Indian Pediatrics 2003; 40:213-220
Nutrition, Brain and Environment: How to have Smarter Babies?
The quality of human brain development depends upon the interaction between the genetic endowment and environmental factors like nutrition, stimulation and attitude of the parents. The association between nutrition and brain functions has been recognized for almost 100 years. It is not generally realized that brain cells are more sensitive compared to other body cells to nutrients and dietary chemicals. Brain is our most precious physical possession, the holistic seat of our entire existence i.e., intelligence, personality, emotional well being, mind, spirituality and soul. Nothing is more central to a successful and fulfilling life than an optimally functioning brain. The good news is that we can create more connections, synapses, dendrites and receptors through diet, nutritional adequacy and by mental and physical activity(1,2). There are over 100 billion synaptic connections in the brain and their integrity depends upon intake of appropriate diet and micronutrients as well as mental and physical activity.
The last 3 months of pregnancy and first 3 years of post-natal life are most crucial for brain development. Health and nutritional status of mother during pregnancy has significant effect on the development of brain during fetal life(3,4). Brain size of the baby at birth is almost 70% of adult size of the brain but his body weight is only 5% of an adult. During first year of life 15% brain growth occurs thus emphasizing the need for promotion of breast feeding to enhance brain growth. The remaining 10% of brain growth occurs during preschool years wherein special attention needs to be paid to complementary feeds and optimal intake of micronutrients comprising of vitamins and trace minerals. Environmental stimulation, interaction with parents and environment, playful activity and fun games are important for the growth of neurons and proliferation of network of synapses, dendrites and receptors.
Diet and brain
"The food that is good for the heart is likely to be good for the brain."
Nutrition of the mother before and during pregnancy is most crucial for optimal development of the fetal brain. In view of the fact that 70% of the brain growth occurs during fetal life, the diet of the mother during pregnancy is critical for optimal brain development. The studies have shown that the structure of the fetal brain is influenced by what mother eats during pregnancy. Several nutrients are required but availability of choline is critical for development of human brain(5).
Breastfeeding is best for brain growth and neuromotor development of the babies. Nearly two-third of the brain weight is due to phospholipids and long chain fatty acids. Docosahexaenoic acid (DHA) and arachi-donic acid (AA) are key fatty acids for growth of the brain. Human milk contains 30 times more DHA than cow’s milk. According to WHO, infants should get 20 mg DHA/kg every day. Human milk is rich in choline, taurine and zinc which are required for brain growth. Human milk contains almost double the quantity of lactose compared with milk of other mammals. Lactose is credited to facilitate the synthesis of cerebrosides and myelination of central nervous system (CNS). Breast fed babies have at least 8 points higher intelligence quotient in later life as compared to formula fed babies(6,7).
There is enough evidence to suggest that the food we eat influence our memory, concentration, comprehension, judgement, intellect, mood and emotions. There are at least 50 brain chemicals or neurotransmitters that are affected by the intake of food and micronutrients(8).
Physiological effects of nutrients on brain growth
A number of amino acids are recognized as precursors of neurotransmitters. Trypto-phan is required for production of serotonin which improves the mood and sense of well being. Choline is required for production of acetylcholine which is critical for our memory. Tyrosine helps in motor coordina-tion by elaboration of dopamine. Taurine is required for maturation of retina.
Micronutrients are required for production of several enzymes and co-factors for a number of metabolic pathways. It is known since ages that pellagra (niacin deficiency) leads to reduced cognition and dementia. A number of other B-complex vitamins especially B1, B2, B6, B12, niacin and folic acid are needed for synthesis of several neuro-transmitters. Thiamin deficiency hampers the ability of the brain to utilize glucose. Deficiency of folate, B6, B12 and choline are associated with elevation of plasma homocysteine level which may lead to thromboembolic complications and stroke(9). Iodine is required for synthesis of tri-iodothyronine and thyroxine. Iron deficiency is associated with reduced physical activity, neuromotor incoordination and reduced cognition(10). Cytochrome oxidase in the mitochondria is an iron-dependant enzyme. Oligodendrocytes require iron to synthesize fatty acids and cholesterol for myelin production and its integrity. Iron is also required for functioning of neurotransmission system such as dopamine, serotonin and GABA. Iron deficiency has been shown to adversely affect brain stem auditory activity and visual evoked potentials which may persist even after correction of iron deficiency anemia. There is some evidence to suggest that excessive tissue concentration of iron may lead to Parkinson’s disease in adults. Zinc is an important component of over 200 metalloenzymes and there is high concentration of zinc in the brain(11). Copper is an important component of cytochrome oxidase and superoxide dismutase in the brain. Copper deficiency is associated with Menke’s disease while copper excess is a recognized marker of Wilson’s disease, familial amyotrophic lateral sclerosis and Alzheimer’s disease.
