Enzymes

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Enzymes are biological catalysts, or chemicals that speed up the rate of reaction between substances without themselves being consumed in the reaction. As such, they are vital to such bodily functions as digestion, and they make possible processes that normally could not occur except at temperatures so high they would threaten the well-being of the body. A type of protein, enzymes sometimes work in tandem with non-proteins called coenzymes. Among the processes in which enzymes play a vital role is fermentation, which takes place in the production of alcohol or the baking of bread and also plays a part in numerous other natural phenomena, such as the purification of wastewater.

What role do enzymes play in nutrition?

To better understand digestive enzymes, we must first understand the role of NUTRITION in our health. Nutrition is the body's ability to use and metabolize food. There are 45 known essential nutrients that are required in specific amounts for the body to function properly. The term "essential," as used here, means the body cannot synthesize them internally. Therefore all "essential" nutrients must come from exogenous, or outside, sources. In addition to carbohydrates, fats (lipids), complete proteins, and water, there are at least 13 kinds of vitamins, and at least 20 kinds of minerals required for proper metabolic function.

Once consumed, the food containing these nutrients must be digested, meaning they must be broken apart and reduced to a state that the nutrients can be absorbed into and transported by the blood stream to all parts of the body.

Our body's cells are programmed to direct each nutrient to combine and interact with other nutrients and chemicals to create still other chemicals and compounds which, in turn, are used to build and repair the body's cells, bones, tissue, and organs. The process is called metabolism.
Each metabolic reaction is started, controlled, and terminated by enzymes.

Without enzymes, no metabolic activity will occur. A body that does not consistently and efficiently metabolize the essential food nutrients necessary for life will fare poorly, and many illnesses are the result of a dietary problem that causes toxemia inside of the body.

What are the types of enzymes?

Enzymes are classified into three categories.

* DIGESTIVE ENZYMES
* FOOD ENZYMES
* METABOLIC ENZYMES

Metabolic enzymes run the body. They exist throughout the body in the organs, the bones, the blood, and inside the cells themselves. These enzymes are instrumental in the growth of new cells and the maintenance of all tissue. Every organ and tissue has its own group of specialized enzymes. They are trained to run and maintain their host. When these enzymes are healthy, robust, and present in adequate numbers, they do an excellent job carrying out their mission.

The two kinds of enzymes we are concentrating on here are DIGESTIVE ENZYMES and FOOD ENZYMES. These two are active only within our digestive system. These enzymes have one main job — to digest our food.

DIGESTIVE ENZYMES are made by our body's organs. Digestive enzymes are secreted by the salivary glands, stomach, pancreas, and the small intestine. [Technically, digestive enzymes are also considered to be metabolic enzymes whose metabolic role is to digest food. We are specifically distinguishing these particular enzymes here, because they deal with digestion and they can be supplemented from an outside source.]

FOOD ENZYMES are already present WITHIN the food we eat. Food enzymes exist naturally in raw food. If the food is cooked, however, the high temperature involved in the cooking process will destroy the enzymes.

Digestive enzymes and food enzymes basically serve the same function, which is to digest our food so it can be absorbed through the walls of the small intestine into the blood stream. From this viewpoint the only real difference between food enzymes and digestive enzymes is whether they come from inside our body or from the food we eat.

Why are enzymes so important for digestion?

Most food, when it is uncooked, contains enough natural food enzymes to digest that food. When you cook the food the enzymes are inactivated (denatured) and can no longer assist in the digestive (breaking down) process. Eating raw food is totally acceptable in some cases and quite unacceptable in others. We eat raw fruit and many raw vegetables, but less often do we eat raw meat, raw fish (not withstanding sushi), or raw pork. Eating uncooked rice is nearly a guaranteed trip to your dentist! So, obviously we cook our food.

