Emerging Clinical Science of Bifunctional Support for Detoxification By DeAnn J. Liska, Ph.D. and Jeffrey S. Bland, Ph.D. -------------------------------------------------------------------------------- An enormous amount of research literature associating toxin exposure to disease has been published, and current estimates suggest that between $568 and $793 billion dollars is spent in the U.S. and Canada every year on toxicity-related diseases.(Muir and Zegarac, 2001) Exposure to toxins -- such as heavy metals, pesticides, industrial compounds and pollutants -- is a causative factor for many types of cancers, Parkinson's disease, conditions such as chronic fatigue syndrome (CFS) and multiple chemical sensitivities (MCS), and is suggested to affect diverse conditions such as atherosclerosis and diabetes.(Sherer et al., 2002; Racciatti et al., 2001; Olmstead, 2000; Silkworth and Brown, 1996) Cancer statistics alone are alarming; environment may account for as much as 80% of cancer cases.(Lichtenstein et al., 2000) Cancer is the third leading cause of death in children.(CDC, 2000) In particular, the incidence of non-Hodgkin's lymphoma and brain cancer in children have increased 30% and 21%, respectively, between 1973 and 1997, and strong associations exist between these cancers and exposure to environmental toxins like organochlorinated pesticides.(Buckley et al., 2000; Daniels et al., 1997; Meinert et al., 2000; Rothman et al., 1997; Webster et al., 2002) The question for preventive medicine is: How do we protect ourselves and our patients from the damage toxins can produce in order to promote optimal health and longevity? Certainly, decreasing the amount of toxins in the environment, and minimizing exposure to toxins are key in any strategy to decrease risk of myriad conditions. Yet, these strategies alone are not enough. We can't escape toxin exposure in today's world. A 2001 pilot study looking at residential toxin exposure detected the presence of 33 different carcinogens implicated in breast cancer in house dust, and 24 different compounds in air.(Rudel et al., 2001) Investigations on tissue samples in humans show that we maintain a level of toxin contamination within our bodies on a regular basis. For example, studies in 1995 showed that several toxins, including naphthols and chlorinated polyphenols, were found in tissues from at least 64% of the 1000 people studied, with the majority of these toxins present in over 80% of the tissues sampled.(Levin, 1999) These data indicate that we are all carrying a toxic load within our bodies due to a lifetime of exposure, and this toxic burden can accumulate so the body tissues are exposed to much higher doses than the environmental concentrations would suggest are present. We simply cannot remove ourselves from all exposures to toxins. What we can do to provide protection from the influence these toxins can have on our health by promoting the endogenous systems that protect the body from their effects. The primary system that performs this task is the detoxification, or biotransformation system of enzymes, which includes Phase I bioactivation, and the Phase II conjugation. And, since these enzyme systems require many key nutrients to function optimally, phytonutrients can play a major role in promoting healthy detoxification and protection from toxicity. Detoxification: One of the body's major defenses to environmental stress One of the consequences of Phase I bioactivation is that the product, called the reactive intermediate, is quite often more reactive -- and potentially more toxic -- than the parent molecule. Therefore, it is important that this molecule be converted to a non-toxic, water-soluble molecule as soon as possible. Conjugation of the reactive intermediate to a water-soluble molecule is accomplished by the Phase II conjugation reactions, which include glucuronidation, sulfation, glutathione conjugation, amino acid conjugation, methylation, and acetylation. These Phase II reactions require a replenishable source of cofactors-such as sulfate in the case of sulfation or specific amino acids the case of amino acid conjugation -- since these cofactors are attached to the toxin and then lost through excretion. The