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12.2: Infancy and Nutrition

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    Learning Objectives

    • Summarize nutritional requirements and dietary recommendations for infants.
    • Describe the physiologic basis for lactation and the specific components of human milk.
    • Discuss the benefits and barriers related to breastfeeding.
    • Examine feeding problems that parents and caregivers may face with infants.

    Diet and nutrition have a major impact on a child’s development from infancy into the adolescent years. A healthy diet not only affects growth, but also immunity, intellectual capabilities, and emotional well-being. It's important to ensure that children receive an adequate amount of needed nutrients to provide a strong foundation for the rest of their lives.

    Infancy (Birth to Age One)

    Healthy infants grow steadily, but not always at an even pace. For example, during the first year of life, height increases by 50%, while weight triples. Physicians and other health professionals can use growth charts to track an infant’s development process. Because infants cannot stand, length is used instead of height to determine the rate of a child’s growth. Other important developmental measurements include head circumference and weight. All of these must be tracked and compared against standard measurements for an infant’s age. Nationally-accepted growth charts are based on data collected by the National Center for Health Statistics. These charts allow for tracking trends over time and comparing with other infants among percentiles within the United States. Growth charts may provide warnings that a child has a medical problem or is malnourished. Insufficient weight or height gain during infancy may indicate a condition known as failure-to-thrive (FTT), which is characterized by poor growth. FTT can happen at any age, but in infancy, it typically occurs after six months. Some causes include poverty, lack of enough food, feeding inappropriate foods, and excessive intake of fruit juice.

    Nutritional Requirements

    Requirements for macronutrients and micronutrients on a per-kilogram basis are higher during infancy than at any other stage in the human life cycle. These needs are affected by the rapid cell division that occurs during growth, which requires energy and protein, along with the nutrients that are involved in DNA synthesis. During this period, children are entirely dependent on parents and caregivers to meet these needs. For almost all infants six months or younger, human milk is the best source to fulfill nutritional requirements. An infant may require feedings eight to twelve times a day or more in the beginning. Typically, after about six months, infants can gradually begin to consume solid foods to help meet nutrient needs.


    Energy needs relative to size are much greater in an infant than an adult; infant energy needs are high to support rapid growth. An infant needs about 40-50 calories per pound of body weight per day.1 How often an infant wants to eat will also change over time due to growth spurts, which typically occur at about two weeks and six weeks of age, and again at about three months and six months of age.


    Dietary recommendations for infants are different from recommendations for adults. About 40-50% of an infant's calorie intake should come from fat. A high-fat diet is necessary to encourage the development of neural pathways in the brain and other parts of the body. Infants 0 to 6 months of age need approximately 9 grams of protein per day; infants 7-12 months need 11 grams of protein per day to support growth. Because infants' kidneys are still immature, having too much protein makes it difficult for the kidneys to process and excrete excess nitrogen; therefore, no more than 20% of an infant's calories should come from protein. Carbohydrate recommendations are set at 60 grams per day for infants 0-6 months old and 95 grams per day for infants 7-12 months old. These levels reflect the lactose content of human milk. Almost all of the carbohydrate in human milk is lactose, which infants digest and tolerate well.


    Almost all of the nutrients that infants require can be met if they consume an adequate amount of human milk or formula. There are a few exceptions, though. Human milk is low in vitamin D, which is needed for calcium absorption and building bone, among other things. Therefore, infants and children consuming human milk often need to take a vitamin D supplement in the form of drops. Human milk is not high in iron, but the iron in human milk is well absorbed by infants. After four to six months, however, an infant needs an additional source of iron other than human milk; the source of iron typically comes from solid foods that are introduced. For formula-fed infants, supplementation depends on the particular formula being used; for example, many formulas are fortified with iron.


    Infants have a high need for fluids, 1.5 milliliters per kilocalorie consumed compared to 1.0 milliliters per kilocalorie consumed for adults. This is because children have larger body surface area per unit of body weight and a reduced capacity for perspiration. Therefore, they are at greater risk of dehydration. However, parents or other caregivers can meet an infant’s fluid needs with human milk or formula. As solid foods are introduced, parents and caregivers must make sure that young children continue to drink fluids throughout the day.


    The alveoli cells produce milk (Figure \(\PageIndex{1}\)). To secrete it, they contract and push milk into the ducts and sinuses, which collects the milk. When a breastfeeding infant’s gums press on the areola and nipple, the sinuses squeeze the milk into the baby’s mouth.

