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Apr 10th, 2006 - 12:14:17 |
In the early 1930s, Dr. Edward Howell of the Lindlar Sanitarium postulated his theory about food enzymes and coined it the food enzyme concept. He contended that the act of cooking or processing food kills the enzymes present in raw food, thereby putting the entire digestive burden on the body. This leads to an imbalance in the production of metabolic enzymes according to the law of adaptive secretion. His research showed that humans in comparison to animals have a disproportionate amount of digestive enzymes. He believed that nature's plan call for food enzymes (enzymes in raw food) to help with digestion instead of forcing the body's digestive enzymes to carry the whole load. He wrote a number of papers about his work and also published a book in 1946, The Status of Food Enzymes in Digestion and Metabolism. The book was then reprinted with the title Food Enzymes for Health and Longevity. His pioneering theories about food enzymes fervently advocate using supplemental digestive enzymes with a cooked and processed food diet.
Today, many people take supplemental digestive enzymes to help them digest their food resulting in a healthy lifestyle. Over the past several decades many researchers have used Howell's theories as foundation for their research. Modem science has proved the efficacy of supplemental digestive enzymes and their impact on human health.
Before we talk about the recent developments and studies in the field of supplemental digestive enzymes, I would like to discuss the general role of enzymes in digestion. Have you ever wondered why your stomach grumbles when you are hungry or why you start salivating when you smell your favorite food? These are physiological responses mediated by hormones in anticipation of food.
The primary neurotransmitter or hormone secreted at the sight, smell or taste of food is acetylcholine. Acetylcholine and other hormones like gastrin and histamine are mainly responsible for the secretion of stomach acid and pepsinogen. This is the beginning of the digestive process. The presence of food in the mouth or just the smell of food initiates the production of saliva. The digestion of food starts in the mouth, continues in the stomach, and is, in effect, completed in the small intestine. The actual chemical reactions that are necessary for digestion of food are catalyzed by a group of enzymes called digestive enzymes.
The chemical reaction catalyzed by digestive enzymes is called hydrolysis. Hydrolysis is defined as the addition of water across a chemical bond resulting in the breaking of that bond. Almost all food is digested or broken down by the process of hydrolysis. These reactions can occur without enzymes too, so why do we need digestive enzymes? Well, without digestive enzymes, digesting a T bone steak could take a lifetime. The
function of digestive enzymes is to speed up the process of digestion to a biologically significant level. There are three main types of digestive enzymes: proteases, amylases, and lipases. Proteases are responsible for the digestion of proteins, amylases for carbohydrates, and lipases for fats.
The very first enzyme that food encounters in the process of digestion is called ptyalin, an a amylase secreted by the salivary glands in response to the presence of food in the mouth. The pH of saliva is 6.0 7.4, which is optimum for ptyalin activity. Ptyalin works in the mouth and keeps working in the stomach until the stomach pH becomes acidic. It takes 1 2 hours before the stomach acidity gets low enough to inhibit amylase activity. The salivary glands also secrete a lingual lipase, but the amount is very small and the activity is almost undetectable. Along with its enzymatic properties, saliva also serves as a lubricant and protects the walls of the gut from food particles.
This brings up another interesting question: How does food move in your gastrointestinal tract? Gravity does contribute a little to the movement of food, but the main driving force is a phenomenon called peristalsis. Your body sends waves through the GI tract at regular intervals propelling the contents downward. The wave distends and contracts the gut at fixed intervals of time and distance. The phenomenon is analogous to pinching a soft pipe full of sludge at different points in a single direction. This process is mainly responsible for the movement of food in the GI tract.
The next major step in the human digestive process is the digestion of proteins in the stomach. The tubular glands of the stomach secrete hydrochloric acid, pepsinogen, intrinsic factor, gastrin, and mucus. The pH of the gastric secretions of the stomach is 1 3.5. Pepsinogen is the inactive form of the proteolytic enzyme called pepsin. Pepsinogen is activated when the stomach pH falls to about 3. Stomach acid serves a dual purpose, not only does it activate pepsin but it also denatures the proteins, making pepsin's job easier. The acid also kills many of the exogenous bacteria that might be harmful to the body. The intrinsic factor is required for the absorption of vitamin B 12 and gastrin is responsible for signaling the pancreas to produce digestive juices. Small quantities of other enzymes are also secreted in the stomach juices: gastric lipase, gastric amylase, and gelatinase.
