Friendly gut bacteria explained

You may not be aware, but there are millions of bacteria living inside your gut. This bacteria is also known as your microbiome or your gut flora.

Everyone’s microbiome is unique to them and is shaped by many factors including our genetics and DNA.

Studies on twins have shown that family members share common gut flora which could affect how much body weight we gain and where we store it.¹

Now, unless you’ve been living on a tropical island for the past few years (which does sound lovely, by the way), you must have heard all the hype surrounding friendly bacteria and the benefits it has on our gut health.

Scientists are still discovering exactly how our gut has an impact on our wider health and wellbeing, but we do know that friendly, or ‘good’, bacteria has a key role to play.

In this article, you’ll discover

• What bacteria is
• What friendly bacteria is
• Why it matters
• What friendly bacteria does
• Types of friendly bacteria
• What the gut microbiome is
• How diet affects the microbiome
• Microbiome diet
• 5 tips for a healthy gut
• Fibre and friendly bacteria

What are bacteria?

Bacteria are tiny living organisms – usually consisting of just one cell – that can be found just about anywhere, including in our guts!

Most bacteria are ‘good’ and help our body perform certain tasks. However, some are ‘bad’ and can cause infections and illness.

The key is to strike a balance between good and bad bacteria that live in the gut.

Researchers say that when gut bacteria becomes out of balance, it can cause health issues which may lead to an increased risk of conditions like heart disease.²

On the Huffington Post blog, Raphael Kellman, MD author of The Microbiome Diet explains:

“When your microbiome is balanced, you have a terrific ally that keeps your body healthy, promoting good digestion, clear thinking, balanced mood, and glowing overall health.

"When your microbiome goes out of balance, however, you risk such symptoms as brain fog, depression, anxiety, bad skin and insomnia — and, down the road, obesity, diabetes, and cancer.” ³

What is friendly bacteria?

Next time you pick up a yoghurt that is packed with friendly bacteria, take a look at the label.

It may contain Lactobacillus acidophilus or Bifidobacterium bifidum – these are common bacterial cultures that have been shown to have a beneficial effect on our health.⁴

They’re called good or friendly bacteria because they can help restore the balance of bacteria in our gut following a bout of diarrhoea, a course of antibiotics or an episode of irritable bowel syndrome (IBS), for example.⁵

Your gut bacteria are so important because they form a key part of the microbiome – the collective name given to the bacteria that live inside every one of us.

Your microbiome is unique – a bit like your genes – and is formed from the moment you’re born.

Scientists are now beginning to discover that what we eat directly impacts on the balance of our gut bacteria and, in turn, our general health.

Why bacteria matters

A healthy microbiome is important to keep your digestive system ticking over efficiently. But scientists are learning there are other health reasons to feed your gut bugs.

Certain types of fibre are fermented in your large intestine by gut bacteria, producing short-chain fatty acids, which have been shown to support your immune system and general wellbeing.⁶

Resistant starch, another type of fibre, has also been shown to feed good gut bacteria. Studies suggest this starch may be linked with managing risk of obesity.⁷

What do friendly bacteria do?

Friendly bacteria have mainly been studied for their beneficial effect on gastro-intestinal issues such as traveller’s diarrhoea, antibiotic-associated diarrhoea, IBS and inflammatory bowel disease (IBD).⁸

But there are some new areas of research that show good bacteria may also be helpful for:

1. Dental health  – it’s thought that replacing bad bacteria in your mouth with good bacteria can help protect your teeth and gums^9,10
2. Mood-boosting – a 2017 Canadian study found friendly bacteria could control  anxiety and symptoms of depression, most likely due to the gut-brain axis; the link between our gut and central nervous system¹¹
3. Urinary tract infections – taking friendly bacteria may help rebalance bacteria in the vagina and bladder, fighting infections¹²

Many people also take friendly bacteria to:

• Support symptoms of eczema¹³
• Support the immune system¹⁴
• Help maintain a healthy weight¹⁵

However, there’s currently not enough clinical evidence to prove that friendly bacteria has these effects.

