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Supplemental Enzymes for Digestion
Lary D. Andrews, Ph.D.


You are a human being and enzymes are what make your body tick. They are protein molecules and come in over 4,000 varieties in your body. Fortunately, you don't have to know anything about them for them to work. However, IF you know something about them you can better understand why paying attention to enzymes can probably improve your health. The qualification "probably" is included in the previous sentence because there are individuals (I know, I used to be one of them!) who have -- or at least believe they have--perfect health already. For you lucky few, knowing something about enzymes will help you understand why paying attention to them can help you maintain your health (hopefully better than I did!).

We will explore what enzymes are, what they do, and the role they play in health and disease. We will pay special attention to the benefits of oral supplementation with enzymes.

Overview of Enzymes:
Enzymes are useful because of their activity rather than their size, shape, strength or other structural properties (proteins which are useful for these reasons--size, shape, strength--are called 'structural proteins'). The function of enzymes is to catalyze chemical reactions, which means to cause the rate of the production of "products" from "substrates" to be much greater than it would be in comparable conditions but lacking the enzyme. They do this by lowering the "activation energy" of the reaction, which is usually represented graphically as a "hill" that must be climbed for the reaction to proceed. The top of the "hill" is the "transition state" and is intrinsically unstable. Lowering the "hill" causes the reaction to go much faster.
This diagram illustrates an 'exothermic' reaction, i.e. one in which the product has a lower free energy than the substrate. Enzymes also catalyze 'endothermic' reactions in which the opposite is true. For endothermic reactions to occur a source of energy much be supplied (such as ATP). Virtually every significant chemical reaction in every cell of all plants and all animals (and all prokaryotes) requires enzymatic catalysis if it is to occur at a biologically satisfactory rate.

Pie pieces For many years the catalysis of biochemical reactions by enzymes was inherently mysterious to me. I knew they did it and something of the chemistry and mathematics of it, but it was still -- at bottom -- a mystery. One day the light came on (!) and I "got it". All enzymatic catalysis, regardless of the overall nature of the reaction catalyzed, involves breaking chemical bonds. The energy required to do this is, in essence, the height of the "hill" shown above. When a substrate is bound in the "active site" of an enzyme (see figure), interaction with the enzyme leads to changes in the shapes of both the substrate and the enzyme, with the latter "relaxing" into a lower energy mode while the substrate is "stretched" into a higher energy state. It is now closer, as it were, to the top of the hill. The energy needed to boost it over the top, i.e. to actually break a bond, is supplied by heat. After the substrate has undergone its reaction the products no longer hold the enzyme in its "relaxed" state, so it reverts to its normal state and is therefore ready to go through the whole thing again.

Cell diagram All biological macromolecules, including all enzymes, are synthesized (manufactured) by a complicated process within cells. This process requires the use of many enzymes, the expenditure of considerable cellular energy, and the availability of the required nutrient building

blocks. All aspects of cellular metabolism, including the synthesis of enzymes, require enzymes! Broadly speaking, enzymes can be categorized according to their function. At the highest level we may categorize enzymes according to whether they do their work inside or outside of cells. The former category comprises metabolic/cellular enzymes, and in the latter category our focus will be on digestive enzymes.

Metabolic / Cellular Enzymes:

Enzymes within cells are responsible for making molecules, such as ATP, that provide the energy needed to accomplish cellular work. Enzymes catalyze the synthesis of the molecular components of the cell. Enzymes also break down unwanted or worn-out components of the cell. Enzymes vary greatly in function and are categorized as follows:

