You Are What You Eat

You Are What You Eat

When you sit down to eat, you are not only feeding yourself but also the trillions of tiny organisms (microbiota) living in your gut. Collectively referred to as your gut’s microbiome, these tiny organisms (mostly bacteria, but also viruses, fungi and protozoa) impact almost every aspect of your health.

The microbiome is now best thought of as a virtual organ of the body because it plays so many critical roles in promoting the human body’s smooth daily operations. It provides essential nutrients and metabolites for the body, stimulates the immune system, is involved in energy regulation, prevents bad bacteria from colonising in your gut, helps control your brain health and helps synthesise certain vitamins and amino acids, including B vitamins and vitamin K.

Our microbiome changes dramatically throughout our lives. Most of us get our first big dose of microbes at birth while travelling through the birth canal and then pick up more while breastfeeding. Therefore, precisely which microorganisms you are exposed to as an infant depends entirely on the species found in your mother. As we get older, our lifestyle choices become the predominant factor shaping our microbiome’s health, with changes in diet having the biggest impact.

Fact: dietary changes account for up to 57% of your gut microbiota changes. whereas genes account for no more than 12%!

Let food be thy medicine and medicine be thy food


This famous quote by Hippocrates, the ancient Greek figurehead of western medical philosophy, has stood the test of time. Utilising food as medicine has become a hot topic of debate over the last few years as more people turn towards preventative medicine to avoid developing diseases or illnesses in the first place. From drinking kefir to taking prebiotics, caring for our gut has never been more popular, and for good reasons.

For your gut to be healthy, the gut microbiome must also be balanced and healthy. In the past decade, the microbiome has been shown to play a role in a wide range of diseases, including obesity, diabetes, cardiovascular disease, and autoimmune diseases. Recent research shows that the microbiome can even influence your mood due to the so-called gut-brain axis (see more detail below).

Due to the close relationship between your diet, gut microbiome, and overall health, new research is looking at whether modulating people’s diets can improve health.

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Figure 1: Dietary changes (1) can cause the types of bacteria in your gut (2) to be altered, which can cause a negative effect; increasing the levels of inflammation in your body and altering the function of your immune system and metabolism (3). These negative changes can increase your chance of developing chronic diseases like cardiovascular disease, obesity, diabetes and autoimmune diseases (4) (adapted from Rasnik

The gut-brain axis (GBA) refers to the physical and chemical connections between your gut and brain. This is a two-way connection, meaning that your gut health affects your brain health, and visa versa. 

Millions of nerves and neurons run between your gut and brain. Neurotransmitters and other chemicals produced in your gut also affect your brain. 

Research has recently demonstrated that the gut microbiome (the trillions of microorganisms in the gut) is an equally important part of the communication link between the gut and brain.

Together, the GBA axis is a complex interconnected circuit. This means that when an issue arises at any point within these communication loops, it can affect the whole system. 

When this happens, a number of health conditions, such as IBS, depression, anxiety, obesity, autism and more may arise. 

1. GBA and Digestive Disorders 

Changes in the GBA axis, caused by things like stress, can lead to digestive conditions such as IBS. This is due to activation of the body’s fight-or-flight response and changes in the gut microbiota. 

2. GBA and Depression and Anxiety

Dysbiosis in the gut microbiota is a direct factor that influences the gut-brain axis’ normal functioning and leads to mental health conditions like depression and anxiety. 

What is Gut Dysbiosis?

Your microbiome primarily consists of bacteria, both good and bad, which impact virtually every aspect of your health. Most microbes are symbiotic (where both the human body and microbiota benefit). Some, in small numbers, are pathogenic (promote disease). In a healthy microbiome, the symbiotic (good) and pathogenic (bad) bacteria coexist peacefully together, without a problem. However, when an imbalance in the number of good and bad bacteria occurs, this can cause dysbiosis, negatively impacting your wellbeing.

Diversity in the microbiome is a key measure of gut health. Over 1000 different bacteria species are present in a healthy microbiome, containing enough of the right bacteria to produce important nutrients that keep the gut lining healthy and defend against intruders that could cause dysbiosis by taking over the ecosystem.

If there is a negative alteration in your guts microbiome and the number of unhelpful microbes overpowers those that are more beneficial, dysbiosis occurs, which can have a knock-on effect on your health.