The friendly bacteria

These bacteria are some of the most beneficial in terms of keeping your digestion and gut healthy:

1. Lactobacillus

This bacteria plays a key role in gut health.

Found in the mouth, gastrointestinal tract and female genital tract, lactobacillus produces lactic acid and helps to protect against harmful microorganisms.¹⁶

A 2016 report published in World Journal of Gastroenterology found that lactobacilli can ease symptoms of IBS, like stomach bloating, potentially preventing or easing IBS symptoms.^17,18

Handpicked content: What is Irritable Bowel Syndrome (IBS) and how can you treat it?

2. Bifidobacteria

This is the first bacteria to colonise babies’ guts, and it’s also thought to play an important role in immune system health.

Also known as a probiotic, bifidobacteria may also be able to ease the symptoms of IBS and may be able to prevent babies from developing eczema.^19,20

However, scientists are still investigating how bifidobacteria has this effect.^21,22

Handpicked content: What is my immune system and why is it so important?

3. Christensenella

This type of friendly bacteria has been linked with a healthy gut as it helps to maintain microbial symbiosis – aka, when different species of microorganisms can inhabit the same space and benefit each other.^23,24

As part of a twin study at New York State’s Cornell University and King’s College London, researchers found that slim people have higher levels of a particular strain of this bacteria – Christensenellaceae minuta – suggesting it may play a role in managing body weight.²⁵

What is the gut microbiome?

The gut microbiome is a collective term for the trillions of bacteria, fungi and other microorganisms that live in there.

It influences many aspects of human health, from your immunity to your metabolism.²⁶

Both environmental exposures and the diet can affect the gut microbiome, find out more on the latter below.²⁷

How does your diet affect the microbiome?

What we eat can have a big impact on the health of our gut and our individual microbiome can affect our metabolism, digestion and weight.

A large study in the Netherlands found that everything we drink or eat has an effect on the bacteria living in our digestive systems as well as our overall health.²⁸

Other evidence suggests that a diet high in sugar and fat changes the bacteria in the microbiome and leads to obesity.²⁹

So, to keep our microbiomes healthy, a varied diet is essential.

Researchers believe that a diverse diet leads to a diverse microbiome that is able to deal with any bacteria that is harmful to your health.³⁰

What is a microbiome diet?

The idea is to eat a diet full of foods that helps support levels of good bacteria in your gut.

A healthy gut diet plan is full of whole foods and nutrients – basically, foods that help your digestive system work at its best - and less processed and harder-to-digest foods.

These foods can include:

• Fruit and vegetables

Packed with essential vitamins, minerals and dietary fibre, getting your 5 a day is essential for a healthy, balanced microbiome.

Aim to fill your plate with a variety of fresh fruit and veg like broccoli, spinach, carrots, blueberries, apples and strawberries.

• Herbs and spices

Flavour your food with aromatic spices like ginger and turmeric. Both are known for managing immune responses in the body.

How can I consume friendly bacteria?

Friendly bacteria are found naturally in some foods, such as kimchi, miso, sauerkraut and kombucha, a fermented tea.

These foods and drinks are more popular in other parts of the world, but they are starting to grow in popularity in the UK.

Most of us are currently more likely to consume good bacteria in yoghurts, yoghurt drinks such as kefir, supplements or powders.³¹

Friendly bacteria supporting foods

Foods that contain friendly bacteria may help restore good bacteria in your gut and keep it healthy.³²

In fact, the Netherlands study found that people who regularly ate yoghurt had more diverse gut bacteria.³³

As well as yoghurt, fermented foods like kefir, miso or kombucha also contain friendly bacteria.

• Omega-3s

Evidence suggests that Omega-3 fatty acids can help support the body’s natural immune response.³⁴

To get your fill, go for oily fish like salmon or tuna, chia seeds or flaxseeds.

• Wholegrains

According to research, wholegrains aren’t just a nutritious way to provide your body with digestive-friendly fibre, they could also support the balance of bacteria in your microbiome.³⁵

Staple wholegrains of a gut health diet include: porridge oats, brown rice, quinoa, bulgur wheat, barley, popcorn, whole-wheat bread and buckwheat.

These hearty grains may also keep you feeling fuller for longer.

