Macronutrients Flashcards
Macro vs micronutrients
. Macros: carbs, fat, protein
. Micro: vitamins and minerals
Dietary reference intake
. Establish upper limits on consumption of some nutrients and incorporate role of nutrients in lifelong health going beyond diseases
. Estimated average requirement (median of distribution)
. Recommended dietary allowance (RDA) is requirements for highest end of distribution
. Adequate intake (AI)
. Tolerable upper intake level (UL)
Daily values
. Include daily reference values (DRV) and reference daily intakes (RDI)
. DRV: energy producing nutrients based on the number of calories consumed per day (2,000 calories reference)
Energy requirements for person
. Accounts for resting metabolic rate, food intake effect, and physical activity
Total energy expenditure
. Number of kilocalories expended by essential energy uses in 24 hour period
Resting metabolic rate (RMR)
. Energy expended by individual at resting, postabsorptive state
. Represents energy required to carry out normal body functions (blood flow, ion transport)
. Determined by measuring O2 consumed or CO2 produced
. largest component of energy expenditure in humans (60-70% daily energy expenditure)
Food intake effect
. Food ingestion stimulates metabolism requiring energy to meet activities of digestion and transport of nutrients
. Overall metabolic stimulation called their mic effect of food (TEF)
. 10-15% of total energy needs used in metabolizing food
Caloric value
. Amount of heat required o raise temp. Of 1g of H2O by 1 degree Celsius
. Each 1g of carb consumed yields 4 kcal
. Fat provides 9 kcal/g
. Proteins provide energy when shortage of supply occurs but use 4kcal/g when they are used
Type of carbs in the body
. Available carbs to be digested, absorbed, and used in body (mono-, di-, and polysaccharides)
. Unavailable carbs like dietary fiber
Acceptable macronutrient distribution range (AMDR) for carbs
. 45-65% of caloric intake
. Less than 60 carbs/day causes Ketosis
Dietary fiber
. Plant cell wall components that can’t be digested
. Classified as water-soluble (pectins, gums, mucilages, some hemicellulose) or insoluble (cellulose, lignin, and most hemicellulose)
. Soluble: delay stomach emptying and transit of chyme through intestines, lower blood cholesterol by binding to bile acids
. Insoluble: accelerate transit of chyme through intestine, inc. fecal weight diluting fecal mutagens and preventing contact w/ colonic mucosa
. Dec. risk for constipation
. Recommendations: 25g/day ladies, 38 for men
Proteins
. Required for building and repairing tissue, prodded AA and AA nitrogen requirements
. Digested and enters as individual AAs
. Requires 20 AA to synthesize specific proteins and other N-containing compounds
. Excess protein treated as energy source (glucogenic AAs converted to glucose and ketogenic to FAs and ketoacids) that as converted to fat if not used
. Inc. protein eliminated from body as urinary N, often accompanied by inc. urinary Ca inc. risk for kidney stones and osteoporosis
. 12% of total energy supplied as protein is adequate
Essential Amino acids
. Phe . Val, Leu, Iso (BCAAs) . Thr . Trp . Met . His . Arg . Lys
Tissue protein balance
. Dynamic equilibrium btw turnover of protein and resynthesis
. Turnover highest in intestinal mucosa, pancreas, kidney, and plasma
. Lower in muscle and brain tissues
Muscle protein is only AA reserve in body capable of ___
. Significant losses w/o compromising ability to sustain life
. In fasted state, skeletal m. Breakdown inc. to sustain free AA pool
. When fed, AAs stimulate m. Protein synthesis
