The Reliability of Non-Cognitive Admissions Measures in Predicting Non-traditional Doctor of Pharmacy Student Performance O... American Journal of Pharmaceutical Education 2003; 67 (2) Article 64. TEACHERS TOPICS Biochemistry of the Water Soluble Vitamins: A Lecture for First Year Pharmacy Students Michael G. Bartlett, PhD Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, Athens, GA 30602-2352 Keywords: Biochemistry, vitamins This manuscript describes the lecture on vitamins contained in the core course entitled, “The Bio- chemical Basis of Drugs and Diseases” (Pharmacy 3050). In the first year, our curriculum is designed to focus on systems and diseases. As such, this course acts in concert with both the Anatomy & Physiology course and the Pathophysiology course to present an integrated view of human diseases and systems. The second year of our curriculum is focused on learning about drugs classes and the mechanism of action. The third year of the curriculum is focused on simulated patients, while the forth year of the curriculum the students are presented with real patients. The lecture on vitamins is the last topic of a course focused primarily on metabolism. Because many vitamins play major roles in metabolic cycles, this lecture allows for a brief review of much of the ma- terial covered throughout the course. Therefore, vitamin examples are primarily chosen to reinforce major metabolic cycles and also their role in human disease. There is more clinical information that is relevant to vitamins than what is presented in this lecture. However, since first year students in our curriculum have almost no knowledge of therapeutics, the focus of the lecture is on diseases and not clinical practice. INTRODUCTION Vitamins are a multibillion dollar industry.1 They are readily available to the public and are the focus of the most frequently asked questions to pharmacists. 2 Sur- prisingly, most pharmacy students receive little train- ing on the many roles of vitamins in nutrition.2 There- fore, this lecture attempts to not only reinforce fun- damental biochemical and metabolic pathways in the human body, but also to provide pharmacy students with practical information. The diet is a vast source of important nutrients. These nutrients include several important classes of biomolecules such as: (1) energy yielding components (carbohydrates, lipids, and proteins), (2) essential and nonessential amino acids, (3) essential fatty acids, (4) minerals, and (5) vitamins. Vitamins are organic sub- stances that must be provided by the diet either because they cannot be biosynthesized or the amount that is pro- vided through biosynthesis is inadequate for maintaining normal health. Vitamins are broadly divided into 2 classes based upon their hydrophobicity. The more hy- drophilic vitamins are termed the water-soluble vitamins and are composed of the B-complex vitamins and vita- min C. The more hydrophobic vitamins, referred to as the fat-soluble vitamins, are composed of Vitamins A, D, E, and K. This article focuses primarily on the water- soluble vitamins due to their greater role in the major metabolic cycles, which are the primary focus of this course. The normal North American diet is sufficient to pre- vent significant vitamin deficiencies and the related dis- eases associated with these deficiencies. However, there is increasing concern that slight vitamin deficiencies in a number of water-soluble vitamins (B1, B6, B12, folate and vitamin C) are risk factors for diseases such as Corresponding Author: Michael G. Bartlett, PhD. Mail- ing Address: Department of Pharmaceutical and Bio- medical Sciences, College of Pharmacy, University of Georgia, Athens, GA 30602-2352. Tel: (706) 542- 5390. Fax: (706) 542-5358. E-mail: bart- lett@rx.uga.edu. 1 American Journal of Pharmaceutical Education 2003; 67 (2) Article 64. Mild deficiencies of thiamin are sometimes ob- served in the elderly and in low-income groups on re- stricted diets. The earliest symptoms of thiamin defi- ciency are loss of appetite, constipation, and nausea. Other symptoms such as mental depression, peripheral neuropathy, irritability, and fatigue are related to the role of thiamin in maintaining a healthy nervous system. such as depression, cancer, cardiovascular disease, and neural tube defects. The prevalence of this slight vitamin deficiency is likely related to diet, since most of these vitamins are supplied by fruit and vegetable intake. A recent survey has shown that only 25% of the population meets their daily intake of 5 servings.3 Food preparation is another source of vitamin loss. For example, heating food for more than 2 hours causes more than a 10% loss of most water-soluble vitamins. Refrigeration, freezing, and reheating have all been shown to lead to further loss of vitamins. Ex- posure to light causes significant loss of riboflavin from foods and the combination of heating and light can almost