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Nutrition and the brain
B
Nutrition and the Brain
o o K
S
Nutrition and the Brain, Vol. 1, Determinations of the Availability of Nutrients to the Brain; Vol. 2, Control of Feeding Behavior and Biology of the Brain in Protein Calorie Malnutrition, Wurtman, R. J. and J. J. Wurtman, Eds., Raven
Press, 1140 Avenue of the Americas, New York, NY 10036, 1977,324 pp., 313 pp., $25 per volume. For much of the infancy and adolescence of the science of nutrition, the brain was regarded as an organ nongrata, not because it was thought to be unimportant, but because investigators were busy answering very fundamental questions concerning metabolism and developing methodologies for studying nutrition. After all, the liver is much more accessible to the biochemist than the brain. As nutritional science matured, the brain became more attractive as a focus of study, in part because of its essentiality (important for writing the "signifIcance" sections of grant proposals), but perhaps more so because research was starting to suggest that the chemical composition of the brain can be irreversibly affected by poor nutrition imposed during "critical periods" in development. This laboratory observation was coupled with clinical reports that children who had suffered severe malnutrition early in life showed retarded motor and intellectual development. This problem-the relationship between early nutrition, brain development, and ultimate cognitive potential-had both suffIcient political appeal to open a flow of money into research and scientific appeal to allow a truly multidisciplinary approach to flourish. A steady stream of research has continued for approximately fifteen years and many researchers as well as politicians are asking the question, "What have we learned?" The two volume series Nutrition and the Brain offers comprehensive reviews of our knowledge today. The series contains articles ranging from brain amino acid metabolism to reviews of the diet of subhuman primates. In general, all the reviews are quite comprehensive and include extensive references. Like most multi-authored books, howeve!;, there are a number of literary limitations. Perhaps the most serious of these is a lack of continuity among articles. It is quite diffIcult for readers to proceed from chapter one, "On the Natural Diet of Primates and Humans," to chapter two, "Cerebral Nutrition and Energy Metabolism," without wondering whether they are still in the same book. Editorialized transitions between articles might have been helpful, but there is also an inherent diffIculty in compiling a book suitable for a vast audience ranging from social scientists to students of specific metabolic pathways. The leading chapter by Gaulin and Konner presents some very interesting findings in anthropology and field ecology concerning nutrient balancing and energy allocation. These findings may prove quite important to theories of international nutrition planning. The chapter "Cerebral Nutrition and Energy Metabolism" by Sokoloff, Fitzgerald, and Kaufman is lucid and well documented. The chapter "Regulation of Amino Acid Availability to the Brain" by Pardridge is especially clear in presenting the controversy concerning whether proteinbound or free tryptophan is the primary determinant of brain tryptophan. Although Pardridge does a fine job of explaining brain methylation processes, it is unfortunate that
38
Journal of Nutrition Education Vol. 10
No. I January-March 1978
the abnormal methylation hypothesis of human psychosis is not discussed. The chapters "Control of the Availability to the Brain of Folic Acid, Vitamin B-12 and Choline" by Ordonez and "B-Vitamins and Nervous System Function" by Dakshinamurti are excellent reviews with extensive bibliographies. However, I would have liked a discussion of the use of high levels of niacin to have been included. It is about time neuroscientists who know what they are talking about openly criticized many of the outrageous claims of the vitamin "faddists," particularly when their claims center around brain metabolism and behavorial function. Exploration of the effect of malnutrition on brain metabolism is presented in Volume II by Novak and Munro in "Effects of Protein-Calorie Malnutrition on Biochemical Aspects of Brain Development," which is one of the best chapters in the series. It is a clear, comprehensive presentation on protein metabolism as well as a scholarly discourse on the effects of amino acid deficiency and excesses on brain protein metabolism. There are only two chapters in the series devoted to the effect of nutrition on brain function, i.e., behavior. The first of these chapters by Lytle is restricted to feeding behavior. Almost all major topics of contemporary research into feeding behavior are covered. Although the chapter is an excellent review, it lacks a sense of conclusiveness that characterizes most of the other chapters. The other chapter relating the effect of nutrition to brain function concerns an aspect of brain function which is quite far removed from brain metabolism, neurons, or neurotransmitters. "Protein-Calorie Malnutrition and Behavior" by Pollitt and Thompson is perhaps one of the best discussions of the problems in establishing a relationship between malnutrition and intelligence that is available today. The major fault of the book lies in what is not included. On the one hand, very thorough reviews of the effects of nutrition on brain chemistry and metabolism are presented. At the other extreme, excellent discussions of human studies of intelligence and nutrition are included. However, between these two extremes is a major gap-the direct effects of altered brain chemistry on behaviors other than feeding behavior, behaviors such as learning, aggression, sexual behavior, sleep, and emotional reactivity. The omission of this aspect of the problem is probably not an accident. Most of the work in this area is methodologically poor and scientifically naive. The reason may be that competent psychologists and ethologists are not attracted to these problems of nutrition and brain chemistry. Nevertheless, the omission of a chapter on nutrition, brain chemistry, and behavior is a grave commentary on the state of the field. After all, what is the importance of all the research described on the relationship between nutrition and brain chemistry if we don't know what these brain changes mean in terms of brain function? Even though there seems to be an onslaught of books on malnutrition and behavior in recent years, this series is a worthy addition to any nutrition library as a readable and comprehensive set of reviews on the subject. David A. Levitsky, Ph.D., Associate Professor, Division of Nutritional Sciences and Department of Psychology, Cornell University, Ithaca, NY 14853.
