Deficiencies of digestive enzymes and imbalances in gastrointestinal pH are common causes of impaired digestion which can contribute to malabsorption of nutrients, food intolerance, food allergy and endotoxemia. Foods which are not completely digested can putrefy or ferment in the intestine resulting in the production of endotoxins. Undigested dietary proteins and large polypeptides can have significant allergenic potential both locally and systemically.
Thorough digestion can reduce allergic reactions to foods and the production of endotoxins. Proteolytic enzymes are particularly important because of their ability to digest and break down protein-based food antigens. pH-sensitive digestive enzymes, such as pancreatin and pepsin, may be inactive in individuals with gastric or pancreatic hypofunction. Certain plant enzyme preparations, however, are stable and active in both acid and alkaline environments. Such preparations are capable of promoting digestion and absorption of nutrients even in individuals with imbalances in gastrointestinal pH.
Lifestyle factors also play
a role in digestive function. Chewing foods thoroughly is indispensable
for good digestion by providing mechanical breakdown of foods and adequate
surface area for enzymatic activity. Eating in a relaxed frame of mind
helps to maintain normal digestive secretions and motility which can be
impaired by strong emotions such as anxiety and depression. Ample use of
raw foods can help to promote digestion due to their content of naturally
occurring enzymes.
The clinical importance of dietary fiber and its metabolic products has been well established. Dietary fiber contains soluble and insoluble components which play an essential role in colon health. Soluble fiber is fermented by colonic microflora resulting in the production of short chain fatty acids (SCFAs), such as butyric acid. Butyric acid is utilized as the preferred fuel source by the colonic mucosa in addition to being secondarily metabolized to glutamine - an essential fuel for the cells of the small intestine. Fiber has been shown to restore the normal architecture and physiology of the intestinal microvilli and to prevent bacterial translocation in patients on total parenteral nutrition.
Fiber has emerged as a leading dietary factor for prevention and treatment in a number of chronic and degenerative diseases. High fiber diets are associated with improved gastrointestinal function, reduced risk of certain cancers, enhanced weight control and a lower risk of coronary artery disease and high blood pressure. Current guidelines advise doubling the average fiber intake for Americans. Psyllium, oat products, guar gum and certain fruits and vegetables provide a good source of soluble fiber while most plant foods provide insoluble fiber. In addition to promoting beneficial SCFA production and intestinal motility, dietary fiber can help to bind endotoxins and facilitate their elimination via the bowel. Oral use of bentonite has also been shown to help bind endotoxins and prevent their systemic absorption.
Rebuilding The Intestinal Mucosa
The healthy intestinal lining is selectively permeable, acting as an absorptive surface for nutrients and a barrier which prevents harmful compounds from entering the body. Under pathological conditions, however, bacteria, toxins, antigens and other noxious compounds from the intestine can be absorbed into the body and lead to a wide range of chronic and degenerative disorders.
Leaky gut syndrome refers to a damaged mucosa with increased permeability which allows the passage or translocation of antigenic macromolecules and other harmful compounds into the general circulation. Antigenic compounds can cause local and systemic allergic responses by stimulating the production of antibodies which cross react with immunologically similar tissues. Research indicates that certain autoimmune diseases are caused by this mechanism. Inflammatory bowel disease, food allergies, rheumatoid arthritis, ankylosing spondylitis, chronic hepatitis, celiac disease, and Reiters syndrome all have been shown to be associated with antigen uptake from the intestine.
The gastrointestinal tract is considered one of the largest immune organs of the body. Disruption of bowel mucosa not only compromises digestive and absorptive functions, but also vital immune functions. Gut-associated lymphatic tissue (GALT) confers specific immunity in the form of secretory immunoglobulin-A (sIgA) while specialized cells in the mucosa, such as macrophages, natural killer cells, mast cells and intraepithelial lymphocytes, protect against absorption of intestinal toxins and pathogens. Non-specific immunity is conferred by gastric acidity, mucus, motility, digestive enzymes and normal bacterial flora. Chronic permeability defects and associated mucosal damage may therefore lead to considerable compromise of immune function.
Common causes of permeability
defects include the use of alcohol and non-steroidal anti-inflammatory
drugs (NSAIDs). Intestinal parasites, dysbiosis, impaired digestion, pancreatic
insufficiency and food allergies also contribute. Permeability defects
are also associated with inflammatory bowel disease, post-surgical trauma,
extended immobility, prolonged fasting and starvation, certain autoimmune
diseases, AIDS/ARC and environmental illness. Re-establishing a healthy
intestinal lining with an intact physical and immune barrier requires the
presence of nutrients that act as intestinal cellular fuels and mucosal
building blocks. Glutamine is a key fuel for the cells of the small intestine,
or enterocytes. Considered a conditionally essential amino acid, L-glutamine
is required for normal structure and barrier function of the small intestinal
mucosa. Other nutrients, such as N-acetyl-D-glucosamine, support normal
mucosal secretion, being a constituent of the most superficial mucosal
layer known as the glycocalyx. Gamma-linolenic acid (GLA) stimulates the
production of the E series prostaglandins which have been shown to reduce
both intestinal permeability and inflammation. Gamma oryzanol, a component
of rice bran oil, has been shown to reduce small bowel ulcer formation
and to have antioxidant effects on the gastrointestinal mucosa. Phosphatidyl
choline has been shown to support normal mucosal barrier function.
