Imbalances of the Digestive System
Sensory stimulation plays in significant role in our food choices. The sight and smell of foods initiate the body’s response. Salivary glands are stimulated prior to eating. Taste will further stimulate the release of digestive enzymes produced by the salivary glands of the mouth. Amylase to begin the process of carbohydrate breakdown and Lipase for triglycerides. Saliva also contains anti-microbial agents that help to prevent microbes from entering the body.
The body’s response to the feeling of hunger is not a simple relationship. For example it has been found that we tend to overeat when there is a greater variety of foods within our diet. That the body tends to crave carbohydrates when it is depleted of Serotonin. Low Serotonin levels are often associated with depression. Also the body finds a diet high in fats and sugars more satisfying. Often one has become out of touch with our body’s needs and can mistake the sensation of being thirsty as one of being hungry.
With the availability of foods 24/7 for many people this results in a diet that tends to be highly satisfying but with little nutritional variety. It is not surprising that in the traditional western diet of today that there is a tendency to be overfed but conversely lacking in many important nutrients. This has resulted in obesity levels increasing, with its associated decline in health.
The digestion of macronutrients requires a great deal of enzymatic processes. When food is initially ingested salivary amylase begins the breakdown of carbohydrates. The food then travels to the stomach where is encounters a more acidic environment, which also helps to kill off any unwanted microbes. It is here within the acidic environment that proteins begin to be broken down into smaller polypeptides prior to entering the duodenum.
Once the food leaves the mouth it then enters the stomach where Gastric acid provides an environment which facilitates the further breakdown of the foods. It also kills off any ingested microbes. Pepsin acts on proteins to break them down into peptides and Lipase acts on triglycerides to produce fatty acids and monoglycerides.
Hypochlorhydria is a condition in which the body has a low level of stomach acid. There are a number of factors that can cause this condition, for example; age, stress, medications, zinc deficiency, and surgery. This condition can result in a number of symptoms, such as; bloating, belching, burning sensation and flatulance within moments of ingesting a meal. It can also compromise the absorption of Vitamins B6 and B12, and the minerals, Iron and Calcium. It can also lead to bacterial overgrowth in the small intestine. It has been associated with the development of allergies, rheumatoid arthritis, Acne Rosacea and Asthma.
When acid from the stomach is sensed by the Duodenum (the next stage in the digestion of foods) Secretin is released which stimulates the Pancreas into releasing Bicarbonate and water, which neutralises the PH. Secretin also slows down gastric emptying and the release of Gastrin in the stomach. Gastrin stimulates the release of Hydrochloric acid.
Break down Carbohydrates
Proteases: Trypsin, Chymotrypsin, Elastase
Break down Proteins to Peptides
Break down Peptides into Amino acids
Breaks down Triglycerides that have been emulsified by Bile Salts into Fatty acids and monoglycerides
Breaks down RNA and DNA into nucleotides
The Small Intestines
The Duodenum is the first segment of the small intestine which receives Chyme from the stomach. Secretin stimulates the release of Bicarbonate and water which helps to neutralise the acidity. Cholecystokinin, produced by cells in the duodenal lining when fat and protein are detected, stimulates the Pancreas into releasing enzymes, and also the release of bile from the gallbladder. Cholecystokinin also slows down the emptying of food from the stomach and so indirectly contributes to a sense of fulness. The Pancreas produces a variety of enzymes that facilitate the breakdown of the food.
In the small intestine carbohydrates continue to be broken down into monosaccharides, and proteins into amino acids. Fats are broken down into monoglycerides, free fatty acids, and cholesterol. Bile salts from the gallbladder aid in the digestion of lipids (fats), through emulsification. Thereby breaking them down into smaller packages, called micelles. This helps Lipase to break down the lipids into monoglycerides and free fatty acids. These micelles will then disassociate allowing the monoglycerides and free fatty to be absorbed into the Enterocytes (intestinal absorptive cells). Any cholesterol contained within the micelles will also be absorbed. Most carbohydrates are easily absorbed when broken down into monosaccharides. Indigestible fibre is eliminated in the faeces.