  • Oxidoreductases transfer hydrogen ions;
  • Transferases transfer chemical groups between different molecules;
  • Hydrolases usually split their substrates with the aid of water;
  • Lyases split their substrates without aid;
  • Isomerases rearrange the molecules of their substrates;
  • Ligases help release energy.
The following table lists the various types of enzymes and gives some examples of each.
 Enzyme  Action  Source
Acetylcholineesterase Inhibits signals between Nerve tissues, muscles
  nerve cells  
Lipase Splits fats Stomach, pancreas
Lysozyme Splits bacterial carbohydrates Spleen, egg white
Maltase Splits maltose Small intestine
Pepsin Splits proteins Stomach
Rennin Curdles milk Stomach
Ribonuclease Splits compounds in food for Pancreas
  inclusion in ribonucleic acid  
Trypsin Splits proteins Pancreas
Adenosine deaminase Breaks down amino acid Kidney, liver, muscles
Glutamine Transfers part of glutamic acid Liver, kidney
  transaminase to another amino acid
Phosphoglucomutase Exchanges phosphates All tissues
  between carbohydrates  
Aconitase Rearranges citric acid All tissues
Phosphohexose Rearranges a carbohydrate Muscles
Cytochronies Transfer electrons in cell Cell mitochondria
Glutamine synthetase Helps build amino acid Brain

Currently about 4,000 enzymes have been identified in human cells. Life depends on enzymes to:

  • provide nutrients necessary for cellular energy and biosynthesis,
  • catalyze the reactions by which cells utilize nutrients to produce energy and synthesize biomolecules, and
  • perform the various specific functions for which each cell is designed.
It is interesting to note that a number of serious or fatal genetic disorders called ‘inborn errors of metabolism have been characterized in which all of the observed pathology comes about because a single enzyme is missing.

Digestive Enzymes:

Many organisms (such as human beings) depend upon enzyme catalyzed extracellular chemical reactions, such as the enzymatic digestion of food. The enzymes used in these situations are made within cells and then secreted into the appropriate sites where the reactions they catalyze will occur.

The majority of the events that are significant for digestion occur in the stomach, the small intestines (duodenum, jejunum and ileum), or the large intestines (colon). Food is held in the stomach for up to an hour before significant digestive activity begins. The first stage of activity is the acidification of the food by hydrochloric acid (HCl) and the beginning of protein digestion by pepsin (a proteolytic enzyme), both released by cells lining the stomach. The partially liquified and acidic material, now called chyme, is passed to the duodenum (the first third of the small intestine). The major portion of digestion is begun through the release of large quantities of enzymes by the pancreas, which pass into the duodenum via a duct. Pancreatic enzymes are not active in an acidic environment (low pH), such as the chyme entering the duodenum. The pH of the chyme is increased through the addition of bicarbonate synthesized largely by cells within the epithelia lining the pancreatic ducts.

Bile is also added from the gallbladder in order to emulsify fats. This brings them into suspension to facilitate enzymatic attack. All of these activities are closely regulated and interrelated, subject to control by the nervous system and hormones.

The goal of digestion is to release small molecules (nutrients) which can then be absorbed through the wall of the gut, taken up by the circulatory system, and transported to cells and tissues throughout the body. More specifically, digestive enzymes function to break down ingested food into usable nutrients. These nutrients are distributed by the circulatory system and taken into cells for the work of metabolism. Since digestion occurs outside of cells, digestive enzymes must be secreted (released from the cells that synthesize them). Digestive enzymes are principally made by cells in exocrine glands; i.e. glands with ducts that pass the secretory product to the digestive tract where they encounter ingested material. Some cells in the lining epithelium of the digestive tract do secrete digestive enzymes, especially those that are involved in the final stages of digestion such as breaking disaccharides into simple sugars.