completely remove this vitamin from food.4 The most common form of thiamin deficiency in the United States is alcoholic neuritis. Because alcoholics normally have a poor appetite, overall food consumption is low. In addition, alcoholics are predisposed to devel- oping nutritional deficiencies since alcohol is their pri- mary calorie source. Under the broad umbrella of alco- holic neuritis come two disorders, Wernicke’s Syn- drome and Korsakoff’s Psychosis.7 The symptoms of Wernicke’s Syndrome (ophthalmoplegia, nystagmus, and ataxia) respond quickly to administration of thia- min, whereas the more severe memory and learning dis- orders associated with Korsakoff’s Psychosis are refrac- tory to thiamin treatment. Thiamin (Vitamin B1) Thiamin functions in the body as thiamin pyrophosphate (TPP) an important enzyme co-factor.5 Thiamin reacts with adenosine triphosphate (ATP) to form thiamin pyrophosphate through a reaction medi- ated by the enzyme thiamin diphosphokinase. Follow- ing its production, TPP is incorporated into 2 impor- tant enzymes: pyruvate dehydrogenase and α- ketoglutarate dehydrogenase. Pyruvate dehydrogenase is part of a multi-enzyme complex that acts to convert pyruvate generated in glycolysis into acetyl-CoA for entry into the tricarboxylic acid (TCA) cycle. Thiamin pyrophosphate is also used as a co-factor for the en- zyme α-ketoglutarate dehydrogenase, which is a key point of regulation in the TCA cycle. α-Ketoglutarate dehydrogenase is involved in the conversion of α- ketoglutarate to succinyl CoA. In the case of both en- zymes, TPP assists in decarboxylation of a small ke- toacid. Riboflavin (Vitamin B2) Riboflavin functions in the body as an enzyme co- factor in many oxidation/reduction reactions and has a central role in energy production and cellular respira- tion. Riboflavin reacts with ATP to form flavin mono- nucleotide (FMN). Flavin mononucleotide then reacts with a second molecule of ATP to form a molecule of flavin adenine dinucleotide (FAD). Within cellular me- tabolism, enzymes such as succinyl dehydrogenase (TCA cycle), AcylCoA Dehydrogenase (β-Oxidation), and Glycerol-3-phosphate Dehydrogenase (Glycerol Phosphate Shuttle) use FAD as a cofactor. The enzyme NADH-CoEnzyme Q oxidoreductase (Complex I, Elec- tron Transport Chain) uses FMN as a co-factor. As en- zyme co-factors, FAD and FMN are able to function as electron acceptors. The addition of 2 electrons to FAD results in the formation of a molecule of FADH2, while the addition of 2 electrons to FMN causes the formation of a molecule of FMNH2. In addition to its uses in metabolism, thiamin may enhance circulation and blood formation. It is re- quired for maintenance of the nervous system and is used in the biosynthesis of the neurotransmitters ace- tylcholine and γ-hydroxybutyrate (GABA). Thiamin also is used in the production of hydrochloric acid in the stomach and, therefore, has a role in digestion. Riboflavin + ATP → FMN + 2e- ↔ FMNH2 FMN + ATP → FAD + 2e- ↔ FADH2 Thiamin is provided in the diet through most grains. A deficiency of thiamin is called beriberi and it is most often observed in Southeast Asia.6 The main staple of diet in this part of the world is rice, which does not provide dietary thiamin to as great an extent as other grains. The symptoms of beriberi include limb pain, muscle weakness, and low cardiac output. All symptoms are related to the diminished capacity of the major energy producing pathways that are de- pendent on TPP as a co-factor. The reduced forms of these enzyme co-factors can donate these electrons to return to their previous fully oxidized forms. It is this ability to act as a conduit for electron transfer reactions that makes FAD and FMN such important enzyme cofactors. Riboflavin is available from a wide variety of die- tary sources such as milk, cheese, meat, eggs, and cereal products. Symptoms associated with riboflavin defi- ciency include sore throat, dermatitis, anemia, neuropa- 2 American Journal of Pharmaceutical Education 2003; 67 (2) Article 64. thy, and cataract formation. Riboflavin deficiency is not normally observed in the United States; however, deficiency may be observed as part of a general case of malnutrition or in cases of chronic alcoholism.8 The conversion of riboflavin to FMN is required for absorption and transport into many tissues. The con- version has been shown to be inhibited by hypothy- roidism and the structurally similar medications chlorpromazine, adriamycin, quinacrine, tetracycline, and tricyclic antidepressants.9-12 Niacin (Vitamin B3) The vitamin niacin (nicotinic acid) and its struc- tural analog nicotinamide have identical function due to their facile interconversion in the body. Niacin is converted through a series of reactions to its active form nicotinamide adenine dinucleotide (NAD+). NAD+ can be converted to a reduced form NADH by gaining 2 electrons through a process similar to FAD