Your gut tends to be discreet. It may occasionally gain your attention with gurgling or gas, but it usually remains invisible and ignored.

Meanwhile foods are ever temptingly on display. They can trigger programmed visual, salivary and emotional responses. You select, swallow and forget. Though some people have the benefit of chronic discomfort to inspire recall and analysis (see TIPS: Pain).

Without good gut health, myriad problems with digestion and elimination can occur. Perhaps less obvious is the link with immunity, pain, vitality, hormones, mood and memory: almost every suboptimal state from acne and arthritis, to anxiety and Alzheimer’s.

The gut comprises the small and large intestine. It starts where the stomach ends. Bend your left elbow and where it hits your chest is the stomach area. The small intestine has 3 main sections starting with the duodenum, then the jejunum and lastly the ileum. Nutrients are absorbed from particular sites such as iron in the duodenum, and B12 in the ileum. At its end it connects with the start of the large intestine (bowel or colon). This rises up on your lower right near the pelvic bone (ascending bowel), moves horizontally under your belly/navel area (transverse bowel) and down on the left side (descending bowel). It ends with the rectum and narrow muscular anus to control continence.

The small intestine is about two fingers wide with a cavity called the lumen. Coiled and greyish purple, it fills up your lower belly with some 7 metres of length. Exceedingly thin, it is minutely folded and lined with millions of finger-like projections called villi to maximise absorption. The villi contain lymphatic vessels (to regulate fluids; transport fats and wastes) and blood vessels (to transport other nutrients). The reddish large intestine is only 1.5 metres long but is named for its greater 6-7 cm width. If opened up, the entire gut is larger than a tennis court.

An average meal will spend 1½ hours in the stomach. Carbohydrates are the fastest to be processed and leave; proteins are next; fats take the longest. Enzymes and highly acidic stomach juices turn the contents into a creamy mush which passes into the duodenum. Alkaline chemicals from the gut, pancreas and liver further break down the soupy mix into particles that can be absorbed into the (alkaline) bloodstream – a process of about 4 hours. The soft, elastic gut is made of membranes controlled by nerves and muscles. About 90% of what you eat is digested and absorbed here: most fats, all amino acids (from protein) and monosaccharides (simple sugars). This passes into blood vessels and is collected by the hepatic vein carrying its contents to the liver: the master chemist that turns nutrients into fuel and building materials.

Digestive wastes and old cells are pushed into the large intestine. It absorbs water and electrolytes to produce solid feces over 24-30 hours. Any roughage scours the bowel wall of damaged or cancerous cells. Billions of good guy bacteria ferment their favourite food: fibre. The feasting creates an environment that inhibits pathogens (viral, bacterial, fungal and parasitic); produces some vitamins (especially K and biotin) and fatty acids (used as bowel fuel and by the liver to produce HDL cholesterol to remove artery-blocking LDL). As well as unwanted invaders, antibiotics destroy the 700 plus species of friendly bacteria. This encourages dysbiosis where yeast and other undesirables proliferate. Probiotic supplements containing acidophilus and other strains can help repopulate the bowel. Foods such as psyllium, slippery elm, linseed (not the oil) are prebiotics. They supply specific types of fibre so good bacteria feast and multiply.

How Is Your Gut Intelligence?

All gastrointestinal (GI) organs have a critical lining called the mucosa. This contains tiny glands that produce digestive juices. You need some 9 litres daily. Good quality fluids, fats, fat-soluble vitamins (A, D, E and K) are imperative for mucosal maintenance. Most life-sustaining action takes place on lining and surface cells called epithelial which protect, sense, secrete, absorb and transport – or can trigger tumours. These cells are also found in your top layer of Skin, which provide clues to the state beneath. Such tissue needs Essential Fatty Acids (TIPS: The Fats of Life), minerals such as silica and Zinc for repair. Also alertly at work in the epithelium are endocrine cells which sense the lumenal environment and adjust hormone levels accordingly. The GI tract is the largest endocrine gland in the body, responding to a wide range of stimuli – perhaps the physiology behind ‘gut feelings’. Its hormones control secretion of stomach acids (for iron, folic acid, B12 absorption; initial protein breakdown); pancreatic enzymes (for protein, fat and carbohydrate breakdown) and bile (for fat digestion; liver and gallbladder health; toxin elimination). Chronic diarrhea, bloating and gas indicate poor absorption.