Sea food is eminently brain-friendly food. Fish and fish oils are important sources of omega-3 fatty acids and DHA. Omega-3 fatty acids are credited to reduce cellular and vascular inflammation in the brain, promote vasodilatation and ensure integrity of brain cell membranes to keep them soft and pliable(12,13). DHA constitutes almost one-half of the total fat in the brain cell membranes. DHA is the building material for fabrication of synaptic communication centres in the brain. It increases the level of "feel good" neurotransmitter serotonin and the "memory boosting" chemical acetylcholine.
Unlike adults, infants cannot convert a short chain fatty acid alpha- linolenic acid into DHA and they must be provided with this essential nutrient de novo in the diet. Table I lists the essential nutrients required for the development of CNS(1). Fish is a good source of omega-3 fatty acids, taurine, iodine and zinc. Incidentally, junk food is rich in omega-6 transfatty acids which compromise the integrity of the CNS by making cell membranes less pliable and more rigid.
Table 1 –Smart Nutrients for the Brain
• Omega-3 fatty acids, dcosahexaenoic acid (DHA) and arachidonic acid
• Vitamin B complex, folic acid, vitamin C, vitamin E
• Iodine, iron, zinc, selenium
• Essential amino acids including taurine
Apart from direct adverse effects of nutritional deficiencies on the brain, there are indirect consequences of undernutrition on brain development. Children with under-nutrition are apathetic and listless with poor interest to explore their environment. Because they are small in size, they are treated as "too young" and given inappropriate stimulation by their parents. The altered behavior and mood of the undernourished children often leads to the altered attitude of the caretakers towards them with poor level of interaction and play activity.
Role of antioxidants
Brain is metabolically the most active organ of the body and consumes maximum amount of glucose and oxygen. The brain constitutes only 2% of the body weight but it consumes 20-30% of the entire energy. When mitochondria burn oxygen to produce energy, a large number of oxygen-free radicals are released as a byproduct. Reactive oxygen-free radicals act like missiles and attack walls of the mitochondria, membranes of cell walls and penetrate deep to damage nuclear DNA. They damage the communication system of CNS by causing shrinkage and dissolution of dendrites and synapses. Brain is the fattiest organ of the body which makes it most vulnerable to lipid peroxidation by oxygen-free radicals. Antioxidants have an important role in dousing this raging fire in the mitochondria and cell membranes(14). Apart from endogenous antioxidants, a number of exogenous or dietary antioxidants like vitamin C, vitamin E, beta-carotene and various phytonutrients are useful to protect neurons and cell membranes against the damaging effects of oxygen-free radicals. A number of micronutrients like copper, zinc, selenium iron, vitamin B2 and vitamin B6 etc. are also required for optimal functioning of endogenous antioxidants like glutathione peroxidase, superoxide dismutase, catalases and ceruloplasmin.
Neuropsychological consequences of nutritional deficiencies
Protein-energy malnutrition is an important cause of stunting, delayed neuromotor development, reduced physical activity, laziness and poor cognition(15-17). Over 50% of under-five children in our country are stunted. Stunted children have smaller head size, impaired neuromotor coordination, sub-optimal learning skills and mental capabilities. Stunted children have around 11 points lower intelligence quotient compared to normal children(18). Stunting is thus associated with poor quality of life and sub-optimal human resource development. Promotion of breast-feeding and introduc- tion of energy-dense nutritionally balanced complementary feeds around 6 months of age is essential to prevent stunting and promote brain growth. Children should be encouraged to consume brain-friendly diet (Table II). The last trimester of pregnancy and first 3 years of post-natal life are most critical and vulnerable to the effects of nutritional deficiencies and should be accorded special focus and attention by the obstetricians and pediatricians.
Table II –Brain-friendly Diet (1)
Surveys have shown that almost 50% school-going children miss their breakfast regularly. It has been shown that skipping of breakfast adversely affects physical growth, vigour and zest, learning capabilities, memory, academic performance and emo-tional and psychological well being(19).
The clinical correlates of malfunctioning of the central nervous system due to deficiency of various micronutrients are shown in Table III(20-28). Nutritional supple-ments to infants and toddlers have boon shown to improve memory and cognition and the beneficial effects persist during school years(29).