Here's where the problem occurs. Cooked food contains no enzymes because they have been destroyed. If you eat a meal consisting of a salad, a steak and a baked potato, there are likely enough food enzymes contained in the salad to digest it (break it down so your body can use its nutrients). But, there are no extra enzymes available to help digest the steak or the baked potato. Because the steak and potato are cooked, there are no FOOD ENZYMES available to digest them, so our body must take over and internally create the needed amount of DIGESTIVE ENZYMES to handle the digestive task.

The more we depend on our internally generated DIGESTIVE ENZYMES, the more stress we put on our body's systems and organs and the less time these systems and organs have for rebuilding and replacing worn out and damaged cells and tissue and keeping our immune system strong. Your body’s top priority is making sure it has enough nutrients to run its systems. This means digesting food and converting it into nutrients. There is no activity more important to the body than this. This takes a lot of energy and enzymes, particularly if the body must make most or all of these enzymes. Remember that no food can be digested without digestive enzymes.

Dr. DicQie Fuller, in her book The Healing Power of Enzymes, emphasizes the importance of enzymes for digestion:

"Eighty percent of our body's energy is expended by the digestive process. If you are run down, under stress, living in a very hot or very cold climate, pregnant, or are a frequent air traveler, then enormous quantities of extra enzymes are required by your body. Because our entire system functions through enzymatic action, we must supplement our enzymes. Aging deprives us of our ability to produce necessary enzymes. The medical profession tells us that all disease is due to a lack or imbalance of enzymes. Our very lives are dependent upon them!"

Which digestive enzymes digest food?

You know that proteins, carbohydrates, and fats are the three main food groups that make up the bulk of our daily diet. A "balanced" diet means we consume the proper proportions of these three basic food groups on a daily basis. This balance, when combined with the assurance that we also get the essential nutrients, can help provide a healthy life — IF we properly process and metabolize these nutrients. To do this we also need an adequate source of the major types of digestive enzymes: Proteases, Amylases, and Lipases.

FOOD
GROUP

%
OF
DAILY DIET

ENZYME
CLASS
ENZYME'S
FUNCTION
Proteins 20-25
%
Protease Digests
Protein
Carbohydrates 50-60
%
Amylase Digests
Carbohydrates
Fats 20-30
%
Lipase Digests
Fat (lipids)

There are numerous categories of digestive enzymes, but for the purpose of this discussion, we will cover the three primary classes of digestive enzymes that digest our food. [NOTE: generally speaking, enzymes end with the suffix "ase."]

If the proper QUANTITY and required TYPE of enzymes are not present, your body becomes TOXIC from the left over waste of incomplete digestion. This is the reason why most illnesses and diseases are initially a dietary mistake. This can be prevented and it can be reversed. It’s all a matter of having the right amount and the right kind of enzymes available at the right time to prevent your body from becoming a receptacle for pollution and waste — a receptacle that then breeds and harbors disease.

The Body, Food, and Digestion

Enzymes enable the many chemical reactions that are taking place at any second inside the body of a plant or animal. One example of an enzyme is cytochrome, which aids the respiratory system by catalyzing the combination of oxygen with hydrogen within the cells. Other enzymes facilitate the conversion of food to energy and make possible a variety of other necessary biological functions. Enzymes in the human body fulfill one of three basic functions. The largest of all enzyme types, sometimes called metabolic enzymes, assist in a wide range of basic bodily processes, from breathing to thinking. Some such enzymes are devoted to maintaining the immune system, which protects us against disease, and others are involved in controlling the effects of toxins, such as tobacco smoke, converting them to forms that the body can expel more easily.

A second category of enzyme is in the diet and consists of enzymes in raw foods that aid in the process of digesting those foods. They include proteases, which implement the digestion of protein; lipases, which help in digesting lipids or fats; and amylases, which make it possible to digest carbohydrates. Such enzymes set in motion the digestive process even when food is still in the mouth. As these enzymes move with the food into the upper portion of the stomach, they continue to assist with digestion.

