国外的营养学课件3－NUTRITION ACROSS THE LIFE SPAN.ppt

1、1,NUTRITION ACROSS THE LIFE SPAN,Elderly,Adulthood,Adolescence,Pregnancy,Infancy,Childhood,Growth Development Maintenance of health Prevention of disease Treatment of disease Slowing down of aging process,Role of Diet for human beings, gestation lasts from 38 - 42 weeks & is commonly divided into th

2、ree periods called trimesters gestational age = stage of foetal growth & development at birth, varying from a premature delivery to full term or post term trimester = three 13-14 week periods into which normal pregnancy of 38-42 weeks is divided arbitrarily for purposes of discussion and analysis cr

3、itical periods = finite periods during development in which certain events may occur that will have irreversible effects on later developmental stages,7,Physical Changes during Pregnancy,Cessation of monthly menstruation Abdomen protruding Breasts enlarge Weight gain Common swelling (edema), especia

4、lly in the legs need to urinate more often and more urgently nausea and vomiting, particularly in the mornings (morning sickness), heartburn constipation backache in varying degrees,8,Physiological Changes during Pregnancy,Endocrine Body composition Blood volume & composition Metabolism Cardiovascul

5、ar Respiration Kidney Gastrointestinal,Why do these changes occur? to regulate maternal /fetal metabolism & waste removal to promote foetal growth (supply nutrients & oxygen ) to prepare mother for labour & lactation,9,1) Endocrine,The placenta forms large quantities of Human chorionic gonadotropin

6、prevent degeneration of corpus luteum, causes it to secrete large amounts of estrogen & progesterone. Effects prevent menstruation, endometrium grows and stores large amounts of nutrients Estrogen enlargement of uterus, enlargement of breast & growth of breast ductal structure, relaxes pelvic ligame

7、nts easier passage of fetus through birth canal Progesterone development of uterine endometrium, prevent uterine contractions, helps estrogen prepare breast for lactation Human chorionic somatomammotropin decrease utilization of glucose by mother (make large quantities available to fetus), release f

8、ree fatty acids from maternal fat stores,10,An average weight gain of 12.5 kg in a typical 40 week pregnancy amounts to approximately 20% increase in body weight Most weight gain occurs in the last 20 weeks of pregnancy 40% weight gain fetus, placenta, amniotic fluid 60% maternal (6-8 kg) increased

9、fluid volume, protein deposition and fat stores (due to increased mammary, uterine, kidney, heart tissue volume, increase in total fluid volume and body fat). About 1/3 of weight gain (3-6 kg) is fat,2) Body Composition,11,45-50% increase in blood volume (hypervolemia) Needed to provide for extra bl

10、ood flow to the uterus, extra metabolic needs of the fetus, increased perfusion of other organs esp kidneys Smaller increase in other blood components (e.g. RBC, blood proteins, lipids, enzymes) compared to increase in plasma volume hemodilution “physiologic anaemia of pregnancy” Iron supplementatio

11、n modifies but does not obliterate the usual fall in Hb and Hct Erythropoiesis (production of RBC in the marrows) need more dietary iron, micronutrients (e.g. folate, zinc),3) Blood Volume & Composition,12,4) Metabolic, BMR 15% in later half of pregnancy. Mother frequently has sensations of becoming

12、 overheated Due to tissues actively synthesised in the foetus and associated supportive structures Due to extra load, greater amounts of energy is expended during muscle activity Major source of fuel for maternal tissue : FAT Major source of fetal energy : GLUCOSE Thus, Maternal fat use to free gluc

13、ose for foetus Maternal lipolysis during 3rd trimester Maternal glucose levels fall as foetal demands ,13,5) Cardiovascular,Cardiac output due to increased stroke volume & heart rate : to meet oxygen demand Peripheral resistance declines blood flow increases to the uterus, placenta, kidney. Little c

14、hange in systolic BP, diastolic pressure declines,6) Respiratory,Increase in basal metabolic rate, increase in body size : maternal O2 requirements (about 20% above nonpregnant levels) As growing fetus presses against the diaphragm, expansion of diaphragm is decreased increased respiratory rate to m

