Presented here is an overview of the pathway from early nutrient deficiency to long-term brain function, cognition, and productivity, focusing on research from low- and middle-income countries.
Animal models have demonstrated the importance of adequate nutrition for the neurodevelopmental processes that occur rapidly during pregnancy and infancy, such as neuron proliferation and myelination. However, several factors influence whether nutrient deficiencies during this period cause permanent cognitive deficits in human populations, including the child's interaction with the environment, the timing and degree of nutrient deficiency, and the possibility of recovery. These factors should be taken into account in the design and interpretation of future research. Certain types of nutritional deficiency clearly impair brain development, including severe acute malnutrition, chronic undernutrition, iron deficiency, and iodine deficiency. While strategies such as salt iodization and micronutrient powders have been shown to improve these conditions, direct evidence of their impact on brain development is scarce. Other strategies also require further research, including supplementation with iron and other micronutrients, essential fatty acids, and fortified food supplements during pregnancy and infancy.
Adequate nutrition is necessary for normal brain development. Nutrition is especially important during pregnancy and infancy, which are crucial periods for the formation of the brain, laying the foundation for the development of cognitive, motor, and socio-emotional skills throughout childhood and adulthood. Thus, nutritional deficiencies during pregnancy and infancy are likely to affect cognition, behavior, and productivity throughout the school years and adulthood. Focusing on this early period for the prevention of nutrient deficiencies may have long-term and widespread benefits for individuals and societies.
Role of Nutrients in Brain Development
Approximately 22 days after conception, the neural plate begins to fold inward, forming the neural tube, which eventually becomes the brain and spinal cord.2 Adequate nutrition is necessary from the beginning, with the formation of the neural plate and neural tube affected by nutrients such as folic acid, copper, and vitamin A. Seven weeks after conception, cell division begins within the neural tube, creating nerve cells (neurons) and glial cells (cells that support neurons). After a neuron is created, it migrates to its place in the brain, where it then grows axons and dendrites projecting out from its cell body. These branching projections make connections with other cells, called synapses, through which nerve signals travel from one cell to another. These neurodevelopmental processes begin during gestation and continue throughout infancy.
Groups of neurons form pathways, which are refined through the programmed elimination of cells and connections. About half of all the cells that are produced in the brain are subsequently eliminated throughout childhood and adolescence. Synapses are also overproduced and then selectively eliminated. Some of this refining of neural pathways depends on the child's experience, or in other words, input from the child's environment. Cells and connections that are activated are retained and strengthened while those that are not used are eliminated. This is thought to be one of the primary mechanisms of brain plasticity, allowing the brain to organize itself to adapt to the environment and reorganize itself to recover from injury during development.
Although the necessity of nutrients for brain development is evident, the extent to which nutrient deprivation during gestation and infancy results in long-term effects on brain function in free-living human populations is not yet clear. The actual impact depends on several factors, including 1) the child's experience and input from the environment, 2) the timing of nutrient deprivation, 3) the degree of nutrient deficiency, and 4) the possibility of recovery.
Experience and input from the environment
Adequate nutrition can be considered an aspect of the environment that is expected by the brain for normal development.48An environment with poor quality and variety of sensory and social input. impairs some of the same neurodevelopmental processes as nutrient deprivation during early development.
Timing of nutrient deprivation or supplementation
Nutrient deficiency is more likely to impair brain development if the deficiency occurs during a time period when the need for that nutrient for neurodevelopment is high. Various nutrients are necessary for specific neurodevelopmental processes. Each process occurs in different, overlapping time periods in different brain areas. Future studies that examine precise hypotheses related to specific nutrients, neurodevelopmental processes, timing, and brain areas are needed to clarify the relationship between nutrition and brain development and its mechanisms.
Degree of nutrient deficiency
Much evidence shows that brain development may be compromised when nutrient deficiency is severe to moderate but spared when deficiency is mild to moderate. A number of homeostatic mechanisms protect the developing fetus and the developing brain from nutrient deficiency to a certain degree. For example, in the case of placental insufficiency, when insufficient nutrients and oxygen are available, fetal cardiac output is redistributed such that blood flow to the peripheral tissues decreases and blood flow to the brain, adrenal glands, and heart increases. This leads to brain sparing, or the sparing of brain growth even when overall fetal growth is reduced. Another mechanism that protects the fetus from iron deficiency to a certain degree is the increased transfer of iron across the placenta as maternal levels decrease. For each nutrient, there is likely to be a threshold at which deficiency results in impairment for the child. Exactly where this line is drawn is an important question which must be answered for each nutrient individually. In summary, greater severity of nutritional deficiency increases both the likelihood of negative effects on brain development and the likelihood of positively responding to nutritional supplementation.