Phase II reactions not only require a steady source of cofactors, but also use large amounts of energy in the form of adenosine triphosphate (ATP). Therefore, ATP must be adequately replenished for optimal, balanced detoxification. The detoxification system is quite complex. It occurs mainly in the liver, although the small intestine is very important in removing toxins during first-pass metabolism. In fact, about 25% of detoxification and removal of toxins occurs in the intestine, which is significant not only in the amount of activity but also because once toxins are deactivated in the intestines they never enter the body. So, intestinal health is also important for optimal detoxification. However, it is important to note that all cells in the body have some of the Phase I and Phase II enzymes with which to perform detoxification and provide protection from toxins. Phase I Bioactivation Requires NADH (produced from niacin) Conjugation reactions include glucuronidation, sulfation, methylation, amino
acid conjugation, glutathione conjugation, and acetylation -------------------------------------------------------------------------------- Clinical Considerations for Programs to Support Optimal, Balanced Biotransformation Decrease total load and exposure to toxins. -------------------------------------------------------------------------------- Clinical programs to promote healthy balanced detoxification should take into consideration several factors. Adequate nutriture for overall support of biotransformation and excretion is key, as well as provision of the full spectrum of Phase II cofactors. In addition, emerging research suggests that many phytonutrients that are associated with lower risk of cancers may exert their protective influence because they are bifunctional modulators of the detoxification system. A brief review of these clinical considerations is provided below. Decrease total load and exposure to toxicants. A high-quality, complete source of protein should be low-allergy-potential in order to decrease the body's burden of inflammation and potential allergen toxins. High-quality protein is a good source of methionine, cysteine, glutamine, and glycine in a form that provides high absorption; these amino acids can be used to generate sulfation, glutathione and amino acid conjugation cofactors. A high-quality protein also may benefit those with toxic burdens of mercury, since mercury exposure is associated with depletion of the specific amino acids that are precursors to neurotransmitters. Cell culture studies have shown that mercury inhibits uptake and release of neurotransmitters such as dopamine, norepinephrine, and serotonin.(Quig, 1998) Methionine is also a component of the homocysteine cycle, which provides S-adenosylmethionine, the cofactor for Phase II methylation. Support for energy production is also vital during detoxification; therefore, adequate intake of high energy-supportive nutrients are essential.(Lall et al., 1999) Fats can be problematic, since many people consume too many of the wrong kind. Moreover, individuals with toxicity-related conditions may have altered intestinal permeability (leaky gut) as one of the consequences of toxic exposure and, therefore, may not efficiently absorb nutrients like long-chain fats through the intestinal tract. Provision of a highly bioavailable source of fats that can be used directly to support energy production is beneficial. The medium chain triglycerides (MCTs) are fats that fit this profile.(DeGaetano et al., 1994) MCTs are not absorbed like long-chain fats, but are quickly metabolized in the small intestine and can be absorbed without the presence of bile. Moreover, the small intestine has greater capacity to absorb MCTs, and MCTs have been shown to support patients with malabsorption syndrome. MCTs have been shown to prevent early alcohol-induced liver injury in animals, possibly due to their ability to inhibit generation of reactive oxygen species.