Gut health | How to feed your gut

Probiotics: Fertiliser or fallacy?

Do you get confused by all that microbiome information out there?

I do. 

One minute you can re-arrange the population of your gut. The next minute you can’t: it’s unchangeable, set in stone, and you are at the mercy of the attention your mother paid to your early nutrition. If she fed you packets of crisps and endless biscuits, your gut is likely to be garbage. Lots of fruit, vegetables and fibre and you are probably the proud owner of a gut garden the rest of us can only dream of.

So, are you entirely responsible for the state of your health, depending on how you stoke your gut boiler, or are you powerless?

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Gut health and probiotics

I had always thought that it was more or less simple to give myself the happiest intestines out there. Probiotics, of course, would charge to the rescue of any deficit in my gut garden. A healthy diet, some fermented foods like sauerkraut, kimchi, yoghurt and cheese, add in the probiotics and that’s about it. Microbes love fibre, fruit and vegetables, and you can boost their numbers by eating more of them and eating a wider variety. Nothing to worry about clearly.

But then I found some research that says it’s not just about high or low bacterial diversity. You can’t just bung stuff in and hope. The gardening of your gut must be targeted, very specifically.

So then I dreamed of a future where probiotics would be carefully targeted to achieve specific outcomes - calming coeliac disease, reducing weight, relieving depression. A probiotic for each and every issue. Simple and effective. 

But last week my hopes were dashed entirely. I found an article in a respected journal that says that probiotics are virtually useless. Apparently 99% of the microbes that live in your gut are anaerobic, which means they are unable to use or eat oxygen. And all the fermented foods and the probiotics we buy in the shops only contain bacteria that live off oxygen. Which means that probiotics are incompatible with the majority of your gut guests, and can only affect around 1% of your microbes positively.

No research paper I found could clearly answer whether probiotics make a significant difference or not. In order to actively impact the gut microbiome, the bacteria in the probiotics need to be able to survive the stomach and travel to the large intestine, where most of the gut bacteria are located. So they have to get past all that acid and travel pretty far unscathed. It is also a bit of a toss up whether the bacteria, if they do survive all that, are then able to colonise the gut or whether they will be flushed right through the GI tract.

So who to believe? Confusing yet again. And what can we do that we know works whilst the controversy waits for resolution?


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Practical gut health Do’s and Don't’s

The only things that seem, according to research, to make a difference to your internal microbe collections are changing your diet, losing or gaining weight, moving to an entirely different country or blasting your microbes with antibiotics. But I wouldn’t recommend that one. Popping a course of antibiotics is very similar to setting off a bomb inside your gut. They wipe out everything, good and bad bacteria included, so make sure you take probiotics during (at a different time of day) and afterwards, and eat super sensibly to reseed your gut for several weeks afterwards, and add in prebiotics to feed them and give them the strength they need to recolonise.

What do your different strains of gut microbes do?

Some of them do good things, and some do bad. We are gradually learning which variety does what. The majority of microbes play a part in keeping you healthy and sorting your body systems. Research shows that they can speed up or slow down your metabolism. The charmingly named F. prausnitzii is said to have anti-inflammatory properties. Christensella has been identified as an anti-fat bacteria. (Akkermansia Goodrich jk et al. Cell 2014 Nov 6 159(4). 789-99.) Useful information, and I immediately went off hunting for both of them. Entirely unsuccessfully. Try as I might, I can’t find either in the endless pots of probiotics in any of my local health stores.

Remember: you want fewer Firmicutes in your stool sample and more Bacteroidetes. So how to get them?

Minimise your stress levels. From a microbe point of view, stress upsets your digestion and reduces your Bacteroidetes, which as you now know, risks you getting fatter – which will make you more stressed and on it goes!

For the same reason, add more vegetables, fruits and fibre to your diet because Bacteroidetes love them.

Eat more beans and pulses which will also raise your Bacteroidetes levels.

Eat less fat. Lots of fatty foods will encourage your Firmicutes to multiply because they are in charge of soaking up fat – and again, you will get fatter.  Which you probably don’t want.

Eat less sugar, because again, Firmicutes love sugar, and they, and the sugar will make you fat – which will make you stressed etc… etc…

Eat widely, because diversity of food equals diversity of gut bacteria. (Zuridis Z knight R j Nutri 2015 Jan 113 suppl s1-5)

Microbes and health

Research shows that if the microbes natural balance is disturbed they can trigger disease. Obesity, IBS, leaky gut, diabetes and some autoimmune diseases have been linked to the microbes of the gut. There may well be connections with asthma, cancer and heart disease. The microbiome is also thought to affect your mood, sleep patterns and anxiety levels, and some bacteria can throw hormones out of balance. 

Studies show that the number of Clostridium species found in the stools of children with autism is far higher than in the general population. Bacteroidetes levels are extremely high levels in severely autistic children and Bifidobacterium levels are much lower than average. (Finegold et al. 2010). Firmicutes and Clostridia are reduced in type 2 diabetes compared to standard samples (Larsen et al. 2010).

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Which probiotic to choose?

If you are looking for a good all round probiotic, then right now, based on what you can buy in the shops, Lactobacillus and Bifidobacterium are the names to choose. Lactobacillus acidophilus and Lactobacillus plantarum are important strains, plus Bifidobacterium Lactis, Bifidobacterium longum and Bifidobacterium Bifidum (Boesten and De Vos 2008; Kleerebezem). Lactobacillus rhamnosus helps with diarrohea; Lactobacillus Fermentum is another good one for a healthy gut. Higher numbers are better, so look for a count of 50 billion or higher in each dose. Look for a product with as many different strains as possible but more is not necessarily better than a few strategically targeted strains, so check on the web for information about research into probiotics that might works for your health issue. 

It is clear that managing your gut is vital for both your health and happiness. It all seems like a huge responsibility that I didn’t know I had to have and one that I am undertaking effectively blindfold. But overall, the discovery of the importance of the microbiome seems to be up there with the discovery of gravity. Properly managed, as I keep saying (sorry to be boring but it’s really important!) this could be the ultimate health tool of the future, changing the face of medicine as we know it. 


Written by health advocate Sara Davenport, who founded one of the UK's largest breast cancer charities, The Haven, twenty years ago. With Reboot Health, Sara aims to bring the best preventative and curative health solutions ranging from nutrition, alternative therapies, fitness and conventional medicine.

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