reduction. NADH is produced in large quantities by the TCA cycle and β-Oxidation and to a lesser extent by glycolysis. Reduced NADH is returned to its oxi- dized form under normal cellular conditions by the electron transport chain. This newly reformed NAD+ can then return to other metabolic pathways to harvest more electrons. In the body the ratio of NAD+/NADH is approximately 1000 demonstrating the primary role of NAD+ in supporting cellular oxidation. NADH also can react with ATP to form NADPH. As opposed to the unphosphorylated form, the ratio of NADP+/NADPH is only 0.01. This ratio points to the role of NADPH in supporting reductive processes in the body. Niacin → NAD+ + 2e- ↔ NADH NADH + ATP ↔ NADPH + ADP Niacin can be found in foods such as meats, breads, and beans. Mild niacin deficiencies have simi- lar symptoms to those observed with riboflavin, which is not surprising due to the similar roles both of these vitamins play in biochemical reactions. Niacin deficiencies are occasionally observed in alcoholics, cases of general malnutrition, and in the elderly on restricted diets. A severe deficiency of niacin is known as pellagra, which is derived from the Italian phrase meaning rough skin. Pellagra is marked by dermatitis and also is notable for causing a blackening of the tongue. Early cases of pellagra were first ob- served in Europe shortly after the introduction of corn from the voyages of Christopher Columbus. In these cases, poor farmers who were raising corn as animal feed were particularly susceptible. Because niacin in corn is not bioavailable unless treated with a strong base such as lye, the farmers developed niacin deficien- cies. Europeans did not know this processing method until revealed to them by Native-Americans during the early colonial period of North America. However, the connection between pellagra and niacin was not known until the early 20th century. Pellagra was a significant health issue in the United States over the period from 1900-1940 resulting in over 100,000 deaths. Today most diets are supplemented with niacin through enriched flour, which receives its name because of the added nia- cin.13 Niacin can be administered in doses of 2g to 4g to causes a decrease in circulating levels of cholesterol and LDL. While the cholesterol lowering effects of niacin are desirable there are potential side effects from such large doses of this vitamin. The most immediate reaction observed from large doses of niacin is vasodilation re- sulting in flushing. Over time there may be a reduction in fatty acid mobilization causing a depletion of glyco- gen and lipid stores in muscle tissue. Long-term expo- sure may also elevate blood glucose and uric acid levels, suggesting increased risk for patients who are on the borderline for diseases such as diabetes and gout. Pro- longed use of high doses of niacin can lead to elevated levels of the serum enzymes alanine aminotransferase and aspartate aminotransferase, which may suggest liver damage. Pyridoxine (Vitamin B6) Pyridoxine is the precursor to the active enzyme co- factor pyridoxal phosphate (PLP). Pyridoxal phosphate is a critical co-factor for enzymes involved in reactions involving many amino acids. The N-terminus of the amino acid forms a covalent bond to PLP, allowing a wide variety of displacement reactions to occur at the alpha carbon. These include decarboxylations, transami- nations, and transfers of side chains. Pyridoxine, there- fore, plays a central role in the production of many neu- rotransmitters, such as serotonin, norepinephrine, and histamine. Pyridoxine also is important in the produc- tion of heme. The PLP co-factor in several enzymes is a therapeu- tic target due to the ability to form irreversible covalent bonds with agents containing a hydrazine moiety, such as carbidopa, isoniazid, and hydralazine.14 The combina- tion of L-Dopa and carbidopa is a widely used therapy that has a biochemical mechanism involving vitamin B6. The conversion of L-Dopa to dopamine is catalyzed by the PLP-dependent enzyme L-aromatic amino acid decarboxylase (LAAAD). L-DOPA → Dopamine 3 American Journal of Pharmaceutical Education 2003; 67 (2) Article 64. The enzyme LAAAD is present in both the gut and in the brain. This presents a problem because L- dopa is readily transported across the blood brain bar- rier while dopamine is not. Therefore, orally adminis- tered L-dopa is rendered ineffective in the gut by LAAAD. Co-administration of carbidopa resolves this dilemma by inactivating LAAAD in the gut. Like do- pamine, carbidopa cannot cross the blood brain bar- rier leaving LAAAD in the brain free to carry out the production of dopamine at the site of action. In addi- tion to hydrazine containing drugs, penicillamine, used in the treatment of Wilson’s disease, cystinuria, and rheumatoid arthritis reacts with and inactivates pyridoxal phosphate.15 Patients treated with penicil- lamine occasionally