Possibility of recovery
The brain's potential for recovery from early damage has been widely studied in the context of neurological injury during development. When a certain part of the brain is damaged during early life, recovery happens in three ways, depending on the timing of the injury and subsequent experience. First, there are changes in the organization of the remaining intact circuits in the brain that were left uninjured, involving the generation of new synapses in existing pathways. Second, new circuitry that did not exist before the injury develops. Third, neurons and glia are generated to replace the injured neurons and glia. In the case of brain alterations caused by nutrient deficiency, recovery is plausible if nutrients become available during the time that the affected growth process is still occurring. In addition to nutrient repletion, enhanced sensory, linguistic, and social interactions may also facilitate recovery.
Data from the study of undernourished Korean orphans under the age of 2, and children experiencing nutrient deprivation in utero but adequate nutrition and health care thereafter both suggest that improved conditions earlier rather than later in childhood provide a greater benefit, and that some, but not all, of the negative effects of early undernutrition on brain development can be reversed through subsequent improvement in nutrition, health care, and enriched environments.
When a child is adequately nourished from conception through infancy, the essential energy, protein, fatty acids, and micronutrients necessary for brain development are available during this foundational period, establishing the basis for lifetime brain function. The well-nourished child is also better able to interact with his or her caregivers and environment in a way that provides the experiences necessary for optimal brain development. Children who are not adequately nourished are at risk for failing to reach their developmental potential in cognitive, motor, and socioemotional abilities. These abilities are strongly linked to academic achievement and economic productivity. Therefore, preventing or reversing developmental losses in early childhood is crucial for fostering economic development in low- and middle-income areas as well as reducing economic disparities in high-income areas.
The following interventions are examples of strategies that have been found to be effective in preventing or improving these conditions: salt iodization to prevent iodine deficiency, provision of iron via home fortification (e.g., with micronutrient powders) to prevent IDA, and educational interventions in conjunction with food supplementation in food-insecure populations. Strategies to promote exclusive breastfeeding during the first 6 months of life and continued breastfeeding thereafter, along with adequate complementary feeding, are also likely to improve cognitive development.
The following interventions are promising for preventing developmental loss: supplementation with iron and folic acid and/or multiple micronutrients during pregnancy, provision of multiple micronutrients (in addition to iron) during infancy, supplementation with essential fatty acids during pregnancy and infancy, fortified food supplements provided during pregnancy and infancy. Interventions to improve the home environment and the quality of caregiver-infant interaction are also recommended to complement and enhance the effect of improved nutrition.
Integrated strategies targeting multiple risk factors, including nutrition, are necessary to reduce inequality and promote cognitive, motor, and socioemotional development in disadvantaged children worldwide, ensuring that all children have the opportunity to fulfill their developmental potential.
Source: Elizabeth L Prado, Kathryn G Dewey; Nutrition and brain development in early life, Nutrition Reviews, Volume 72, Issue 4, 1 April 2014, Pages 267–284
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This video offers best practices for bottle feeding your infant to ensure safe feeding and provide a special bonding opportunity for you and baby.
How long should I breastfeed my baby?
When should my baby begin solid foods?
Is it possible to re-lactate if I have stopped (or never started) breastfeeding?
What are good first (solid) foods for baby?
- Single-grain cereal (with breastmilk or formula)
- Mashed banana, avocado, cooked beans
- Cooked and pureed carrots, peas, sweet potato
- Cooked and pureed meat or poultry
When can my baby have different types of milks (cow, goat, soy or nut milks)?
- Cow's Milk: Your baby can start drinking cow's milk at 1 year of age. Breast milk or formula is best for your baby's first year because they provide the most complete nutrition for your growing child. In addition, the protein found in cow's milk is hard for your baby to digest. When your baby starts drinking cow's milk, whole milk is best because it provides the fat needed for development of the nervous system and immune system. After age 2, you can change to 2 percent, 1 percent or nonfat milk. By this age, children's diets are more varied and they aren't as dependent on milk to provide the fat their bodies need. Learn More
- Goat's Milk: Goats' milk is very similar to cows' milk and can be given to toddlers as a main drink. after 12 months. It is very important that goats' milk is pasteurised, as fresh goat’s milk can contain germs that could make a young child ill. Refer to ‘untreated cow’s milk’ section. Goats' milk has less of some vitamins than are in regular cows' milk – in particular folic acid (folate). To help with this, make sure your child eats other foods high in folate such as green leafy vegetables, fruit and fortified cereals. For very fussy eaters, a folic acid supplement may be worthwhile if they are only drinking goats' milk Learn More
- Soy Milk: Soy milk can be used instead of cow’s milk if preferred. Choose soy milk that has added calcium (at least 100mg calcium per 100ml). Full fat soy beverages which have calcium added are suitable for use after 1 year of age. Like cow's milk, soy milk should be included as part of a healthy varied diet. It is only one part of what toddlers eat and drink, and other foods are needed. Other soy drinks that do not have calcium added are not best for toddlers. Learn More
- Almond Milk: Toddlers can drink almond milk once or twice a day in between periods of breast-feeding or eating their other foods, but only when they are over 12 months old. Learn More
When can my child have shellfish?
