13 Nutritional Requirements for Normal Growth from Infancy to Old Age

Dr. Renu Tyagi

Introduction

Stages in the human life can be broadly classified as prenatal and post natal. The post natal life begins with the birth and different stages in this phase can be classified as infancy, childhood, adolescence, adulthood and old age (Timiras 1972). An understanding of the changes in growth and maturation of the body is important to identify the energy and nutrient requirement. Diet and nutrition have a major impact on an individual’s development from infancy to old age. For a normal growth of human being, an adequate supply of food and nutrients is important. The people of all ages need the similar basic nutrients—protein, carbohydrates, fats, vitamins and minerals—to sustain life and health. However, there is variation in the amount of each of these nutrients in different age groups. Body size and physical activity levels are two major determinants of human nutrient requirements. A healthy diet affects growth, immunity, intellectual capabilities, and emotional well-being of an individual. Nutrition is a process that is influenced by the social and cultural context within which infant, children, adolescents, adults and senior citizens live. Food has an important influence on physical health and independence with advancing age. It also adds to social, cultural and psychological quality of life of an individual (American Dietetic Association 2005).Inadequate and improper nutrition at any stage of life could influence the body adversely. Many communities are bearing a double burden of disease—both under nutrition in infants, children and women, and over nutrition in the adults, especially in older women (Popkin et al 2001, Popkin 2002). Anthropometric assessment is one of the most commonly used approaches for finding out nutritional status because of the relative ease, reproducibility, availability of standards based on normal population for comparison and established association between abnormal measurements and clinical illnesses. Height is influenced by genetic and environmental factors including dietary intake. Stunting reflects the cumulative impact of under nutrition in the past. Weight is the index which reflects partly the cumulative impact of past under nutrition and partly current nutritional status (WHO 2010, Kapoor et al 2012; Ramchandran 2013).There are widespread effects of early diet on later body composition, physiology and cognition. Such observations support the recent shift from ‘defining nutritional needs for prevention of acute deficiency symptoms’ to ‘long term prevention of morbidity and mortality’ (Roberts 2001).The present paper aims to understand the relevance of nutritional requirement at different stage of life. It further explains the growth and development with differential energy and nutrients requirement through various life stages. The paper concludes with some suggestions and recommendations.

Nutritional Requirements at different stages

It is crucial to consume healthy foods at every phase of life. A good nutritional intake during pregnancy helps both i.e. the expectant mother to remain healthy, and for normal development of the fetus which ensures that the baby grow well in infancy and beyond. During pregnancy, a woman’s needs increase for certain nutrients more than for others and lack of these nutrients could result in low birth weight. Pregnant women must consume good amount of calories and nutrients in the second and third trimesters. However, the average recommended daily caloric intake can vary depending on activity level and normal weight of the expectant mother. Some prenatal supplements to ensure adequate intake of the needed micronutrients are very important during pregnancy. Stunting is reported to be linked to nutrition during pregnancy & fetal growth (WHO 2010). An adequate postnatal nutritional environment is important in bringing to the fore a risk associated with fetal growth retardation (Aboderin et al 2002; Darnton et al 2004). An increased attention to nutrition during the postnatal growth is important as well as challenging (Bateson 2001).

Infancy

Infancy is a period characterized by the supreme growth and physical development throughout life. A number of major physical and physiological changes occur during infancy. The infants double their birth weight by age 4 to 6 months and triple it by age 1 year. Infants usually increase their length by 50% in the first year of life, but the rate of increase slows during the second half of the year and it further slows in second year. The organs and organ systems grow at a rapid rate, especially the brain. Various motor skills include sitting up without support, learning to walk, teething, and vocalizing develop during this period. All these drastic changes require adequate nutrition to ensure development at the appropriate rate (Beverly McMillan 2008). In order to meet such growth demands, infants require a high intake of calories and adequate intakes of fat, protein, vitamins, and minerals. The infants need energy from food for activity ,growth, and normal development. Requirements for both, macronutrients and micronutrients on a per-kilogram basis are higher during infancy than at any other stage in the human life cycle. Energy needs relative to size are much greater in an infant than an adult as the baby’s resting metabolic rate is two times that of an adult. From the age one to age two, the estimated requirement rises to 844–1,050 kilocalories per day for boys and 768–997 kilocalories per day for girls (FNB 2005).An infant’s energy or caloric requirement depends on many factors, including body size and composition, metabolic rate (the energy the body expends at rest), physical activity, size at birth, age, gender, genetic factors, energy intake, health conditions, and growth rate. Physicians and other health specialists use growth charts to track a baby’s development process. Anthropometric measurements viz. length, head circumference and weight are the important developmental measurements which are used to determine the rate of a child’s growth. A comparison of such growth charts against standard measurements for an infant’s growth may provide important information of an infant normal growth as well the warnings that a child has a medical problem or is malnourished. During the first year of life, good nutrition is very important to infants overall healthy development.