Many lifestyle factors can negatively influence diversity and, therefore, the health of your gut microbiome, including:

  • Prolonged antibiotic use
  • Infectious illness
  • Unhealthy diet
  • High stress levels
  • Alcohol Abuse

Dysbiosis can cause immune dysregulation, altered energy regulation (reduced metabolic rate), altered gut hormone regulation and low-grade inflammation, all of which are associated with numerous health conditions. These include:

  • Inflammatory bowel disease (IBD)
  • Irritable bowel syndrome (IBS)
  • Obesity
  • Metabolic syndrome
  • Type 2 diabetes
  • Atopic eczema
  • Rheumatoid arthritis
  • Ankylosing spondylitis
  • Parkinson’s disease
  • Alzheimer’s disease
  • Cardiovascular disease

The benefits of a balanced microbiome

When your microbiome is balanced, your entire body benefits, a healthy microbiome supports the following functions:

  • Supports digestion
  • Supports a healthy immune system
  • Supports bone health 
  • Supports a healthy weight
  • Supports brain health

How your diet impacts your gut health

What you eat daily has a profound effect on gut microbiota composition, diversity and richness. As described above, this has a knock-on effect throughout the body and can potentially influence your sleep, weight, food, allergies and the likelihood of developing certain diseases.

To demonstrate the profound effect diet has on the gut microbiome, many studies have compared the typical Western diet to a Mediterranean diet, which many believe to be among the planet’s healthiest diets.

The typical western diet is characterised by low fruit and vegetable intake and high consumption of animal-derived protein (meat and processed meat), saturated fats, refined grains, sugar, salt, alcohol and corn-derived fructose.

In contrast, the Mediterranean diet is characterised by a high intake of non-refined grains, legumes, and a large diversity of fresh fruit and vegetables; a moderate intake of fish and unsaturated fats such as olive oil; And a low intake of meat and dairy products.

The typical Western and Mediterranean diet have polar opposite effects on gut microbiome’s diversity. The former promotes gut dysbiosis, whilst the latter promotes increased microbiome diversity and functionality. The Mediterranean diet has been shown to have protective effects against several diseases, including obesity, diabetes, hypertension, cardiovascular disease, cancers, allergic diseases, and Parkinson’s and Alzheimer’s disease. In contrast, a Western diet has been associated with an increased risk of all the above.

Luckily for us, our gut microbes respond quickly to a change in diet. Therefore, our gut’s health can easily be transformed through dietary changes.

Eating for gut health

The amount of protein, saturated and unsaturated, carbohydrates, and dietary fibre, can influence the abundance of different gut bacteria types. The microbiota can also be modified by adding live microorganisms in the form of probiotics or synbiotics (a mixture of prebiotics plus probiotics) to your diet.

Consume probiotics

Probiotics are defined as “live microorganisms, which when consumed adequate amounts, confer a health effect on the host”. Probiotics can come in several forms, whether via a food source (kefir, yoghurt, sauerkraut) or in tablet form.

Although you might think that probiotics excerpt their effect directly on your gut microbiome, there is little evidence suggesting that probiotics can reach the gut intact and affect the resident community. Instead, there is evidence that they act independently of the gut microbiota and instead directly influence the host (aka you) through immune modulation and producing helpful compounds for the body.

There have been numerous studies looking at the beneficial effects of the regular consumption of probiotics, with evidence that they can help restore the natural balance of bacteria in your gut, improving digestive issues (such as diarrhoea and constipation), relieve IBS and IBD, strengthen your immune system, stimulate weight loss and help prevent respiratory infections.

Get enough prebiotic fibre

Fibre is essential to gut health, literally feeding and making the bacteria we thrive on. Not getting enough fibre can cause gut dysbiosis and lead to poor digestion, a high risk of cardiovascular disease, weight gain and poor blood sugar control, among other things.

There is convincing evidence that a Western diet, which is low in fibre, degrades the gut’s lining, making the gut susceptible to pathogen invasion and inflammation. This could provide a potential mechanism to link the Western diet with chronic diseases like diabetes, obesity and cardiovascular disease.

Therefore, there is robust evidence to suggest that enriching your diet with fibre could maintain your gut lining and protect you from these chronic diseases.

Fact: Dietary fibre intake is recommended at 25g/day for women and 28/day for men. However, fibre intake has been reported to be as low as 15g/day in 90% of the population in developed countries

To increase your fibre intake, try including more high-fibre foods in your diet. This includes grains, legumes and cruciferous vegetables such as broccoli, Brussel sprouts, cabbage, cauliflower, collard greens, kale, radish and rhubarb.