Categories of digestive enzymes

Supplemental Enzymes for Digestion: Carbohydrates:

  • Amylase-multipurpose group of enzymes which attack carbohydrates at many types of bonds
  • Glucoamylase-a specialized enzyme which breaks bonds involving glucose
  • Invertase-the same as the enzyme "sucrase"normally found in the human digestive tract
  • Lactase-breaks down lactose (milk sugar); good for lactose intolerance
Supplemental Enzymes for Digestion: Fat
  • Lipase-produces free fatty acids but does not degrade them; fatty acids are absorbed by enterocytes (cells lining the digestive tract) which resynthesize phospholipids from them, which are then released into the lymphatic circulation
  • Bile also contributes to fat digestion and comes from the liver through the gallbladder; it acts like a detergent to dissolve fat, helping lipase work
Supplemental Enzymes for Digestion: Fiber
  • Cellulase-humans do not make cellulase; its purpose is not to break cellulose down into absorbable components, but to liberate other nutrients bound to or trapped by cellulose
  • Pectinase-breaks down pectin, a soluble, non-cellulose polysaccharide in fruits and vegetables
  • Phytase-breaks down phytic acid, releasing phosphorus and improving absorption of minerals
Supplemental Enzymes for Digestion: Protein
  • Protease-consists of alkaline, neutral and acid proteases plus peptidase and includes both endo- and exoproteases
  • Bromelain—a group of proteases from the stem of the pineapple
Papain-a group of proteases from the papaya plant

Overview of Digestion in Health:

Good digestion promotes good health in two ways. One is by the good things that need to happen happening, and the other is by the bad things that can happen not happening. To clarify, consider the following table of "good things that need to happen" and "bad things that can happen:"

1a. Everything moves in the right direction 1b. Sometimes things go the wrong way
2a. Everything moves at the right speed 2b. Sometimes (usually) things move too slowly or too quickly
3a. Nutrients are released from food consumed 3b. Some (or most) of the nutrients are not released from food consumed
4a. Released nutrients are absorbed 4b. Released nutrients are not absorbed
5a. "Good" bacteria thrive and bad ones do not 5b. Bad bacteria thrive

Everything moves in the right direction/sometimes things go the wrong way

The digestive tract is so constructed,by means of the smooth muscle built into it and the reflexes which control the contractions of that muscle, to cause ingested material and its byproducts to move unidirectionaly from mouth to anus. By appropriately controlling the contractions of its smooth muscles the digestive tract is equipped with sphincters which prohibit material from moving backward (or forward) and paristaltic contractions which move material forward. These sphincters are not bank-vault-doors, however. If material which has passed into the small intestine is being digested slowly, the sphincter which allows material to pass into it from the stomach remains closed. Material kept in the stomach too long can produce gas which produces pressure which can force the acidic stomach content into the esophagus. This is known as heartburn, which can can be a symptom of gastroesophageal reflux disease (GERD).

"Gastroesophageal reflux disease (GERD) is the most common disorder of the esophagus and probably the most prevalent condition originating in the gastrointestinal (GI) tract.[1] GERD is estimated to affect between 25% and 35% . . ."
The most severe complications of GERD are cancers of the esophagus and larynx, and the incidence of esophageal adenocarcinoma has increased alarmingly." (John Robert Claussen, PA-C, MPAS [Clinician Reviews 9(6):69-72, 75-77, 80-82, 85, 1999. © 1999 Clinicians Publishing Group and Williams & Wilkins.])

There are many causes of GERD in addition to the one described above. But since healthy people commonly have several episodes of gastroesophageal reflux per hour during the first few hours after a meal, it is beneficial for everyone to ensure that digestion occurs as rapidly and completely as possible.

Everything moves at the right speed / Sometimes (usually) things move too slowly or too quickly:

There are people, it is said, who are always happy with their bowels. No one knows where they are, however, so it is impossible to talk to them to learn their secrets. The rest of us spend a significant portion of our lives with "things moving too slowly or too quickly". Taking supplemental digestive enzymes, often for other reasons, has been found by many happily surprised people to bring relief after a lifetime of constipation. Again, both constipation and diarrhea may arise from a wide variety of causes, some serious. Supporting the thorough digestion of ingested food with supplemental enzymes is a safe and easy intervention which has helped many.