    Drawing of breast anatomy including areola surrounding nipple and flow of human milk from alveoli and lactiferous ducts to nipple.
    Figure \(\PageIndex{1}\): Anatomy of the breast. (CC BY 4.0; by OpenStax)

    After the birth of the baby, nutritional needs must be met to ensure that an infant not only survives, but thrives from infancy into childhood. Breastfeeding provides the fuel a newborn needs for rapid growth and development. As a result, the World Health Organization (WHO) and the American Academy of Pediatrics (AAP) recommend that breastfeeding be done exclusively for the first six months of an infant’s life.2,3


    Lactation is the process that makes breastfeeding possible, and is the synthesis and secretion of human milk. Early in a pregnancy, mammary glands begin to prepare for milk production. Hormones play a major role in this, particularly during the second and third trimesters. At that point, levels of the hormone prolactin increase to stimulate the growth of the milk duct system, which initiates and maintains milk production. Levels of the hormone oxytocin also rise to promote the release of human milk when the infant suckles, which is known as the milk ejection reflex. However, levels of the hormone progesterone need to decrease for successful milk production, because progesterone inhibits milk secretion. Shortly after birth, the expulsion of the placenta triggers progesterone levels to fall, which activates lactation.

    Caloric and fluid intake must be adjusted to make breastfeeding possible. The Estimated Energy Requirement (EER) is 330 additional calories (beyond pre-pregnancy needs) during the first six months of lactation and 400 additional calories during the second six months of lactation. The energy needed to support breastfeeding comes from both increased food/beverage intake and from stored fat. For example, it's estimated that milk production requires 700-800 calories per day. During the first six months after a baby is born, 330 of those calories would come from increased intake and 370-470 calories would come from the birthing parent's fat stores that built up during pregnancy. This helps explain why breastfeeding may promote weight loss after pregnancy. Those who are lactating should also drink 3.8 liters of liquids per day (about 16 cups) to maintain milk production.4 As is the case during pregnancy, the DRI for nearly all vitamins and minerals increases for those who are breastfeeding their babies. Table \(\PageIndex{1}\) compares the recommended vitamins and minerals during lactation to the levels during non-pregnancy and pregnancy.

    Table \(\PageIndex{1}\): Recommended Nutrient Intakes during Lactation4
    Nutrient Recommendations during Non-pregnancy Recommendations during Pregnancy Recommendations during Lactation
    Vitamin A (mcg) 700 770 1,300
    Vitamin B6 (mg) 1.5 1.9 2.0
    Vitamin B12 (mcg) 2.4 2.6 2.8
    Vitamin C (mg) 75 85 120
    Vitamin D (mcg) 15 15 15
    Vitamin E (mg) 15 15 19
    Calcium (mg) 1,000 1,000 1,000
    Folate (mcg) 400 600 500
    Iron (mg) 18 27 9
    Magnesium (mg) 320 360 320
    Niacin (B3) (mg) 14 18 17
    Phosphorus (mg) 700 700 700
    Riboflavin (B2) (mg) 1.1 1.4 1.6
    Thiamin (B1) (mg) 1.1 1.4 1.4
    Zinc (mg) 8 11 12

    Calcium requirements do not change during breastfeeding because of more efficient absorption (which is the case during pregnancy, too). However, the reasons for this differ. During pregnancy, there is enhanced absorption within the gastrointestinal tract. During lactation, there is enhanced retention by the kidneys.

    Components of Human Milk

    Human milk not only provides adequate nutrition for infants, it also helps protect newborns from disease. In addition, human milk is rich in cholesterol, which is needed for brain development. It is helpful to know the different types and components of human milk, along with the nutrients they provide that enable an infant to survive and thrive. The components of human milk include:

