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  1. Today & next few lectures • Look through & selectively read from the “hunger/nutrition issues” links on Blackboard • Today • Biology of human nutrition • Traditional diets & protein-calorie nutrition • Vitamins, minerals, & deficiency diseases • Synergies between nutrition & disease • Next week • Malnutrition & hunger • The Entitlement concept • Causes of hunger – the Irish famine example • Nutrition transition

  2. Nutrition and Hunger • Biology of Nutrition • Active adults and growing children need most food/body weight • But, small children, infants, and the aged are most at risk to severe consequences of nutritional problems • Nutritional needs • Energy: commonly measured in kilocalories (kcal) or what we usually call “calories” • Protein: variable in “quality” for human use

  3. Energy • Body “burns” carbohydrates, fats, and sugars for the energy to live • Proteins also can be converted by the liver to sugars for energy if necessary, but not vice versa (not very efficient) • Calories in excess of need => storage as fat

  4. Severely Insufficient Nutrition • Calorie or protein-calorie malnutrition • Severe forms of this in infants especially can lead to marasmus • Body breaks down lean muscle and tissue to produce calories • Severe protein malnutrition can lead to kwashiorkor

  5. Marasmus • Stick-like limbs, bloated belly, wide eyes: • From Greek “to waste away” • Lacking calories (as well as protein), children may weight less than half of normal • Brings diarrhea, apathy, and brain damage • Bloated look as fluids are accumulated to push against wasted muscles.

  6. Kwashiorkor • Severe protein deficiency • Bloated body • Fluids stuffed in cells against wasted muscles • Results in diarrhea, apathy, brain damage

  7. Protein • There are 22 amino acids needed to create the thousands of proteins humans need to create: e.g., blood, hormones, hair, muscle, antibodies, etc. • We make all the amino acids needed except for 9 that must be in foods: • leucine, valine, tryptophan, phenylaline, isoleucine, threonine, lysine, cystine, and methionine • Foods vary in their composition of these so vary in “quality” of protein (% protein that is usable) • Foods also vary in total quantity of protein per gram

  8. “Quality” of protein I • Animal foods: • Quality is relatively high • e.g., eggs = 98%; milk = 80%; fish = 80%; meat = 70% • Quantity is relatively high as well • Grains: • Quality is relatively high • e.g., rice, wheat, oats = 70%; millet, rye = 55-60% • Quantity is relatively low • ~ 10-15% by weight is protein

  9. “Quality” of protein II • Legumes (pulses): • Quality is so-so – usually deficient on one or more of the 9 amino acids • e.g., soy beans = 60%; lima beans = 50%; lentils = 30% • Quantity is relatively high • Other vegetables • Quality is so-so to poor • Quantity frequently low also

  10. Traditional diets I • Traditional Mesoamerican bean burrito • Beans • Short of methionine, cystine • Lots of lots of lysine, tryptophan, isoleucine • Corn (maize) • Short of tryptophan & lysine (OK otherwise) • So the beans balance the shortage of tryptophan and lysine in the corn making the overall protein quality very good

  11. Traditional diets II • Hamburger & wheat bun • Wheat • Short of lysine • Lots of methionine, tryptophan, isoleucine • Beef • Lots of lysine • So the two balance each other out • Rice and Soy • Rice is short on lysine so mixed with most beans => good • Soybeans have lots of lysine and tryptophan so good with rice

  12. Vitamins & minerals • Chronic shortages may not show obvious effects but at the biochemical level there are problems • Variety in diet best solution • Shortages can be precipitated by some diseases (e.g., parasites such as hook worm, malaria, etc.)

  13. Historical acute deficiency diseases • Beri-beri: thiamine (vitamin B1) • Found in rice eating pops in Asia • More varied diet => not a major problem now • Common vegetable sources are various legumes and whole grains -- polished (white) rice is deficient • Pellagra: niacin (vitamin B3) • In populations who consume maize or sorghum as main foods since both are low • Not in Mesoamerica, however, because of the treatment of maize (nixtamalization) => increases niacin and beans have it as well

  14. Historical acute deficiency diseases • Scurvy: vitamin C • Formerly a major problem for sea-going navies and explorers • Early 19th C British Navy solution – eating limes => Brits commonly called “Limeys” • Sauerkraut also works fine! • Periodically a problem in refugee pops who don't get enough fresh fruits and vegetables • Rickets: vitamin D • Lack of sufficient sunlight in winter

  15. Contemporary acute deficiency diseases: Iron • Iron deficiency: • Most common single nutrient deficiency in the world • > 1/3 of pop in many developing countries • Reduces cognitive performance, energy and work ability, and resistance to infection (especially to diarrheal and respiratory diseases) even in mild cases • Severe forms = anemia

  16. Contemporary acute deficiency diseases: Iodine • Iodine deficiency: • Iodine is lacking in soils from some mountain areas and in domr highly leached soils • e,.g., Andes, Himalayas, C Africa, SE Asia... • Major consequences: • Swelling of thyroid (goiter) • Important mental deficiencies (cretinism) in kids if deficient in pregnant women

  17. Contemporary acute deficiency diseases: Vitamin A • Vitamin A deficiency: • Major consequences • To vision can lead to blindness • Also decreased immune function • Kids with severe protein-calorie malnutrition often have impaired sight as a result of this

