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BIOS 5445: Human Ecology Dr. S. Malcolm Lecture 7: Slide - 1
• Lecture 7. Mortality - Malnutrition:
– Lecture summary: • Nutritional problems:
– Malnutrition. – Proteins & Calories. – Effects.
• Vitamin deficiencies. • Mineral deficiencies.
BIOS 5445: Human Ecology Dr. Stephen Malcolm, Department of Biological Sciences
American Gothic by Grant Wood, 1930
BIOS 5445: Human Ecology Dr. S. Malcolm Lecture 7: Slide - 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.
BIOS 5445: Human Ecology Dr. S. Malcolm Lecture 7: Slide - 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.
BIOS 5445: Human Ecology Dr. S. Malcolm Lecture 7: Slide - 4
4. Protein content of food (Fig. 9-1) - balanced Mesoamerican diet: beans balance isoleucine & lysine deficiencies of maize & vice versa for methionine & cystine.
BIOS 5445: Human Ecology Dr. S. Malcolm Lecture 7: Slide - 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. http://www.nlm.nih.gov/medlineplus/ency/imagepages/9563.htm
BIOS 5445: Human Ecology Dr. S. Malcolm Lecture 7: Slide - 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
BIOS 5445: Human Ecology Dr. S. Malcolm Lecture 7: Slide - 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.
BIOS 5445: Human Ecology Dr. S. Malcolm Lecture 7: Slide - 8
8. Vitamin deficiencies:
• Vitamin A (retinol): – In green & yellow vegetables & dairy products. – Needed for epithelial cell function (including vision).
• Vitamin B1 (thiamine): – In most foods - deficient in rice. – Needed for carbohydrate metabolism. – Severe deficiency results in beriberi disease
• Vitamin B3 (niacin): – Low in maize (corn). – Deficiency disease is pellagra.
BIOS 5445: Human Ecology Dr. S. Malcolm Lecture 7: Slide - 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.
BIOS 5445: Human Ecology Dr. S. Malcolm Lecture 7: Slide - 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.
BIOS 5445: Human Ecology Dr. S. Malcolm Lecture 7: Slide - 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.
BIOS 5445: Human Ecology Dr. S. Malcolm Lecture 7: Slide - 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.
BIOS 5445: Human Ecology Dr. S. Malcolm Lecture 6: Slide - 13
13. References: • Kormondy, E.J., & D.E. Brown. 1998. Fundamentals of human
ecology. Prentice Hall. 503 pp. (chapter 9).
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