University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 5-2002 Carnitine, Choline and Caffeine Promote Fat Loss and Metabolism in Rats and Humans Nobuko Hongu University of Tennessee, Knoxville Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Part of the Home Economics Commons Recommended Citation Hongu, Nobuko, "Carnitine, Choline and Caffeine Promote Fat Loss and Metabolism in Rats and Humans. " PhD diss., University of Tennessee, 2002. https://trace.tennessee.edu/utk_graddiss/3818 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Nobuko Hongu entitled "Carnitine, Choline and Caffeine Promote Fat Loss and Metabolism in Rats and Humans." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Doctor of Philosophy, with a major in Human Ecology. DiLeep S. Sachan, Major Professor We have read this dissertation and recommend its acceptance: Edward T. Howley, Naima Moustaid Moussa, Jean D. Skinner Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) To the Graduate Council: I am submitting herewith a dissertation written by Nobuko Hongu entitled "Carnitine, Choline and CaffeinePromote Fat Loss and Metabolism in Rats and Humans." I have examined the finalpaper copy of this dissertation forform and content andrecommend that it be accepted in partialfulfilment ofthe requirements forthe degree of Doctor of Philosophy, with a major in Human Ecology. an, D.V.M., Ph.D., Major Professor we have read this dissertation and recommend its acceptance: t.1.�?r�� Edward T. Howley, Ph.D. -=----=-/ �J�� Naimanvu"� Moustaid Mou�h.D . J�J)��- D. Skinner, Ph.D., R.D. Accepted for the Council: C)a�r Vice Provost an:: Graduate Studies Carnitine, Choline and Caffeine Promote Fat Loss and Metabolism in Rats and Humans A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville Nobuko Hongu May 2002 DEDICATION This dissertation is dedicated to my parents Mr. Teruhiko Kikugawa and Mrs. Yoshiko Kikugawa, for ensuring the quality of my early education; and my husband Dr. Yuji Hongu, for his encouragement, patience, and support throughout this study. 11 ACKNOWLEDGMENTS I would like to express my sincere appreciation to all those who contributed to the success of this study. First and foremost, I must mention my committee members. Dr. Dileep S. Sachan, my major professor, guided me throughout my graduate career and provided numerous opportunities forpractical training and financial support. He introduced me to the importance of nutrient-nutrient interaction. Through his class, he has taught me the value of nutrition under normal and disease conditions. It was a privilege to work under the direction of such a talented scientist. Dr. Nai'.maMoustai'.d Moussa showed great interest in our research and spend many hours discussing the importance of fatmetabolism, always asking questions that forced me to go back and reevaluate our perspective. Dr. Jean D. Skinner provided valuable insights regarding the meaning of nutrient anlayses. Dr. Edward T. Howley, for his knowledge of exercise gave me direction in my research. Their professionalism and commitment to a high quality of research have been an inspiration for me to keep searching for truth in my study. I owe many thanks to the faculty of the Nutrition Department: Dr. James W. Bailey, Dr. Betty Ruth Carruth, Dr. Betsy Haughton, Dr. Jay Whelan and Dr. Michael B. Zemel. They managed to keep graduate school exciting and challenging through many years. Additionally, I owe many thanks to the members of the Sachan's laboratory, Dr. James W. Daily III, Dr. Mei-Shin Mong, and Dr. Ayub M. Yatim who taught me how to run camitine assays and their own skills and techniques in the lab. I am extremely gratefulfor the time we spent together and their friendship. Ill I am also gratefulto the formerprofessors and the special friends, Dr. Ralph 0. Blackwood, Dr. Nancy Paisley, Dr. Tuyoshi Shimizu, Mrs. Julia A. Eckard,Ms. Karen Sprang and Ms. Denise Serrano, whose long-standing beliefs in my ability to complete the study and produce a dissertation. They made this study possible by their friendship and emotional support. I can not forgetto thank all men and women who came to participate our study. Their effortsto followthe experimental procedures, which were tedious and time consuming, were greatly appreciated. Without their help the project could not have accomplished. Finally, I am gratefulto my parentsTeruhiko Kikugawa and Yoshiko Kikugawa, and my sister Yasuyo