(Kono et al., 2000) Interestingly, olive oil, in contrast to sunflower, corn, or fish oil, was found to be protective against chemically-induced fibrosis in rats,(Szende et al., 1994) suggesting it may also be a good source of fat for a detoxification program. Bifunctional Support for Detoxification: Achieving Balance As can be elucidated from its name, a compound that provides bifuctional modulation for detoxification is one that supports healthy, optimal activity of both Phase I and Phase II. In the case of Phase II, healthy, optimal activity is associated with induction of the enzymes, thereby providing for higher activity. Support for healthy, optimal Phase I requires managing a balanced level of Phase I enzymes. Bifunctional modulators often are capable of inhibiting the induction of Phase I enzymes by toxins, without inhibiting Phase I entirely. Since there are many Phase II enzymes, an effective bifunctional modulator will promote several of these Phase II activities at the same time. Many of the bifunctional modulators also promote optimal balance by their ability to act as antioxidants and quench reactive oxygen species from Phase I reactions. Therefore, bifunctional modulators support optimal detoxification balance by modulating Phase I activities, inducing several Phase II activities, and minimizing damage by reactive molecules. Several phytonutrients that are associated with protection from toxin damage do so by acting as bifunctional modulators; these include ellagic acid, found in pomegranate and many berries, catechins from green tea and grapes, and the glucosinolates found in crucifers, such as watercress and broccoli. Ellagic Acid Catechins Interestingly, catechins have been shown to induce some Phase I activities;(Abbas et al., 1994; Xu et al., 1996) however, data also suggests that catechins selectively inhibit some Phase I activities as well.(Dashwood et al., 1999) A recent cell culture study showed that catechins inhibited the over-induction of Phase I activities by a toxic substance, but were able to moderately induce the Phase I activity themselves when the carcinogen was not present.(Williams et al., 2000) This ability to modify levels of Phase I -- promoting a moderate induction and inhibiting an over-induction -- may account for some of the beneficial activities of catechins. This study also indicated that the full spectrum of catechins was necessary for this effect, and different catechins provide differential Phase I antagonist and agonist functions. The strong antioxidant activity of catechins also provides ability of catechins to bind to the reactive intermediates produced by Phase I that are not immediately conjugated by a Phase II reactions, which is another reason catechins may promote balance. Green tea catechins have also been shown to promote healthy microflora, pH, and bowel function(Goto et al., 1999), which may further support detoxification. One cup of tea contains between 100 an 200 mg of catechins(Ahmad and Muktar, 1999), which is suggested to account for at least 90% of the observed beneficial effects of green tea.(Williams et al., 2000) Watercress There are many Phase II activities, and support for all of these activities is essential to achieve healthy, balanced, complete detoxification. Therefore, high Phase II activity, and a full spectrum of cofactors for Phase II activities are required. Provision of the amino acid conjugation cofactors, which include glycine, glutamine (from protein), and taurine, is important. Providing sulfation cofactors is particularly important since serum sulfate can be easily decreased after toxic exposure. For instance, subchronic acetaminophen (650 mg) doses over four consecutive days resulted in a decrease in serum sulfate levels in healthy subjects.(Hoffman et al., 1990) Sulfate cofactors also support production of glutahione. Methylation support is particularly important for optimal, full spectrum Phase II activity since methylation is a key player in excretion of steroids and steroid-like toxins. Sulfation Support with N-Acetylcysteine and Sodium Sulfate Methylation and the Labile Methyls in Detoxification Provision of choline is particularly important. Because choline can be synthesized endogenously from methionine, it has been assumed dietary sources are not required; however, much experimental data has challenged this assumption and shown that dietary sources of choline are essential. For example, choline deficiency has been shown to result in fatty liver and other liver diseases.(Buchman et al., 2001; Zeisel, 2000) Recently, the Food and Nutrition Board of the National Academy of Sciences has designated choline as an essential nutrient.(Miller, 2002) Healthy liver function and antioxidant supports to protect from oxidative