15、aintain adequate ventilation Oxygen-carrying capacity of blood increases,14,7) Renal,Blood flow through kidney to facilitate clearance of waste products resulting from fetal & maternal metabolism Glomerular filtration rate about 50% causes tubules to be exposed with greater quantities of nutrients t

16、han can be reabsorbed (proteinuria & glycosuria & loss of some water-soluble vitamins) Increased production of hormones by placenta enhances reabsorption of sodium, chloride and water Enlarging uterus presses against urinary bladder increased urinary frequency,15,8) Gastrointestinal,Appetite partly

17、as a result of removal of food substrates from the mothers blood and partly hormonal. Nausea & vomiting may occur. Sense of taste altered GI motility diminished (slowed gastric emptying and transit of food) leading to : heartburn also due to relaxation of lower esophageal sphincter & elevation of st

18、omach by enlarging uterus constipation due to increased water absorption from colon & pressure of enlarging uterus on the bowel. Reduced physical activity may also contribute haemorrhoids absorption of nutrients enhanced,16,Nutritional Requirements in Pregnancy,There is increased need for energy and

19、 nutrients to support growth of the fetus, placenta and maternal tissue. Physiologic changes that cause hemodilution causes changes in nutrient turnover and homeostasis that affects requirements. Fetal demands occurs primarily during the second half of pregnancy when more than 90% of growth occurs.,

20、17,Energy Needs,1st trimester additional energy requirement is small 2nd / 3rd trimester + 200 - 300 kcal/day Pregnant teenagers, underweight women, physically active women need more Increased energy due to 25% increase in basal energy requirements (growth of fetus, accessory tissues, maternal suppo

21、rting tissues) and increased requirement by mother due to her increased weight,18,as energy requirement increases the need for thiamin, niacin & riboflavin increase proportionally they are coenzymes in reactions that releases energy from CHO, protein and fat,Energy & Related Nutrient Needs,19,Protei

22、n essential for: synthesis of fetal & placental protein increased maternal protein synthesis to support expansion of blood volume & growth of breasts & uterus Vitamin B6 (pyridoxine) required for protein synthesis, therefore increase requirement during pregnancy CHO & fats help make up calories, spa

23、re protein,Macronutrient Needs,20,EFA linoleic (C18, 6) found in vegetable oils and alpha-linolenic acid (C18, 3) found mainly in fish and seed oils. These parent fatty acids can be further elongated and desaturated to DHA, EPA (3) AA (6) These fatty acids are precursors of prostaglandins (important

24、 physiological functions) and structural elements of cell membranes. Needed for brain growth, eye and optimal central nervous system development. DHA (v high demand in pregnancy), AA important structural fatty acids in neural tissue Throughout gestation, accretion of maternal, placental and fetal ti

25、ssue occurs requirements are higher, especially in the 3rd trimester with rapid synthesis of brain tissue. Brain is 60% fat, in 3 and 6 derivatives which the fetus/infant draws from the mother during pregnancy and lactation,Macronutrient Needs,21,Vitamins & minerals for bone/skeletal health/developm

26、ent,Vitamin & Mineral Needs,Calcium, phosphorus and magnesium are accumulated by the fetus in large quantities, esp in the last trimester, to support the formation of teeth, bones & skeleton CALCIUM To meet requirements, maternal calcium absorption If maternal Ca intake is inadequate, the fetus obta

27、ins calcium from mobilization of calcium from maternal skeletal stores,22,CALCIUM The demands of the fetus is met at the expense of the mother risk of osteoporosis later on in life Adequate level important for maintaining the bone integrity of a pregnant woman and providing for the skeletal developm

28、ent of the fetus Growing fetus needs calcium for normal heart rhythm, blood clotting, nerve, heart, muscle development PHOSPHORUS necessary for all cell growth & healthy muscle function,Vitamin & Mineral Needs,Vitamins & minerals for bone/skeletal health/development,23,VITAMIN D increases absorption

29、 of calcium promote deposition of calcium in growing fetus vegans, women with little sunlight exposure or those who avoid milk need more FLOURIDE mineralisation of babys teeth,Vitamin & Mineral Needs,Vitamins & minerals for bone/skeletal health/development,24,Vitamins & minerals for blood production

30、 & cell growth,Folate & Vit B12 required for cell division & synthesis of DNA and RNA increased amounts Folate important during first few days & weeks of pregnancy when cell division is occurring very rapidly (hyperplasia) to prevent occurrence of neural tube defects Iron needed for manufacture of H