The small intestines absorb the vitamins that occur naturally in foods. The Fat-soluble vitamins A,D,E and K are absorbed along with dietary lipids. B12 is absorbed within the Ileum of the small intestines. However a high dairy diet can impair the absorption of B12. The gut microflora can also synthesise B12 but it is not known how much of this, if any, can be assimilated by the body. Microflora produce about 50% of the Vitamin K required by the body.
- The body requires fats within the diet for a variety of functions, and for the absorption of the fat soluble vitamins; A, D, E and K.
- The Hypo-secretion of Pancreatic enzymes can lead to fat and protein maldigestion, malabsorption, and micronutrient deficiencies. For example B12 requires the protease enzymes to separate B12 from its carrier molecule. It then binds with Intrinsic factor for absorption. It will then need to bind to another protein carrier to enable it to be transported within the blood.
- Foods that have not been adequately digested can ‘leak’ into systemic circulation across the gut wall can lead to food allergies as they stimulate an immune response.
Absorption of amino-acids, monosaccharides, disaccharide, medium-chain fatty acids, and water-soluble vitamins occurs in the jejunum and ileum. They enter the portal vein and are delivered to the Liver. Longer-chain fats acids are packages into chylomicrons and then absorbed into lymphatic vessels before reaching the thoracic duct and the systemic circulation. Fat soluble vitamins are absorbed with fats.
- Carbohydrates are absorbed as monosaccharides
- Proteins are absorbed as amino acids, dipeptides and tripeptides
- Fats are absorbed as monoglycerides and fatty-acids
There are different methods whereby a substance is absorbed into the body;
- Passive Diffusion: water, short-chain fatty acids, gases H2O and CO2 (water and carbon dioxide)
- Mediated Transport which requires carrier proteins: Na/K. Sodium pumped out and Potassium in. Glucose and Galactose are taken in by facilitated diffusion of Na (Sodium). Fructose uses another transporter (GLUT5).
- Pinocytosis: fat droplets and larger molecules
- Paracellular: water and electrolytes.
Short-chain fatty acids are relatively water-soluble and can be absorbed directly. However large long chain fatty acids are enclosed within micelles. This process enables the fatty acids to be broken down into smaller packages which aids absorption. They are then combined again within the enterocytes to form triglycerides. These are packaged into particles called chylomicrons. The Chylomicrons are then transported into the lymphatic vessels and eventually into the bloodstream. Once in the bloodstream the enzyme lipoprotein lipase, contained in the cell walls of adipose and muscle cells, break down the triglycerides into free fats acids and glycerol. These breakdown products are then passed through the cell wall to be used for energy by muscle cells, or stored in adipose tissue. Any excess is carried to the liver.
Absorbed Glucose first enters the liver; some is used to make ATP (the energy currency of the body). Any excess is converted to glycogen (the storage form of glucose), and the remainder to form Fatty Acids. Together with any excess triglycerides they are then packaged to form VLDL (very low density lipoproteins) these will also contain cholesterol and are delivered through the blood where the triglycerides will be stored in adipose tissue, or used for energy. Removal of the triglycerides from cells will result in the production of an IDL (immediate density lipoprotein) which will travel to the liver. Through the action of the liver any remaining triglycerides will be removed, resulting in the formation of LDL (low density lipoproteins) which contains mostly cholesterol. These are then released into the bloodstream. Once attached to cells the cholesterol is taken up and used to form; plasma membranes, the myelin sheath around neurones, and for the synthesis of steroid hormones (cortisol, aldosterone, oestrogen and testosterone). Any excess cholesterol is removed from the cell and eventually forms HDL (high density lipoprotein) which delivers the excess cholesterol back to the liver, where it is used to form bile, and eventually removed from the body.
