Digestive Health

No one likes to talk about their bowels - the rumbles, the grumbles and lets not even start on ...flatulence. But what’s normal bowel behaviour and what’s considered tummy trouble?

The story of digestion...

The notion that humans are just one long tube is sadly somewhat true. Simply put, food enters through the mouth and leaves through the anus. But, what happens in between?

Our digestive system comprises of the stomach, the small and large intestine. However, some argue that digestion begins in our mouthes. When food enters our mouth, it is chewed or masticated into smaller pieces by our teeth. Our teeth are specifically designed by evolution to grind and crunch all our food into smaller particles. It does so, so that it is easier to digest. This is because there is a larger surface area on each particle of food matter. This improves the efficiency of digestion. Furthermore, human saliva contains an enzyme called amylase that begins the breakdown of starch within the mouth. This is the first stage of digestion complete. The food is then swallowed down the oesophagus to the stomach.

The stomach is the second stage of the digestive system. This is commonly known as the acidic portion of the digestive system. Cells within the stomach release hydrochloric acid onto the food to further digestion. The stomach is a muscle, therefore, it breaks down food via a mechanical contraction. Within the stomach, other enzymes are releases, mainly proteases, such as pepsin. These are enzymes that enzymatically breakdown proteins. Then, Lipases are secreted to breakdown fats and lipids. These enzymes include renin and gastric lipase. Once this stage has reached completion the food that once entered your mouth as a solid form is a thick and sticky liquid. Theviscousfluidthenpassesthroughtheexitofourstomachknownas the pyloric sphincter. This is a 2mm hole that leads to the small intestine. 

The small intestine includes the duodenum, jejunum and the ileum. The food then moves along the tube via peristalsis. This is a sequential contracting of the intestine to move the food through the small intestine and onto the next stage. The small intestine is specially designed to improve absorption of nutrients by increasing surface area. Here the food meets the alkaline portion of the digestive system whereby alkaline bile is released onto the food, thus neutralising it. Bile acids are released with lipase in order to aid the breakdown and digestion of fats within the GI (gastrointestinal) tract.

Finally, the large intestine. This is made up of the caecum, colon, rectum and anus. This is the final stage of digestion. Some water is reabsorbed along with a few nutrients. Finally, faeces are formed and pass out the anus. This is made up of insoluble fibre and undigested food.

Problems with digestion

One of the most common complaints that Nutritionists hear are complaints regarding digestion. Typically, most people will jump to the idea that gluten or dairy are the cause of all their problems and that excluding these elements from their diet will solve all these problems - let’s explore that idea.

Reduced motility can cause issues such as bloating, constipation, inconsistent appetite and accidental soiling. It is thought to be caused by a neural issue with less stimulation to the peristalsis muscle movement within the gut. This can be one cause of digestive distress.

IBS or Irritable bowel syndrome is a common digestive complaint. Although the cause of the disorder is unclear, what is clear is that the bowel can go through periods of constipation or increased laxity. Research speculates that this may be caused by some fermentable foods, however, this is yet to be confirmed as the cause. Symptoms of IBS include diarrhoea, constipation and cramping of the gastrointestinal regions. The best thing for those suffering from IBS is to follow a FODMAP diet. FODMAP stands for Fermentable Oligosaccharides Disaccharides monosaccharides and polyols. Yes, this sounds like a load of gobbledygook! However, this is the idea that you can reduce the fermentable sugars in the diet to improve symptoms. These are foods that can create flatulence bloating and cramping. This includes foods such as onions, cauliflower, apples, ripe bananas, legumes and beans.

Reduced absorption diseases can be found throughout the majority of the GI tract. This can be caused by reduced enzymatic activity and malformations in the structure of the GI system. In turn, this reduces the absorption of nutrients which can cause deficiencies, fatigue and related disorders in sufferers. For example, Vitamin K is absorbed in the bowel or large intestine. If a person has inflammatory bowel disease they struggle to absorb enough vitamin K. Vitamin K is required for blood clotting and therefore they may require Vitamin K supplementation.

Other issues can include dysphagia (problems swallowing), dental and periodontal issues, gastroesophageal reflux disorder and many others.

How to keep digestion regular and healthy?


Fibre is well known for its effect on digestive health. Fibre can be soluble or insoluble and is used to bulk up the faeces and allow it to pass easily through the gut. Fibre is typically found in whole grains such as wholegrain pasta, bread, rice, nuts, seeds and also in the skins of all fruits and vegetables. At present the UK does not eat close to enough fibre, typically taking preference for white bread and pasta over the more beneficial whole grains. Research shows that females in the UK eat on average 17.2g fibre/day, whereas men eat 20.1g/day. The UK recommendation is 30 grams of fibre/day, and very few reach this. The concern being for digestive health and discomfort but particularly the correlational link between colorectal cancer and decreased fibre intake. Studies have shown that sufficient dietary fibre in a humans diet significantly reduces the risk of colorectal cancer.


Supplements for digestion are incredibly varied in their effects. To reduce flatulence and decrease bloating the best supplements include fennel, peppermint and activated charcoal. To improve digestive movement, the best supplements are those rich in fibre, therefore we recommend psyllium husk or a powdered fibre supplement, i.e inulin, citrus fibre etc. Lastly, to improve gastric digestion, we recommend digestive enzymes (papain, bromelain, lactase, lipase etc), or Calcium and chloride supplements, Calcium and Chloride both carry EFSA (European food safety authority) approved health claims. Calcium contributes to the normal function of digestive enzymes. Whereas chloride contributes to normal digestion by production of hydrochloric acid in the stomach.


Probiotic is an area of emerging research with nutritional sciences. It’s the idea that the natural gut flora or bacteria can be repopulated with live bacteria in order to improve health. In the industry, we call the ‘microbiome’. Changes in the microbiome have been linked with illnesses or disorders such as obesity, diabetes, and some mood disorders. As for digestion, studies have shown that malnutrition isn’t always caused by a lack of quantity and or quality of food, but the gut bacteria within the gut. In particular, the bacteria are used for the metabolism and fermentation of fibres. Studies show that eating a microbiome-friendly diet improves the absorption of nutrients.

Lactobacillus acidophilus is a type of probiotic. A live bacteria consumed in order to stimulate and repopulate the microbiome. One study showed vast improvement in digestive health and discomfort in IBS sufferers once treated with a mix of Lactobacillus strains, including Lactobacillus acidophilus.


Lastly, intolerances are well known and well claimed amongst the general public, Both gluten and lactose intolerances are totally real. However, they should not be claimed by all. Speak to your Nutritionist and Doctor for advice on whether you have the disorder, how to manage it and how to avoid deficiencies.

Don’t ignore poor digestion and absorption it doesn’t have to be this way! Digestion doesn’t have to mean discomfort.

Oxford Handbook of Nutrition and Dietetics











Harriet Hunter, ANutr. Nutritionist