What are the best protein sources for my child?
- Eggs: Eggs are an excellent source of protein for kids because they contain high-quality, complete protein and are easy for young children to chew. One large egg contains about 6 grams of protein. Children with an egg allergy should avoid eating eggs. However, KidsHealth.org reports that most kids outgrow egg allergies by the time they turn 5 years old.
- Lean Meats: Meats like skinless chicken and lean beef are rich in protein, iron and zinc, which are all important nutrients for proper childhood development. The Academy of Nutrition and Dietetics reports that 2 ounces of chicken breast contain 18 grams of protein, and 2 ounces of lean ground beef provide 14 grams. Fish is also rich in protein, but the U.S. Food and Drug Administration encourages young children to limit their fish intake to 12 ounces of low-mercury selections, like salmon, catfish, pollock and canned light tuna, weekly.
- Plant-Based Proteins: Many plant-based foods are also rich in protein. According to the Academy of Nutrition and Dietetics, children who follow vegetarian, including vegan, diets can get all the nutrients they need from eating a variety of nutrient-dense foods. Examples of plant-based protein foods include soy milk, soy yogurt, tofu, seitan -- a wheat protein -- legumes, nuts, seeds and nut butters. However, ask your pediatrician before offering young children nuts, seeds or nut butter, since they may pose a choking risk. Since soy milk contains estrogen-like compounds, Dr. Walter Willett at Harvard Medical School suggests limiting your child’s soy milk intake to 2 cups daily.
What is a "healthy diet"?
Does my child need fruit juice?
How often should my child have a snack?
I'm concerned that my child weighs too much — what should I do?
I'm concerned my child doesn't eat enough — what should I do?
- Baby Center has a great resource guide for feeding your baby. This guide provides age-by-age information about what types of nutrients baby needs at any age.
- Parenting.com is an excellent resource for all things baby, including this link for information on the best ways to feed your baby.
- Mayo Clinic is the go-to expert for health and wellness. Click the resources below for information on infant development and best ways to feed your newborn: Infant and Toddler Health
Solid Foods: How to Get Your Baby Started
- Kids Health has more information on the best ways to feed your newborn baby.
- The World Health Organization has recommendations accepted globally on best practices for parents when feeding newborns.
- This is an interactive link with specific information for feeding your baby by age
- Is your baby ready for solid foods? Click the link here to Know if Your Baby is Ready for Solid Foods.
- Wondering about the best nutrients for baby? 5 Foods Pregnant Women Should Eat for Baby's Healthy Heart.
Create Fruit & Veggie Snacks
- Description: Help children use toothpicks to make their three-dimensional objects. Encourage children to eat their fruit/vegetable creation for morning or afternoon snack.
Choose a letter of the week
- Description: Each week taste and discuss healthy foods which start with the chosen letter of the week. For example, for the letter ‘A’ try different types of apples.
Fruit Plate Self
- Description: Fruit Plate (lunch or snack) Give each child a paper plate and sliced fruit. Ask them to create themselves or a friend using the slices of fruit. (Example grapes for eyes, sliced apple for eye brows, banana sliced lengthwise for a mouth and a kiwi slice for a nose.) This presents an ideal time to discuss the importance of eating well to maintain healthy bodies. When their creation is finished they may eat the fruit plate for snack!
- Description: Cut up and clean various food items. Blindfold your child and have him/her taste and smell different foods. Have him/her describe the various tastes, smells and textures before they guess what it is.
- Description: Mix one cup of beans, one cup of salt and one cup of rice together in a bowl. Provide the children with a strainer and a colander and tell them to separate the items in the bowl into three separate bowls–one with beans, one with salt and one with rice.
Paper Plate Meals
- Description: Have the children look through magazines to find pictures of different kinds of foods. Then have them cut out the pictures and glue them onto paper plates to make ‘breakfasts’, ‘lunches’ or ‘dinners’.
- Adult cuts a watermelon in half.
- Have kids scoop out the inside using an ice cream scoop or melon baller.
- Cut open other melons and have kids make balls with the melon ball scoop from the other melons. Fill the watermelon with balls from the various melons. This makes a great summer snack or dessert.