The partially digested food mass, called chyme, then passes on to the duodenum. There it mixes with bile, which is secreted by the liver and functions as an emulsifying agent for fats, making them available for digestion by water soluble pancreatic lipase. The presence of acidic chyme in the upper portion of the small intestine jump starts the pancreas into action. The pancreatic secretions mainly contain various digestive enzymes, insulin and copious amounts of bicarbonate ion. The bicarbonate neutralizes the acidic chyme bringing its pH up between 7.5 and 8. The neutralization process is important since the pancreatic enzymes have optimum activity between pH 7 and 8. The various digestive enzymes secreted by the pancreas are: trypsin, chymotrypsin, carboxypolypeptidase, lipase, amylase, cholesterolesterase, phospholipase, various elastases, and nucleases. While in the pancreas the proteolytic enzymes such as trypsin, chymotrypsin and carboxypolypeptidase exist in their inactive forms namely tlypsinogen, chymotrypsinogen, and procarboxypolypeptidase. This is very important since the active forms of these enzymes would digest the pancreas themselves.
The pancreas also secretes a trypsin inhibitor to protect itself in case there is any trypsin present. Trypsinogen, when released in the small intestine, is activated into trypsin by an enzyme called enterokinase. Enterokinase is secreted by the intestinal mucosa when chyme comes in contact with the mucosa. Trypsin in turn can autocatalytically activate trypsinogen and other pancreatic proteases. Trypsin and chymotrypsin then cleave the partially digested protein into smaller peptides but not individual amino acids. Finally, carboxypolypeptidase works to release individual amino acids from smaller peptides. Thus all the proteases have to act in tandem on food protein to produce amino acids that can be absorbed by the body.
Pancreatic amylase hydrolyzes carbohydrates such as starches and glycogen to give disaccharides and trisaccharides. These di and trisaccharides are then converted into simple sugars such as glucose, galactose, fructose, etc. by various enzymes such as maltase, invertase, and lactase. Pancreatic lipase is responsible for digestion of fats wherein it releases fatty acids and monoglycerides from neutral fat or triglycerides. Cholesterolesterase releases fatty acids and cholesterol from cholesterol esters whereas phospholipase splits fatty acids from phospholipids. Most of the nutrients are absorbed in the small intestine and the nutrient deprived chyme then passes on to the large intestine.
RESILIENT BUT AILING
The human digestive process is very resilient and can adapt itself to many types of food. In spite of that, a large portion of the Western population suffers from some kind of digestive disorder. Gas, bloating, heartburn, constipation, et al. are just some of the digestive maladies that people endure on a daily basis. Now, if our digestive system is so resilient and adaptable, why do we still face these digestive problems? Stress and medication do play a role, but the main problem is the modern diet.
The modem diet mostly consists of cooked and processed food that is devoid of all the natural enzymes and has lost many of its nutrients. This diet could not only be implicated in the most common problems associated with digestion but can also cause or exacerbate serious disease conditions like celiac sprue, irritable bowel syndrome, acid reflux, and even autism.
The modern diet and lifestyle put an unusual stress on the digestive system resulting in incomplete digestion of food and malabsorption. We are not receiving all the nutrients from food first of all because our food is nutrient depleted and secondly because our digestive system is unable to extract all the nutrients from food. A majority of the population takes some kind of vitamin and mineral supplement to make up for the loss of essential nutrients in food. Incomplete digestion can be overcome by taking supplemental digestive enzymes.
Our bodies are machines and just like machines they age and become less efficient. Studies have shown that the secretion of pancreatic enzymes decreases with age which means that you lose your digestive capacity as you get older.' That is why many older adults complain of not being able to eat what they once did. The use of supplemental digestive enzymes after every meal can replace the digestive enzymes lost due to aging. A recent study also shows improvement in protein utilization in nursing home patients supplemented with a digestive enzyme supplement.' Another research article that focuses on gastric emptying time concluded that fatty food increases gastric emptying time.' But when subjects were administered the same fatty meal with supplemental lipase, the gastric emptying time was reduced significantly. This has direct implication for people suffering from heartburn and indigestion where fatty foods are the culprit. A 1971 British clinical study showed that taking a digestive enzyme supplement significantly alleviates the symptoms of dyspepsia.(5)
So far the studies conducted on the efficacy of digestive enzyme supplements have been few and far between.
