Digestion is the process by which the body breaks down food in order to obtain the 50+ nutrients needed for optimal health. There are two aspects of digestion: 1) the mechanical breakdown via chewing and the action of stomach contractions and 2) the chemical breakdown by the enzymes that are excreted in the mouth, by the pancreas, and the brush boarder enzymes that are excreted along the length of the small intestines. Some chemical breakdown occurs as well by stomach acid. The ultimate goal is to ensure that nutrients are made available for absorption.
Digestion begins in the mouth with the mastication of food by our teeth, at the same time; an enzyme called amylase, that digests carbohydrate, is excreted by the salivary glands. Saliva helps to moisten and compact food so that your tongue can push it to the back of your mouth where it can be swallowed; sending the food down the slide of your gullet (esophagus) into your stomach. Food then enters the stomach where it encounters a potent blend of enzymes, hydrochloric acid, and mucus.
One stomach enzyme — gastric alcohol dehydrogenase — digests small amounts of alcohol, an unusual nutrient that can be absorbed directly from your stomach into your bloodstream even before it’s been digested. The primary purpose of the stomach is to breakdown proteins and fats into their basic components: amino acids and fatty acids – the digestion of carbohydrate basically comes to a stop since the stomach acid neutralizes the enzyme [since it’s a protein and proteins are broken down in the stomach] amylase that was excreted with saliva.
Next stop, small intestines. A lot goes on in the 6 metres, or 20 feet worth, of tubing that makes up this important part of the journey. The gallbladder secretes bile which helps to digest fat. The pancreas releases all the enzymes needed for the digestion of fat, protein and carbohydrate in the partially digested food that leaves stomach. There are also enzymes found on the surface of the intestines, along the length of it, to further help digest these nutrients. The small intestine is divided into three sections where absorption of nutrients occurs at different areas along its length.
Duodenum The first section of the small intestines; some 25 – 38 cm (10 – 15 inches) long, is the duodenum which connects the stomach to the jejunum. Vitamin A, B1, the minerals iron, and calcium, simple sugars (the end products of carbohydrate digestion), amino acids (the end products of protein metabolism), and fatty acids (the end products of fat digestion) are primarily absorbed here.
Jejunum The middle part of the small intestines, sometimes called the mid-gut; much longer than the duodenum at 2.4 metres (8 feet) is the jejunum. More of the simple sugars, amino acids and fatty acids, the water-soluble vitamins (vitamin C and the rest of the B vitamins, other than vitamin B12), the fat soluble vitamins D, E and K, the minerals copper, zinc, potassium, iodine, calcium, magnesium and phosphorus are absorbed.
Ileum The last part of the small intestines, the ileum is about 3.7 metres, or 12 feet long. Here vitamin B12, and the
Myth-busting! There has been a lot of chatter of late on the benefits of eating raw foods for their enzyme content as well as taking digestive enzyme supplements to aid with digestion. It has also been suggested that humans are born with a finite number of enzymes and that dietary enzymes are needed to ease the burden of digestion as the body’s own enzyme stores are depleted over time. Nothing could be further from the truth! Enzymes found in plants are produced by plants for their own metabolic needs and are not design for human digestion.
Furthermore, these enzymes, like salivary amylase, are rendered inactive by stomach acid. This is because enzymes are proteins, and proteins are broken down by stomach acid into smaller subunits. Additionally, cells that make up the human digestive system contain genes, as part of our DNA, and genes produce enzymes as needed. Enzymes are proteins, and our genes sole purpose is to produce proteins on demand. A similar example is with red blood cells, the main transporter of oxygen. Red blood cells have a life cycle of 120 days, and are constantly being synthesized to maintain levels. When new red bloods cells are needed, genes in the cells of the kidneys are stimulated to produce a hormone [protein] called erythropoietin which in turn stimulates the bone marrow to produce red blood cells. To suggest that we are born with have a finite number of erythropoietin molecules in our kidneys is absurd.
It would be very inefficient and more importantly, impossible because the kidney wouldn’t have enough space to store them. This is no different for the pancreas; it simply isn’t big enough to store enough enzymes for a month, let alone a life time or part thereof. There are some medical conditions, such as cystic fibrosis, where this is an exception and pharmaceutical grade digestive enzymes supplements are required, but for the average person, supplemental enzymes are not needed nor do they benefit digestion as far as I’ve been able to determine [I am open to review any randomized, placebo-controlled research that suggests otherwise]. The body will not ‘run out‘ of digestive enzymes.
Large intestine or colon. The chyme [the mostly digested food] moves from the small intestines through the large intestine, bacteria digest substances in the chyme that are not digestible by the human digestive system. Bacterial fermentation converts the chyme into feces and releases vitamins including vitamins K, B1, B2, B6, B12, and biotin. Here the minerals chloride, sodium and water are also absorbed.
5 tips for better digestion!
1. Mindful eating
Slow down and chew slowly. Too often people eat in a rush, take large bites and swallow poorly chewed mouthfuls of food along with air. The result: belching and a general uncomfortable feeling. Chewing is an important way to help make food more digestible by breaking it down into smaller pieces allowing both the salivary enzymes and stomach acids to do their job. Eating is supposed to be enjoyable – relax!
Drinking fluids has not been proven to ‘dilute’ stomach acid or enzymes but limiting fluids at meal time will help to prevent feeling bloated or full. Drinking some water or other beverages with a meal can help to moisten food and make it easier to swallow.
Including a source of fiber at every meal will ensure you meet your daily fire requirement [at least 25 g for women and 35 g for men]. Fiber helps to prevent and relieve constipation by helping to move food through the digestive tract. Fiber also acts as a food supply [prebiotic] for the bacteria that live in our digestive tract which are needed to help digest food, support the immune system, keep the number of unfavourable bacteria in check and to keep the bowels healthy in general. Be sure to include 100% whole grains, 100% whole grain breads, cereals, rice and pasta, fruits and vegetables, pulses [chickpeas, lentils, beans and peas], as well as, nuts and seeds. Try ground flax and chia.
Ginger has a long standing history for aiding all aspects of digestion including: indigestion, gas and bloating, nausea, diarrhea, and irritable bowel syndrome. It turns out there is some truth to this home remedy. A study in the European Journal of Gastroenterology and Hepatology, found that ginger stimulates digestion by speeding up the movement of food from the stomach into the upper small intestine. This is probably how ginger exerts it’s most well-known benefit: reducing nausea. Try including home-made ginger tea more often and include dried or fresh ginger in your meals. Use fresh ginger to add some zing to your juices. It pairs well with apple, carrot and beet.
Tip: to make fresh ginger tea, simple take an inch of fresh ginger root and slice it thinly, boil in 2 cups of water for 10 minutes. Enjoy with fresh lemon and honey.
5. Fermented foods and probiotics
A great way to support your gut bacteria is to include some authentic fermented foods such as kefir, yogurt with live active bacterial cultures, sauerkraut, kimchi, or fermented vegetables such as carrots, celergy, beets and more. You may want to include a good probiotic if you’re about to take a course of antibiotics, have taken a recent course, or are experiencing general indigestion. It’s best to speak to a qualified health professional who can help you choose the right one for your needs.
Photo credit: Pyramid Ferments