The third group of enzymes also is involved in digestion, but these enzymes are already in the body. The digestive glands secrete juices containing enzymes that break down nutrients chemically into smaller molecules that are more easily absorbed by the body. Amylase in the saliva begins the process of breaking down complex carbohydrates into simple sugars. While food is still in the mouth, the stomach begins producing pepsin, which, like protease, helps digest protein.

Later, when food enters the small intestine, the pancreas secretes pancreatic juice—which contains three enzymes that break down carbohydrates, fats, and proteins—into the duodenum, which is part of the small intestine. Enzymes from food wind up among the nutrients circulated to the body through plasma, a watery liquid in which red blood cells are suspended. These enzymes in the blood assist the body in everything from growth to protection against infection.

One digestive enzyme that should be in the body, but is not always present, is lactase. As we noted earlier, lactase works on lactose, the principal carbohydrate in milk, to implement its digestion. If a person lacks this enzyme, consuming dairy products may cause diarrhea, bloating, and cramping. Such a person is said to be "lactose intolerant," and if he or she is to consume dairy products at all, they must be in forms that contain lactase. For this reason, Lactaid milk is sold in the specialty dairy section of major supermarkets, while many health-food stores sell lactaid tablets.

Digestive Enzymes

Description

Enzymes are catalysts for virtually every biological and chemical reaction in the body, and digestive enzymes are crucial for the breakdown of food into nutrients that the body can absorb. Digestive enzymes, of which a variety are herbs, are used to treat a number of digestive problems and other conditions.

General Use

Digestive enzymes are used for relief of a number of digestive conditions, including:

* flatulence
* heartburn
* diarrhea
* spasms
* inflammation
* constipation
* gastroesophageal reflux
* peptic ulcers
* indigestion

Minor digestive complaints can be relieved by these mild digestive enzymes, rather than the more pharmacologically active ones.

Digestive enzymes also may be used to treat and to provide relief to other conditions, such as anorexia, Crohn's disease, ulcerative colitis, parasitic infections, cystic fibrosis, and pancreatitis.

Carminative Herbs

Carminative herbs are considered to be mild and are rich in volatile oils, which have antibacterial properties. These herbs include peppermint (Mentha spicata), ginger (Zingiber officinale), fennel (Foeniculum vulgare), anise (Pimpinella anisum), and lemon balm (Melissa officinalis). Carminative herbs help to stimulate peristalsis, which is the wave-like action that pushes food through the digestive tract. These herbs can also help to relax the smooth muscle of the digestive tract, helping to reduce spasms. The antibacterial properties of the volatile oils aid in reducing gas pains that result from bacteria in the intestines acting on pieces of food that have not been digested fully.

Peppermint is one of the oldest medicinal herbs. Peppermint has three major actions in the body: it reduces nausea and vomiting, it encourages the liver to produce bile, and it clears the stomach of imbalanced bacteria. It is particularly useful for treating spastic colon, irritable bowel syndrome and diarrhea. Peppermint is also useful for reducing gas pain and indigestion.

Demulcent herbs can help ease heartburn, another bothersome digestive condition. These herbs are rich in mucilage, soothing irritated or inflamed tissue. Examples of demulcent herbs include marsh mallow root (Althaea officinalis), Irish moss (Chondrus crispus), and slippery elm (Ulmus rubra).

Herbs, known as bitters, can relieve constipation and assist the stomach in acid digestion. Bitter herbs stimulate bile production, and bile is the body's natural laxative. Taking bitters in a capsule or pill form will not work because in order for the liver to produce bile, the bitters must be tasted, not just ingested. Some examples of a bitter herb are dandelion root (Taraxacum officinale), ginger, and aloe (Aloe vera).

Ginger has been found to be particularly useful in treating nausea. In a 1988 study involving 80 Danish naval cadets who were unaccustomed to sailing heavy seas, ginger capsules were found to be very beneficial in reducing seasickness. Another study in 1990 at Bartholomew Hospital in London found ginger to be effective in reducing post-operative nausea. Ginger has stimulating and antiemetic properties that warm the stomach to reduce intestinal and gas pain.