31、b in maternal and fetal RBC to support fetus developing blood supply, mothers increased blood supply, developing blood vessels in placenta,Vitamin & Mineral Needs,25,IRON The fetus accumulates most of its iron during the last trimester. It ensures its own requirement is met by drawing from maternal

32、stores. At birth, the iron stores of the fetus represents about 1/3 of total body iron. This store is meant to meet its needs for 3-6 months after birth. Maternal iron deficiency will not cause an anemic infant. BUT an anemic mother may feel lethargic, find it harder for her body to fight infection,

33、 is more likely to have problems if she loses a lot of blood during delivery is at a higher risk for having a preterm delivery or a low-birthweight baby may affect her babys iron stores at birth, increasing his risk for anemia later in infancy The most common cause of iron deficiency in infants is p

34、rematurity shorter gestation: not enough time to build up iron stores,Vitamin & Mineral Needs,Vitamins & minerals for blood production & cell growth,26,IRON Fe needs roughly doubles during pregnancy but Singapore RDDA does not change: same 19 mg/d. Why? blood losses due to menstruation ceased during

35、 pregnancy body conserves iron very well improved iron absorption (US RDA females 19-50: 18 mg/day. For pregnancy 27mg/day) Most women enter pregnancy with low Fe stores so supplements are often recommended ZINC Linked to DNA & RNA synthesis, facilitate cell division Maternal deficiency could influe

36、nce critical events during fetal development teratogenic effect,Vitamin & Mineral Needs,Vitamins & minerals for blood production & cell growth,27,Other vitamins & minerals,VITAMIN A important role in visual function & other basic physiologic processes (growth, reproduction, immunity, epithelial tiss

37、ue maintenance) is essential throughout the entire life span, yet particularly critical during periods when cells proliferate rapidly and differentiate, such as during pregnancy and early childhood,Vitamin & Mineral Needs,28,Other vitamins & minerals,VITAMIN A Vitamin A is highly teratogenic in preg

38、nancy, especially in the first 8 weeks with daily intake more than 10,000 IU (3000 mcg RE) Beta-carotene (provitamin A) is converted to retinol but has not been shown to be teratogenic VITAMIN C essential for the formation, growth and repair of bone, skin and connective tissue, maintain healthy teet

39、h & gums absorption of non-heme iron an antioxidant -protects cells against damage by free radicals,Vitamin & Mineral Needs,29,Other vitamins & minerals,VITAMIN E contributes to the health of new cells developing in the fetus mothers pass vitamin E to their fetus in the last 12 weeks of pregnancy -

40、some very premature babies show signs of deficiency soon after birth if they are born before this transfer is able to take place. This can lead to haemolytic anemia, where their RBC break down and cause anemia Antioxidant IODINE increased requirement due to the transfer of thyroxine (T4) and of iodi

41、de from mother to fetus during pregnancy to ensure normal brain development and prevention of mental retardation in the fetus,Vitamin & Mineral Needs,30,Critical Periods,Critical periods = finite periods during development in which certain events may occur that will have irreversible effects on late

42、r developmental stages A critical period is usually a period of rapid cell division i.e. embryonic/fetal development Neural Tube Defects & Folate Supplements The neural tube is the embryos precursor to the CNS. About 20- 28 days after conception, the neural tube closes to form the brain and the spin

43、al cord. If this tube fails to close, a NTD occurs Folic acid plays an essential role in cellular division. It is also needed for the proper closure of the neural tube NTDs occur between the 20 - 28th day after conception, before most women know that they are pregnant. Because about half of all preg

44、nancies are unplanned, it is important to include at least 400 mcg of folic acid in every childbearing age womans diet. (US RDA),Vulnerable Periods of Foetal Development,31,Critical periods occur early in development. An adverse influence occuring early can have a much more severe & prolonged impact

45、 than one occurring later on.,Critical Periods,32,Teratogen,Teratogen = any substance, agent or process that induces the formation of developmental abnormalities in a fetus e.g. Thalidomide, alcohol, German measles, cytomegalovirus, irradiation with X-rays, ionising radiation,1957 to 1962 in UK, Can

