ch 1 nutrition - Chapter 1 Ecological Perspective...

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Chapter 1 Ecological Perspective Ecology =study of flow of nutrients and energy through the environment Food chain =representation of relationships in natural world Nutrients Essential (necessary to life and the body cannon synthesize itself) 1) Water (more than any other): forms cells, cools us, flushed wastes, disovles substances, provides solvent for chemical reactions 2) Macronutrients : big nutrients needed in large quantities a. Carbohydrate : supply energy; powers movement and nervous activity; Only fuel brain can use i. Simple: sugars; rapidly absorbed ii. Complex: starch and fiber; made of polymers of sugars (chains of simple sugar molecules linked together); slowly absorbed b. Fat (lipid) : supply energy, contains many calories; body stores extra energy as fat, not starch (since it is more energy-dense) c. Protein : makes up dry weight; forms muscle and connective tissue, bone and skin i. Enzymes: most vital chemical regulators 3) Energy : movement, growth, brain function, chemical reactions; unit=calories 4) Micronutrients: needed in tiny amounts a. Vitamins: soluble in either fat or water; organic (contain carbon) b. Minerals: inorganic (no carbon) 5) Non-nutrients a. Phytochemicals: chemicals produced by plants, may be improtant in chronic disease prevention Science of Nutrition Problems of Anecdotal Evidence (personal experience) o Unreliable; different causes; placebo effect; safety risks Scientific Method o Hypothesis: untested working assumption that serves as starting point Experiemental Design o Experiemental group : treatment group o Control group : recieves no treatment o Evaluate outcome : measure being studied (similar outcome = not effective) Experimental Design in Nutrition 1) Case studies: anecdotal evidence published in scientific journal 2) Epidemiological Studies: natural experiment that a population conducts on itself a. Exposure (hypothetical cause of outcome) varies in large enough population b. Correlation: relationship between two associated things (does not prove cause and effect) c. Confounder: confuses study and prevents discovery of true relationship between variables 3) Animal studies 4) Human studies a. More complications than animal studies i. Solved by: randomization, placebo
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Generalizability vs. Control o Generalizability: degree to which finding can apply to other situation or group o Control: only difference between groups is the experimental variable Low- humans, epidemiological High- animals Evolution of the Human Diet Survey of Ancient Diets o Ethnography : study of indigenous human cultural and ethnic groups 1) Hunter-gatherers: hunt animals and gather plants; Diet depends on environment a. Eskimo (Inuit): Arctic- Siberia, Alaska, Canada, Greenland i. Harsh environment=food in short supply; therefore- meat-based diet b.
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