This intelligent lining selects which particles can pass, be prohibited or destroyed. Its cells are normally joined by tight junctions built from protein. If the lining is compromised it can become too permeable, a condition termed intestinal hyperpermeability or leaky gut. Then undigested food particles, pathogens, toxins and antigens (substances that stimulate antibodies and encourage allergies) break between cells – rather than through them into blood or lymph. These circulate dangerously with some pathogens piggy-backing on antigens to enable escape.

The lymphatic system is far more extensive than the blood system and is meant to filter impurities from it. It also produces white blood cells to target and destroy invaders. Too much debris, too many poor quality fats, too little good quality fluid will impede its work. Especially critical is regular exercise and deep breathing. While the cardiovascular system has the heart as a pump, the lymphatic system relies on the pumping action of muscles to efficiently move its contents.

The response to gut leakage is inflammation and the release of markers called cytokines. These get cycled back to the gut and cause further irritation. Many people experience the process with classic digestive symptoms such as gas, bloating or bowel disturbance. But due to inherited or lifestyle reasons any area can be your inflammatory registry point. The liver must process unfriendly particles, stretching its detoxification resources. Its oxidative stress is linked with insulin resistance, obesity and osteoarthritis. Along the gut lies 80% of your immune system which can become over-reactive (as with auto-immune disorders such as chronic fatigue, lupus, fibromyalgia, coeliac disease, rheumatoid arthritis and rosacea) or under-functioning (hay fever; nasal drip; frequent, fleeting or lingering colds, sore throats, bronchitis).

Or your gut state may primarily affect your moods – with stress in turn weakening gut cells. 100 million gut neurons send messages to keep the brain up-to-date. The gut contains every class of chemical messenger or neurotransmitter found in the brain. Epithelial cells secrete 95% of your feel-good serotonin, which is low in people with depression; some sleep, learning and chronic pain problems. Medications such as for mood disorders and cancer can alter serotonin levels and thus lead to nausea and bowel problems.

Steroids such as cortisone, radiation treatment, aspirin and other pain relievers can also increase permeability. Inflammation is further linked with skin and cardiovascular problems, asthma and weak bones. Intestinal wall damage may lead to the pain, weakness, diarrhea and bleeding of Inflammatory Bowel Disease (IBD) such as colitis and Crohn’s. These are linked to an over-reactive immune system along the GI tract. Irritable Bowel Syndrome (IBS) may have similar symptoms but no observable damage to the gut wall. With Coeliac Disease the gut cannot process grains such as wheat. The immune system produces gluten antibodies which attack the villi leading to malnourishment.

Feed Both of Your Brains

GI motility relies on the rippling contraction and relaxation of muscle. This looks like an ocean wave moving through links of sausage. Squeezed pockets of air or liquid may elicit gurgling. Gas is produced by bowel bacteria trying to digest food the small intestine hasn’t managed (primarily sugars and starches). Muscles may weaken with low mineral levels, and a bulge in the intestinal wall or hernia may develop. Muscle fibres are connected by gap junctions. They work electrically to couple and decouple in sectioned, coordinated contractions while mixing contents. This requires balanced electrolytes: dissolved minerals that conduct electricity. Within 15 minutes of eating there is increased electrical activity in the bowel.

Muscle governing minerals are conveniently also nerve regulating ones, chiefly: potassium, sodium, calcium, magnesium. Their levels can be evident according to your bowel function, blood pressure, sleep, acidity, nails, menses and stress. The enteric (gut) nervous system is termed the ‘second brain’. It has some independence so digestion and survival is ensured if the ‘first brain’ is injured. The gut and brain form from the same clump of tissue that divides during fetal development. Your longest cranial nerve – the vagus nerve -stretches between them. Nerve cells communicate with gut receptors to get enzymes flowing and food propelled. During sleep both the brain and gut have 90 minute cycles. In the brain, slow wave sleep is interrupted by periods of rapid eye movement (REM) when dreams occur (Sleep). In the gut, slow waves of muscle contractions are punctuated by bursts of rapid activity. Many people with stomach or gut problems report poor sleep, or feeling unrefreshed. One brain influences the other.

Ensure balanced nerve and muscle minerals. Glutamine can assist mucosal repair; zinc helps ‘tighten up’ weak junctures; kiwifruit fibre can encourage new epithelial cells. Take time to prepare for and eat meals. The processes of digestion initiate in both brains as you just think about food. Honouring such simple pleasures triggers positive endocrine responses and antidotes stress. Contact this office for an allergy test so you can give your gut a structured holiday period from reactive substances. Repopulate gut flora. Especially take supplemental probiotics when travelling and after antibiotics. Try yoga; break up sedentary periods of over one hour with activity. Eat, drink, move and laugh well – your gut is listening.