Nutrition and the Brain
o o K
S
Nutrition and the Brain, Vol. 1, Determinations of the Availability of Nutrients to the Brain; Vol. 2, Control of Feeding Behavior and Biology of the Brain in Protein Calorie Malnutrition, Wurtman, R. J. and J. J. Wurtman, Eds., Raven
Press, 1140 Avenue of the Americas, New York, NY 10036, 1977,324 pp., 313 pp., $25 per volume. For much of the infancy and adolescence of the science of nutrition, the brain was regarded as an organ nongrata, not because it was thought to be unimportant, but because investigators were busy answering very fundamental questions concerning metabolism and developing methodologies for studying nutrition. After all, the liver is much more accessible to the biochemist than the brain. As nutritional science matured, the brain became more attractive as a focus of study, in part because of its essentiality (important for writing the "signifIcance" sections of grant proposals), but perhaps more so because research was starting to suggest that the chemical composition of the brain can be irreversibly affected by poor nutrition imposed during "critical periods" in development. This laboratory observation was coupled with clinical reports that children who had suffered severe malnutrition early in life showed retarded motor and intellectual development. This problem-the relationship between early nutrition, brain development, and ultimate cognitive potential-had both suffIcient political appeal to open a flow of money into research and scientific appeal to allow a truly multidisciplinary approach to flourish. A steady stream of research has continued for approximately fifteen years and many researchers as well as politicians are asking the question, "What have we learned?" The two volume series Nutrition and the Brain offers comprehensive reviews of our knowledge today. The series contains articles ranging from brain amino acid metabolism to reviews of the diet of subhuman primates. In general, all the reviews are quite comprehensive and include extensive references. Like most multi-authored books, howeve!;, there are a number of literary limitations. Perhaps the most serious of these is a lack of continuity among articles. It is quite diffIcult for readers to proceed from chapter one, "On the Natural Diet of Primates and Humans," to chapter two, "Cerebral Nutrition and Energy Metabolism," without wondering whether they are still in the same book. Editorialized transitions between articles might have been helpful, but there is also an inherent diffIculty in compiling a book suitable for a vast audience ranging from social scientists to students of specific metabolic pathways. The leading chapter by Gaulin and Konner presents some very interesting findings in anthropology and field ecology concerning nutrient balancing and energy allocation. These findings may prove quite important to theories of international nutrition planning. The chapter "Cerebral Nutrition and Energy Metabolism" by Sokoloff, Fitzgerald, and Kaufman is lucid and well documented. The chapter "Regulation of Amino Acid Availability to the Brain" by Pardridge is especially clear in presenting the controversy concerning whether proteinbound or free tryptophan is the primary determinant of brain tryptophan. Although Pardridge does a fine job of explaining brain methylation processes, it is unfortunate that
38
Journal of Nutrition Education Vol. 10
No. I January-March 1978
the abnormal methylation hypothesis of human psychosis is not discussed. The chapters "Control of the Availability to the Brain of Folic Acid, Vitamin B-12 and Choline" by Ordonez and "B-Vitamins and Nervous System Function" by Dakshinamurti are excellent reviews with extensive bibliographies. However, I would have liked a discussion of the use of high levels of niacin to have been included. It is about time neuroscientists who know what they are talking about openly criticized many of the outrageous claims of the vitamin "faddists," particularly when their claims center around brain metabolism and behavorial function. Exploration of the effect of malnutrition on brain metabolism is presented in Volume II by Novak and Munro in "Effects of Protein-Calorie Malnutrition on Biochemical Aspects of Brain Development," which is one of the best chapters in the series. It is a clear, comprehensive presentation on protein metabolism as well as a scholarly discourse on the effects of amino acid deficiency and excesses on brain protein metabolism. There are only two chapters in the series devoted to the effect of nutrition on brain function, i.e., behavior. The first of these chapters by Lytle is restricted to feeding behavior. Almost all major topics of contemporary research into feeding behavior are covered. Although the chapter is an excellent review, it lacks a sense of conclusiveness that characterizes most of the other chapters. The other chapter relating the effect of nutrition to brain function concerns an aspect of brain function which is quite far removed from brain metabolism, neurons, or neurotransmitters. "Protein-Calorie Malnutrition and Behavior" by Pollitt and Thompson is perhaps one of the best discussions of the problems in establishing a relationship between malnutrition and intelligence that is available today. The major fault of the book lies in what is not included. On the one hand, very thorough reviews of the effects of nutrition on brain chemistry and metabolism are presented. At the other extreme, excellent discussions of human studies of intelligence and nutrition are included. However, between these two extremes is a major gap-the direct effects of altered brain chemistry on behaviors other than feeding behavior, behaviors such as learning, aggression, sexual behavior, sleep, and emotional reactivity. The omission of this aspect of the problem is probably not an accident. Most of the work in this area is methodologically poor and scientifically naive. The reason may be that competent psychologists and ethologists are not attracted to these problems of nutrition and brain chemistry. Nevertheless, the omission of a chapter on nutrition, brain chemistry, and behavior is a grave commentary on the state of the field. After all, what is the importance of all the research described on the relationship between nutrition and brain chemistry if we don't know what these brain changes mean in terms of brain function? Even though there seems to be an onslaught of books on malnutrition and behavior in recent years, this series is a worthy addition to any nutrition library as a readable and comprehensive set of reviews on the subject. David A. Levitsky, Ph.D., Associate Professor, Division of Nutritional Sciences and Department of Psychology, Cornell University, Ithaca, NY 14853.