Digestive Disorders
Our digestive tract is a highly sophisticated system that uses chewing and churning, enzymes and water, acids and alkalis to break down the complex foods we eat into small, easily absorbable molecules. The body then selectively filters and absorbs these molecules according to its needs. The unabsorbed portion is then passed out through stools and other waste products.
When we chew food, the pieces are cut, torn and ground into smaller particles, while saliva is secreted and mixed with food in the mouth. The saliva is alkaline and contains an enzyme called amylase that breaks down starch. It also has antibiotic-like substances called lysozymes and white blood cells, which help destroy micro-organisms like bacteria and viruses in the food.
Proper chewing of food facilitates digestion by ensuring the digestive enzymes are mixed intimately with the food particles. This enables the enzymes to break down the food into an absorbable form. It also allows the lysozymes and white blood cells to seek out invading bacteria and viruses and destroy them before they can attack the body.
Food then passes into the stomach through a tube called the oesophagus. In the stomach, gastric juices containing hydrochloric acid and enzymes are secreted to sterilise the food and to break down protein. This hydrochloric acid has two essential functions: It helps break down proteins and destroys microorganisms like bacteria, parasites and viruses that may be present in the food. Hence, the use of medication to reduce or neutralise stomach acid secretion deprives us of this essential protective mechanism and makes us more prone to infections in the stomach and intestines. Heliobacter pylori is a bacteria often found in the gastric secretions of people with peptic ulcers and is often mistakenly blamed as a cause for peptic ulcers.
Drugs that reduce stomach acid secretions allow these bacteria to establish themselves in the stomach lining. An established H. pylori infection may need to be treated with antibiotics for an ulcer to heal. The stomach also secretes an enzyme called pepsin, which helps digest protein. The stomach churns the food into a paste, mixes it, pours fluid into it, and then acts as a reservoir, gradually releasing small quantities of food into the duodenum.
The duodenum is the first part of the small intestine, where alkaline fluids like bile, pancreatic juices, and intestinal juices are secreted. These juices are alkaline and rich in enzymes, carrying out a significant portion of digestion. They change the food's pH from the highly acidic stomach to the highly alkaline. This alkaline fluid can destroy any acid-resistant bacteria that have survived the transit through the stomach.
The digestive process is carried out by enzymes that break down complex foods like protein, carbohydrates and fat to amino acids, simple sugars like glucose, glycerine and fatty acids. An enzyme is like a key that unlocks small molecules like glucose from starch by adding water. A constant secretion of fluid accompanies the digestion of food. All these secretions aim to break down and liquefy the food into a dilute solution containing glucose, amino acids, fatty acids and ions, as the body can only absorb the nutrition in this form.
Protein molecules comprise several thousand to hundreds of thousands of amino acids. An enzyme acts like a key and helps break down the protein for absorption by unlocking these molecules by adding water to the protein and setting free an amino acid. The liberation of each amino acid requires a molecule of water, so the breakdown of dietary proteins for absorption requires a large amount of water in the digestive system. A starch molecule comprises several hundred thousand glucose molecules linked together by removing water in the plant to make it unabsorbable and insoluble in water. An enzyme helps break down starch (contained in Cereals and potatoes) into glucose by adding water to the starch molecule and unlocking a glucose molecule for absorption.
Each enzyme molecule is capable of unlocking several thousands of glucose molecules in a few seconds. This process isadding many thousands of molecules of water to starch to convert it into glucose, carried out by the only form in which the body can absorb carbohydrates. The limiting factors in digestion are water availability and the fact that the enzyme has to move from molecule to molecule, unlocking it.
Digestive enzymes work better and faster in a liquid medium. Hence, liquid foods are easier to digest than solid foods. This fact is made use of in folk wisdom and hospitals where invalids, infants, and older adults are fed liquid diets like soups, porridge, gruel, khichdi, etc., as they are easier to digest. The commonly held belief that one should not drink water with meals is thus a fallacy.
Drinking water with meals helps digestion, making the process of digestion quicker and more efficient, allowing better digestion and absorption of food. It also helps to prevent overeating. The body excretes most of the toxic waste products of metabolism and many drugs through the urine. The kidneys also balance the body's pH by excretion through the urine. An adequate water intake ensures that the body can digest food well and eliminate waste products of metabolism through the Urine. Good removal of waste and toxic products from the body keeps us healthy.
Water intake should be between 3 and 4 litres per day, increasing with exercise and excessive perspiration. In cooler climates, an intake of 2.5 to 3 litres is essential for maintaining good health. A daily urine output of 1 to 1.5 litres indicates that the water intake is adequate.
The digested and liquefied food is then absorbed throughout the small intestine. The remaining food matter is then dehydrated further and solidified to be passed out of the body as Faeces.
Food digestion takes between 8 and 18 hours, depending on the type of food eaten. Sweets, fruits, and highly processed starch are digested and absorbed within 3 to 4 hours. High-protein and fatty foods take 12-18 hours for digestion and absorption. Salads and high-fibre foods take 12-24 hours for digestion and absorption.
The faeces are an essential channel of elimination as the liver eliminates toxins, heavy metals, pesticides and many waste products from the breakdown and repair of the body through the bile. These waste products give the faeces their brown colour. High-fibre foods aid this elimination, while highly processed foods encourage the reabsorption of these waste products, leading to illness.