46、ada, Germany, Japan - not FDA approved prevented morning sickness 12,000 babies who survived, with phocomelia (flipper-like arms or legs),33,Assessing Nutritional Status In Pregnancy,ANTHROPOMETRIC MEASUREMENTS weight, height, BMI, fatfolds, waist circumference? BIOCHEMICAL PARAMETERS blood test, ur

47、ine test levels of vitamins, minerals, protein? CLINICAL ASSESSMENT skin, glands, muscle, bones & joints, cardiovascular, gastrointestinal, nervous system? DIETARY INTAKE 24 hr recall, dietary history, food records, FFQ?,34,Maternal Weight & Weight Gain,Optimal pregnancy outcome (appropriate infant

48、birth weight and well being of both infant & mother) reflects an interaction between gestational weight gain and the pregravid weight status of the mother Underweight mothers inadequate nutrient reserves to support the critical period of organogenesis & continued fetal growth & development high risk

49、 of birth defects, growth restriction (SGA), preterm, foetal & neonatal mortality, maternal complications like antepartum hemorrhage, premature rupture of the membranes & anemia Solution: gain sufficient wt pre-conception & extra wt during pregnancy,Assessing Nutritional Status In Pregnancy,35,Mater

50、nal Weight & Weight Gain,Overweight mother high risk of medical complications (pregnancy induced hypertension, diabetes mellitus, thromboembolic disease), complicated delivery, post-term birth, late foetal deaths, poor developments in infants Solution: achieve healthy weight pre-pregnancy & avoid ex

51、cessive weight gain during pregnancy. Postpone weight loss until after childbirth,Assessing Nutritional Status In Pregnancy,36,Maternal Weight & Weight Gain,Mothers underweight before pregnancy had the lowest perinatal mortality when they gained at least 16 kg while obese women had the lowest perina

52、tal mortality when they gained only 7 kg,Assessing Nutritional Status In Pregnancy,Mitchell (2003). Nutrition Across the Lifespan. Saunders,37,Maternal Weight & Weight Gain,Assessing Nutritional Status In Pregnancy,Taken from Eating for a Healthy Baby Food & Nutrition Department, MOH, 1997,38,Inadeq

53、uate gestational weight gain indicator of the inadequacy of the maternal diet All pregnant women must gain weight Low weight gains especially in underweight women associated with increased risk of perinatal mortality and fetal growth restriction. High weight gains especially in obese women associate

54、d with increased birth weight and greater likelihood of prolonged labour, complicated delivery, birth trauma, asphyxia Energy restriction is potentially harmful Restriction of fat pad development can be detrimental Diets low in energy are likely to be inadequate for other nutrients as well,Assessing

55、 Nutritional Status In Pregnancy,Maternal Weight & Weight Gain,39,Quality of Weight Gain,Components of weight gain during pregnancy 64%: maternal tissue & fluid accumulation 25%:foetus 5%: placenta 6%: amniotic fluid wt gain should be the result of a high-quality diet gradual & consistent gains in w

56、eight throughout pregnancy foods consumed should be nutritious (not contributing only “empty calories”),Assessing Nutritional Status In Pregnancy,40,Special Nutritional Requirements Prior To Pregnancy,To provide a most suitable environment for the fetus to develop in, a woman must establish healthfu

57、l habits physically, mentally, psychologically.maintain healthy body weight - not be under/overweight, choose diet adequate in nutrients, be physically active, avoid harmful environmental factors. Severe undernutrition superimposed on previous marginal nutrition : low fertility rates & if conception

58、 occurs birth defects, preterm births & neonatal deaths Undernutrition that occurs later part of pregnancy less likely to result in birth defects but causes fetal growth restriction & LBW,Good nutritional status before pregnancy is important for successful outcome.,41,Malnutrition & Foetal Growth &

59、Development,After fertilisation: zygote stage (0 - 2 wks) embryonic stage (2 - 8 wks): Hyperplasia (in cell no) fetal stage (8 - 38/42 wks): Hyperplasia & hypertrophy ( in cell size) Effects of malnutrition depends on the stage of gestation & also duration Malnutrition early in gestation : teratogenic effects during organogenesis e.g. folate with NTDs Malnutrition in last trimester : not teratogenic but restrictions can have serious effects as the fetus gains 2/3 of its full term weight in 3rd