Aloe can be a powerful laxative when used internally. It takes 10-15 hours to work in the body, so it is best used in the evening before bedtime. Do not use aloe for an extended period of time, or dependency can develop. Overuse of aloe can result in loss of intestinal tone. Overdoses of aloe can result in diarrhea, intestinal distress, and kidney problems, so caution should be taken when using this herb.

Astringent herbs are beneficial in slowing down diarrhea. These herbs contain tannin, a substance that causes protein in body tissues to tighten up. When an astringent herb is taken, the proteins in the digestive tract tighten up to form a protective barrier that reduces fluid and electrolyte loss.

Preparations

A few suggestions apply before using any of the various herbal supplements to aid digestion. It is best not to overeat, and snacking between meals on anything other than fruit should be avoided. Increase the consumption of fruit, vegetables and whole grains, and try to decrease the amount of fatty foods, red meat, dairy products, nuts, and nut butters from the diet. Try to relax while eating, chew food 10–20 times, and avoid distractions while eating, such as reading or watching television. Drink at least eight glasses of water each day.

Many of these herbs make delicious teas, and are commonly available as packaged teas. Those who wish to make their own tea should try steeping one teaspoon of dry herb per cup of boiled water for five to 10 minutes. Be sure to cover the tea so that the volatile oils do not evaporate. An Indian custom that is also helpful for digestion is to keep fennel or anise seed available at the table to pass around following a meal.

Precautions

There have been very few scientific studies to prove either the adverse or the beneficial health effects of the 1,500-plus herbal products that are available throughout the United States. Furthermore, under the Dietary Supplement Health and Education Act of 1994, herbal products are not required to be proven safe before they are marketed. After the product is marketed, the U.S. Food and Drug Administration (FDA) must prove the dietary supplement unsafe before it can be removed from the shelves. Many people associate the term "natural" with "safe," and that is not always the case. Anyone taking herbal products of any kind should be certain to discuss this with their physician. As is the case with some prescription medications, dependency on some herbal supplements is possible. No herbal supplements should be taken for extended periods of time without discussing this with a physician first.

Herbal preparations can vary widely from one brand to another, and within the same brand from one purchase to the next, making inconsistency in the concentration of ingredients a potential risk. Anyone using herbal products should be careful and try to use well-known brands because these products are largely unregulated.

Side Effects & Interactions

Anyone taking herbal products should always discuss this with their physician. Herbs have the potential to interact with any prescription medication, as well as with other herbs. So, persons wishing to take digestive enzymes should consult a physician.

Resources

Periodicals

Starbuck, J. "3 Herbs for Good Digestion: Ginger, Peppermint and Aloe." Better Nutrition (1999): 44-49.

Sullivan, K. "Oh, What a Relief It Is." Vegetarian Times (1996): 94-99.

Organizations

Alternative Medicine Foundation, Inc. 5411 W. Cedar Lane, Suite 205-A, Bethesda, MD 20814. (301) 581-0116.

American Botanical Council. P.O. Box 144345, Austin, TX 78714-4345. (512) 926-4900. Fax: (512) 926-2345. http://www.herbalgram.org.

Enzymes: Part II

Enzymes are most familiarly associated with digestion, as substances in the alimentary tract that are necessary for the breakdown of food into simpler stuffs that can be absorbed into the body proper. These are indeed important, but they are in a small minority among the vast population of the body's enzymes. They also differ from the majority in acting outside rather than inside the cells that make them.

All living cells are teeming with enzymes. The name comes from the Greek meaning ‘in leaven’ or yeast. They are proteins, synthesized in cells, which act as catalysts, causing all the body's chemical processes to advance with the necessary rapidity and completeness. Enzymes are ubiquitous in body cells and fluids, and they are specific — each enzyme is responsible for catalyzing one particular chemical process. Their existence and their function came to be recognized during the nineteenth century; understanding advanced with burgeoning twentieth-century biochemistry; and molecular biologists continue to elucidate their ultimate structure and mode of action, and the genes that make them.

