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Prebiotics & Probiotics – What’s the Difference & Why do we Need Both?

Whether you have an interest in nutrition or not it can’t have escaped any of us the hot topic of our microbiome or gut health. You will have seen supermarket shelves with whole sections of chiller cabinets devoted to probiotics, maybe bought them under the impression they were ‘good for you,’ but carried on with your usual diet as before.

The importance of them and the vital roles they play, crops up time and time again with clients. Taking account of the reason the client has come, their present diet usually has had some impact and could be better supported by addressing their gut health – and possibly be the answer to a return to health.

I will describe a little of how we function to better understand why we need both prebiotics and probiotics and the important roles they play.

Our microbiome is not a fad diet trend, it’s a scientific breakthrough and as more research is collected, the positive effects of a healthy gut goes far beyond our digestive system, and there are increasing studies to show a healthy microbiota can impact us in far reaching ways. We have literally trillions of live bacteria within our digestive tract alone. Some are beneficial and some are not, the undesirable ones leading to health challenges. By incorporating foods that feed the good bacteria we can maintain a healthy gut biome. Here are a few of the beneficial ways our health is impacted aside from the digestive tract, if we maintain a healthy balance of good bacteria through our diet.

  • Improves our immune function, with up to 70% directly influenced by bacteria in the gut.
  • Influences our mood by positively decreasing anxiety and depression through the neurotransmitter serotonin (our happy, feel good hormone!). 90% of the body’s serotonin is made in the gut. It also helps to control appetite, libido and blood clotting.
  • A healthy gut biome can influence behaviour and cognitive functions such as learning, memory and decision-making.

Just a mention of what our gut actually is, to be clear on it’s importance. It’s the term given to the length of 9 metre long digestive tract from the mouth to the colon. Impressive! Its many functions include ingesting, digesting and assimilating nutrients and vitamins from the foods we eat, giving us energy (from macronutrients) and disease prevention (from vitamins and minerals).

The gut is a unique organ because it can act independently from the brain and central nervous system through it’s own ‘mini-brain’ known as the enteric nervous system. The gut ‘mini brain’ is connected to our central nervous system via the vagus nerve of which much research is ongoing. It has been proved that this connection creates an ongoing, bidirectional pathway between the major brain and the ‘mini brain’ sometimes called the gut-brain axis.

Further to this link, another communication channel is being explored and that is the one between our gut flora (bacteria) and the brain, known as the ‘microbiota-brain axis’.

An interesting discovery is that these trillions of live bacteria are unique to each individual, the same as our DNA and fingerprint! We inherited most of our bacteria through our mothers during birth as we pass through the birth canal. From here, it evolves and develops to be our unique microbiome within the first 1,000 days of life. This is shaped by our mother’s breast milk, our first solids and any early antibiotic use.

I think whenever it is safely possible to give birth naturally and breast feed when possible, we can be sure of giving our babies a healthy microbiome start in life, something we are only now being made aware of through recent research. Also, taking decisions about if or when antibiotic use is needed. Studies have shown that antibiotic use decreases the diversity and richness of the good bacteria by indiscriminately killing off all bacteria irrespective of whether it is good, or the bad that antibiotic use was prescribed for. We have trillions of bacteria within all of our body so taking an antibiotic if not necessary will affect the balance in our other organs too. Some of these good bacteria don’t return even past a 6-month period.

There is so much to say on this topic but hopefully this sets out their important place in our diet when planning meals or taking a supplement, building robust, good health.

Prebiotics and Probiotics sound very similar, but they have very different roles in our digestive tract.

What are these prebiotics?

This term refers to prebiotic fibre which is a non-digestible part of foods like bananas, onions, artichoke, chicory root, beans, and many others. Prebiotic fibre from these foods especially, passes through the small intestine undigested and is fermented when it reaches the large colon.

This fermentation process feeds our beneficial bacteria colonies (including probiotic bacteria) and helps to increase the number of desirable bacteria in our digestive systems (the gut), that are associated with better health and reduced disease risk.

Prebiotic fibre is not as fragile as probiotic bacteria because it is not affected by heat, stomach acid, or time. Nor does the fermentation process differ from individual to individual.

By boosting our total daily consumption of fibre, we will set the right conditions to begin improving our strains of beneficial bacteria.

The suggested dietary amounts on a daily basis are 25-38 grams with prebiotic fibre accounting for at least 5-20 grams of the this.

Many high fibre foods are also high in prebiotic fibre and here I list the main sources.