Infants and Nutrition

For almost all infants six months or younger, breast milk is the best source to fulfill nutritional requirements. Children need to be exclusively breastfed for the first six months of life, followed by the introduction of safe and adequate complementary foods together with continued breastfeeding for up to two years (WHO 2001). The exclusively breastfed infants in developing and developed countries can receive similar volumes of milk (Institute of Medicine 1991; Picciano 2001), though this does not guarantee that these infants also receive adequate amounts of nutrients for optimal growth and development due to differential maternal nutrition and hence milk quality(Allen 2012). Growth rates of exclusively breastfed and formula-fed infants differ. Breastfed infants grow more rapidly during the first 6 months of life but less rapidly during the remainder of the first year. Breastfeeding provides a number of benefits for both mother and her infant. For babies, breast milk boosts the immune system to protect against disease. The anti-infective properties of human milk protect infants against gastrointestinal infections. Antibodies and lactoferrin in breast milk protect infants. Breast milk contains the fatty acids, Docosahexaenoic acid (DHA) and Arachidonic acid (ARA), which are vital for brain and vision development (APA 2012). For mothers, the breastfeeding has some health benefits, like reducing the risk of breast cancer and ovarian cancer. The infant who are not breast fed and are given ‘Bottle Formula’ do not receive the adequate nutrients as the formula does not contain immune protective factors. Though the Formula contains more iron than breast milk, but it is not absorbed as easily as in the breast fed infants (APA 2012).

The dietary recommendations for infants are based on the nutritional composition of human breast milk. Carbohydrates make up about 45 to 65 percent and protein makes up about 5 to 20 percent of the caloric content of breast milk. Infants have a high need for protein to support growth and development. About 30to 40 percent of the caloric content in breast milk is made up of fat. A good amount of fat is necessary to encourage the development of neural pathways in the brain and other parts of the body. However, saturated fats and Trans fatty acids inhibit this growth so the infants who are over the age of six months and are no longer exclusively breastfed, should not consume foods that are high in these types of fats. Most of the nutrients that infants require can be obtained if they consume an adequate amount of breast milk with a few exceptions. However, human milk is low in vitamin D, needed for calcium absorption and building bone, among other things. Therefore, breastfed children often need to take a vitamin D supplement. The breast milk is not high in iron, but the iron in breast milk is well absorbed by infants. After four to six months, however, an infant needs an additional source of iron other than breast milk. An infant has a high need for fluids than an adult which can be adequately met with breast milk or formula. As solids are introduced, parents must make sure that young children continue to drink fluids throughout the day. By nine months to a year, infants are able to chew soft foods and can eat well chopped or mashed solids. Infants who are fed solid foods too soon are susceptible to developing food allergies.

Childhood & Adolescence: Nutritional Requirement

Childhood can be subdivided as early childhood, middle childhood and late childhood. The early childhood (i.e. milk teeth period) occurs during age two to six years. Developmental changes during early childhood include running, drawing, toilet training, and self-feeding etc. During age two to three years children are mobile and grow more slowly than infants, but are much more active. The child experience immense intellectual, emotional, and social changes. The food and nutrition continue to play an important role in a child’s development. During this stage, the diet completely shifts from breastfeeding or bottle-feeding to solid foods. The fluid requirements relative to body size are higher in childhood as they are at risk of dehydration. The middle childhood is during age seven to ten and the late childhood period is from ages ten to puberty. The onset of puberty is the beginning of adolescence, and it is the bridge between the childhood years and young adulthood. The adolescence is six years following puberty which generally range from ages twelve to fifteen for girls and from thirteen to sixteen for boys. During puberty there is development of primary sex characteristics, and appearance of secondary sex characteristics with a rapid growth and alterations in body proportions (Elaine et al 2003). Body mass index (BMI) changes substantially during middle childhood. After age 2, the BMI begins to decline, and it continues to decrease during the preschool years until it reaches its lowest point at around ages 5 to 6. Subsequently, BMI-for-age begins a gradual increase that is continued through adolescence and into adulthood. However, an early BMI rebound (occurring before ages5–6), may be associated with obesity in adulthood (Whitaker et al 1998). All major physical changes with mental and emotional adjustments need to be supported with sound nutrition.