Table III–CNS Manifestations of Deficiencies of Micronutrients(20-28)
Stimulation and brain development
Our brain is divided into two equal halves or hemispheres. The left hemisphere is mainly responsible for logic, reasoning, cognition and analytical skills like language, public speaking and mathematics. The cortex of the right hemisphere is responsible for development of artistic characteristics like music, dance, painting, poetry, peace, poise, insight, emotions, extrasensory perception, creativity, intuitive thoughts and spirituality. Any activity that stimulates both the hemis-pheres simultaneously promotes development of global intelligence. Hippocampus is concerned with social interactions, emotions and memory while pineal gland is believed to be the seat of spirituality.
Babies have a biological need to learn. Any stimulation through his special senses (hearing, sight, taste, smell and touch) provided during fetal life and preschool years has profound effect on growth and maturation of brain(30). It has been shown that stimulation program can promote faster growth, improve coordination of muscular movements, increase span of concentration and raise baby’s IQ by as much as 15 points. There is experimental evidence to suggest that rats reared in stimulating environment with rollicking fun and games had extra 50,000 brain cells on each side of their hippocampus compared to rats reared in ordinary cages. When rats are placed on a treadmill, it induces their brain cells to produce a "growth factor" that stimulates the growth of dendrites thus expanding communication network. Neuronal growth occurred not only in parts of brain that control motor functions but also in areas that control memory, reasoning, thinking and learning. Exercise, play activity and inter-active functioning are credited to improve circulation of the brain and production of antioxidants.
The stimulation of the baby should begin in the womb. It is well known that fetuses do respond to their mother’s heart beat and voice. We have several examples of learning in the womb in Indian mythology. Abhimanyu learnt in his mother’s womb, how to enter chakarvyuh when his father Arjun explained the principles and technique of the entry procedure to his pregnant wife Subadhra. Mother should give positive suggestions to her baby whenever she is in a relaxed mood and before going to sleep. The fetus is most alert during the evening and night between eight o’clock until about midnight. It seems that when mother lies down for rest, her baby wakes up and kicks around. Mother can call her baby by his pet name and say for example, "this is your mummy, I love you Karan, I adore you, you are going to be a smart baby. You are going to be kind, generous and compassionate human being". She should repeat these suggestions at night till she goes to sleep. She can also hum a soothing song, recite a nursery rhyme or story of valour or sing a lullaby. After 5 months of pregnancy, mother should rock gently and slowly in a rocking chair at the rate of 20 rocks per minute several times in a day. It is likely to enhance neuromotor development and coordination ability of the baby.
During infancy and preschool years, parents should actively interact with their baby. The baby should not be left alone in his crib or with his toys. The baby should be stimulated when he is alert and attentive and not when he is exhausted, sleepy or hungry. Extra stroking, touching, caressing, cuddling, skin-to-skin contact and massage are very stimulating. During first six months, infants love to look at black and white stripes, checker boards, bull’ s eyes and squares. They should be provided opportunities to fix on these and other objects of bright colors. Music has tempo, rhythm, melody and harmony and it stimulates the brain in many ways. Babies love to listen to classical or instrumental music and most children exhibit spontaneous dancing movements when watching rollicking fast music on TV. Children enjoy lying on their tummy and making swimming move-ments. Babies learn newer skills through repetition and parents should repeat a stimulus till habituation occurs and baby is no longer interested or he is bored. Apart from improving neuromotor development and enhancing maturation of the brain, interactive play activity provides great enjoyment and fun to parents and improves parent-child bonding.
1. Optimal nutrition during pregnancy and first 3 years of life is most crucial because 70% of the human brain develops during fetal life and the remaining 30% during preschool years.
2. Every baby must be breast fed to promote rapid brain growth during infancy. Optimal nutrition of nursing mother improves the quality of breast milk by ensuring adequate concentration of smart nutrients.
3. Children should be encouraged to take brain-friendly diet rich in smart nutrients and antioxidants. Intake of junk food and soft drinks should be discouraged. When 100% RDA’s of all micronutrients cannot be met through dietary sources due to food preferences or fussiness, nutritional supplements are recommended to ensure optimal brain development.
4. School-going children should not miss their breakfast because of its adverse effects on physical growth and learning capabilities.
5. Apart from nutrition, physical activity and stimulation are equally important to promote brain development by formation of interneuronal connections, synapses and dendrites. Stimulation of the baby should begin in utero and continued throughout the formative years of childhood.
Competing interests: None stated.
Meharban Singh ,