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Requirements at Different Life Stages
Primates require a wide variety of essential nutrients, which are biochemical elements that cannot be manufactured within the body and must be acquired via the diet. Humans require about 50 essential nutrients, in six classes (see MOCA23.05 Food components). At present it is believed that all anthropoid primate species have the same essential nutrient requirements. Energy and nutrient needs at different life stages are related, in general, to changes in rates of growth (higher per unit body weight during faster growth such as human infancy, adolescence, and pregnancy). Prior to birth, the maternal diet and body stores supply all nutrients. During infancy, lactation supplies all requirements and Primate milk composition is broadly similar across species. Age at weaning is highly variable across primate species. Many primate species introduce various transitional foods into the infant’s diet while still nursing. Human beings do so at about age 6 months, when the infant’s body size and rate of growth requires additional energy to be sustained. Human infants are also fed complementary foods, which are highly processed and nutrient-rich foods supplied by older members of the social group. It is hypothesized that the human use of complementary foods is unique among primates. In traditional societies, human infants are weaned (termination of lactation), on average, at 30-36 months and then enter the childhood stage of life history (see MOCA ??.?? Childhood). Children require continued provisioning of food; complementary foods at first and family foods by the end of the stage (about age 6.9 years). Human infants and children may require additional intake of omega-3 fatty acids, such as docosahexaenoic acid (DHA), to support the rapid growth of the brain and central nervous system. The onset of the human juvenile stage (about age 7.0 years) is marked by the ability to acquire, process, chew and digest many family foods. But, human juveniles and adolescents, still depend on the provision and sharing of food to achieve nutritional balance. This is because many years of learning and practice are required to produce some foods and cultural rules limit or prohibit people of certain age, sex, or social statuses from certain food producing activities. The human adolescent stage begins with puberty and ends with the completion of growth in stature. Most boys and girls experience an adolescent growth spurt in the rate of skeletal growth and this increases the need for energy and most nutrients, relative to total body mass. Girls begin to menstruate during adolescence and by adulthood (~ 18 years) have monthly cycles. The loss of blood from copious menstruation, which is not found in most other primates, requires additional intake of iron until the cycles end, usually in the 5th decade of life. Adults in their prime reproductive years need energy and nutrient intakes at levels to replace losses from work and illness. Nutrient regimes for older adults, and younger adults trying to delay senescence, are active areas of research and medical quackery. There are no proven additional nutrients requirements for adults of any age that will delay senescence.
References: Sellen DW (2007) Evolution of infant and young child feeding: implications for
contemporary public health. Annu. Rev. Nutr. 2007. 27:123–48.
new life history stages of childhood and adolescence
universal in all human populations