• Red wine

In moderation, red wine could help keep your microbiome diverse.

It contains resveratrol, which one study found may lessen the risk of heart disease by adapting the gut microbiome.³⁶

What to look for in friendly bacteria

Not all good bacteria foods or supplements are made the same, so you need to know how to pick the right one for you:

• Does it contain enough friendly bacteria to be effective? In 2013, Italian researchers concluded that the amount for good general gut health was between 10million to 1 billion CFU (colony forming units) a day.³⁷
• Will the bacteria reach your intestines intact? Many are destroyed by stomach acid before they can actually do any good in your gut.³⁸
• Are you taking the right one for your symptoms? Different types of bacteria may be better for certain conditions. Talk to your GP or a specialist dietician for advice if you’re unsure.³⁹

You can help support boost the good bacteria already living in your gut by eating fermented foods such as kimchi or sourdough bread, consuming more high-fibre foods to help feed your microbiome and tackling stress.

Stress can make your gut more sensitive (making IBS worse) and can lead to poor food choices that don’t feed your gut bacteria.⁴⁰

What is fibre?

Sometimes known as ‘roughage’, fibre is made up of a group of substances found in plant foods.

These include lignin, waxes and polysaccharides, such as pectin and cellulose. Most fibre passes through your digestive system, pushing food along and helping to keep bowel movements regular.

That’s why, if you don’t have enough, you can become constipated.

Handpicked content: What is digestion?

Are you getting enough?

Unfortunately, in the UK, we don’t eat anywhere near enough fibre to keep our tummy bugs happy.

We should have 30g of fibre a day but, on average, we only manage 18g – about 60% of what we should be aiming for. So our good bugs aren’t getting the fertiliser they need.⁴⁶

Go up gradually

Convinced you need more fibre? A word of warning before you start loading up on lentils, brown rice and veg.

Lots of people find they get more wind when they suddenly increase their intake, which is why it’s a good idea to increase it gradually.

This will settle as your gut gets used to your new way of eating.

And check with your doctor or nutritionist if you have IBS.

Guidelines from NICE (National Institute for Health and Care Excellence) state that, for people with IBS, it may actually be helpful to reduce high-fibre cereal-based foods such as brown bread and brown rice, as they are too much for a sensitive digestive system.⁴⁷

But you could discuss other ways to pack it into your diet.

Handpicked content: What is IBS and how can you treat it?

What foods should you avoid on a microbiome diet?

There are a few foods that you should avoid on a microbiome diet...

1. Alcohol

Research shows that drinking excessively or for long periods may affect the microbiome which could, in turn, lead to liver disease.⁴⁸

2. Refined carbohydrates

Evidence shows that eating refined carbohydrates on a regular basis could have an inflammatory effect on the body.⁴⁹

Instead, cut down on white bread and pasta in favour of whole grains, which are much better for a good gut health diet.

3. Hydrogenated fat

Research suggests that processed food that contains hydrogenated (trans) fat may cause inflammation.⁵⁰

These foods are also often high in calories, which may decrease the diversity of our gut bacteria.⁵¹

Making some changes to your diet helps support your microbiome, but remember that there is no “one size fits all” approach. 

“But there is a good correlation between diversity and health: greater diversity is better,” researcher Alexandra Zhernakova MD PhD says.

And Dr Kelleman agrees: “The key is to keep supporting your little friends inside — your microbiome.”

The final say

The three main types of good bacteria in the body are Lactobacillus Acidophilus, Bifidobacterium and Christensenella.

They can have a range of potential health benefits, from supporting your immune system and energy levels to controlling your weight and helping your metabolism.

Thankfully, you can increase the level of these friendly bacteria in your gut by eating a healthy balanced diet full of wholegrains, fruits, vegetables and fermented foods.

Or if you need a little extra help, you can include in your diet purchase lactobacillus probiotic supplements or other friendly bacteria capsules.

The advice in this article is for information only and should not replace medical care. Please check with your GP or healthcare professional before trying any supplements, treatments or remedies. Food supplements must not be used as a substitute for a varied and balanced diet and a healthy lifestyle.

Last updated: 26 January 2022