Macronutrients Flashcards
What consumed fuels do we oxidate for life?
Carbs, lipids, proteins
Addition of what three things = Energy Intake
Energy Expenditure + Energy Excretion + Energy Storage
What makes up our energy expenditure?
Resting energy expenditure, thermogenesis, activity
What makes up our energy excretion?
Fecal loss, urinary loss
What makes up energy storage?
Weight changes, composition (adipose is more dense than lean body mass)
What is the formula for digestible energy?
Energy Intake - Energy lost in feces
What is formula for metabolizable energy?
Energy Intake - Energy lost in feces AND urine
What methods do we use to measure energy expenditure?
Direct calorimetry
Indirect calorimetry
What is indirect calorimetry?
Estimation of energy expenditure from measurements of respiratory gas exchange (O2 consumption and CO2 production) and urinary nitrogen losses
What are the products after you oxidize fats, carbohydrates, and proteins (oxidie = add O2)
CO2 and H2O
With protein you also get NH3, which becomes urea
What is the formula for respiratory quotient (RQ)?
RQ = CO2 production/O2 consumption
What does measurement of RQ allow estimation of?
Substrate utilization
T or F. There are several inert protein stores in the body.
False - there are none
What are the three concepts related to dietary amino acid composition?
- Protein quality
- Limiting AA
- Complementary protein sources
What does the concept of limiting amino acid refer to?
All AA’s must be available at intracellular sites of protein synthesis, otherwise rates of protein synthesis will be lmtd by AA present in least concentration
What does the concept of complementary protein sources refer to?
Combining dietary protein sources to meet all AA requirements
What is lactose a disaccharide of?
Glucose - galactose
What is sucrose a disaccharide of?
Glucose-fructose
Which enzyme has low activity compared to other brush border enzymes?
Lactase
Which sugar is used in sweeteners?
Sucrose
What is fructose a disaccharide of?
It’s a monosaccharide
T or F. Glucose polymers contribute less to intraluminal osmotic load than mono or disaccharides.
T
What are fats good for? (3 things)
- Fuel
- Components of membrane phospholipids
- Precursors of bioactive cmpds
18:2ω6
What does each number mean for this fatty acid
18 carbons, 2 double bonds, first double bond at carbon 6
What are the essential fatty acids?
n-6 and n-3 (FA’s whose first double bonds are at carbons 6 and 3)
What are the “parent” fatty acids of the essential fatty acids?
Linoleic acid (18:2n-6) and alpha-linolenic acid (18:3n-3)
What types of fatty acids are linoleic and linolenic acid converted to?
Longer-chain, more unsaturated derivatives
Linoleic –> arachidonic acid
Linolenic –> eicosapentaenoic acid
What does “classic” essential FA deficiency refer to?
Dietary linoleic acid (18:2n-6) deficiency
What happens metabolically and clinically to someone with a linoleic acid deficiency?
Less arachidonic acid is produced, elevated triene/tetraene ratio
Skin changes occur - dry scaly skin, desquamation
What are end products of both linoleic and a-linolenic fatty acids?
Eicosanoids (prostaglandin)
What are arachidonic acid and docosahexaenoic acid important for synthesis of?
Membranes
What is an important source of longer-chain, polyunsaturated n-3 fatty acids?
Fish oil
What is the most important dietary monounsaturated fatty acid? What is its dietary benefit? What oil is it common in?
Oleic acid (18:1n-9)
Decreases risk of CVD and type 2 DM
Olive oil
What is the adverse effect of saturated FA’s in the diet? What type of food are they high in?
Increases risk of CVD and type 2 DM
Animal fats
What saturated fatty acid may not raise LDL cholesterol and is seen in dark chocolate?
Stearic acid
What is the worst FA?
Trans fatty acids
What fats can be useful in hepatobiliary or pancreatic disorders and are absorbed into portal circulation?
Medium-chain triglycerides
Which has a higher RQ - fat or carbs?
Carbs (more CO2 production)
What are two protein undernutrition disorders?
Marasmus (non-edematous)
Kwashiorkor (edematous)
What is dietary fiber?
Nondigestible carbs and lignin that are intrinsic and intact in plants
What is functional fiber?
Isolated, nondigestible carbs that have beneficial physiological effects in humans
What types of foods are soluble fibers found in?
Fruits, oats, barley
What types of foods are insoluble fibers found in?
Cereals, wheat bran, stalks and peels of fruits and veggies
What does fiber do physiologically to?
Increase stool volume and water content
What are health benefits of fiber?
Lowers LDL cholesterol, attenuation of blood glucose responses, lower risk of type 2 DM, lower prevalence of obesity
What are prebiotics?
Non-digestible food ingredient that beneficially affects host by stimulating growth of specific bacteria in bowel
What are probiotics?
Preparation or product containing viable microorganisms in sufficient numbers to beneficially alter microflora of host
What are the acceptable macronutrient distribution ranges (AMDR) of energy intake composition for carbs, fat, protein
Carbs: 45-65%
Fat: 20-35%
Protein: 10-35%
What is the calorie amount and RQ for fat?
9 kcal/g, 0.71
What is the calorie amount and RQ for carbs?
4 kcal/g, 1.0
What is the caloria mount and RQ for protein?
4 kcal/g, 0.85