stress are essential in detoxification In addition to focused antioxidant support, protection of the liver from oxidative stress damage and provision phytonutrients and botanicals that support healthy liver function is particularly important in detoxification. Silymarin Artichoke A source of fiber and healthy excretion are important to maintain removal
of biotransformed toxins. Fiber can benefit a detoxification program in many
ways. Fiber supports intestinal mucosal cell barriers and colonic health,
which decrease toxic burden on the body and provide a first line of defense
to the system. Fiber promotes removal of the conjugated toxins that are excreted
via bile, and may decrease the absorption of some toxins. Most notably, fibers
in rice bran have been shown to preferentially bind mutagens over wheat,
corn, barley, or oat fibers, thereby removing the toxins before they can
even interact with the body and cause damage at any level.(Harris et al.,
1998) References Agarwal R, Mukhtar H. Cancer chemoprevention by polyphenols in green tea and artichoke. Adv Exp Med Biol. 1996;401:35-50. Ahmad N, Muktar H. Green tea polyphenols and cancer: biological mechanisms and practical implications. Nutr Rev. 1999;57(3):78-83. Ahmed S, Rahman A, Saleem M, Athar M, Sultana S. Ellagic acid ameliorates nickel induced biochemical alterations: diminution of oxidative stress. Human Exp Toxicol. 1999;18:691-98. Ahn D, Putt D, Kresty L, Stoner GD, Fromm D, Hollenberg PF. The effects of dietary ellagic acid on rat hepatic and esophageal mucosal cytochromes P450 and phase II enzymes. Carcinogenesis. 1996;17(4):821-28. Aruoma OI. Nutrition and health aspects of free radicals and antioxidants. Food Chem Toxic. 1994;32:671-83. Aw TY, Jones DP. Nutrient supply and mitochondrial function. Annu Rev Nutr. 1989;9:229-51. Barch DH, Rundhaugen LM, Stoner GD, Pillay NS, Rosche WA. Structure-function relationships of the dietary anticarcinogen ellagic acid. Carcinogenesis. 1996;17(2):265-69. Bell IR, Baldwin JC, Schwartz GE. Sensitization studies in chemically intolerant individuals: implications for individual difference research. Ann N Y Acad Sci. 2001;933:38-47. Buchman AL, Ament ME, Sohel M, et al. Choline deficiency causes reversible hepatic abnormalities in patients receiving parenteral nutrition: Proof of a human choline requirement: A placebo-controlled trial. J Parenteral Enteral Nutr. 2001;25:260-68. Buckley JD, Meadows AT, Kadin ME, Le Beau MM, Siegel S, Robison LL. Pesticide exposures in children with non-Hodgkin lymphoma. Cancer. 2000;89(11):2315-21. CDC. National Center for Health Statistics. 2000.; NCI. SEER Cancer Statistics Review, 1973-1997. Checkoway H, Powers K, Smith-Weller T, Franklin GM, Longstreth WT Jr, Swanson PD. Parkinson's disease risks associated with cigarette smoking, alcohol consumption, and caffeine intake. Am J Epidemiol. 2002;155(8):732-38. Chung FL, Conaway CC, Rao CV, Reddy BS. Chemoprevention of colonic aberrant crypt foci in Fischer rats by sulforaphane and phenethyl isothiocyanate. Carcinogenesis. 2000;21(12):2287-91. Clapper ML. Genetic polymorphism and cancer risk. Curr Oncol Rep. 2000;2(3):251-6. Daniels JL, Olshan AF, Savitz DA. Pesticides and childhood cancers. Environ Health Perspect. 1997;105(10):1068-77. Dashwood RH, Xu M, Hernaez JF, Hasaniya N, Youn K, Razzuk A. Cancer chemopreventive mechanisms of tea against heterocyclic amine mutagens from cooked meat. Proc Soc Exp Biol Med. 1999;220(4):239-43. DeGaetano A, Castagneto M, Mingrone G, et al. Kinetics of the medium-chain triglycerides and free fatty acids in healthy volunteers and surgically stressed patients. J Parenteral Enteral Nutr. 1994;18:134-40. Fry JR, Sinclair D, Piper CH, Townsend SL, Thomas NW. Depression of glutathione content, elevation of CYP2E1-dependent activation, and the principal determinant of the fasting-mediated enhancement of 1,3-dichloro-2-propanol hepatotoxicity in the rat. Food Chem Toxicol. 