Nutrition in the Lifecycles (PDF)

NUTRITION IN THE LIFECYCLE The human lifecycle ◦ Pregnancy. The development of a zygote into an embryo and then into a foetus in preparation for childbirth. ◦ Infancy. The earliest part of childhood. It is the period from birth through age 1. ◦ Toddler years. Occur during ages 2 and 3 and are the...

NUTRITION IN THE LIFECYCLE The human lifecycle ◦ Pregnancy. The development of a zygote into an embryo and then into a foetus in preparation for childbirth. ◦ Infancy. The earliest part of childhood. It is the period from birth through age 1. ◦ Toddler years. Occur during ages 2 and 3 and are the end of early childhood. ◦ Childhood. Takes place from ages 4 to 8. ◦ Puberty. The period from ages 9 to 13, which is the beginning of adolescence. ◦ Older adolescence. The stage that takes place between ages 14 and 18. ◦ Adulthood. The period from adolescence to the end of life. Begins at age 19. ◦ Middle age. The period of adulthood that stretches from age 31 to 50. ◦ Senior years, or old age. Extends from age 51 until the end of life (some refs: >65) Nutrition in Pregnancy and Lactation ◦ Preconception and Fertility ◦ Conception ◦ Pregnancy ◦ Postpartum Period ◦ Lactation Preconception and Fertility Preparing for a healthy pregnancy Recommendations for both MEN and WOMEN 1. Achieve & maintain healthy body weight 2. Choose adequate & balanced diet 3. Be physically active 4. Receive regular medical care 5. Manage chronic conditions 6. Avoid harmful influences Preparing for a healthy pregnancy Achieve & maintain healthy body weight ◦ Both underweight and overweight are associated with infertility. ◦ Men who are overweight or obese have low sperm counts and hormonal imbalances that reduce fertility ◦ In women, excess body fat disrupts menstrual regularity and ovarian hormone production. ◦ In couples where both partners are obese, it seems to take longer to conceive. ◦ Should a pregnancy occur, mothers, both underweight and overweight, and their newborns face increased risks of complications.  Pregnancy Conception through to birth Growth and development during pregnancy ◦ Placental Development ◦ Foetal Growth & Development ◦ Critical Periods 280 days, 40 weeks, 9 months, 3 trimesters Weeks in each trimester  Placenta ◦ A metabolically active organ that requires energy and nutrients ◦ It produces a number of hormones that maintain pregnancy and prepare the mother’s breasts for lactation ◦ A healthy placenta is essential for the developing foetus to attain its full potential.  Placenta A healthy placenta is the single most important factor in producing a healthy baby. Development of the placenta  Foetal and embryonic development (4 stages) Critical periods in foetal development Critical periods: ◦ Time of intense development and rapid cell division ◦ “Critical” because those cellular activities can occur only at those times. ◦ If cell division and number are limited during a critical period, full recovery is not possible. ◦ Damage during these critical times of pregnancy has permanent consequences for the life and health of the foetus. ◦ The development of each organ and tissue is most vulnerable to adverse influences (such as nutrient deficiencies or toxins) during its own critical period. Critical periods in foetal development ◦ Maternal nutrition before and during pregnancy affects both the mother’s health and the infant’s growth. As the infant develops through its three stages—the zygote, embryo, and fetus—its organs and tissues grow, each on its own schedule. ◦ Times of intense development (critical periods) depend on nutrients to proceed smoothly. ◦ Example Folate(discussed in detail later) - the neural tube fails to develop completely during the first month of pregnancy, prompting recommendations that all women of childbearing age take folate daily. Critical periods Critical periods From 2 - 8 weeks (embryonic), many tissues are in their critical periods. Events occur that will have irreversible effects on the development of those tissues. In the later stages of development, the tissues continue to grow and change, but the events are less critical because they are relatively minor or reversible.  