Plant foods also contains an undigestible component which is referred to as Dietary Fibre. It has two-forms. Soluble, which dissolves in water, and Insoluble, which does not. Both have beneficial effects towards health. Together they help remove excess cholesterol from the body, control blood glucose levels, decreases constipation, and thereby reducing the risk of developing haemorrhoids, and colorectal cancer. High fibre foods tend to be more filling than low fire foods thereby helping to control body weight. Increasing the amount of plant based foods into the diet will naturally increase the amount of fibre ingested.
Has two responsibilities, fermentation and absorption. The ascending colon produces short-chain fatty acids which are used as fuel for the enterocytes (the cells of the intestinal lining) Some of the short-chain fatty acids are absorbed and are utilised by other tissues of the body for fuel. In the descending colon water and electrolytes are absorbed, and it is here that stool is formed.
Within the colon can be found bacteria that are beneficial to health. They also synthesise certain B vitamins: biotin, folate and vitamin B12. However it is believed that the B12 produces is not assimilated into the body. As B12 is such an essential vitamin and is not contained within a Vegan diet. Therefore it is important that Vegans obtain the vitamin through supplements, for example in fortified plant based milks. The bacteria also synthesise Vitamin K which is required for blood clotting. Bacterial imbalances (Dysbiosis) can affect the levels of oestrogen.
Other benefits produced by microflora include:
- They produce P450 like enzymes which aid in detoxification.
- Enhance the absorption of nutrients.
- Combat diarrea.
- Interact with the immune system to improve resistance.
- They are antimutagenic and anti-tutor and are therefore protective from developing Colon cancer.
- They protect against developing what is referred to as ‘leaky gut’ (increased intestinal permeability).
Gut bacteria also require energy and nutrients. These are called Prebiotics and come in the form of Fructooligosaccharides, which include: onion, burdock root, asparagus, rye, Jerusalem artichokes, banana, sugar maple, Chinese chive, garlic.
- Compromised motility and peristalsis which are features of a low-fibre, high animal product diet can lead to excess gut permeability. Other factors are: radiation or chemotherapy as well as chronic stress. Gut permeability can also be affected by; poor nutrition, incompletely digested food, an imbalance of intestinal flora, drugs, fasting, food allergies, NSAIDs, whole for exposure before 4 months.
- Abnormal or increased intestinal permeability commonly seen in patients presenting with intestinal inflammation: for allergies and intolerance and celiac sprue.
- 60% of the immune system is located in the mucosa of the Gastrointestinal tract, GALT (gut associated lymphoid tissue). GALT reacts to invading pathogens through producing antibodies and cytokines which initiate an inflammatory response. However this response can also damage healthy tissue as well as killing invading pathogens.
- Oral tolerance is when the body becomes able to recognise food molecules and not respond to them. This is stimulated by commensal intestinal microbes. Supporting a healthy gut-liver axis
Problems Related to Digestion and Absorption
Imbalances can occur throughout the digestive system as a result of physical as well as functional causes. Nutritional support is concerned with essentially functional causes. These may occur due to deficiencies within the diet, or the inability of the body to utilise those nutrients. Some physical dysfunctions may be diet related, or exasperated by the diet, for example, Coeliac disease, where the individual will need to follow a strict gluten-free diet.
Genetic dispositions may also play a significant role as in Phenylketonuria, PKU, which is an inherited disorder, where the body's inability to metabolise Phenylalanine effectively results in an increasing levels in the blood, causing intellectual disability and other serious health problems. Therefore a strict diet consisting of a low-phenylalanine diet would need to be adhered to.
Gastric acid is required to begin the process of the digestion of proteins. Common signs and symptoms of low gastric activity include; bloating, belching, burning, and flatulence within 1 to 2 hours after meals, the sensation of fullness after eating, undigested food in the stools, and delayed protein breakdown. Other signs include foul smelling stools, chronic Dysbiosis (candida, parasites, abnormal flora), indigestion, diarrhoea, constipation, Iron deficiency, multiple food allergies/sensitivities, nausea after taking medications, post adolescent acne, and week cracked fingernails. If experiencing such symptoms it may be worth considering Gastric acid supplements.