1999;37(4):351-55. Gebhardt R. Antioxidant and protective properties of extracts from leaves of the artichoke (Cynara scolymus L.) against hydroperoxide-induced oxidative stress in cultured rat hepatocytes. Toxicol Appl Pharmacol. 1997;144:279-86. Getahun SM, Chung F-L. Conversion of glucosinolates to isothiocyanates in humans after ingestion of cooked watercress. Cancer Epidemiol Biomarkers Prev. 1999;8:447-51. Goto K, Kanaya S, Ishigami T, Hara Y. The effects of tea catechins on fecal conditions of elderly residents in a long-term care facility. J Nutr Sci Vitaminol. 1999;45:135-41 Harris PJ, Sasidharan VK, Roberton AM, Triggs CM, Blakeney AB, Ferguson LR. Adsorption of a hydrophobic mutagen to cereal brans and cereal bran dietary fibres. Mutation Res. 1998;412:323-31. Hecht SS. Chemoprevention of cancer by isothiocyanates, modifiers of carcinogen metabolism. J Nutr. 1999;129:768S-74S. Hoffman DA, Wallace SM, Verbeeck RK. Circadian rhythm of serum sulfate levels in man and acetaminophen pharmacokinetics. Eur J Clin Pharmacol. 1990;39(2):143-48. Ingelman-Sundberg M. Genetic variability in susceptibility and response to toxicants. Toxicol Lett. 2001;120(1-3):259-68. Kall MA, Clausen J. Dietary effect on mixed function P450 a!2 activity assayed by estimation of caffeine metabolism in man. Human Exp Toxicol. 1995;14:801-7. Khanduja KL, Gandhi RK, Pathania V, Syal N. Prevention of N-nitrosodiethylamine-induced lung tumorigenesis by ellagic acid and quercetin in mice. Food Chem Toxicol. 1999;37(4):313-18. Kono H, Enomoto N, Connor HD, et al. Medium-chain triglycerides inhibit free radical formation and TNF-alpha production in rats given enteral ethanol. Am J Physiol Gastrointest Liver Physiol. 2000;278:G467-G76. Kosina P, Kren V, Gebhardt R, Grambal F, Ulrichova J, Walterova D. Antioxidant properties of silybin glycosides. Phytotherapy Res. 2002;16:S33-S39. Krul C, Humblot C, Phillippe C, et al. Metabolism of sinigrin (2-propenyl glucosinolate) by the human coloni microflora in a dynamic in vitro large-intestine model. Carcinogenesis. 2002;23:1009-16. Lall SB, Singh B, Gulati K, Seth SD. Role of nutrition in toxic injury. Indian J Exp Biol. 1999;37(2):109-16. Leclercq I, Desager JP, Horsmans Y. Inhibition of chlorzoxazone metabolism, a clinical probe for CYP2E1, by a single ingestion of watercress. Clin Pharmacol Ther. 1998;64(2):144-49. Levin B. Environmental Nutrition. Vashon Is, WA:HingePin Press;1999:179-84. Lichtenstein P, Holm NV, Verkasalo PK, et al. Environmental and heritable factors in the causation of cancer. N Eng J Med. 2000;343:78-85. Liska DJ. The detoxification enzyme systems. Altern Med Rev. 1998;3(3):187-98. Llorach R, Espin JC, Thomas-Barberan FA, Ferreres F. Artichoke (Cynara scolymus L.) byproducts as a potential source of health-romoting antioxidant phenolics. J Agric Food Chem. 2002;50:3458-64. Marshall K-A, Reist M, Jenner P, Halliwell B. The neuronal toxicity of sulfite plus peroxynitrite is enhanced by glutathione depletion: implications for Parkinson's disease. Free Rad Biol Med. 1999;27:515-20. McDanell RE, Henderson LA, Russell K, McLean AEM. The effect of Brassica vegetable consumption on caffeine metabolism in humans. Human Exp Toxicol. 1992;11:167-172. McKay DL, Blumberg JB. The role of tea in human health: an update. J Am Coll Nutr. 2002;21(1):1-13. Meinert R, Schuz J, Kaletsch U, Kaatsch P, Michaelis J. Leukemia and non-Hodgkin's lymphoma in childhood and exposure to pesticides: results of a register-based case-control study in Germany. Am J Epidemiol. 2000;151(7):639-46, 647-50. Miller DL. Health benefits of lecithin and choline. Cereal Foods World. 2002;47:178-84. Muir T, Zegarac M. Societal costs of exposure to toxic substances: economic and health costs of four case studies that are candidates for environmental causation. Environ Health Perspect. 2001;109Suppl 6:885-903. Olmstead MJ. Heavy metal sources, effects, and detoxification. Altern Ther Complement Med. 2000;Dec;347-354. Pall ML, Satterle JD. Elevated nitric oxide/peroxynitrite mechanism for the common etiology of multiple chemical sensitivity, chronic fatigue syndrome, and posttraumatic stress disorder. Ann N Y Acad Sci. 2001;933:323-29. Perez-Garcia F, Adzet T, Canigueral S. Activity of artichoke leaf extract on reactive oxygen species in human leukocytes. Free Rad Res. 2000;33:661-65. Quig D. Cysteine metabolism and metal toxicity. Altern Med Rev. 1998;3(4):262-70. Racciatti D, Vecchiet J, Ceccomancini A, Ricci F, Pizzigallo E. Chronic fatigue syndrome following a toxic exposure. Sci Total Environ. 