Nutrients are released from food consumed / Some (or most) of the nutrients are not released from food consumed:

Nutrients are categorized either as MACROnutrients or MICROnutrients. The distinction is in terms of how much of them we need to maintain good health. We need a good deal of the MACROnutrients and just a little of the MICROnutrients. An example of the former is the family of amino acids obtained from digesting protein. An example of the latter is the family of vitamins. Protein that is consumed provides NO nutrients unless digestion proceeds all the way to single amino acids. Incompletely digested protein can leak into the blood stream and produce or stimulate food allergies. Carbohydrates which are consumed provide NO nutrients unless digestion proceeds all the way to single sugars (monosaccharides). Incompletely digested carbohydrates, such as disaccharides like lactose, can produce a variety of unpleasant symptoms (ask someone who is lactose intolerant). The digestion of fats is more compicated, but one part of it is fairly simple. Much is being said about "good" fats, such as monounsaturated and omega-3 fatty acids. These fatty acids are consumed in a form in which they cannot be absorbed. They require the action of lipases, which release the fatty acids and allow them to be absorbed. Incompletely digested fats often lead to diarrhea.

Released nutrients are absorbed / Released nutrients are not absorbed:
Phytic Acid

This category differs from the one above in that here we are focusing on what are called "antinutritives". These are ingested substances which bind nutrients before they are absorbed and, in fact, prevent this absorption. A very important example of this is phytic acid. Phytic acid is very common (it is the principal storage form for phosphorus in plants) and it binds numerous minerals (e.g., iron and zinc; see figure). Iron and zinc deficiencies are common in under-nourished children. Phytase (an enzyme) breaks down phytic acid and increases absorption of bound minerals.

"Good" bacteria thrive and bad ones do not / Bad bacteria thrive:

It has been estimated that the enteric flora comprise approximately 95% of the total number of cells in the human body. They are capable of eliciting immune responses while also protecting against microbial pathogens. Specific probiotic microbes, mainly lactic acid bacteria and bifidobacteria, can alleviate or prevent diverse intestinal disorders and reduce the risk of some intestinal diseases.

Digestive Stress:

There is tremendous interest in the health consequences of the quantity, quality, and composition of absorbed nutrients. There is also a vast library of information on this subject, which unfortunately is often conflicting. Regardless of one’s opinion on what constitutes a "healthy" diet, it is clear that digestion of the diet consumed is critical. Digestion cannot occur without the necessary enzymes. Synthesis of these enzymes requires a very large amount of metabolic machinery (many cells devoted to the task) and metabolic energy. Therefore, another factor in the "healthiness" of diet is the magnitude of the burden placed on the body in order to digest that which is eaten. This burden may be thought of as "digestive stress".

The subject of stress is quite prominent in our current understanding of health and disease. Stress involves the gradual depletion of reserve capacity needed to deal with more extreme challenges to a system. The more reserve capacity a system has the less likely it is to encounter extreme challenges with which it cannot cope. As reserve capacity is depleted, less extreme and therefore more probable circumstances will result in damage to the system.

The interplay of stress, reserve capacity, and damage may be understood through an analogy to automotive tires. Driving produces stress on the tire's tread, which gradually removes rubber. This "depletes the reserve capacity" of the tire, i.e. decreases the thickness of the tread. Bad road surfaces and/or sudden vehicle maneuvers are "extreme circumstances" which must be handled. As the tire’s tread gets thin there is a reduction in traction and therefore the chance for "structural damage" increases. Safe, low stress driving (e.g., good paved roads) minimizes the rate of tread wear.

Low Stress Diet:

A "low stress" diet is one that minimizes digestive and systemic stress. The value of balanced ingestion is only realized if there is also thorough digestion, which produces the needed nutrients from the ingested food, and absorption which places nutrients in the circulation and therefore makes them available for use. Minimizing digestive stress requires the consumption of digestive enzymes along with food, which may be either in the food naturally or may be taken as supplements. Active enzymes are only naturally present in raw food. Consider what happens to a freshly picked apple if it is not eaten for many days. The "meat" of the apple will become soft and start to liquefy as a result of the action of enzymes present in the apple. Those same enzymes are available to assist our bodies in digesting the apple after we eat it. This reduces the requirement on our digestive glands for digestive enzyme secretion, and thus reduces digestive stress.