develop convulsions, which can be prevented by supplementation with vitamin B6. Pyridoxine is found in foods such as meats, breads, eggs, soybeans, and many vegetables. A defi- ciency in pyridoxine can cause facial lesions, depres- sion, peripheral neuropathy, and glossitis. The neuro- logical complications can be directly linked to the effects on neurotransmitter production. Mild pyridox- ine deficiencies are sometimes observed in young women taking oral contraceptives. Deficiencies have also been observed in patients with gasteroenteritis or Crohn’s Disease, presumably due to poor absorption. Mild deficiencies are of concern due to a correlation with an increased incidence of breast cancer and to the risk of coronary heart disease.16,17 Neurotoxicity has been noted with doses of vitamin B6 in excess of 500 mg/day. Cobalamin (Vitamin B12) Cobalamin is vital for cell growth and replication. Its major site of action is at the interface between the folic acid cycle and the active methyl cycle, where cobalamin is a co-factor for the enzyme homocysteine methyltransferase. This enzyme catalyzes the transfer of a methyl group from tetrahydrofolate to homocys- teine, forming the amino acid methionine. These 2 cycles impact many other pathways due to the large number of methylation reactions in the body, espe- cially nucleic acid biosynthesis and neurotransmitter biosynthesis. Cobalamin is found in meats and dairy products. Deficiencies are not common because the liver can store a 6-year supply of cobalamin. In addition, co- balamin is highly conserved by enterohepatic recircu- lation. Strict vegetarians (vegans) may take up to 20 to 30 years to develop a deficiency, whereas inade- quate absorption from the ileum due to ileitis or loss of a glycoprotein that complexes with cobalamin prior to absorption may take from 2 to 10 years to become symptomatic. The anesthetic nitrous oxide inactivates cobalamin and can cause patients with marginal serum levels to develop deficiencies within a week.19 While rare, deficiencies in vitamin B12 are severe and manifest in erythrocytes and nervous tissue. In erythrocytes, nu- cleic acid biosynthesis is slowed. This results in stem cells that are committed to development into erythro- cytes possessing twice their normal protein content but lacking the necessary nuclear material for proper cell division. The resulting anemia, termed megaloblastic anemia, can be quite severe. Cobalamin deficiency can also cause permanent damage to the nervous system. The results are swelling of neurons and demylination of nerve cells, followed by cell death. These progressive manifestations cause a wide range of neurological symp- toms including unsteadiness, decreased reflexes, pares- thesias of the extremities, and ultimately confusion, memory loss, hallucinations, and psychosis. The neuro- logical symptoms of cobalamin deficiency may be mis- taken for multiple sclerosis. In the elderly and in alco- holics, cobalamin deficiency should be considered as a possible cause of dementia even in the absence of ane- mia. The neurological symptoms associated with co- balamin deficiency are not directly related to irregulari- ties in the formation of erythrocytes.20 Folic Acid (Pteroylglutamic Acid) Folic acid is derived from the addition of a pteroyl group to the amino acid glutamate. Folic acid can be reduced to form tetrahydrofolate, which is an important acceptor of one-carbon units. Folic acid plays an impor- tant role in the conversion of homocysteine to methion- ine by providing the methyl to the vitamin B12 depend- ent methyl transferase. Therefore, folic acid levels have a strong influence on the endogenous concentration of homocysteine. Elevated levels of homocysteine are as- sociated with increased risk of coronary heart disease. Supplementation with folic acid has been shown to cor- rect plasma homocysteine levels and decrease the mor- bidity and mortality from atherosclerotic disease.21 Folic acid plays an important role in the biochemis- try of amino acids; it is critical for the interconversion of the amino acids serine and glycine and in histidine me- tabolism. Folic acid also is necessary for the biosynthe- sis of the nucleic acids thymidine, adenine, guanine, and inosine. Because of its role in amino acid and nucleic acid biosynthesis, folic acid supplementation during pregnancy has been shown to prevent most birth defects involving the brain and spinal cord, known as neural tube defects.22 4 American Journal of Pharmaceutical Education 2003; 67 (2) Article 64. Folic acid is found in organ meats such as liver, green leafy vegetables, yeast, and some fruits. Defi- ciencies in folic acid are most often observed with poor intake or alcoholism but are sometimes seen in pregnancy where there is an increased need for folic acid. The recommended daily allowance for pregnant women is at least twice that for nonpregnant women.23 Folic acid deficiencies