Reducing Oxidative Damage
Free radicals, or pro-oxidants, have been implicated in the development of over 50 human diseases including chronic inflammatory bowel disease and bowel cancer. Oxidative stress occurs when the antioxidant/pro-oxidant equilibrium becomes imbalanced. Once antioxidant stores are depleted, oxidative stress in the gastrointestinal tract results in tissue damage and inflammation, and has been implicated in malignant transformation.
Antioxidant depletion can occur as a result of tissue damage from disease or injury, exposure to environmental pollution and radiation, chronic drug and alcohol use, the use of NSAIDs and antibiotics, unnecessary iron supplementation and numerous other causes. Intestinal pathogens and dysbiosis can also contribute to antioxidant depletion both directly and by the production of endotoxins.
Several antioxidants have
been shown to be effective in preventing damage due to free radicals. Glutathione
and glutathione precursors such as N-acetylcysteine, vitamin E, vitamin
C, beta carotene, and selenium are among the most widely researched of
the natural antioxidants. Potent phytochemical antioxidants are also found
in plant flavonoids such as quercetin and ginkgo flavone glycosides. Research
indicates that quercetin acts to stabilize intestinal mast cell membranes,
thus inhibiting the release of histamine and other inflammatory mediators.
Ginkgo flavone glycosides have been shown to exert direct antioxidant effects
on the gastrointestinal mucosa and to improve gastrointestinal circulation.
Normal bowel flora help to prevent the establishment of intestinal pathogens through competitive inhibition. Beneficial bacteria or probiotics, such as Lactobacillus and Bifidobacteria species, contribute to a healthy intestinal environment by maintaining optimum pH and producing important nutrients and certain enzymes. In addition, Lactobacilli produce natural antibiotics and other antimicrobial substances that suppress the growth of pathogenic organisms and reduce putrefaction and endotoxemia. Both Lactobacilli and Bifidobacteria are known to have beneficial immunological effects by reducing production of procarcinogens and inducing large increases in sIgA production.
Indigenous flora play an important role in immune homeostasis. Interactions of intestinal microflora with GALT and the liver play an important role in overall immunocompetence. Healthy bacterial microflora are required for maturation of the intestinal immune system, whereas translocation of pathogenic microorganisms has been shown to suppress T-cell formation and to alter immune function of the liver.
Research indicates oral
preparations of probiotic bacteria and microflora growth promoters such
as fructooligosaccharides (FOS) can play a significant role in re-establishing
the natural balance of healthy bowel flora. Human studies have shown significant
increases in populations of beneficial intestinal Bifidobacteria following
oral administration of short-chain FOS. Lactobacillus and Bifidobacterium
species along with S. faecium constitute an integral part of the healthy
intestinal microecology.
Eliminating Intestinal Pathogens
Detection and elimination of intestinal pathogens are key steps in re-establishing a healthy gastrointestinal tract. Dysbiosis, candidiasis and the presence of intestinal parasites have been linked to a number of chronic illnesses. Pathogenic E. coli, Enterobacter, Klebsiella, Pseudomonas, Sertia and Bacteroides are common intestinal pathogens which are often involved in endotoxemia. Endotoxins can cause local and systemic inflammation via activation of the alternate complement pathway and have been implicated in the development of psoriasis, systemic lupus erythematosis, dermatomyositis, pancreatitis and other chronic disorders.
Cross reactivity of bacterial antigens to normal human tissues is one mechanism by which intestinal pathogens can contribute to the development of chronic degenerative disease. Studies indicate ankylosing spondylitis and other diseases associated with HLA-B27 may develop in response to an antigenic trigger acting across a mucous membrane, such as that of the gut mucosa. Intestinal pathogens have been implicated in cases of diabetes myelitis, ulcerative colitis, thyroid disease and other disorders.
Active principles obtained
from traditional medicinal plants such as Artemesia annua, Quassia amara,
Hydrastis canadensis, Juglans nigra and Allium sativa are used worldwide
for the treatment of protozoal and other infectious diseases. Constituents
from these plants including quassin, artemesinin, allicin, berberine and
indole alkaloids have been shown to possess anti-protozoal activity. A
number of these phytochemicals have provided the basis for development
of important synthetic analogs such as the quinine-based anti-malarials.