It is almost impossible, however, to eat a diet composed entirely of raw food containing their full complement of enzymes. Cooking and processing food exposes the enzymes in it to chemical and/or thermal conditions that cause the protein molecules, including the enzymes, to "denature". This means that they completely unfold, so much so that they cannot refold even if returned to desirable conditions (see insert on protein structure). In the unfolded state, enzyme molecules retain no enzymatic activity.

The implication of this is that the "average" diet eaten in most developing countries, and especially in the United States, is largely devoid of active digestive enzymes, leaving the entire burden of digestion to the body.

High Stress Diet:

A "high stress" diet is one that causes either digestive or systemic stress. If most of the diet lacks digestive enzymes (endogenous or supplementary), then the body is required to endure either digestive stress, as discussed above, or nutritional deficiencies. In the worst case both of these may occur. Systemic stress may occur even with proper digestion and absorption if the nutrients needed by the body are simply not present in the body. Thus a high stress diet will have one or more of the following characteristics:

  • the nutrients ingested are substantially out of balance with the body’s metabolic requirements (too little or too much of anything);
  • the nutrients ingested are not "bioavailable" because of insufficiency in digestive capacity;
  • the foods ingested cause excessive digestive stress to the body.
Results of eating a high stress diet may include any combination of the following:
  • lack of energy;
  • frequent illnesses from poorly functioning immune system;
  • wasting and/or brittleness of bones;
  • poor weight control (over- or under-weight);
  • indigestion, bloating, gas;
  • hormonal imbalances;
  • dry or oily skin;
  • poor elimination (constipation or frequent, loose stool)
It is therefore highly desirable to supplement our "normal" diets, which are primarily composed of cooked and processed foods, with active digestive enzymes and thus reduce the digestive stress on our bodies.

Overview of Digestion in Disease:

In disease, one or more organs or systems is under attack. The ability of the body to return to health is dependent upon the presence of sufficient capacity in other organs and systems not only to support their own continued functioning, but also to come to the assistance of the organ(s) or system(s) under attack. Nutritional support is generally not the principal mechanism with which attacks of disease are met, but nutritional support is vital for the rest of the body. "Persons face acute illness or chronic disease and its treatment in a variety of settings: the acute care hospital, the long-term rehabilitation center, the extended care facility, the clinic, the private office, and the home. In all instances, however, nutritional care is fundamental. It supports any medical treatment being given and frequently provides the primary therapy" (Nutrition and Diet Therapy, SR Williams & SL Anderson, Mosby, St. Louis, 1993, pp. 457-8). Thus there are special requirements for nutrients in a body responding to disease, and these must be met by the nutrients in the diet. The body must also be able to digest and absorb these nutrients. In disease it is especially important for ingested food to be accompanied by sufficient digestive enzymes to relieve digestive stress.

Lack of necessary nutrients in the food ingested obviously deprives the body of necessary metabolic energy needed to fight disease and, perhaps, even to maintain residual health. Clearly, if appetite is suppressed by disease, the possibility exists for a downward spiral in which undernutrition leads to worsening of health and even further reduction of appetite, leading to even greater undernutrition, etc.

Even if the necessary nutrients are ingested, they may not be digested and absorbed unless sufficient digestive enzymes are present. If the body is required to provide all the necessary enzymes by itself, this may or may not occur. Even if it does occur, the large expenditure of metabolic reserves of energy and biosynthesis may be taken from stores that were needed for the efforts of the body to combat disease. This digestive stress then not only leads to a general weakening of the system, but also directly impedes the body's attempts to heal itself.