    • Colostrum. Colostrum is produced immediately after birth, prior to the start of milk production, and lasts for several days after the arrival of the baby. Colostrum is thicker than human milk, and is yellowish or creamy in color. This protein-rich liquid fulfills an infant’s nutrient needs during those early days. Although low in volume, colostrum is packed with concentrated nutrition for newborns. Colostrum is high in fat-soluble vitamins, minerals, and immunoglobulins (antibodies). Immunoglobulins pass from the lactating parent to the infant via human milk; this provides passive immunity for the newborn and protects the baby from bacterial and viral diseases.5
    • Transitional Milk. Around two to four days after birth, colostrum is replaced by transitional milk. Transitional milk is a creamy liquid that lasts for approximately two weeks and includes high levels of fat, lactose, and water-soluble vitamins. It also contains more calories than colostrum. When production of transitional milk begins, there is typically a noticeable change in the volume and type of liquid secreted from the breasts as well as an increase in the weight and size of the breasts.5
    • Mature Milk. Mature milk is the type of human milk that is produced after the first two weeks. About 90% of mature milk is water, which helps an infant remain hydrated. The other 10% contains carbohydrates, proteins, and fats, which support energy and growth. Similar to cow’s milk, the main carbohydrate of mature milk is lactose. Human milk contains vital fatty acids, such as docosahexaenoic acid (DHA) and arachidonic acid (ARA). Lactalbumin is the major protein found in human milk. In terms of protein, human milk contains more whey than casein (which is the reverse of cow’s milk). Whey is much easier for infants to digest than casein. There are two types of mature milk, which, combined ensure that a baby receives adequate nutrients to grow and develop properly:
      • Foremilk occurs at the beginning of a breastfeeding session and includes water, vitamins, and protein.
      • Hind-milk occurs after the initial release of milk and contains higher levels of fat, which is necessary for weight gain.5

    In addition, human milk provides adequate vitamins and minerals. Although absolute amounts of some micronutrients are low, they are more efficiently absorbed by infants. Other essential components include digestive enzymes that help a baby digest the human milk.

    Diet and Milk Quality

    Diet can have a major impact on milk production and quality. As during pregnancy, those who are lactating should avoid illegal substances and cigarettes. Some legal drugs and herbal products can be harmful as well, so it is helpful to discuss them with a health care provider. Some people who are lactating may need to avoid certain things, such as spicy foods, that can produce gas in sensitive infants. Lactating people can drink alcohol, though they must avoid breastfeeding until the alcohol has completely cleared from their milk. Typically, this takes 2-3 hours for a standard drink (12 ounces of beer, 5 ounces of wine, or 1.5 ounces of liquor), depending on the person’s body weight.6

    Benefits of Breastfeeding

    Breastfeeding has a number of benefits, several of which are listed in Table \(\PageIndex{2}\). Human milk contains immunoglobulins, enzymes, immune factors, and white blood cells. As a result, breastfeeding boosts the baby’s immune system and lowers the incidence of diarrhea, along with respiratory diseases, gastrointestinal problems, and ear infections. Babies fed human milk are also less likely to develop asthma and allergies, and breastfeeding lowers the risk of sudden infant death syndrome. In addition, human milk is a rich source of microbes that have the potential to influence infant health; for example, human milk encourages the growth of healthy bacteria in an infant’s intestinal tract.7

    Table \(\PageIndex{2}\): Benefits of Breastfeeding8
    Breastfed babies have a lower risk of: Birthing parents who breastfeed their child(ren) have a lower risk of:
    Asthma Breast cancer
    Obesity Ovarian cancer
    Type 1 diabetes Type 2 diabetes
    Severe lower respiratory disease High blood pressure
    Acute otitis media (ear infections)  
    Sudden infant death syndrome (SIDS)  
    Gastrointestinal infections (diarrhea/vomiting)  

    Breastfeeding has a number of other important benefits. It is easier for babies to digest human milk than formula. Formula contains proteins made from cow’s milk that require an adjustment period for infant digestive systems. Breastfeeding is more sustainable and results in less plastic waste and other trash. Breastfeeding can also save families money because it does not incur the same cost as purchasing formula. Other benefits include that human milk does not have to be mixed, heated, or prepared - it is always at the right temperature.

    Some initiatives related to feeding infants human milk include:

    Barriers to Breastfeeding

    Although human milk is ideal for almost all infants, there are some challenges that people may face when starting and continuing to breastfeed their infants. These obstacles include painful engorgement or fullness in the breasts, sore and tender nipples, lack of comfort or confidence in public, and lack of accommodation to breastfeed or express milk in the workplace. One of the first challenges faced is learning the correct technique for breastfeeding. It may take a little time for the lactating person to help their baby properly latch on to the nipple. Improper latching can result in inadequate intake, which could slow growth and development. However, International Board Certified Lactation Consultants (IBCLCs) are health care professionals trained to help people learn the proper technique. Additional barriers include social concerns such as breastfeeding in public and conflicts with the breastfeeding parent's employment. Education, the length of maternity leave, and laws to protect public breastfeeding, among other measures, can all help to facilitate breastfeeding for many lactating people and their newborns.

