Gut health: Foods to eat and avoid to improve your wellbeing
Gut health can affect everything from our skin and hormones to our immunity and mood.
Luckily, through diet, we have the power to boost and control what is known as our 'gut microbiome' – this refers to all the microbes which live in your intestines, some good and some bad. But if we get the balance right, we can improve our overall physical and mental health.
But what exactly is the 'microbiome' and what gut-friendly foods should we be eating? We asked the experts for the answers and also to explain the benefits.
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What is the gut microbiome?
Microbes are tiny living things that are too small to see with a microscope.
"There are 100 trillion microbes which live on and in every person, making up the human microbiome. The microbes consist of fungi, bacteria, and viruses and 95% of these are within are gastrointestinal tract [which includes the gut]," explains Dr Helen Evans-Howells, GP and allergy specialist.
"The human microbiome is a fine balance which is easily disturbed by our lifestyles; what we eat, how much we exercise and what medications we take.
"It is the focus of much research, and we now know that most chronic health illnesses (such as heart disease, allergies, diabetes, dementia, and some cancers) can be linked back to the microbiome. Within our bodies we have ‘good’ bacteria which bring us benefits and ‘bad’ bacteria which promote inflammation and problems."
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So, when we have an imbalance between our 'healthy' and 'harmful' bacteria, we can experience undesired effects. This is because the microbiome plays an important roll in managing many of the body's processes, impacting sleep, immunity, skin, digestion, weight and more.
"It is important to have a wide variety of foods because each item in our diet will feed different bacteria within the microbiome," adds Dr Helen. "Whilst the net effect of these bacteria is to promote a healthy body, the actions of each bacteria are different.
"Some bacteria will aid digestion, others produce essential nutrients and some maintain the body’s immune system. If our diet is limited, there will be low levels of crucial bacteria and this can allow illness to form."
So, which foods should we be stocking up on?
Gut-friendly foods
Prebiotics
Prebiotics are the foods that feed the good bacteria within our gut.
"In order to achieve a diverse array of fungi, bacteria and viruses within our gut, it is recommended that we eat a wide range of plant-based foods such as fruit, vegetables, nuts, pulses, seeds and legumes is important to feed the beneficial bacteria we have," says Dr Helen.
"The larger the variety of plant-based foods we eat, the more diverse our microbiome will be."
Polyphenols
Polyphenols sound slightly alien but it's likely they're in many of the foods you already eat.
"Polyphenols are compounds that are found in plant-based foods such as fruits, vegetables, dark chocolate and extra virgin olive oil. These substances also promote the growth of beneficial gut bacteria."
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Omega 3 sources
Foods such as fatty fish are high in Omega 3, while vegan and vegetarian sources include nuts, seeds, and plant oils.
"These foods will increase the development of beneficial bacteria that produce short chain fatty acids [produced by beneficial bacteria in your microbiome] like butyrate and anti-inflammatory compounds," says Dr Helen.
Fibre
It's recommended we eat 6g of fibre a day.
"As humans we are not able to digest fibre, but it will be broken down by the bacteria within our gut to produce short chain fatty acids and these substances are beneficial for health," explains Dr Helen.
"Sources of fibre include – whole grains such as brown rice, wholemeal bread, and oats."
The good news is that fibre can help in endless ways.
"Soluble fibre (such as oats and legumes) can help regulate blood sugar levels by causing a slow release of sugar into the blood stream. This will help weight management. It also helps to reduce the LDL cholesterol in our body – the ‘bad’ cholesterol which increases risk of heart disease and strokes," says Dr Helen.
"High fibre foods such as wholemeal bread can help you feel full and are important for weight management.
"Regular intake of fibre will keep our bowel movements regular and help prevent constipation, especially in conjunction with good fluid intake and exercise."
Regularly consuming fibre can help lower your risk of chronic diseases like heart disease, stroke and diabetes. An example of a short chain fatty acid is butyrate, which is important in the maintenance of the intestinal barrier (around the intestines) and immune function.
Probiotics
Probiotics refer to the bacteria themselves.
"Some foods are rich in probiotics such as kimchi, kefir, yogurt, miso and sauerkraut. It is hoped that eating foods rich in probiotics may help other beneficial microbes to thrive," Dr Helen explains.
What are the health benefits?
Making small challenges to your diet will lead to a real positive impact on your health, which you might see within months, according to Dr Helen.
To re-cap, she says, "Following a Mediterranean diet (rich in fruit, vegetables, nuts and legumes) is likely to improve your sleep and energy levels. Instead of sugar peaks within the blood stream, you will achieve a steadier release of sugar which will improve your energy and have a positive impact on your mental health.
"Your weight is also likely to change and this will have a positive outcome on physical health. Long term changes will bring the most benefits."
Plus, Dr Helen adds, "Whilst it has been noted that individuals with food allergies, eczema and asthma have an imbalance in their gut microbiota with a greater swing towards adverse bacteria; there is not yet conclusive evidence that manipulating the gut with probiotic medication will definitely bring benefit.
"Many allergists like myself believe that it is worth taking the probiotics to try, however, benefit is not certain and we would be more likely to influence overall change by making a sustained change to our diets."
The brain-gut connection
Good gut health can help us both physically and mentally.
"The gut-brain axis is a communication pathway between the gut and the brain. In a healthy gut microbiome, there will be a release of neurotransmitters such as serotonin and GABA (gamma-aminobutyric acid)," explains Dr Helen.
"These neurotransmitters play a crucial role in sleep and our mental health. Low levels of serotonin have been linked to depression and anxiety, and many anti-depressant medications act to increase the amount of serotonin within the brain."
While you should always speak to a healthcare professional if you are struggling with mental health, you may also want to consider the effect your diet is having on this.
Which foods should you avoid for good gut-health?
A healthy diet shouldn't involve ruling out any food groups, however it's good to be aware of what not to have too much of.
"Eating foods which are high in fat, sugar, salt and processed meat have been linked to a decrease in the beneficial bacteria. These foods may cause increased intestinal permeability (a 'leaky gut') and inflammation," says Dr Helen.
"It is thought that these foods promote the growth of non-beneficial bacteria and diets high in these foods have been linked to the development of colorectal cancer, liver cirrhosis and inflammatory bowel disease."
Incorporate gut-friendly foods into a balanced diet of at least five fruit and veg a day, high fibre starchy foods, dairy or non-dairy alternatives, protein, unsaturated oils and spreads and six-to-eight glasses of fluids a day.
Here's to a happy gut, and a happy you.
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