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  • Writer's pictureMelanie

What does healthy digestion look like and What are the symptoms of poor gut health?

Updated: Jul 10, 2023

Many of my clients come to me with gut health symptoms that they consider to be normal because they have had them for so long and so they have become part of everyday life. People often assume their digestion is healthy and don't realise they have the symptoms of poor gut health.

digestive organs in a female body

What is normal?

Do you take Imodium before you leave the house?

Do you take Nexium or Omeprazole for heartburn?

Do you get through a packet of Rennie's on a regular basis?

Do you rely on laxatives more than once a year?

Do you struggle with constipation?

Do you get regular boats of diarrhoea?

Do you get heartburn or bloated after eating?

If you answered yes to any of the above questions, your gut is calling out for help. It is not normal to rely on medication to manage gut health symptoms, or to have chronic diarrhoea, constipation, bloating or heartburn.

This is what healthy digestion looks like:

No heartburn or bloating after eating, feeling comfortably full not overly full, having 2-3 easy-to-pass bowel movements a day.

A healthy gut is the key to good health as it affects how the rest of our body functions, from hormonal health to brain health.

Below are just some of the symptoms that are linked to poor gut function:

Headache/migraine, eczema, asthma, hayfever, poor immunity, joint pain, period problems, perimenopause/menopause symptoms, disrupted sleep, weight gain or weight loss, anxiety, depression, bad breath, sinus congestion, and brain fog.

Gut health is also implicated in various chronic conditions such as chronic fatigue syndrome, restless leg syndrome, rheumatoid arthritis, ulcerative colitis, lupus, fibromyalgia, Crohn’s disease, and diverticulitis, obesity, type 2 diabetes, PCOS, endometriosis and hypothyroidism, to name but a few!


With a few simple changes, you can begin to improve the function and health of your gut, and impact your overall health and wellbeing.

In this article, we shall look at the stages of digestion along with some simple actions so that you understand why the actions suggested support your gut function.

digestive system diagram from mouth to anus

Cephalic phase

This phase of digestion starts before we have even taken a mouthful. It is the phase in which our digestive juices begin to flow; saliva is released into the mouth and stomach acid production begins. This stage is crucial as it means that we start to digest our food as soon as we begin to eat. Saliva is needed to moisten the food; enzymes are released that begin to break down foods while in the mouth. Stomach acid and enzymes also need to be generated at this phase. To instigate the cephalic phase, it is important that we take time to think about the food we are about to eat, to smell it and to observe it before we take our first mouthful. Digging straight in and not paying attention to our food inhibits this stage of digestion, leading to indigestion and heartburn/reflux.

Action: pause before you eat, observe your plate, and smell your food.

Chewing and swallowing

Chewing is mechanical digestion; it is key to helping to break down the structure of foods. It is vital that foods are chewed several times rather than swallowed after only a couple of chews, as the more you chew, the easier it is for your stomach to continue the digestion process. As you chew, saliva moistens the food and an enzyme called amylase begins the process of breaking down starches (carbohydrates). When we swallow, food is moved by muscular contractions called peristalsis down the oesophagus to the stomach.

Action: Eat slowly and mindfully. Chew each mouthful 10-20 times, more if you can!


The stomach is a bag-like organ that is also muscular. Here mechanical action continues the breakdown of food into a more liquid state called chyme. This more liquid state allows for better nutrient absorption later in the digestive tract. Chemical digestion is also part of the digestive process of the stomach; stomach acid and intrinsic factor are released from special cells. Intrinsic factor is needed to facilitate the absorption of vitamin B12. Stomach acid kills unwanted pathogens in the food. Stomach acid production is regulated both by enzymes and by our stress response, you are more likely to experience acid reflux if you eat in a stressed state. Two enzymes called pepsin and lipase are also released in the stomach, these begin the process of protein and fat breakdown. Long-term use of antacids and anti-histamines disrupts the production of stomach acid and can lead to problems like small intestine bacterial overgrowth (SIBO), IBS and reduced nutrient absorption, particularly of vitamin B12, iron and vitamin C.

Action: Review your use of antacids and antihistamines (with your G.P. if prescribed). Ensure you are relaxed when eating. Certain foods are more likely to trigger acid reflux such as caffeinated drinks, spicy foods, alcohol and chocolate; note if any of these trigger a response for you and remove them from your diet. 20 minutes before a meal have drink of hot water with lemon, or a glass of water with a teaspoon of apple cider vinegar to stimulate your digestive juices.