Maldigestion due to the lack of digestive enzymes can result in, gas, bloating, abdominal pain, and diarrhoea. Foods that also help to stimulate digestion are; Green leafy vegetables, Ginger, Turmeric, Fermented foods, and Chia seeds. Sweet potatoes can also aid digestion. Digestive enzymes are required for Carbohydrate, Protein and Lipid digestion. Maldigestion can result in, gas, bloating, abdominal pain, and diarrhoea. Digestive bitters are an alternative to enzyme replacement. 10-20 dropped are often taken in water before the meal for the bitter principal effect via the stimulation of the vagus nerve. These may included Swedish bitters or herbal extract formulas containing gentian, dandelion root or artichoke.
Low bile salts are associated with; constipation, fat malabsorption, steatorrhoea, floating stools, fatty food intolerance, gall stones, and nausea. Bile excretion needs water 6 to 8 glasses a day. Hydrochloric acid may increase bile production. Olive oil stimulates secretion. Choleretics, agents that stimulate the flow of bile into the duodenum include; dandelion root (Taxaxacum officinale), Silymarin (Silybum marianum), globe artichoke (cynara scolymus), Turmeric (curcuma longa).
Also important for health is intestinal flora which acts symbiotically within the body. It plays an important role in gut health and also has a positive effect upon the immune system. Half of our daily requirement of Vitamin K is produced within the gut flora. It also synthesises Thiamine, folic acid, Biotin, Riboflavin, Pantothenic acid, and VitaminB12. Many of these vitamins are also within our diet, however it is unclear whether the body is able to the use the B12 produced within the gut flora. Microflora also produce SCFA (short-chained fatty acids) which are believed to be beneficial for cognition and emotion. They have anti-inflammatory properties, and are preventative of certain cancers, in particular colon cancer. They are also beneficial in controlling blood-sugar levels. Prebiotics help to promote the growth of healthy bacteria and can be obtained from; artichokes, asparagus, bananas, Barley, berries, chicory, garlic, green vegetables, legumes, oats, onions, soybeans, and wheat.
There are many conditions that have been associated with problems of increased gut permeability, for example; inflammatory bowel disease, Crohn's disease, food allergy and coeliac disease.
Supporting Gastrointestinal Health
The most common complaints to the Doctor tend to be related to gastrointestinal health. Many seemingly idiopathic syndromes have been found to be post infections or autoimmune conditions.
The gastrointestinal system is regulated in a number ways. It is particularly dependent upon enzymes to break down the macronutrients into smaller particles so that they can be absorbed. Hormones and neurons play a significant role in the release of these enzymes and other substances required, for example Bile which aids in the breakdown of fats. Fibre in the diet, found in fruit and vegetables, whole grain products, legumes, nuts and seeds, also help to regulate bowel movement, and also helps to lower cholesterol levels, control blood sugar levels and aids in the removal of toxins from the body.
A treatment protocol to support gastrointestinal Health
Oligoantigenic/Elimination Diet. If an individual suspects that they have an adverse reaction towards certain foods then an elimination diet can help to identify the causative element and help to restore gastrointestinal health. It can help in:
- Reducing inflammation
- Help restore gut permeability
- Improve digestive enzymes to aid in the breakdown of macronutrients
- Optimise the absorption of nutrients into body
- Modulate immune interactions
- Improve gastrointestinal microflora
The 4R program
- Removing factors that contribute to the situation, for example; Stress, certain hyper-allergic foods, and pathogens.
- Replacing deficiencies with the necessary digestive enzymes and hydrochloric acid required.
- Reinoculating with the beneficial bacteria, and prebiotics to support.
- Repair by reducing any inflammation present and supporting cells growth; Omega 3 fatty acid, zinc. Vitamin B5 and Vitamin D are used as supporting supplements.
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