    Contraindications to Breastfeeding

    Although there are numerous benefits to breastfeeding, in some cases there are also risks that must be considered. In the developed world, someone with HIV should not breastfeed, because the infection can be transmitted through human milk. This is typically not an issue as there is access to formula that is a safe alternative to human milk. However, in developing nations where HIV infection rates are high and acceptable infant formula can be difficult to come by, many newborns would be deprived of the nutrients they need to develop and grow. As a result, the WHO recommends that people infected with HIV in the developing world should feed their infants human milk while taking antiretroviral medications to lower the risk of transmission.10

    Formula Feeding

    For parents and caregivers who choose to formula feed, infant formula provides a balance of nutrients. However, not all formulas are the same and there are important considerations that parents and caregivers must weigh. Standard formulas use cow’s milk as a base. They have 20 calories per fluid ounce, similar to human milk, with vitamins and minerals added. Soy-based formulas are usually given to infants who develop diarrhea, constipation, vomiting, colic, or abdominal pain, or to infants with a cow’s milk protein allergy. Hypoallergenic protein hydrolysate formulas are usually given to infants who are allergic to cow’s milk and soy protein. This type of formula uses hydrolyzed protein, meaning that the protein is broken down into amino acids and small peptides, which makes it easier to digest. Preterm infant formulas are given to low birth weight infants, if human milk is unavailable. Preterm infant formulas have 24 calories per fluid ounce and are given until the infant reaches a desired weight.

    Infant formula comes in three basic types:

    1. Powder that requires mixing with water. This is the least expensive type of formula.
    2. Concentrates, which are liquids that must be diluted with water. This type is slightly more expensive.
    3. Ready-to-use liquids that can be poured directly into bottles. This is the most expensive type of formula. However, it requires the least amount of preparation.

    When preparing formula, parents and caregivers should carefully follow the safety guidelines, since an infant has an immature immune system. All equipment used in formula preparation should be sterilized. Prepared, unused formula should be refrigerated to prevent bacterial growth. Parents and caregivers should make sure not to use contaminated water to mix formula in order to prevent foodborne illnesses. Follow the instructions for powdered and concentrated formula carefully—formula that is over-diluted would not provide adequate calories and protein, while over-concentrated formula provides too much protein and too little water which can impair kidney function.

    Introducing Solid Foods

    Infants should be breastfed or formula fed exclusively for the first six months of life. Infants should not consume solid foods prior to six months because solid foods do not contain the right nutrient mix that infants need. Also, eating solids may mean drinking less human milk or formula. If that occurs, an infant may not consume the right quantities of various nutrients. If parents or caregivers try to feed an infant who is too young or is not ready, their tongue will push the food out, which is called the extrusion reflex. The extrusion reflex begins to lessen around 4-6 months of age. Other developmental milestones that indicate readiness for solid foods include the infant's ability to hold up their head, sit up, open mouth to signal readiness to eat, and move food from the front of the mouth to the back where it can be safely swallowed.

    Solid baby foods can be bought commercially or prepared from regular food using a food processor, blender, food mill, or grinder at home. Usually, an iron-fortified infant cereal is the first solid food introduced to an infant (around the age of 6 months) as it is easy to digest and rarely causes an allergic response. Introducing an iron-fortified infant cereal at this time is also advantageous to prevent anemia in the infant; infants are born with an iron supply that lasts approximately 6 months. By 9-12 months of age, infants are able to chew soft foods and can eat solids that are well chopped or mashed.

    Learning to Self-Feed

    With the introduction of solid foods, young children begin to learn how to handle food and how to feed themselves. Initially, infants use their whole hand to pick up items (this is known as the palmer grasp). They can lift larger items, but picking up smaller pieces of food is difficult. Between 8 and 12 months of age, infants develop a pincer grasp, which uses fingers to pick up objects. After the age of one, children slowly begin to use utensils to handle their food. Unbreakable dishes and cups are essential, since very young children may play with them or throw them when they become bored with their food.

    Feeding Problems during Infancy

    Parents and caregivers should be mindful of certain diet-related problems that may arise during infancy. Heating an infant’s food presents a risk of accidental injury or burns, which may occur if the food is heated unevenly or excessively. Keep in mind that an infant cannot communicate that the food is too hot. Some foods and beverages are not safe for infants, including:

    • Honey and corn syrup. These may contain spores of Clostridium botulinum which is a bacteria that can produce a poisonous toxin in an infant’s intestines and cause the foodborne illness botulism. Botulism can be fatal. After the age of one, it is safe to give a child honey or corn syrup because their digestive tract is mature enough to kill the bacteria.
    • Foods that can cause choking. Certain foods are choking hazards, including foods with skins or foods that are very small, such as grapes. Other examples of potential choking hazards include raw carrots and apples, raisins, and hard candy. Parents and caregivers should never leave a baby alone at mealtime, because an infant can accidentally choke on pieces of food that are too big or have not been adequately chewed.
    • Cow's milk, goat's milk, and plant-based milk alternatives. These milks do not have the appropriate mix of nutrients to meet an infant's needs and can be difficult for an infant to digest. These milks tend to have too much protein and too few carbohydrates for an infant. Offering these milks after the age of one is ok.