The names and nature of enzymes

The naming of enzymes in most cases reveals their function; ‘-ase’ is added to the name either of the substance (the substrate) on which they act (like peptidase for those acting on peptides), or of the type of reaction induced (such as hydrolase, for those causing hydrolysis, the splitting of a substance with addition of water, or transferase, for those moving some chemical group from one molecule to another). Some of the first enzymes to be discovered have unique names, such as pepsin in the stomach, and trypsin from the pancreas, which are both proteinases.

So what sort of proteins are they, and how do they function? With molecular masses of 10, 000 to 1, 000, 000, enzymes are themselves large molecules, but some also exist in larger complexes that facilitate a sequence of changes. An enzyme molecule is a ‘globular’ protein that has an area on its surface to which can be bound only the specific substrate that the enzyme is designed to accept. This binding leads to changes in both molecules that result in the formation of the required product, and restoration of the enzyme molecule to its original state, ready to take on another substrate molecule. With progressively higher concentrations of substrate the rate of product yield increases, but the increment in rate diminishes as it approaches a maximum at a certain substrate concentration; beyond this point only an increase in the concentration of the enzyme itself can accelerate the process. This behaviour is consistent with progressive occupation of binding sites on all available enzymes, until they are all functioning at a maximal turnover rate.

Range and sites of enzyme function

Enzymes operate at every stage of life. Even the head of the sperm releases an enzyme that dissolves its path through the outer covering of the ovum to reach and penetrate it. Cell division in the embryo and throughout life involves replication of the DNA that carries the genetic information. A series of specific enzymes is needed for this, to unwind the double helix, to replicate it by the synthesis of new strands, and to put it and the new pairs back together again — whilst other enzymes meanwhile supply energy by the breakdown of adenosine triphosphate (ATP). Yet others are involved in the formation of messenger RNA and in all subsequent synthesis of proteins in a cell that results from the genetic coding.

Enzymes implement every event in the internal life of every cell in the body, and in its interaction with its environment. Each enzyme, or chain of enzymes acting in rapid sequence, has a specific function. There are those that are necessary for respiration and energy production; for transport mechanisms across the cell membrane and between internal components; for modifications of cellular metabolism in response to hormones; and for any specialized activity, including secretion by glandular cells, contraction by muscle cells, synthesis, release, and reuptake of neurotransmitters by nerve cells. The continual potential damage to tissues by the generation of free radicals is crucially limited by the body's antioxidant enzymes.

All cells have enzymes in their membrane, in the cytoplasm, and in the organelles within them. Those at the heart of cellular metabolism are the complex sequence of respiratory enzymes in the mitochondria that make possible the utilization of oxygen for the conversion of nutrient substrates to carbon dioxide and water, synthesis of ATP, and its breakdown for release of energy.

Cell membranes are furnished with ‘sodium pumps’ — protein molecules spanning the cell membrane that pump sodium ions out and potassium ions in. Facing inwards is an enzyme site that binds and breaks down ATP to supply the energy for pumping. Other enzyme molecules in the cell membrane may have, in addition to a site for substrate-binding, another that acts as receptor for a ‘messenger’ that activates the catalytic process: for example, the insulin receptor spans the cell membrane of muscle or fat cells; its outer site binds insulin, and its inner site handles the first of a series of enzyme-catalyzed reactions inside the cell that result in the several effects of insulin.

At synapses between nerves, and at neuromuscular junctions, enzymes are present that break down redundant neurotransmitters, preventing persistence of their effects. An example is acetylcholinesterase, found in the synaptic clefts on motor end plates in skeletal muscle, which hydrolyses excess acetylcholine, the neurotransmitter released by the motor nerve terminals.

Within skeletal muscle fibres, the enzymes vary according to their type of metabolism: whether it is predominantly aerobic (utilizing oxygen: ‘slow’ or ‘red’ muscle) or anaerobic (‘fast’ or ‘pale’ muscle). The sequence of events leading from activation of a muscle fibre by neurotransmitter, to contraction by means of interaction between myosin and actin filaments, depends on enzymes at every stage.