can also be observed from reduced absorption due to diseases in the intes- tine. Additionally anticonvulsants, such as phenytoin, phenobarbital, and primidone appear to not only to inhibit folic acid absorption, but also to increase ca- tabolism.24 There is also concern that supplementation with folic acid may impact the effectiveness of these anticonvulsants. The most common effect of folic acid deficiency is megaloblastic anemia. The appearance of this type of anemia is identical to that observed with vitamin B12 deficiency due to the common pathway shared by the folic acid and the active methyl cycles. One major difference between folic acid deficiency and vitamin B12 deficiency is the absence of the neurological symptoms from lowered serum folic acid levels.25 Pantothenic Acid Pantothenic acid is one of the many B-complex vitamins. Once in the body, pantothenic acid com- bines with ADP and cysteamine to form coenzyme A (HSCoA). Coenzyme A is involved in a number of cellular pathways, most notably in transferring an ace- tyl unit from the pyruvate dehydrogenase complex or from β-oxidation to oxaloacetate in the TCA cycle. Coenzyme A is also involved in the biosynthesis of cholesterol, steroid hormones, fatty acids, and por- phyrins. Pantothenic acid derives its name from the Greek word meaning “from everywhere”, which re- flects its ubiquitous nature in foods. Deficiencies in pantothenic acid are difficult to achieve but result in neuromuscular degeneration.26 Biotin Biotin is an important co-factor for enzymes in- volved in carboxylation reactions. Biotin aids in these reactions by binding carbon dioxide. An important example of a biotin-containing enzyme is pyruvate carboxylase. This enzyme catalyzes the conversion of pyruvate to oxaloacetate as a preliminary step in glu- coneogenesis. Biotin is found in foods such as liver, egg yolks, milk, fish and nuts. Deficiencies in biotin result in dermatitis, glossitis, muscle pain and anorexia. Defi- ciency in biotin has been observed in patients ingest- ing raw eggs over a long period of time. Egg white con- tains avidin, a protein that binds biotin, strongly preventing its absorption from the intestine.27 Biotin deficiency was observed in early attempts at parenteral nutrition before proper vitamin supplementation became standard practice.28 Choline Choline has many important biochemical roles in the body. It is incorporated into the formation of leci- thin, an important structural phospholipid found most abundantly in mitochondrial membranes. It is also in- corporated into platelet-activating factor, an important signaling agent in the clotting cascade. Choline also af- fects lipid mobilization from the liver. However, its most important role is as a precursor for the neurotrans- mitter acetylcholine where it plays a critical role in mo- tor coordination. Choline is found in eggs, peanuts, and liver. Defi- ciency in choline has not been reported in humans. It is believed that daily needs for choline can be met through biosynthesis and diet. Carnitine Carnitine has an important role in the metabolism of fatty acids. Carnitine accepts and donates fatty acids to co-enzyme A. This is an equilibrium process facilitated by cytosolic and mitochondrial enzymes known as car- nitine acyl transferases. The attachment of fatty acids to carnitine is critical for their transport from the cytosol to the mitochondria, where they are later metabolized through β-oxidation. Carnitine is found abundantly in meats and dairy products. Carnitine deficiency is not normally observed in adults unless it is caused by an inherited genetic dis- order related to its transport or biosynthesis. Carnitine deficiency causes the storage of lipids in muscle tissue resulting in functional abnormalities in both cardiac and skeletal muscles. However, carnitine deficiencies are not uncommon in preterm or low birth weight infants. These infants generally respond to supplements of carnitine as well as changing to a low-fat, high-carbohydrate diet.29 Ascorbic Acid (Vitamin C) Ascorbic acid acts as an enzyme co-factor for 2 ma- jor biochemical processes. It is important for many hy- droxylation reactions, especially those involved in the posttranslational hydroxylation of the amino acid proline in the formation of the structural protein colla- gen. In the gut, vitamin C is involved in the reduction of iron (III) to iron (II), allowing iron to be absorbed into the bloodstream. 