Probiotics, fermented foods and your gut

Defined by the World Health Organisation as “Live microorganisms that when administered in adequate amounts, confer a health benefit on the host”. Probiotic bacteria can be added to food products like yoghurt or taken as food supplements, and are often described as "good" or "friendly" bacteria. Probiotics are meant to help correct dysbiosis- a condition where the natural balance of bacteria in your gut is disrupted by an illness or antibiotic or other treatments.

Probiotic bacteria break down fibre and resistant starches in our large bowel, which creates some incredibly useful by-products- short-chain fatty acids (SCFAs). They act as energy fuel for the bowel lining and therefore keep it healthy. They also have a positive impact on inflammatory processes and are protective against cancer cell formation. SCFAs have a huge role in maintaining the integrity of the intestinal barrier which ensures that the nutrients, water and ions are allowed through to the blood, but any pathogens and bacterial toxins are kept within the bowel for excretion with the faeces. Other products of fermentation include gases (hydrogen, carbon dioxide, and sometimes methane), which can make you feel bloated and cause flatulence- a completely natural part of healthy digestion!

In addition to the benefits to the bowel health, gut microorganisms play a pivotal role in the regulation of metabolic, endocrine and immune functions, although the mechanisms via which this is achieved are not yet fully understood.

Probiotics are described first by genus, then species and then by strain (i.e. Bifidobacterium infantis 35624). There are significant differences in their functions even at the strain level; therefore, for example, only because this specific strain (Bifidobacterium infantis 35624) was shown to benefit people with IBS (human trials), it does not mean that all other Bifidobacterium strains will have the same effect! For this reason it is difficult to interpret meta-analysis that combine studies using different probiotic products, because you are not comparing like for like. The best option we have at the moment is look at studies on specific probiotics and whether they show any evidence of positive benefits (providing the studies are of high quality!).

Live microorganisms are found in fermented products such as kefir, kombucha, kimchi and sauerkraut. They cannot be called probiotic products in the EU and UK, because they do not fit the World Health Organisation definition of a probiotic product (see the beginning of this post). We do not know what bacteria strains or how much bacteria a fermented product that you produce at home or buy in a shop contain, therefore, we cannot know exactly what benefits it may bring. Although there is some evidence to suggest that fermented products may offer benefits similar to probiotic supplements, they cannot be prescribed as a treatment for a condition or a disease.

Fermented foods can be a delicious addition to everyone's diet. The fermentation process can make certain foods more easy to tolerate (i.e. sourdough bread and fermented diary= kefir and yoghurt), so they may be preferable if you tend to have difficulties with the unfermented counterparts (i.e. regular yeast bread or regular milk). In addition to improved digestibility and the potential benefit of live microorganisms within, fermented foods contain more vitamins (esp. B12 and folate). If you don’t usually have fermented foods in your diet and want to change this, do so slowly! Too much too quickly can make you experience unpleasant digestive symptoms, especially gassiness and bloating…

Should you take a probiotic alongside a low FODMAP diet?

This question comes up in my clinics all the time and I thought I'd share my thoughts on this here...It is not yet known whether it is better to take a probiotic alongside a low FODMAP diet or not. In 2016, Staudacher and colleagues published a randomised controlled trial looking at the effects on IBS symptom improvement and faecal bacteria with a low FODMAP diet and probiotics (VSL#3) versus a low FODMAP diet alone. IBS symptoms improved to the same extent in both groups, suggesting that VSL#3 did not add any further benefit. However, VSL#3 in combination with low a FODMAP prevented the decline in the numbers of bifidobacteria (beneficial bacteria) that is usually seen in those following a low FODMAP diet. We do not yet know whether the beneficial bacteria comes back with the reintroduction of high FODMAP foods at the later stages of the diet or whether this can only be achieved by adding in a probiotic...


Let’s talk about caffeine (& enjoy our morning coffee)

Caffeine is often unfairly criticised by some, but this is not justified when the evidence from research studies on moderate intakes is considered.In fact, moderate caffeine intake has been associated* with a reduced risk of heart disease in adults. Caffeine also has desirable short-term effects, such as improved alertness, concentration, and reduced perception of fatigue and pain.

Safe upper levels for caffeine consumption for healthy adults (report by EFSA**) have been defined as no more than 200mg as a single dose, and no more than 400mg as a daily dose.

Caffeine content of common drinks (per serving):

  •  espresso: 140mg
  •  filter coffee: 90mg
  •  black tea (teabag): 50mg
  •  decaff coffee: 15mg

Based on the above, up to 8 cups of tea or 2 cups of espresso, can be safely consumed as part of a balanced diet. However, what caffeine should not be used for, is to compensate for inadequate food intake or lack or sleep. Although it may feel like it's helping short-term, it may mess up your hunger signals, make you feel anxious and further disrupt your sleep..

*association studies do not suggest cause & effect, but merely a link, therefore, evidence from these studies need to be taken with a pinch of salt.

**(EFSA) European Food Safety Authority

Do you suspect a food intolerance?

If you suspect you have any other food intolerances, you should see a dietitian who will be able to support you in identifying the culprit for your symptoms. A dietitian’s role is to carefully assess your diet, eating patterns and other potential factors that may impacting on your symptoms and propose dietary/ lifestyle manipulations.
If you are likely to have food intolerance, you may be offered to complete an elimination diet. They require dedication and time, but if done properly, can be invaluable in helping you to find out whether you have any particular food intolerances and how to best cope with these. your digestive symptoms may arise from years of dieting, in which case elimination diets may make things worse, not better. Make sure you see a dietitian with experience in gastroenterology and disordered eating to receive the support that you need.