Overview of Digestion in Aging:

The goal of proper nutrition with enzyme supplementation is to maintain the best health possible for one’s body while aging. As was stressed above, consuming even a perfect diet accomplishes nothing unless the nutrients are digested and absorbed. It must be understood that as the digestive system ages, even under the best circumstances, there is a decline in digestive capacity. As with other aspects of aging, there is great individual variability, and the study of physiological changes with age in humans is often complex and difficult (Holt PR "Effects of aging upon intestinal absorption" in Nutritional Approaches to Aging Research ed. GB Moment, CRC Press, Boca Raton, 1982, pp. 157-175). Since the ability of the body to secrete digestive enzymes seems to decline with age in many individuals (see above ref.), the importance of supplementary enzymes increases with age. The consequences of digestive stress accumulate with aging, so the best lifestyle to minimize the effects of aging includes life-long consumption of a nutritious, balanced diet and enzyme supplementation. One of the most popular theories of aging contends that oxidative damage is an important contributor to many aspects of physiological decline with aging (reviewed in Schneider EL & Reed JD, "Modulations of aging processes" in Handbook of the Biology of Aging ed. CE Finch & EL Schneider, Van Nostrand Reinhold, New York, 1985, pp. 53-59). It is therefore also highly desirable to avoid all types of stress to the extent possible, as well as environmental toxins.

On the other hand, the consequences of eating a diet which stresses the digestive system and does not meet the nutritional needs of the body may be serious and numerous. Over time, physiological stress will result in structural damage. Where and when this damage occurs will vary with each individual according to the timing and location of systemic attacks and their innate reserve capacity. As structural damage accumulates, the physiological resources available to deal with stress will decline, and a downward vicious cycle will be entered which only becomes harder to stop and reverse as time goes on.

Digestive Enzyme Supplementation:
Digestive Support:

There is a large body of literature supporting the efficacy of oral supplementation with digestive enzymes for patients with specific gastrointestinal disorders such as pancreatitis (e.g., Sidhu S & Tandon RK "Chronic pancreatitis: diagnosis and treatment" Postgrad Med J 1996; 72: 327-333). In patients with pancreatitis or cystic fibrosis there is an insufficiency of digestive enzymes available from the pancreas. The digestive process is therefore faulty, with resultant symptoms (e.g., abdominal pain and steatorrhea). Therapeutically, this deficit is addressed with oral supplementation with digestive enzymes. The usefulness of this therapy establishes the general principal that oral digestive enzymes participate with endogenous enzymes in digestion. It is therefore not surprising that the consumption of digestive enzymes with or in food has been shown to enhance digestion in people without such diseases (Prochaska LJ & Piekutowski WV "On the synergistic effects of enzymes in food with enzymes in the human body. A literature survey and analytical report" Med Hypotheses 1994; 42: 355-362).

Because enzymes are very specific in their activities but food is very diverse in its composition, it is very beneficial to supplement the diet with a broad range of enzymes in order to reduce digestive stress. There are two aspects to this desirable diversity. On the one hand it is necessary to supply enzymes from all of the various categories of digestive enzymes. Thus we need proteolytic enzymes (or proteases) for the digestion of proteins, amylases for the digestion of carbohydrates, and lipases for the digestion of fats. Notice that each of these is a family of enzymes, not a single purified enzyme. This brings us to the second kind of desirable diversity, which is within each enzyme class.

To make this idea clear, we may consider the case of the protease family. As discussed above, proteins are long chains of amino acids terminating with chemically different ends, referred to as the "amino teminus" and the "carboxy terminus":

Organisms concerned with digesting proteins synthesize various enzymes for the job, including some which work in the middle of the amino acid chain ("endoproteases") and some which work on the ends (exoproteases). Moreover, different enzymes specialize in cleaving different peptide bonds (characterized by the particular amino acids joined by the bond). The speed and thoroughness with which proteins are digested increases when a variety of enzymes attack the protein in the middle, at both ends, and at various types of peptide bonds.