5 American Journal of Pharmaceutical Education 2003; 67 (2) Article 64. Table 1. Student perception of the most significant part of the lecture, most inter- esting part of the lecture, and the topic they would like to have greater coverage. Response Percentage Significance (N=28) Biochemical function of vitamins 61% Vitamin deficiencies 18% Sources of vitamins 11% Interesting (N=28) Biotin and raw eggs 18% Scurvy and “Limeys” 18% Alcoholism and vitamins 14% Increase Focus (N=27) Folic acid deficiency 8% Alcoholism and vitamin deficiencies 8% Drug interactions and vitamins 8% Humans are one of the few organisms that are in- capable of biosynthesizing ascorbic acid. As such they are highly dependent on obtaining it from their diet. Vitamin C is found in citrus fruits, tomatoes, strawberries, and potatoes. During the Age of Explo- ration, British sailors were given the nickname “lim- eys” due to the barrels of limes that were used on long voyages to supply vitamin C to the crew. The sailors were trying to avoid a deficiency in ascorbic acid known as scurvy.30 The symptoms of scurvy are re- lated to inhibited synthesis of collagen. These effects include failure of wounds to heal, defects in tooth formation, and capillary leakage. Anemia caused from failure to adequately absorb iron is also common.31 Several factors have been shown to lower serum vi- tamin C levels including smoking, oral contracep- tives, and the use of aspirin.32-34 Patients exposed to any of these conditions long-term should consider taking a vitamin C supplement. However, the use of high doses of vitamin C, a theory popularized by No- bel Laureate Linus Pauling, has not been shown to provide any medical benefit.35 The use of high doses of vitamin C has been shown to cause nausea, diar- rhea, and lead to the formation of oxalate kidney stones.18,35 Student Perception of Lecture Student opinions were obtained using minute pa- pers. Minute papers are given to a group of 25-30 stu- dents following each lecture in this course.36 From the results of the minute papers in Table 1, the student’s perception of the lecture is apparent. The students believe that the most significant material in the lecture was the discussion on the major biochemical functions of the vitamins. This is consistent with the intent of the instructor. The students also felt that understanding vi- tamin deficiencies and the sources of the various vita- mins was important. The students were asked what they found interesting about the lecture and not surprisingly they selected various stories as their favorite points. They especially liked the link between biotin, avidin, and eggs, the nautical history of scurvy resulting in the nickname “Limeys” being given to British sailors, and understanding the role of appetite suppression in alco- holism and general vitamin deficiencies. Over the years, students have commented that they enjoy having inter- esting health related facts to aid them in retaining and understanding the utility of biochemical information. Vitamins provide an enormous number of examples that can be used. Finally, the students were asked to recom- mend areas that could have increased focus in the future. In general these comments fall into 2 catagories. The students are either confused and would like more information to more fully understand the topic, or they are genuinely interested and would like to know more. In this case, 71% of the student responded that they did not see anything else to add. There were a few sugges- tions for adding additional information on folic acid deficiency, alcoholism, and drug-vitamin interactions. This text incorporates many of these suggestions with the inclusion of the link between folic acid and neural tube defects, discussions of alcoholism throughout the lecture rather than being highly focused around thiamin, and drug interactions involving the vitamins pyridoxine, folic acid, and riboflavin. 6 American Journal of Pharmaceutical Education 2003; 67 (2) Article 64. CONCLUSIONS Questions concerning the use of vitamins are common. Vitamins have important roles in many of the major metabolic pathways in the human body. In addition, drug interactions with vitamin and diseases involving vitamin deficiencies are important topics for pharmacy curricula. An understanding of the func- tional roles of vitamins can contribute to improved understanding of general biochemistry and help pharmacy students become better prepared for their roles as health care educators. REFERENCES 1. Muth MK, Nardinelli C, Beach RH. The marketplace for die- tary supplements: recent studies. Drug Inf J. 2001; 35:973-83. 2. Joseph CK. Nutritional supplements: amino acids and their derivatives. Am J Pharm Educ. 2002; 66:157-64. 3. Flood A, Schatzkin A. Colorectal cancer: does it matter if you eat your fruits and vegetables? J Nutl Cancer Inst. 2000; 92:1706- 7. 4. Williams PG. Vitamin retention in cook/chill and cook/hot-hold hospital services. J Am Diet Assoc. 1996; 96:490-8. 5. Schenk G, Duggleby RG, Nixon PF. 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Eur J Clin Invest. 1998; 28:695-700. 36. Bartlett MG, Morrow KA. Method for assessing course knowl- edge in a large classroom environment: an improved version of the minute paper. Am J Pharm Ed. 2001; 65:264-8. 7 TEACHERS TOPICS Biochemistry of the Water Soluble Vitamins: A Lecture for First Year Pharmacy Students Response