A schematic diagram of the TIM system and the corresponding parts of the GI tract, as used in research an digestive enzymes by TNO. A. gastric compartment; B. pyloric sphincter; C. duodenal compartment; D. peristaltic valve; E. jejunal compartment; F peristaltic valve; G. ileal compartment; H. ileo caecal valve; I. pH electrodes; J. gastric secretion bottles with acid and enzymes; K. duodenal secretion bottles with bile, pancreatin, bicarbonate; L. secretion of bicarbonate to control the intestinal pH; M. pre filter system; N. hollow fibre semi permeable membrane system; 0. water absorption system; P. closed dialysing system. (Graphic courtesy of National Enzyme Co.)
Also, many of these studies do not have sufficient scientific evidence to convince the medical community of the efficacy of supplemental enzymes. Most medical practitioners believe that supplemental enzymes are destroyed in the acidic environment of the stomach and hence would be inactivated before they reach the small intestine. Last summer, research conducted at TNO Nutrition and Food Research, based in the Netherlands, provided the first quantitative evidence proving the efficacy of supplemental fungal digestive enzymes.' This study not only showed that fungal digestive enzymes survive the harsh environment of the stomach, but are also active in those acidic conditions. To quantify the efficacy of supplemental enzymes, TNO conducted a series of experiments using a dynamic gastrointestinal model (TilvI) which simulates the conditions of the human stomach and small intestine.
An FDA (Food and Drug Administration) type meal was fed to TIM under various physiological conditions with and without fungal supplemental enzymes. The two conditions so far tested are as follows: perfect digestive system with and without digestive enzyme blend, and imperfect digestive system (70 percent reduced pancreatin production) with and without digestive enzyme blend.
These two extreme conditions were chosen expressly because the digestive capabilities of most of us lie somewhere within these parameters. Samples were collected during these experiments at various times and at various parts of the digestive system and subsequently analyzed for glucose and nitrogen content. The glucose analysis represents carbohydrate digestion and protein digestibility is indicated by nitrogen analysis.
Although finding any significant enhancement of nutrient bioaccessibility in condition #1 with supplemental enzymes was unexpected, digestion of carbohydrates was enhanced by a factor of 4. The absorption of nitrogen was not affected by supplemental enzymes for perfect digestion. Dramatic results were obtained for the impaired digestive system of condition # 2 with the addition of fungal supplemental enzymes. The free glucose availability was increased by a factor of 7 and the total nitrogen level was doubled. Results show that fungal digestive enzymes improve the digestibility and bioaccessibility of proteins and carbohydrates in the lumen of the small intestine, not only under impaired digestive conditions, but also in healthy human beings.
The research initiated by Howell many decades ago is truly relevant in these times. Taking supplemental digestive enzymes will not only help your customers digest food properly, but will also make nutrients more bioaccessible. Many health care practitioners believe that all diseases start in the gut. Proper digestion of food and absorption of nutrients is the first step toward a long and healthy life. VR
REFERENCES
1. Howell, E. Food Enzymes for Health and Longevity, 2'' edition, Lotus Press, Twins Lakes, WI.
2. Laugeir, R.; Bernard, J.; Berthezene, P.; Dupuy, P. Changes in Pancreatic Exsocrne Secretion with Age: Pancreatic Exocrine Secretion Does Decrease in the Elderly. Digestion, 1991: 50:202 211.
3. Glade, M. J.; Kendra, D.; Kaminski, M. V. Improvement in Protein Utilization in Nursing Home Patients on Tube Feed Supplemented With an Enzyme product From Aspergillus niger and Bromelain. Nutrition, Vol. 17, Number 4, 2001, 348 349.
4. Nakae, Y.; Onouchi, H.; Kagaya, M.; Kondo, I. Effects of Aging and Gastric Lipolysis on Gastric Emptying of Lipid in Liquid meal. J. Gastroenterology, 1999, 34: 445 449,
5. Karani, S.; Kataria, M. S.; Barber, A. E. A Double blind Clinical Trial with a Digestive Enzyme Product. The British Journal of Clinical Practice, Vol. 25, No, 8, August 1971, 375 377.
6. Details of the study available at waw.nationalenzymecompany.com
Rohit Medhekar, Ph.D. is director, research & development, at National Enzyme Co., based in Forysth, MO.
VITAMIN RETAILER AUG 2004
WWW.VITAMINRETAILER.COM
P42-44
Enzymes and Digestive Health
By Rohit Medhekar. Ph.D.
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