Exoproteases (characterized according to which end of the protein they attack)

  • Aminopeptidases
  • Carboxypeptidases
Endoproteases (characterized by the type of peptide bond they attack)
  • Cysteine - bromelain, papain
  • Serine - bacterial neutral protease (subtilisin)
  • Aspartic - Aspergillus proteases, pepsin

Source of Enzymes:
Environmental activity

The general pattern in which digestion occurs as ingested material passes through the digestive tract was discussed above. One very important aspect of this is the pattern of changing chemical environments in which digestion occurs. Food enters the stomach at a relatively neutral pH, is acidified there to a pH of about 3.0, and then is returned to a nearly neutral pH in the duodenum. As indicated above, pancreatic enzymes are active at a neutral pH but not in an acidic environment. Plant and fungal digestive enzymes, however, have a much broader pH range for high levels of activity. Supplementary enzymes from these sources are therefore able to begin digestion immediately, continue working as food is first held in and then processed by the stomach, and still function after the chyme has been delivered to the duodenum and returned to a neutral pH. Pancreatic enzymes only begin to work in the duodenum, and are often coated so that they are protected from exposure to the acidic environment of the stomach. The following figure gives several curves showing how a mixture of protease enzymes from the fungus Aspergillus oryzae maintains activity over a wide pH range.

Benefits of Digestive Support:

There are two main systemic benefits to nutritional support with digestive enzymes taken with meals. These are improved nutrition and colon health.

Improved nutrition. Nutritional management requires control of consumption and assurance of complete digestion of all types of food.


If sufficient calories are not ingested and digested from these dietary sources the body will break down stored fat, then stored and structural protein to supply the needed energy for life. Incomplete digestion of fats may result in diarrhea and/or, more seriously, essential fatty acid deficiency. Adequate absorption of essential fatty acids is necessary to maintain membrane structure in cells throughout the body and to maintain healthy skin. Essential fatty acid deficiency also reduces blood clotting time and decreases fibrinolytic activity.

Many health-conscious individuals are eating less protein, fat and refined sugar and more complex carbohydrates. Often this takes the form of cooked and/or processed food which has little, if any, remaining active enzymes. In many cases the amount of food eaten is carefully controlled as to calorie content. However, a major stumbling block for most people trying to control their food intake is hunger. Satiety is experienced initially as food is chewed, swallowed, and received in the stomach. Over a longer time period satiety is achieved as the brain reacts to absorbed break down products of all three food categories, i.e. protein, carbohydrates, and fats. Failure to digest fats, especially if their intake is restricted, will reduce or prevent satiety, and thus stimulate overeating. Eating effectively alleviates hunger only if the nutrients ingested are also digested and absorbed.

Fats are often a significant source of dietary calories to supply the energy needed by the body for life. Fats have more than twice the energy available for metabolism per unit weight than either carbohydrates or proteins (4 Cal/g for protein and carbohydrates, 9 Cal/g for fats).


The human body has a complex mechanism for balancing and exchanging proteins and amino acids in order to maintain health. Insufficient amino acids may enter the blood stream due either to insufficient protein intake, improper protein ingestion (emphasis on "incomplete" protein lacking essential amino acids), and/or incomplete protein digestion.

A shortage of amino acids in the blood stream will trigger the breakdown of existing protein in order to make up the deficit. Sources for such protein include plasma protein, liver protein, and tissue protein. When plasma protein levels fall they are replaced at the expense of liver protein. When stored protein from the liver and other tissues is exhausted, structural protein from bodily tissues will begin to be lost. (The above is summarized from: Textbook of Medical Physiology, 9th edition, Guyton & Hall, Saunder, 1996).

  • Loss of plasma protein will degrade the plasma transport of a wide variety of nutrients and other substances in the blood, and cause osmotic imbalance between the plasma and tissue fluids.
  • Loss of tissue protein will have profound and wide ranging effects including:
  • the loss of mass,
  • loss of structural stability, and
  • loss of specific functionality (since all cellular activities are dependent upon enzymes, which are proteins).
Specific effects of deficiencies in protein nutrition are rapidly evident in the immune system. "Because aging and malnutrition exert cumulative influences on immune responses, many elderly people have poor cell-mediated immune responses and are therefore are at a high risk of infection. Nutritional therapy may improve immune responses of elderly patients with protein-energy malnutrition." (B.M. Lesourd, "Nutrition and immunity in the elderly: modification of immune responses with nutritional treatments" Am J Clin Nutrition 1997; 66:478S-84S).

