meal, the pH of the stomach contents rises to a more basic value of around 7, which is less acidic. That means there is less chance of the probiotics dying.  Always take with a full glass of water to help dilute stomach acid.

In a study found in Beneficial Microbes published in 2011, researchers found that probiotics taken within 30 minutes of a meal, or with the meal, survived in much higher numbers than if taken 30 minutes before a meal.

After working their way out of the stomach, the bacteria also have to survive the fluctuating pH of the small intestine. After leaving the stomach, bacteria with food are subjected to a lower pH, similar to the contents of the stomach.

Slightly lower down in the upper small intestine, the contents (food and probiotics) are subjected to bile and pancreatic juices that increase the pH making the environment more alkaline and more favorable for survival.

Should I take them at the same time as my antibiotics?

Probiotics need to be taken at least two hours before or after antibiotics. If you are taking any other prescribed medications discuss with your specialist or GP as to whether probiotics will cause any interactions if taken at the same time.

What are the issues around probiotics?

Probiotics are considered safe overall for healthy people; short-term side effects may include mild gas and bloating. But risks may be greater in those with complicated gastro-intestinal conditions.

A systematic review of probiotic information leaflets in the Annals of Internal Medicine in 2018 found that the reporting of adverse effects is often missing or inadequate. Thus always contact the manufacturer before starting a probiotic regime to discuss any existing health concerns you may have.

The outcome of studies provided by manufacturers depend on those participants with specific criteria who were recruited to take part in these studies. Remember, there is no current standard definition of ‘normal’ microbiota. One study published in the British Medical Journal noted: “The ability to assess the degree of dysbiosis improvement is dependent on the enrolled population and the timing of microbiological assays. The functional claim for correcting dysbiosis is poorly supported for most probiotic strains and requires further research”.

General commercial probiotic strains should be used cautiously by pregnant women, infants and young children and never given to premature infants. Always research or discuss with a health practitioner the appropriate strain of probiotic to take if pregnant or providing probiotic supplements to children.

If you are immunocompromised or have certain bowel problems such as Irritable Bowel Syndrome, Small Intestinal Bacterial Overgrowth or Crohns, avoid probiotics unless your clinician has advised usage. Even in healthy people, the reactions to probiotics vary widely, according to a study in Cell published in 2018.

Remember: probiotics are a live organism so they have a unique set of potential risks that other supplements don’t have. Your gut microbiota is unique to you, each person has their own unique mix and a commercial product that works for one may not work for you. Always discuss with a health practitioner if considering using probiotics.

Evidence for probiotics – are they worth it?

  • The best evidence for probiotics is for reducing diarrhoea, especially following antibiotic use. A 2010 review from the Cochrane Collaboration concluded that probiotics shorten episodes of acute infectious diarrhoea. A 2013 Cochrane review of 23 trials also concluded that probiotics may be effective for preventing antibiotic-related diarrhoea.
  • However, a 2012 research review in the Journal of the American Medical Association (JAMA) found that although probiotics reduced the risk of antibiotic-associated diarrhoea by 42% many of the studies had flaws and the findings should be interpreted with caution.
  • Two large, well-designed studies, in the Lancet in 2013 and the Annals of Internal Medicine in 2014, found that probiotics were no better than a placebo in preventing diarrhoea in older people taking antibiotics.
  • Other claims and evidence around promoting probiotics—that they lower cholesterol, alleviate allergic skin conditions (like eczema), treat ulcers, reduce the risk of colon cancer, ease anxiety and depression are of poor quality. Good longitudinal studies to support these claims is lacking and suggestions can be anecdotal.
  • Probiotics are not all alike. For example, if a specific strain of Lactobacillus helps prevent an illness or improves health and wellbeing, that doesn’t necessarily mean that another strain would have the same effect or that any of the Bifidobacterium probiotics would do the same thing. A promising study on a single strain of a particular species of bacteria should not be taken as proof that all probiotics work equally well. Everybody has a different gut microbiota. There will probably never be a one-size-fits-all probiotic.
  • Manufacturers of probiotics often select specific bacterial strains for their products because they know how to grow them in large numbers, not because they are adapted to the human gut or known to improve health.
  • The particular strains of Bifidobacterium or Lactobacillus that are typically found in many yoghurts and tablets may not be the same kind that can survive the highly acidic environment of the human stomach and from there colonize the gut. Many yoghurts and yoghurt drinks also contain high levels of sugar.
  • There’s also a cost factor – probiotic supplementation can be expensive.
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