2001;270(1-3):27-31. Rechner AR, Pannala AS, Rice-Evans CA. Caffeic acid derivatives in artichoke extract are metabolised to phenolic acids in vivo. Free Rad Res. 2001;35:195-202. Rogers AE. Methyl donors in the diet and responses to chemical carcinogens. Am J Clin Nutr. 1995;61(Suppl):659S-65S. Rose P, Faulkner K, Williamson G, Mithen R. 7-Methylsulfinylheptyl and 8-methylsulfinyloctyl isothiocyanates from watercress are potent inducers of phase II enzymes. Carcinogenesis. 2000;21(11):1983-88.73. Ross GW, Abbott RD, Petrovitch H, et al. Association of coffee and caffeine intake with the risk of Parkinson disease. JAMA. 2000;283:2674-79. Rothman N, Cantor KP, Blair A, et al. A nested case-control study of non-Hodgkin lymphoma and serum organochlorine residues. Lancet. 1997;350:240-44. Rudel RA, Brody JG, Spengler JD, et al. Identification of selected hormonally active agents and animal mammary carcinogens in commercial and residential air and dust samples. J Air Waste Mange Assoc. 2001;51(4):499-513. Saller R, Meier R, Brignoli R. The use of silymarin in the treatment of liver diseases. Drugs. 2001;61(14):2035-63. Scott J. Methyltetrahydrofolate: the superior alternative to folic acid. In:Kramer K, Hoppel P-P, eds. Nutraceuticals in Health and Disease Prevention. New York:Marvel Dekker, 2001;6:75-90. Sherer TB, Betarbet R, Greenamyre JT. Environment, mitochondria, and Parkinson's disease. Neuroscientist. 2002;8(3):192-7. Silkworth JB, Brown JF Jr. Evaluating the impact of exposure to environmental contaminants on human health. Clin Chem. 1996;42:8(B):1345-49. Singh BN. Effects of food on clinical pharmacokinetics. Clin Pharmacokinet. 1999;37(3):213-55. Singh K, Khanna AK, Chander R. Hepatoprotective activity of ellagic acid against carbon tetrachloride induced hepatotoxicity in rats. Indian J Exp Biol. 1999;37(10):1025-26. Steele VE, Kelloff GJ, Balentine D, et al. Comparative chemopreventive mechanisms of green tea, black tea, and selected polyphenol extracts measured by in vitro bioassays. Carcinogenesis. 2000;21(1):63-7. Szende B, Timar F, Hargitai B. Olive oil decreases liver damage in rats caused by carbon tetrachloride (CCl4). Exp Toxicol Pathol. 1994;46:355-59. Umeda S, Muta T, Ohsato T, Takamatsu C, Hamasaki N, Kang D. The D-loop structure of human mtDNA is destabilized directly by 1-methyl-4-phenylpyridinium ion (MPP+), a parkinsonism-causing toxin. Eur J Biochem. 2000;267:200-06. Vanden Heuvel JP, Clark GC, Kohn MC, et al. Dioxin-responsive genes: examination of dose-response relationships using quantitative reverse transcriptase-polymerase chain reaction. Cancer Res. 1994;54:62-8. Webster LR, McKenzie GH, Moriarty HT. Organophosphate-based pesticides and genetic damage implicated in bladder cancer. Cancer Genet Cytogenet. 2002;133(2):112-17. Wellington K, Jarvis B. Silymarin: a review of its clinical properties in the management of hepatic disorders. BioDrugs. 2001;15(7):465-89. Williams SN, Shih H, Guenette DK, et al. Comparative studies on the effects of green tea extracts and individual tea catechins on human CYP1A gene expression. Chem Biol Interact. 2000;128(3):211-29. Xu M, Bailey AC, Hernaez JF, Taoka CR, Schut HAJ, Dashwood RH. Protection by green tea, black tea, and indole-3-carbinol against 2-amino-3-methylimidazo[4,5-f]quinoline-induced DNA adducts and colonic aberrant crypts in the F344 rat. Carcinogenesis. 1996;17(7):1429-34. Zeisel SH. Choline: an essential nutrient for humans. Nutrition. 2000;16:669-71. Zhang J, Henning SM, Heber D, et al. NADPH-cytchrome P-450 reductase, cytochrome P-450 2C11 and P450 A1, and the aryl hydrocarbon receptor in livers of rats fed methyl-folate-deficient diets. Nutrition. 1997;28:160-64. This article appears in the October 2002 issue of the Townsend Letter for Doctors & Patients. For more information contact: Townsend Letter for Doctors & Patients
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