    Food Allergies

    Delaying the introduction of solid foods until the age of 6 months reduces the risk of developing food allergies. It is also recommended to only introduce one new food at a time to help identify allergic responses or food intolerances. One of the most common allergies in infants is to proteins in cow's-milk based formulas. Other common food allergens that can appear just before or after the first year include peanut, egg white, and wheat allergies. Symptoms may include diarrhea, constipation, bloating, blood in the stool and vomiting.

    Early Childhood Caries

    Primary teeth are at risk for a disorder known as early childhood caries (cavities) from human milk, formula, juice, or other drinks fed through a bottle for prolonged periods of time. Liquids can build up in a baby’s mouth, and the natural or added sugars lead to tooth decay. Early childhood caries is caused not only by the kinds of liquids given to an infant, but also by the frequency and length of time that fluids are given. Giving a child a bottle of juice or other sweet liquids several times each day, or letting a baby suck on a bottle longer than a mealtime, either when awake or asleep, can also cause early childhood caries. Providing beverages in a cup starting around 8 months of age and no longer using a bottle after 18 months of age are strategies to prevent early childhood caries from overuse of a bottle.

    Gastroesophageal Reflux

    Small amounts of spitting up during a feeding is normal. However, there is cause for concern if it is too difficult to feed an infant due to gastroesophageal reflux. This condition occurs when stomach muscles open at the wrong times and allow milk or food to go back up into the esophagus. Symptoms of gastroesophageal reflux in infants include severe spitting up, projectile vomiting, arching of the back as though in pain, refusal to eat or pulling away from the breast during feedings, gagging or problems with swallowing, and slow weight gain. For most infants, making adjustments in feeding practices addresses the issue. For example, a parent can feed their baby in an upright position, wait at least an hour after eating for play time, burp more often, or give a child smaller, more frequent feedings.


    Dehydration can result from diarrhea, vomiting, or inadequate fluid intake and is an extremely dangerous situation for infants. Treatment includes providing fluids and electrolytes

    Key Takeaways

    • Growth charts are used to track an infant’s growth and development over time.
    • Dietary recommendations for infants are different from recommendations for adults. For example, about 40-50% of an infant's calorie intake should come from fat.
    • The World Health Organization (WHO) and the American Academy of Pediatrics (AAP) recommend that breastfeeding be done exclusively for the first six months of an infant’s life.
    • Benefits of breastfeeding for an infant include a lower risk of diarrhea, respiratory diseases, gastrointestinal problems, and ear infections. Breastfeeding has several health benefits for the birthing parent as well, such as reducing the risk of breast cancer and ovarian cancer.
    • Solid foods should be introduced after six months of age and introduced one at a time to help identify allergic responses or food intolerances.


    1. National Academies of Sciences, Engineering, and Medicine. 2005. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: The National Academies Press.
    2. Exclusive breastfeeding for six months best for babies everywhere.,of%20two%20years%20or%20beyond.. Accessed July 10, 2020.
    3. Breastfeeding and the Use of Human Milk. Section on Breastfeeding. Pediatrics. 2012;129(3):e827-841.
    4. Summary Report of the Dietary Reference Intakes. Accessed July 10, 2020.
    5. Breastfeeding: Overview. Accessed July 10, 2020.
    6. Alcohol - Breastfeeding. Accessed July 10, 2020.
    7. Notarbartolo V, Giuffrè M, Montante C, Corsello G, Carta M. Composition of Human Breast Milk Microbiota and Its Role in Children's Health. Pediatr Gastroenterol Hepatol Nutr. 2022 May;25(3):194-210. doi: 10.5223/pghn.2022.25.3.194.
    8. Recommendations and Benefits. Accessed July 11, 2020.
    9. The Baby-Friendly Hospital Initiative. Accessed July 11, 2020.
    10. Infant and young child feeding. Accessed July 11, 2020.

    12.2: Infancy and Nutrition is shared under a CC BY-NC-SA 3.0 license and was authored, remixed, and/or curated by LibreTexts.

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