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).