Hayashi, for their unwavering support through the years. My husband, Yuji Hongu, who is a great chemist taught me basic organic chemistry day and night without any hesitation, which greatly helped build my foundationof chemistry. He took many responsibilities so that I could focusmy time and efforton the completion of this dissertation. His encouragement kept me going even when things appearedbleak and slow. This dissertation would not have been possible without assistance of those many individuals. With all of my heart I thank them. lV ABSTRACT Interaction of two nutrients, carnitineand choline, has been reported. Choline supplementation causes a significantconservation of carnitinein normal healthy humans and guinea pigs. The choline supplementationpromoted tissue carnitineaccretion, particularlyin skeletal muscle of guinea pigs, and livers of rats. Also, choline supplemented guinea pigs had lower percentage of carcass fatand higher percentage of protein but the body weights or the respiratory quotient (RQ) were not affected. Based on these observations, we hypothesized that a combination of choline and camitine may further increase camitine accretion by tissues, and if energy needs were increased by exercise and fat mobilization was stimulated by caffeine, there may be reduction in body fat. In other words, simultaneous availability of carnitine, choline, and caffeinemay induce mobilization, transport and delivery of fat as the energy substrate of choice, and therefore, enhance utilization of fat. In a 2 x 2 factorialdesign, male Sprague-Dawley rats were assigned to nonsupplemented and supplemented groups and one-half of each group was exercised. Body weight was significantlyreduced by exercise only, however, regional fatpad weights and serum leptin concentration were significantly reduced by the combination of carnitine, choline and caffeinesupplements as well as by exercise. Regardless of exercise, supplements significantly lowered triglycerides in serum but increased triglycerides in the skeletal muscle. We postulated that fatloss in rats was due to enhanced fatmobilization and fatty acid oxidation. To support this, we determined the RQ and several metabolic markers of fatoxidation in the rat model. No significantdifferences were found in the mean RQ V values of the groups at rest in all groups and at exhaustion between the two exercised groups. However, increased maximal oxygen uptake (V02max) and delayed exhaustion time was foundin the supplemented rats. Post-exercise concentrations of serum triglycerides were decreased, but P-hydroxybutyrate, acylcarnitineand acetylcarnitine were increased in the supplemented rats. The changes in serum metabolites were complemented by the changes in the muscle and urinary metabolites. The magnitude of increase in urinary acylcarnitine(34 to 45-fold)of the supplemented rats is a unique effectof this combination of the supplements. Evidence indicates enhanced P-oxidation of fatty acids without a change in the RQ because acetyl units were excreted in urine as acetylcarnitineand not oxidized to carbon dioxide. For this phenomenon we proposed the term, "fattyacid dumping". Finally, we determined fat loss and metabolic effectsof this unique nutrient­ nutrient interaction in humans. We asked, if the shiftin tissue carnitinepartitioning will result in enhanced fat oxidation in humans. Healthy adults aged 18-54 y were randomly assigned to a placebo or supplement groups. Supplementary choline and camitine increased serum concentration of P-hydroxybutyrate. Another biochemical marker of fatty acid oxidation, acetylcarnitine, was elevated about 2-fold and 3-fold in serum and urine, respectively. Short-chain acylcarnitineswere moderately elevated in serum but significantlyincreased in the urine by the supplementation. The observationsin humans are consistent with those in rats. This research in rats and humans firmlyestablished that the supplementation with camitine, choline and caffeinepromoted fattyacid oxidation to short-chain fattyacids and their disposal in urine as acylcarnitines. VI TABLE OF CONTENTS CHAPTER PAGE I. INTRODUCTION 1 II. LITERATURE REVIEW 4 CARNITINE 4 Dietary Sources of Camitine 6 CamitineHomeostasis 8 Supplement Forms of Camitine 13 Camitine Biosynthesis 14 Absorption 17 Transport and Tissue Uptake 18 Excretion 20 Functions 21 A. Mitochondrial fattyacid oxidation 21 B. Modulation of acyl-CoA/CoA ratio 23 Nutrient-Nutrient