In addition, it is widely known that adequate protein nutrition is essential for the maintenance of good bone health, and it has been estimated that at least one third of all osteoporotic fractures have a nutritional basis (R.P. Heaney, "Food: what a surprise!" Am J Clin Nutrition 1996; 64:791-792). Bones consist of equally important organic and inorganic parts. Calcium (in the form of calcium phosphate crystals) is the most important constituent of the inorganic part. The most important constituent of the organic part is collagen, which is the principal protein of all of the connective tissue of the body. Without adequate collagen, bone loses most of its tensile strength and becomes brittle.


Incomplete digestion of carbohydrates may result in:

  • break down of tissue protein to provide needed energy;
  • various forms of intestinal distress (e.g., diarrhea, bloating, flatulence);
  • failure to achieve satiety from carbohydrates consumed, resulting in overeating and obesity.
The mucosal cells lining the villi of the small intestine are responsible for secreting the enzymes necessary to complete the digestion of carbohydrates to the level of monosaccharides that are absorbed into the blood. Malt diastase functions to produce disaccharides (maltose) from complex carbohydrates. Lactase and sucrase are responsible for breaking two common disaccharides, lactose and sucrose, into their component monosaccharides.

Colon Health:

Colon health is especially important to systemic health because of the bacterial colonization of the colon. There are approximately as many colonic bacteria as there are cells in the entire body. There are usually hundreds of different species of bacteria present in the human colon at any one time. Among these, some of these will make positive contributions to the health of the host organism, and some negative. Those that make a positive contribution are called probiotics, and these are usually lactic acid producing species such as Lactobacillus, Streptococcus and Bifidobacteria. The best recognized, and among the best studied, of these probiotic bacteria is Lactobacillus acidophilus. Extensive research has demonstrated the following actions of Lactobacillus acidophilus which have positive impact on the health of the host organism (Shahani, K.M. "Nutritional, therapeutic and immunomodulatory role of probiotics [particularly about L. acidophilus DDS1] presentation at Amer Coll. Adv. Med.; fall, 1997):

  • digestion of food;
  • production of B vitamins;
  • production of enzymes;
  • production of natural antibiotics;
  • reduction of serum cholesterol;
  • help metabolize calcium;
  • retard cancer multiplication;
  • retard dermatological and skin disorders; and
  • enhance immune factors.

Traditional Chinese Medicine:

There is an excellent correlation between the discussion above and the role played by Spleen Qi in Traditional Chinese Medicine (TCM). According to Lesley Tierra in "TCM, the Spleen and Western Medicine" (1998, Freedom Quest, Inc.), "A deficiency of spleen qi was thus found to correspond to an insufficiency of digestive enzymes and a reduction of enzyme activity, interfering with digestion of proteins." This correlation is especially significant since "the spleen is probably the most important strategy for healing in TCM because it affects the body's immunity and capacity to maintain and heal itself."

Enzymes for Nutritional Supplements:

Enzymes may be used as nutritional supplements, as discussed above. In the world of nutritional supplements enzymes constitute only a very small segment, with the bulk consisting of vitamins, minerals, and herbs. Enzymes are of value in conjunction with other supplements for the same reason that they are of value with food--to increase the absorption of the desired constituents (nutrients or other active ingredients). We have already seen why enzymes such as phytase would be of benefit in conjunction with supplemental iron. Some supplements, such as phytosterols, are fat soluble. The absorption of such fat soluble supplements is degraded if the digestion of fats in accompanying food is incomplete, and is therefore enhanced by supplemental lipase.