  18. Synergy: nutrition and disease • Poor nutrition (protein-calorie or other nutrient shortages) => reduced ability to fend off new infections or makes existing ones more severe • Diseases interfere with nutrient absorption and/or actively deplete nutrients from our bodies

  19. How poor nutrition => disease • Reduction in the body's innate immunities (that react to general patterns of proteins in pathogens) • Less effective phagocytosis (process by which microorganisms are engulfed and encapsulated) • Weakened epithelial barriers (protective coverings on body surfaces inside and out) • Lowered lysozyme production (a bodily protein that functions as an antibacterial)

  20. How poor nutrition => disease II • Reduction in ability to generate acquired immunities - the specific immunities one acquires to a particular disease pathogen • Reduced production of humoral antibodies • Impaired cell-mediated immunity

  21. How disease => poor nutrition • Most infections interfere with the body's ability to absorb nutrition and/or actively deplete nutrients • Reduced appetite • Poorer quality of diet ingested • Diseases deplete bodily tissue • Fevers => increased metabolic rate thus, the body needs more kcal but they may not be there

  22. Special case of GI tract diseases • 1.8 billion cases/yr of infant/weanling GI diseases • Predominantly diarrheas, but also intestinal parasites, cholera, & various types of dysentery • Impede absorption of nutrients (diarrheas just don't let food sit in gut long enough)

  23. Special case of GI tract diseases II • Many if not most deaths (perhaps 1 million/ yr in the world) can be averted with adequate treatment (called Oral Rehydration Therapy) • According to The Lancet (1978), ORT is "potentially the most important medical discovery of the 20th century" • Clean water with 60 cent packets of salts/sugars to recover health • Full recovery => increased nutrition above basic levels – often hard to get

  24. Oral Rehydration Therapy (packet for addition to water) Oral Rehydration Therapy (home made)

  25. Especially vulnerable populations I • Increased likelihood of malnutrition and more serious consequences • Women in general due to cultural traditions that privilege food to males • Pregnant women • Poor nutrition => low birth weight babies • Developmental problems for baby physically and mentally • Reduced resistance to diseases • Less able to breast feed (=> less resistance for the baby as well)

  26. Especially vulnerable populations II • Lactating women • Poor nutrition seldom greatly interferes with ability to produce milk • But, poor nutrition does deplete the mother's body of necessary nutrients • If nutrition is not better between end of lactation and next pregnancy => spiral down to chronic anemia etc. • Elderly • Ability to fend off infections is reduced with great age and malnutrition hurts that as well

  27. Especially vulnerable populations III • Children • Malnutrition in infants and children very problematic if timing coincides with critical growth processes • Up to age 5 risk is greatest • Especially at weaning age (approx 2 yrs) • Due to impure water used to make weaning foods (not sufficiently boiled due to lack of fuel) and general low hygiene => • Kids die from diarrheal diseases and dehydration and malnutrition • Weaning foods are typically not nutrient-rich enough (e.g., maize gruels)

  28. Four Faces of Hunger I • I. Starvation/Famine • Widespread to complete lack of protein/calorie nutrition • A small percentage of global hunger – perhaps 1% at risk annually • Leads to increased mortality (usually to infectious diseases not starvation per se) • Great social disruption => increased problems with diseases and access to food • In any famine not all starve – the well off can buy food -- thus NOT usually only a simple shortage

  29. Four Faces of Hunger II • II. Malnutrition/Undernutrition • Seasonal or periodic P/C under-nutrition • Most serious effects on kids and special needs adults (pregnant and lactating women, the elderly) • measures of malnutrition in children • Stunting - stature too short for age/sex (adjusted for local norms) => chronic • Wasting – weight too light for age/sex (adjusted for local norms) => acute

  30. Four Faces of Hunger III • III. Micro-nutrient deficiencies • Vitamin and mineral shortages • Sometimes called “hidden hunger” • IV. Nutrition-depleting illnesses • Secondary malnutrition • Most common nutrient depleting diseases are infant/weanling diarrheas – 5 million deaths annually world wide

  31. Global Hunger • Global situation late 1990s • Data drawn from FAO’s SOFA report 2002 • http://www.fao.org/DOCREP/004/y6000e/y6000e00.htm • The International Food Policy Research Institute: • http://www.ifpri.org/pubs/fpr/fpr24.pdf • The concept of “food security”

  32. Global Trajectories of Hunger I • Proportions undernourished (or food insecure) • Late 1970s ~ 28% • Late 1990s ~17% • Thus, real progress • Less progress in absolute numbers • Micro-nutrient deficiencies • Iron: 40% of global south • Iodine: 12% of global south • Vitamin A: 14% of kids in global south

  33. Global Trajectories of Hunger II • Absolute numbers undernourished (or food insecure) • 1970s ~ 900m; 2000 ~ > 800 m • => decrease of ~ 100m in absolute numbers (but smaller %) • Children 1993 ~ 200 m; now ~ 175 m • World food summit target in 2015 => 400m • Current trajectory => 475-500m by 2015

  34. Regional differences malnourished or food insecure • Global South • Sub-Saharan Africa • E. Asia, SE Asia, & Pacific • South Asia • Latin America & Caribbean • Near East & N. Africa • Developed Economies (mostly N America)

  35. Countries with food shortfalls – requiring assistance

  36. Source: FAO

  37. Source: FAO

  38. Source: FAO

  39. Number of malnourished children, 1993, 2010, and 2020 Source: IFPRI IMPACT simulations.