Small intestine

The majority of the chemical digestion processes take place in the small intestine, with support from the liver, gallbladder and pancreas which secrete bile and digestive enzymes that break down fats, proteins and carbohydrates. Insulin and glucagon are two enzymes produced that work together to regulate eating patterns, production of digestive juices and maintain stable blood glucose levels. The delicate balance of these enzymes can be disrupted by erratic eating patterns, eating too frequently, eating a diet high in refined carbohydrates/sugar, and high levels of stress; leading to increased risk of diabetes.

Another enzyme produced is lactase. Some people do not produce enough lactase and so are lactose intolerant. Lactose intolerance produces symptoms such as bloating, flatulence, stomach pain, diarrhoea, nausea, eczema, joint pain, brain fog, headaches, sinusitis, and coughing. Lactose intolerance is prevalent in up to 98% of Asians, 89% of African and 15% of white British populations. Other food intolerances also cause similar symptoms.

In addition to enzymes, bile acid is also important in the digestion taking place in the small intestine. Bile acid helps to break down fats and absorb fat-soluble vitamins such as vitamin A,D, E and K. Problems with bile production may be seen in ‘fatty’ or ‘floating’ stools.

As the partially digested food continues to move through the small intestine, 90% of nutrient absorption takes place.

The small intestine contains folds in its surface called microvilli that increase the surface area for absorption. Where there has been damage to the structure of the intestines, such as in coeliac disease or IBD, or through long-term imbalance in the gut, nutrient absorption can be impaired leading to nutrient deficiency.

Actions: If you notice symptoms associated with lactose intolerance, fatty stools, or blood glucose imbalance (such as feeling thirsty, tired, frequent urination, feeling dizzy, sweating, irritable, suddenly hungry), contact your GP. Eating three meals a day that are well balanced is vital. Your Nutritional Therapy Practioner can support you to identifying problem foods and give specific dietary advice to support your symptoms. Coeliac disease will be looked at in a separate article.

Large intestine

Once the food has been processed in the small intestine, it enters the large intestine. Here more nutrients are absorbed, including water, electrolytes and some vitamins, before the food is excreted as a stool (poo) via the rectum. There are no digestive enzymes secreted in the large intestine, however the final processes of digestion take place due to essential colonic bacteria.

Where digestive capacity is not as good as it should be, some nutrients may not have been absorbed earlier on in the digestive tract, leading to problems once they reach the large intestine. Unabsorbed proteins become fermented, releasing small amounts of ‘eggy’ gas. Vitamins may go unabsorbed due to dysbiosis of the gut bacteria.

Constipation can occur where fluid intake is low, if fluids are mainly diuretic such as tea, coffee, orange juice, or where the diet is high in gluten or low in fibre. Sedentary lifestyles compound the effect of low fibre, high gluten and high diuretic intake by slowing down the passage of foods (motility) even more. Symptoms include hard to pass stools, flatulence, bloating, fatigue, lethargy, headaches and hormonal imbalances.

Diarrhoea occurs due to disruptions in motility causing increased emptying of the bowel, digestive issues, microbial imbalance, food intolerance and poor gut integrity.

Some people experience alternating diarrhoea and constipation. This is often associated with IBS.

Actions: If you experience constipation, ensure you are drinking 1.5-2l of fluids a day, this does not include caffeinated drinks. Gradually increase your consumption of fruit and vegetables so that you are eating at least 5 portions of vegetables and 2 of fruit each day. Swap white bread, pasta, rice for wholemeal versions. Get moving, short movement breaks can make a big difference! If you experience diarrhoea or alternating diarrhoea and constipation, or have a diagnosis of IBS, seek the advice of a nutritional therapy practitioner to help you identify the underlying causes of your symptoms so that you can put in place the strategies helpful for you – one size does not fit all!

ask and expert sign in palm of hand of person in a white shirt

The actions outlined above can help you to make positive changes to your gut health. Many symptoms originate from poor gut health and need additional support. Working together we can make positive, achievable and long-lasting changes to your health though using the functional medicine approach to identifying the underlying causes of your symptoms and using scientific evidence-based approaches to support and optimize your health. If this would be of benefit to you, please get in touch.

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