Choose plant-based over animal-based protein

While high protein diets are generally associated with decreased body weight and an improvement in blood metabolic parameters (e.g. insulin levels), they can also negatively impact the gut microbiome and, therefore, should be considered with some caution.

A high protein, low carbohydrate diet (45% protein, 35% carbohydrates) has been shown to have a detrimental effect on the gut microbiota when compared to a normal protein diet (20% protein, 56% carbohydrates).

Your protein source of choice (i.e. animal-derived vs plant-derived) has also been shown to impact gut microbiota composition. Numerous studies have clearly suggested that plant-derived proteins (such as pea, buckwheat, soy protein) are far superior to animal-derived proteins for promoting a beneficial microbiota with positive effects on human metabolism.

Therefore, not following a very high-protein diet and opting for plant-based over animal-based protein could benefit your microbiome and overall health. Try incorporating more protein plant-based in your diet by including:

  • Tofu, tempeh, edamame
  • Lentils
  • Chickpeas
  • Peanuts
  • Almonds
  • Spirulina
  • Quinoa
  • Mycoprotein
  • Chia seeds
  • Hemp seeds
  • Beans
  • Potatoes
  • Seitan
  • Protein-rich vegetables (dark coloured leafy greens)
  • Ezekiel bread

Choose complex over simple carbs

A carbohydrate-rich diet (fibre and plant-derived complex carbs (polysaccharides)) has beneficial effects on the gut microbiome, increasing its diversity and functionality.

Nevertheless, simple sugars such as glucose (the sugar in our blood) and fructose (the sugar in fruit) have been shown to increase the number of harmful bacteria in the gut, markers of metabolic syndrome, inflammation in the body and cause damage to the lining of the gut. A recent study showed that when mice were fed simple sugars such as glucose, fructose and sucrose, the high sugar diet-induced inflammatory bowel disease.

Therefore, if you want to look after your gut, reduce the number of simple sugars you consume and instead opt for complex carbs, such as:

  • Wholegrains
  • Legumes
  • Green vegetables
  • Starchy vegetables

Choose healthy over unhealthy fats

High-fat diets have been associated with gut dysbiosis and an increase in the release of inflammatory substances in the blood, promoting obesity and other health conditions. This means that whilst following a ketogenic diet might induce weight loss and improve conditions like epilepsy and type 2 diabetes, it may in turn have negative side effects on your gut.

Not just the amount but also the type of fat you consume is relevant. The consumption of unhealthy fats, such as trans fats (i.e. margarine) and saturated fats (i.e. palm oil), have been shown to reduce microbial diversity and are associated with an increased risk of certain health conditions.

In contrast, healthy fats have been shown to have positive effects on the gut microbiome. These include monounsaturated fatty acids (e.g. olive oil), polyunsaturated fatty acids, and omega-3 fatty acids (e.g. fish).

Healthier fat sources include:

  • Avocados
  • Dark Chocolate
  • Cheese
  • Whole Eggs
  • Fatty fish
  • Nuts
  • Chia Seeds
  • Extra Virgin Olive Oil
  • Unrefined Coconuts and Coconut Oil
  • Full-fat Yoghurt

Maybe don’t go gluten-free

Gluten-free diets were originally designed for people who have celiac disease. However, in recent years, they have grown in popularity among the general public. Many people believe that eliminating gluten from their diets is beneficial to their health, suggesting that it can help aid weight loss, ease digestive symptoms, improve energy levels, and reduce cardiovascular disease risk. However, a recent study by De Palma et al. showed that a 30-day gluten-free diet actually decreased the population of beneficial bacteria (such as Bifidobacterium and Lactobacillus) and increased unhealthy bacteria (such as E.coli and Enterobacteriaceae). Therefore, when non-celiac sufferers follow a gluten-free diet, it could paradoxically increase their risk of similar health issues and nutrient deficiencies as those commonly seen in individuals with celiac disease!

Take-Home Message

There is a strong link between diet, gut microbiota, and health. A healthy, balanced diet can promote gut health, which in turn can improve your general wellbeing. Many studies have shown that a disruption in your guts microbiome can lead to numerous chronic disease.

The best way to support your gut microbiota is to eat a healthy, balanced diet. Studies have shown that eating adequate amounts of fruit and vegetables, ensuring a rich source of dietary fibre, along with healthy fats, supplementing with probiotics, and a preference towards plant-derived protein, will nourish your gut microbiome and promote gut health.

That does not mean that having the odd donut here and there is bad for you. Moderation is key!!

I hope you found this helpful.

Virtual hugs,

Flora xxx

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