The energy requirements for age’s two to three are about 1,000 to 1,400 calories aday. However, the recommended caloric intake varies with each child’s level of activity. The essential fatty acids are vital for the development of the eyes, along with nerve and other types of tissue. However, children should not consume foods with high amounts of Tran’s fats and saturated fats. The presence and tracking of blood pressure in children and adolescents may occur due to unhealthy lifestyles, including excessive intakes of total and saturated fats, cholesterol and salt, inadequate intakes of potassium, and reduced physical activity (Aboderin et al 2002). As a child grows bigger, the demands for micronutrients increase which can be met with a balanced diet. The children of all ages need vitamin D every day. Children need to have 400 IU per day of vitamin D through vitamin D–fortified milk and vitamin D–fortified foods to prevent rickets and vitamin D deficiency (Wagner & Greer 2008). The children who do not get enough of fluoride and iron should receive a supplement especially for the children between the ages of two and three. The adolescence is a time of tremendous biological, psychosocial and cognitive growth and development. The nutrient needs are greater during adolescence than at any other time in the life cycle, except during pregnancy. The nutrition interventions during adolescence need to be personalized to the developmental level of each individual adolescent. However, habitual alcohol and tobacco use may contribute to raise blood pressure among adolescents (Berenson 1998; Okasha 2000).

Adulthood and Nutrition

The adulthood is more stable period as compared to childhood and adolescence. By this age the physical growth is completed and all of the organs and body systems are fully developed. Proper nutrition at this stage is very important to promote good health for the future. The ‘middle age’ is taken as the period from age thirty-one to fifty. The early period of this stage is very different from the end especially for women. During the early years of middle age, many women experience pregnancy, childbirth, and lactation. In the latter part of this life stage, women face per menopause (transition period that leads up to menopause, or the end of menstruation). Many physical changes take place in the middle-aged years, including alterations in body composition like weight gain in the abdominal area, the loss of bone mass in women due to declining levels of estrogen during menopause.Due to the change in hormones; women need to maintain calcium and vitamin D needs to prevent bone loss before and after menopause. Exercise and healthy food habits are beneficial in preventing illness and bone loss during menopause (Palasuwan 2011).

During the middle-aged years, ‘preventive nutrition’ can promote health and help organ systems to function optimally in later years. Preventive nutrition is defined as dietary practices directed toward reducing disease and promoting health and well-being. Physical activity and proper diet can decrease or prevent weight gain, developing high blood pressure, diabetes and cardiovascular diseases. Healthy eating like eating unrefined carbohydrates instead of refined carbohydrates and avoiding Trans fats and saturated fats—helps to promote health. The revised RDAs for Indians has been given due understanding to the current body weight and physical activity of Indians while computing the energy and nutrient requirements. The Recommended Dietary Allowance (RDA) is the average daily dietary nutrient intake level sufficient to meet the nutrient requirement of nearly all (97 to 98 percent) healthy individuals in a particular life stage and gender group. The gap between actual intake (NNMB) and requirements for the persons with reference body weight for various age and physiological groups is given in Table I. The gap was highest among pregnant and lactating women followed by the gap among adolescent boys and girls. The gap was relatively lower in preschool and under ten children (Pl sees Table 1).

Old Age and Nutrition

Nutrition is one of the important factors that have beneficial or negative effects on the rate of the ageing process (British Nutrition Foundation 2009). A good nutrition in older people is associated with preventing malnutrition, supporting physical function, mental health and preventing disability.

Health and nutritional status in older people is influenced by the ageing process and the cumulative effects of exposure to various risk factors and determinants of health throughout the life span (Kapoor et al 2009, 2010). Among elderly the calorie needs change due to reductions in lean body mass and metabolic rate. Less activity can further decrease calorie needs. Changes in body composition or physiological function that occur with age may have a direct influence on nutrient requirements. Reductions in muscle mass, bone density, immune function, and nutrient absorption and metabolism may make it difficult for older adults to meet nutrition requirements, especially when energy needs are reduced. Total and resting energy requirements decrease progressively with age (Roberts &Dallal 2005) which could be due to the multiple factors like declining loss of skeletal muscle and gains in total body fat and visceral fat content in late life (Evans 2004). When energy needs decline with age, individuals often do not make a comparable reduction in energy intake leading to an increased body fat content (Evans 1998). Sarcopenia is an age-related loss of muscle mass, and results in decreased muscle strength, decreased functional capacity and reduced physical activity. Poor oral health, ill-fitting dentures and dry mouth can result in limited dietary variety, lower nutrient intakes and a decreased enjoyment of food. Changes in taste and smell may affect food selection, food preparation methods, dietary variety and nutrient intakes.

