Chapter 25

nutrients

used to produce energy, provide building blocks, etc.

metabolism

chemical changes that occur within the body

metabolism

anabolism

synthetic rxns; energy-requiring

metabolism

catabolism

breakdown rxns; energy releasing

vitamins

essential for normal metabolism, functions as coenzymes

vitamins

fat-soluble

vit A,D,E,K; cross CM can accumulate in toxic amounts

vitamins

water-soluble

vit C,B complex; ingested excess quickly excreted from the body

minerals

Ca2+

important in bone, muscle contraction, blood clotting, nerve/heart fcn

minerals

Fe

part of Hb

minerals

Na+/K+

osmotic balance; irritability of CM

digestion

mechanical/ chemical breakdown of food into simple nutrients

absorption

nutrients pass through all 4 tunics of gut to reach hepatic portal vessel or lecteals

food pyramid

tier 1- fats, oils, simple sugars

tier 2- dairy products/ meats, eggs, nuts

tier 3- vegetables/ fruit

tier 4- bread, cereal, rice, pasta 

essential nutrients

must be ingested because the body cannot make them

carbohydrates

most common CHOs in diet are glucose & fructose, starch, sucrose, and cellulose (nondigestible, “bulk“, aids in GI motility)

-recommended amts 125-175 g/day; complex rather than simple sugars suggested

-CHO digestion yields 4cal/gm

lipids

~95% in diet are triacylglycerols; saturated and unsaturated fats

~5% are cholesterol (animal product) & phospholipids (lecithin in egg yolks)

-recommended amt <30% of total caloric intake; saturated fats should be no more than 10% of total fat intake 

-keep cholesterol < or equal to 300 mg/day

-cholesterol & saturated fats promote coronary artery disease

-lipid digestion yields 9cal/gm

essential FA

must be ingested, used to synthesize PGs

eg. linoleic acid, EPA (eicosatetraenoic acid)- found in plant oils

proteins

essential aa

9 aa that cannot be synthesized by the body

proteins

nonessential aa

remaining 11 aa, can be made by the body

proteins 

complete proteins 

contains adequate amounts of the 9 essential aa; primarily animal products- milk, meats, egg, cheese

proteins

incomplete proteins 

lack 1 or more of the essential aa; primarily plant products- potential problem for vegetarians 

recommended amount of protein in diet

0.8g/kg body wt, ~ 12% of total calories protein digestion yields 4 cal/g

N balance

amount of N ingested ~ amount of N excreted

children should have positive N balance- N needed for growth, protein synthesis

vitamins

(needed in small amounts)