BIOS 5445: Human Ecology Dr. Stephen Malcolm, Department of Biological Sciences

Transcription

1 BIOS 5445: Human Ecology Dr. Stephen Malcolm, Department of Biological Sciences Lecture 7. Mortality - Malnutrition: Lecture summary: Nutritional problems: Malnutrition. Proteins & Calories. Effects. Vitamin deficiencies. Mineral deficiencies. American Gothic by Grant Wood, 1930 Lecture 7: Slide - 1

2 2. Malnutrition: Any type of poor nutrition: Undernutrition. Overnutrition (lecture 8). Improper nutrient balance. Based on failures of behavior & culture: Economic & sociopolitical problems. We can feed everyone a balanced diet: Nevertheless malnutrition is common. Problems of food distribution. Lecture 7: Slide - 2

3 3. Protein-Calorie malnutrition: Deficiency in energy (kcal) content of food. Total starvation. Undernutrition Sufficient caloric content & insufficient protein: Protein deficiency: Necessary for growth, reproduction & daily survival. 20 amino acids:» 8 essential dietary amino acids + 12 can be synthesized.» Essentials must occur in sufficient proportions.» Protein quality represents amino acid match to required ratios. Lecture 7: Slide - 3

4 4. Protein content of food (Fig. 9-1) - balanced Mesoamerican diet: beans balance isoleucine & lysine deficiencies of maize & vice versa for methionine & cystine. Lecture 7: Slide - 4

5 5. Protein deficiency in children: Combination of: Weaning from breast milk. Rapid growth rate up to age 5. Single plant food rich in carbohydrate & low in protein. Parasitic infections that exploit protein. Kwashiorkor: In Ga language means disease that occurs when displaced from the breast by another child. Protein deficiency reduces immune system function leading to infection. Distended stomach from loss of abdominal muscle tone due to muscle breakdown as protein source. Lecture 7: Slide - 5

6 6. The Cori Cycle (Fig. 9-3) conserves glucose driven by energy from fat metabolism: Energy reserves: Fat = long-term storage: US = 15 kg = 135,000 kcal = 70 days energy/person Glycogen = short-term storage, maintains sugar homeostasis: Glycogenesis: Blood sugar high > hormone insulin secreted:» Glucose > glycogen Glycogenolysis: Blood sugar low > hormone glucogon secreted:» Glycogen > glucose Lecture 7: Slide - 6

7 7. Effects of protein-calorie malnutrition: Loss of body weight: Body fat and body protein (skeletal muscle). Physical work capacity declines. Child birth: Labor can be extended by 5 hours & increase health risks. Can reduce lactation and food availability for infants. Behavioral/psychological effects: Apathy & inactivity (also help to conserve energy). Marasmus: Children combine muscle depletion of kwashiorkor (protein malnutrition) with loss of body fat & cessation of growth. Vomiting & diarrhea common, leading to dehydration. Weakened immune system & disease susceptibility. Lecture 7: Slide - 7

8 8. Vitamin deficiencies: Vitamin A (retinol): In green & yellow vegetables & dairy products. Needed for epithelial cell function (including vision). Vitamin B 1 (thiamine): In most foods - deficient in rice. Needed for carbohydrate metabolism. Severe deficiency results in beriberi disease Vitamin B 3 (niacin): Low in maize (corn). Deficiency disease is pellagra. Lecture 7: Slide - 8

9 9. Vitamin deficiencies (continued): Vitamin C (ascorbic acid): Occurs in fresh fruits & vegetables. Hominoids, 1 bat & guinea pigs cannot synthesize vitamin C. Required for collagen synthesis Deficiency results in poor wound healing & hemorrhaging - scurvy: Constrained sea voyages. British sailors ( limeys ) given lime juice. Lecture 7: Slide - 9

10 10. Vitamin deficiencies (continued): Vitamin D: Eggs, dairy products & synthesized from dietary steroids. Needed for calcium absorption and use. Deficiency leads to rickets in children & osteomalacia in adults. Can be exacerbated by clothing traditions & taboos. Requires UV radiation from sunlight in skin cells. Facilitated by light colored skin: Northern adaptation to enhance synthesis?» But more prone to skin cancer from UV exposure.» Gloger s Rule - skin color lightens with increasing latitude. Dark skin may prevent too much vitamin D. Lecture 7: Slide - 10

11 11. Mineral deficiencies: Iron: Highly prevalent - anemia from lack of iron in hemoglobin. Results in lowered work capacity & lowered intellectual ability. Iodine: In seafood, vegetables & dairy products. Required for thyroid hormones. Deficiency leads to goiter & hypothyroidism or myxedema and cretinism in children: Highest prevalence in mountain people (Alps, Andes & New Guinea). Calcium: Linked to vitamin D. High in dairy products & dark green leafy vegetables. Deficiency can lead to osteoporosis or pibloktok in some Inuits. Lecture 7: Slide - 11

12 12. Adaptation and malnutrition: Nutrients are required chemicals: Carbohydrates, lipids, protein, vitamins & minerals. Food is cultural: Regional variation in preference can shift with cultural change. Predict links between physiological nutritional requirements and cultural behaviors. But these links are not always adaptive. Lecture 7: Slide - 12

13 13. References: Kormondy, E.J., & D.E. Brown Fundamentals of human ecology. Prentice Hall. 503 pp. (chapter 9). Lecture 6: Slide - 13