  • Chicory root – about 65% of the chicory root is fibre by weight and is an extraordinarily rich source.
  • Onions & Garlic – these have about 17% of prebiotic fibre per 2grams.
  • Oatmeal – also a very high source but it must be natural oats, and not as a processed Ready Break style food which has the fibre removed.
  • 100% Stoneground or Wholemeal bread – about 1gm fibre per slice; nearly 70% of the total fibre is in the wheat bran.
  • Asparagus – 2-3grams of prebiotic fibre per 100gram serving
  • Jerusalem artichoke – 2grams of fibre per 100gram serving. 76% comes from inulin prebiotic fibre. You might have seen inulin supplements or powder to add to drinks and meals.
  • Barley – 3-8 grams of prebiotic fibre per 100gram serving. Consider using barley with the husk still intact in casseroles, soups or instead of rice.
  • Apples – 4grams of fibre per apple (mainly in the skin). Pectin, which has prebiotic benefits makes up about 50% of the apple.

If your diet has not included enough fibre rich foods, it may be advisable to slowly introduce quantities because as part of their passage along the gut, this can initially cause gas build up which could be embarrassing…..

What are these probiotics?

Probiotics are what we commonly see advertised and command a large proportion of the chiller cabinets in our supermarkets. One of these categories is fermented foods, which aid the growth of good bacteria in our gut through live organisms called probiotics. A fermented food has undergone a biochemical process, breaking down food to become more readily available as yeasts or bacteria. This might not sound desirable, but humans have been consuming such foods over millennia whether we were aware of it or not! In fact, it is only since the emergence of processed foods and our reliance on them, that we have we been depriving ourselves – possibly not unconnected with the rise of disease and ill-health that has risen so dramatically.

Probiotics have been studied pretty extensively in recent years and when consumed in the right amount have the potential to positively influence our good microbiota by:

  • Increasing the levels of good bacteria and reducing the harmful bacteria
  • Helping to synthesize our nutrients and how well they are use
  • Reducing toxins and blocking toxin receptors in the body

There are instances where fermented foods and probiotics might be avoided until a clinical assessment; that’s when taking certain anti-depressant medication. Better to check first with your doctor.

Some may find taking a certain probiotic species can combat gastrointestinal side effects of medication and also reduce the bacterial growth leading to yeast infections, such as Candida, Cystitis, SIBO. A probiotic is often suggested when taking a course of antibiotics to help rebuild the bacteria colonies in the colon. They have been shown to be helpful for childhood diarrhoea, IBS, and certain bowel infections such as C. Difficile.

It is important to make sure that probiotics are alive, as they are easily killed by stomach acid, heat and time. They are live beneficial bacteria that are naturally created by the process of fermentation in foods like, yogurt, kefir, sauerkraut, miso soup, kombucha, kimchi and others.

Here are some of the main sources of probiotics available.

  • Lactobacillus – the most common probiotic found in yoghurt and other fermented foods.
  • Bifidobacterium – also found in some dairy products. It is naturally present in the large intestine, and may fight harmful bacteria in the intestines, prevent constipation and give the immune system a boost. Furthermore, there is evidence to that indicates bifidobacterial helps to reduce intestinal concentrations of certain carcinogenic enzymes.
  • Kefir- a milk drink that has been fermented with kefir grains, it is an especially potent source of probiotics. Its name comes from the Turkish word ‘Keif’, which means ‘good feeling’, alluding to the health of the people who drink it. It contains both lactobacilli and bifidobacterial in high doses, and also helps diversity too – more than 50 different types of bacteria can be found in kefir which travel through the digestive tract to colonise the colon. Kefir is also a rich source of calcium and may enhance bone health and mineral density.
  • – There is a study to show that consuming 200 ml of kefir daily for 6 weeks lessened inflammation, a key contributor to the development of chronic diseases, like heart disease and many more.
    – As with all these products, look at several brands, just as you would when buying any processed food, and check how many strains of live bacteria they claim it contains, and whether there is any added sugar. Kefir has a tart, sour taste which might take some getting used to. Manufacturers may include a form of sugar to make it more palatable – and increase sales.
  • Kombucha – a fermented product made with bacteria and yeasts, known as a SCOBY. It is added to sweetened green or black tea. The live cultures on the sugar allows them to multiply and thrive. There is no real evidence as yet about its benefits, other than anecdotal. It contains several species of lacto-acid bacteria which may be beneficial. Choose one that hasn’t been pasteurised, as this step kills off all the live bacteria through heat to give it a longer shelf life. Again, check the sugar content.
  • Kimchi & Fermented vegetables – Kimchi and sauerkraut are covered in good bacteria naturally. Easy to make yourself by grating or finely slicing the vegetables, packing into a Kilner jar with salt and vinegar. Leave to ferment in its probiotic brine. There is no conclusive research whether these affect the human microbiome as yet, although it is thought there is potential therapeutic actions with anticancer, anti-obesity and colorectal health promotion. If you are buying a shop bought product, check the salt content first. There are plenty of fermented foods recipes online to make your own.

As mentioned before, as with prebiotics, if taking a probiotic is new for you do introduce small quantities over time because these can also cause gas – which is actually a positive sign because it signifies the beneficial bacteria is ‘gobbling up’ the undesirable bacteria. This won’t last long and may not even be something you experience anyway.

If there is one take home message from this, its to eat more fibre, plant based, diverse foods to help our good bacteria to thrive and survive!