Enzymes in the blood

In the circulating blood there are enzymes both inside the blood cells, and outside in the plasma. Blood cells, in common with all cells, have the necessary enzymes for membrane transport and energy production. White blood cells have respiratory enzymes for aerobic metabolism, and others suited to their particular functions. Red blood cells are without mitochondria and respire anaerobically, so have enzymes appropriate to anaerobic glycolysis. Important for their function in whole-body respiratory gas exchange, they contain carbonic anhydrase, which promotes the uptake from the tissues of carbon dioxide and its carriage in the blood as bicarbonate, by catalyzing its combination with water to form carbonic acid, and its release in the lungs by this reaction in reverse.

Some enzymes exist as pro-enzymes or zymogens; they require some molecular change to be triggered into their active forms. These include proteins in the plasma that are involved in blood clotting: prothrombin is synthesized in the liver, and becomes thrombin when clotting is activated, and plasminogen can come into action as plasmin, a clot-dissolving enzyme. In the stomach, pepsinogen is secreted, and activated into pepsin by the acid that is secreted at the same site.

Enzymes that are normally secreted only into the gut or inside cells may, in pathological conditions, appear in significant quantities in the plasma, so that their measurement may be clinically useful. Examples are digestive enzymes that leak into the blood in acute pancreatitis, and creatine kinase, an enzyme from muscle tissue, that can appear in skeletal muscle disorders or, along with other intracellular enzymes, after a coronary thrombosis resulting in breakdown of some of the cardiac muscle.

Conditions for enzyme activity

All enzymes need the right environment for effective function, notably an optimal acidity, which differs in accordance with the site at which a particular enzyme acts (for example, more acidic inside cells than outside, and, for digestive enzymes, acidic in the stomach and alkaline in the duodenum). Like any chemical reactions, the rate of those that are catalyzed by enzymes varies with temperature. Local heat generation, for example in exercising muscle, enhances all such reactions within it. Likewise, whole-body metabolic rate increases in fever and decreases in hypothermia, because of the effect on all enzyme-catalyzed reactions. Extremes of pH or temperature irreversibly abolish enzyme activity, and so also do some substances that bind to the active sites of particular enzymes. These include an organophosphate ‘nerve gas’ that blocks acetylcholinesterase (causing persistent accumulation of acetylcholine at neuromuscular junctions, and thus uncontrollable muscle contraction). Poisoning by cyanide is due to blocking an essential enzyme in mitochondria and so fatally preventing all tissue respiration.

Medical applications

It is possible to inhibit the action of an enzyme without destroying it, and this has important therapeutic implications. There are substances that compete with the natural substrate for binding to an enzyme by having a similar structure, and others that act on other components of the enzyme molecule, preventing its ability to catalyze. Acetylcholinesterase inhibition is again an example — though in this context useful and reversible — in the treatment of the condition of myasthenia gravis, when the receptors on muscles cells for acetylcholine are deficient; the similar molecular structure of neostigmine allows it to bind to the enzyme, preventing binding and breakdown of acetylcholine; this can then accumulate sufficiently to enhance neuromuscular transmission. Drugs are used similarly to reverse the neuromuscular blockade deliberately induced during general anaesthesia. A different and important medical application of enzyme inhibition is in the use of antibiotics that block enzymes in microorganisms that are essential for their life or growth.

There are also many necessary co-enzymes, or co-factors for enzymes — organic non-protein molecules, smaller than the enzymes themselves, which either enhance or are necessary for the enzyme's activity. These again are widespread throughout the body, and are of many different molecular structures. Some require for their synthesis small amounts of essential substances from the diet. This is the basis of the need for the vitamins of the B group — they provide components for co-enzymes which could not otherwise be made in the body. Ions of several metals are also essential as co-factors, as well as for incorporation in some enzyme molecules themselves.

— Sheila Jennett

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