Non nutritional example (not examinable) ◦ Thalidomide (for morning sickness symptoms) first introduced in in West Germany (1957). ◦ Could be bought without a prescription. ◦ Teratogenic - When taken during the first trimester of pregnancy >> horrific birth defects ("thalidomide embryopathy") ◦ Affected thousands of children around the world, many born with limb and other defects. – became known as "Thalidomide babies". Critical period- neural tube development (example) ◦ The neural tube is a structure that becomes the brain and the spinal cord ◦ Critical period of development is from 17 to 30 days of gestation (vulnerable to nutrient deficiencies, excesses or toxins) ◦ Abnormal development of the neural tube or its failure to close completely can cause a major defect in the central nervous system. Most women don’t know that they are pregnant in this early period Development of the neural tube  Types of neural tube defects: Two common types of neural tube defects anencephaly and spina bifida. Anencephaly The upper end of the neural tube fails to close. ◦ Consequently, the brain is either missing or fails to develop. ◦ Pregnancies affected by anencephaly often end in miscarriage ◦ Infants born with anencephaly die shortly after birth.  Types of neural tube defects Spina Bifida ◦ Characterized by incomplete closure of the spinal cord and its bony encasement. ◦ The meninges membranes covering the spinal cord often protrude as a sac, which may rupture and lead to meningitis. ◦ Depending on severity, Spina bifida can be unnoticed, lead to ◦ paralysis, lead to death. ◦ Common problems include clubfoot, dislocated hip, ◦ kidney disorders, curvature of the spine, muscle weakness, ◦ mental impairments, and motor and sensory losses. Spina Bifida Risk factors for neural tube defects ◦ A personal or family history of a neural tube defect ◦ Maternal diabetes or gestational diabetes * ◦ Maternal ethnicity ◦ Maternal use of certain antiseizure meds ◦ Inadequate folate * ◦ Maternal obesity * Folate supplements ◦ Not all cases of neural tube defects can be prevented, but folate supplementation reduces the incidence and severity. ◦ Folate supplements taken 1 month before conception and continued throughout the first trimester can help prevent neural tube defects, and reduce the severity of defects that do occur. Dosage recommendations:- ◦ 0.4 mg/day, either alone or in multivitamin supplement ◦ South African Department of Health : 5mg/day  Food fortification ◦ “Fortification is the practice of deliberately increasing the content of an essential micronutrient, i.e. vitamins and minerals (including trace elements) in a food, so as to improve the nutritional quality of the food supply and provide a public health benefit with minimal risk to health” ◦ Not a “silver bullet” - a preventative measure as part of a wide reaching strategy to address micronutrient deficiencies in the population. ◦ 7th October 2003 South Africa started mandatory fortification with certain micronutrients in - maize meal (four of the now 18 different maize products) - wheat flour (excluding crushed wheat, pearled wheat, semolina, self-raising flour and flour with an ash content > type 2 diabetes may develop in adulthood. ◦ The pancreatic beta cells (insulin production) normally increase > 130-fold between 12 weeks and 5 months after birth. ◦ Nutrition is a primary determinant of beta cell growth, and infants who have suffered prenatal malnutrition have significantly fewer beta cells than well-nourished infants. ◦ They are also more likely to be low-birthweight infants—and low birthweight correlates with insulin resistance later in life. ◦ One hypothesis suggests that diabetes may develop from the interaction of inadequate nutrition early in life (low birthweight) with abundant nutrition later in life (overweight adult): the small mass of beta cells developed in times of undernutrition during fetal development may be insufficient in times of overnutrition during adulthood when the body needs more insulin.  Maternal weight ◦ Critical periods occur throughout pregnancy therefore good care of her health should be continuous. Weight gain/maintenance is important. ◦ Pre-pregnancy: achieving and maintaining a healthy body weight ◦ Pregnancy: Sufficient weight during pregnancy to support a healthy infant.  Maternal weight prior to Conception (underweight) Underweight ◦ Underweight woman (BMI childhood obesity. ◦ Macrosomia can cause difficult labor and delivery, birth trauma, and cesarean delivery. ◦ Doubles the infant’s risk for neural tube defects. ◦ Greater risk of poor health and death. Ideal weight gain during pregnancy (normal and diabetic) Pre-pregnancy weight Recommended TOTAL Recommended rate of status weight gain weight gain/week in 2nd and 3rd trimesters ONLY Underweight 12.5 -18 kg 0.51 (0.44 -0.58)