A lower energy requirement represents challenging nutrition situation for older adults because vitamin and mineral needs often remain constant or may even increase for many nutrients (CDCP 2004). Consequently consuming a diet that meets nutrition requirements without exceeding energy requirements poses an additional challenge for older adults which can be achieved by selecting the foods which are high in nutrients in relation to their calories i.e. ‘nutrient-dense’ food. For instance low-fat milk is more nutrient dense than regular milk. Protein requirements can vary because of chronic disease. An overall fat content should be reduced to cut calories and hence weight. About 60 percent of calories should come from carbohydrates with majority from complex carbohydrates. Complex carbohydrates put less stress on the circulating blood glucose than do refined carbohydrates. Adequate fiber and fluids, helps maintain normal bowel function and the fiber is believed to decrease risk of intestinal inflammation. Among elderly, vitamin deficiencies may occur during any illness. Medications also interfere with many vitamins. Medications may alter food intake and may cause reactions that interfere with normal nutrient metabolism and requirements (Ministry of Health. 2013).Vitamin D-fortified milk is necessary for the housebound, nursing home residents, and anyone who does not get adequate exposure to sunlight. Iron and calcium intake sometimes appears to be low in many elderly. Inclusion of vitamin C-rich fruits and vegetables with these foods improve absorption of iron. Zinc can be related to specific diseases in the elderly and it can also be a factor with vitamin K in wound healing. Zinc improves taste acuity in people where stores are low. A nutrient-dense, plant-based diet can help prevent or support the healing of a number of disorders that impact the elderly, including macular degeneration and arthritis. The best way to obtain these nutrients is to consume servings of fruits and vegetables, especially dark green, orange and yellow ones. Research has shown that eating foods with vitamin E, like whole grains, peanuts, nuts, vegetable oils, and seeds, may help reduce the risk of Alzheimer’s disease. However, the same benefits did not hold true for vitamin E supplements. Low levels of vitamin B12 have been associated with memory loss and linked to age-related hearing loss in older adults. Folate, helpful in B12 metabolism in the body, may actually improve hearing. However, if B12 levels are not adequate, high folate levels may be a health concern. As we age, the amount of the chemical in the body, needed to absorb vitamin B12 decreases which can be avoided by including related foods. With age, the diet needs to contain enough calcium, fiber, iron, protein, and the vitamins A, C, D and Folacin. It is necessary to eat a variety of foods to get the full gamut of nutrients. Variety often is lacking in the diets of seniors, who often eat the same foods over and over again. With advancing age there is a tendency of occurrence of number of chronic health problems like hypertension, cardiovascular disease, osteoporosis, diabetes and dementia etc. Nutrition has emerged as a major modifiable determinant of chronic disease and age related decline. The dietary modifications influence present health as well regulates chances of developing diseases like cancer, cardiovascular disease and diabetes later in life. Weight-bearing exercise and a diet high in calcium help protect against the osteoporosis. Adequate water intake especially in old age reduces stress on kidney function, which tends to decline with age. Adequate fluid intake also eases constipation. With advancing age, the ability to detect thirst declines. One should keep drinking plenty of water, juice, milk, and coffee or tea to stay hydrated.

Suggestions & Conclusion

The human body changes throughout the life cycle, and food provides the fuel for these changes. Infancy, childhood, adolescence, adulthood and old age are the major stages of the human life cycle

.Adequate nutrition and exercise ensure good health at each stage of the human life cycle. Nutrition plays a crucial role in the prevention and control of disease. Education regarding the early introduction of breastfeeding, exclusive and continued breastfeeding, and good hygiene and sanitation should be promoted to ensure the infant’s optimal health. The recommended intakes of macronutrients and micronutrients for children are higher relative to body size as compared with the nutrient needs during adulthood. The daily energy needs of the children vary depending on their level of physical activity, growth and their gender. Some food- and nutrition-related problems that can affect children include malnutrition, food allergies and food intolerances. During puberty, preteens experience growth spurts and nutrition plays a crucial role at this stage. The nutritional worries for children at this age include malnutrition and obesity. The older adolescents experience numerous physical changes and must increase their energy intake to support these changes. The nutritional concerns for middle-aged adults relate to menopause and the prevention of chronic disease. It is important to balance protein and carbohydrate intake to replace energy stores and build muscle, balance overall caloric intake with activity to prevent weight gain or loss, and balance vitamins and mineral intake during middle ages. Older adults are more susceptible to medical problems, such as disability and disease, which can impact appetite, the ability to plan and prepare food, chewing and swallowing, self-feeding, and general nutrient intake .Some of the important points of consideration regarding nutrition in old age are consuming a variety of whole grains, and other nutrient-dense foods; maintaining a diet high in fiber, low in fat, and low in sodium; avoiding caffeine, spicy foods, and alcohol; eating foods rich in calcium, or taking physician-prescribed calcium supplements and vitamin D. National, state, and local strategies that promote food and nutrition services are essential to maintain independence, functional ability, disease management, and quality at all stages of life. Dietitians, physicians working in the field of nutrition must widen their scope of practice to include prevention, treatment and maintenance of health and quality throughout the human life.