The major change in this Fifth edition is that the paragraphs are made shorter. The important points are given in bold letters, so that students can grasp the subject easily. Moreover, the facts are given in point-wise (with numbers), so as to aid memorisation.

From the first edition onwards, our policy was to provide not only basic essentials, but also some of the advanced knowledge. About 30% contents of the previous editions were not required for a minimum pass. A lot of students have appreciated this approach, as it helped them to pass the PG entrance examinations. However, this asset has paved the way for a general criticism that the extra details are a burden to the average student. Especially when read for the first time, the student may find it difficult to sort out the essential minimum from the desirable total. Thus, in consultation with the Publishers, we have decided to make two different books, one for MBBS and another one for postgraduate courses in Biochemistry. Thus, the content has been made lesser in this textbook. We are bringing out the postgraduate Textbook in due course.

Yet another regular criticism against the previous edition was that the font size was small, and it was difficult to read the book. In this edition this problem is solved by increasing the font size. The readability has thus been markedly improved. While increasing the font size, we were very conscious that the bulk of the book should not be increased. We have reached a compromise in these mutually opposing tasks.

A textbook will be matured only by successive revisions. In the preface for the first edition, we expressed our desire to revise the textbook every 3 years. We have tried to keep that promise. This book has undergone metamorphosis during each edition. Chemical structures with computer technology were introduced in the second edition. Colour printing has been launched in the third edition. The fourth edition came out with multicolour printing. In this Fifth edition, figures are drastically increased; old figures were dramatically improved; tables and boxes were also increased in numbers, quality of paper is improved, altogether making the book more student-friendly.

Essay questions, short notes, problem solving exercises and viva voce type questions are given in a separate book, but free of cost. These questions are compiled from the question papers of various universities during the last decade. These questions will be ideal for students for last-minute preparation for examinations.

We were pleasantly surprised to receive many letters giving constructive criticisms and positive suggestions to improve the textbook. These responses were from all parts of the country, and the contributors include Heads of Departments, very senior professors, middle level teachers and mostly from postgraduate students. We have tried to incorporate most of those suggestions, within the constraints of page contents. In a way, this book thus became multi-authored, and truly national in character. This is to place on record, our deep gratitude for all those pen-friends who have helped us to improve this book. The first author desires more interaction with faculty and students who are using this textbook. All are welcome to communicate at his e-mail address <dmvasudevan@yahoo.co.in>.

The help and assistance rendered by Dr. Subir Kumar Das is gratefully acknowledged. The official website of Nobel Academy has been used for pictures and biographies of Nobel laureates. Web pictures, without copyright, were also used in some figures. This is to record our appreciation for the co-operation extended by Shri Jitendar P Vij, Chairman and Managing Director, Jaypee Brothers Medical Publishers and his associates. The remarkable success of the book was due to the active support of the publishers.

We hope that this Fifth edition will be more friendly to the students and be more attractive to the teachers. Now this is in your hands to judge.

“End of all knowledge must be building up of character”—Gandhiji.

This book is mainly based on the MBBS curriculum. However, some advanced portions have also been given in almost all chapters. These areas will be very beneficial to the readers preparing for their postgraduate entrance examinations.

Chapters on diabetes, cancer and AIDS are included in this book. During their clinical years, the students are going to see such cases quite more often, hence knowledge of applied biochemistry of these diseases will be very helpful. The authors, themselves medical graduates, have tried to emphasise medical applications of the theoretical knowledge in biochemistry in almost all the chapters.

A few questions have been given at the end of most of the chapters. These are not comprehensive to cover all the topics, but have been included only to give emphasis to certain points which may otherwise be left unnoticed by some students.

We are indebted to many persons in compiling this textbook. We are highly obliged to Dr ANP Ummerkutty, Vice-Chancellor, University of Calicut, for his kind gesture of providing an introduction. Dr M Krishnan Nair, Research Director, Veterinary College, Trichur, has provided his unpublished electron micrographs for this book. Dr MV Muraleedharan, Professor of Medicine, and Dr TS Hariharan, Professor of Pharmacology, Medical College, Trichur, have gone through the contents of this book. Their valuable suggestions on the applied aspects of biochemistry have been incorporated. Two of our respected teachers in biochemistry, Prof R Raghunandana Rao and Prof GYN lyer (both retired) have encouraged this venture. Prof PNK Menon, Dr S Gopinathan Nair, Assistant Professor, Dr Shyam Sundar, Dr PS Vasudevan and Mr K Ramesh Kumar, postgraduate students of this department, have helped in collecting the literature and compiling the materials. Mr. Joby Abraham, student of this college has contributed the sketch for some of the figures. Prof CPK Tharakan, retired professor of English, has taken great pains to go through the entire text and correct the usage of English. The secretarial work has been excellently performed by Mrs Lizy Joseph. Many of our innumerable graduate and postgraduate students have indirectly contributed by compelling us to read more widely and thoroughly.

“A lamp that does not glow itself cannot light another lamp” —Tagore

Our expectation is to bring out new editions every 3 years. Suggestions to improve the contents are welcome from the teachers.