nutritional biochem

question

what is the estimated avg requirement, (EAR)?
answer

the requirements expected to satisfy the needs of 50% of people in an age group/gender. (50% risk of inadequacy with this amount of intake)
question

what is the recommended dietary allowance, (RDA)?
answer

the daily dietary intake level of nutrient expected to meet the requirements of 97-98% people in an age group/gender. (with this amount of intake, risk of inadequacy is 2-3%)
question

what is the adequate intake, (AI)? when is it used?
answer

the avg daily dietary intake level based on an estimate of nutrient intake of healthy people. it is used when no EAR or RDA is available.
question

what is the tolerable upper intake level, (UL)? what is it useful for?
answer

the highest avg daily nutrient intake level w/no adverse effects. it is useful in assessing fortified foods and dietary supplements, like vitamin A
question

what does the dietary reference intake, (DRI) consist of?
answer

EAR, RDA, AI, and UL
question

what is the BMI? how does it correlate mortality risk?
answer

body mass index: mass/height^2 (metric) or mass x 703/height^2 (english). 30 is moderate mortality risk, 35+ is high
it is a general equation for establishing height to weight ratios
question

what % of adult americans are overweight? obese?
answer

2/3 adult americans are overweight, 36% obese
question

what is the BMR?
answer

BMR (basal metabolic rate) = REE + AT, where REE is resting energy expenditure, and AT is adaptive thermogenesis
question

how are the calories for BMR calculated?
answer

calories for BMR = weight (kg) x 24 kcal/kg/day
question

what is the REE?
answer

REE = resting energy expenditure, 50 – 70%, digesting food, respiration, blood flow, ion transport
question

how does energy expenditure occur?
answer

through BMR, physical activity, and adaptive thermogenesis
question

what is thermogenesis? are there differnt kinds?
answer

calorie burning conditions, which increase the rate of ATP production in the mitochondria to create more heat that occur on a daily basis. there are 2 kinds: exercise-induced and adaptive thermogenesis
question

what is adaptive thermogenesis? where is it localized?
answer

adaptive thermogenesis is part of the sympathetic nervous system’s attempt at maintaining homeostasis during changing environmental conditions. Typically in response to excessive caloric intake or cold exposure. it is localized to adipose tissue, skeletal muscle, and the heart
question

how is dietary thermogenesis proposed to correlate with the fat mass set point?
answer

the body adjusts its thermogenesis/energy expenditure to maintain a certain level of fat storage. if you eat more than you usually would = thermogenesis goes up but if you eat less than you usually would = thermogenesis goes down
question

what is temperature induced thermogenesis based on?
answer

uncoupling proteins
question

what tissue does the generation of heat occur in via thermogenesis and what does it function to do?
answer

thermogenesis occurs particularly in brown adipose tissue and it provides necessary warmth as well as aiding the body burning excess food & avoid weight gain
question

how do uncoupling proteins generate heat?
answer

uncoupling protein-1 causes an influx of H+ into the matrix of the mitochondria and bypasses the ATP synthase channel. this uncouples oxidative phosphorylation, and the energy from the proton motive force is dissipated as heat rather than producing ATP from ADP

other cellular functions of UCPs:
promotion of FA metabolism in muscle
secretion from pancreas ?-cell
regulation of insulin

question

what disease is the most common reason for death in the US? can dietary adjustment decrease risk of this disease?
answer

heart disease, yes
question

what are dietary recommendations for avoiding heart disease? what is expected with application of these?
answer

balanced eating, portion control, level of physical activity and weight reduction. reasons for these recommendations include increased life expectancy, decreased blood pressure, decreased visceral fat deposition, improved plasma lipid concentration, increased insulin sensitivity and normalized glycemia, improved clotting , improved platelet function, enhanced quality of life
question

what does “diet” refer to as comparted to “nutrition”?
answer

diet=what you ingest, nutrition=chemicals necessary for proper functioning
question

what is the acceptable macro-nutrient range for fat, protein and carbohydrates?
answer

fats 20 – 35 % of energy source, (~10% LCFAm or omega 3,6)
carbohydrates 45 – 65 % of energy source
proteins 10 – 35 % of energy source
question

what is more important than the amount of fat in the diet?
answer

what kind of fat it is
question

what strongly influcences the incidence of coronary heart disease?
answer

dietary fats
question

is there strong evidence for linking dietar fat and CA or obesity?
answer

no
question

what food are more saturated fats found in? how does it affect cardiovascular health?
answer

animal fats and tropical oils. they will raise levels of LDL and total plasma cholesterol, and thereby increase the risk of CHD, (coronary heart disease) little effect on HDL
question

what food is PUFA omega 6 found in? what is it a precursor for? how does it affect cardiovascular health?
answer

PUFA omega 6 is found in sunflower, sesame, soy, corn oil. it is a precursor for ESSENTIAL FA, linoleic acid as well as arachodonic acid, eicosatrienoic acid. omega 3 will lower total blood cholesterol, lower LDL, lower CHD risk, BUT lower HDL
question

what food are more mono-unsaturated fats found in? how does it affect cardiovascular health?
answer

found in fish, avocado, olive oil and canola oil. it will lower total plasma cholesterol and LDL and decrease risk of CHD. HDL levels are increased or maintained
question

what food is PUFA omega 3 found in? what is it a precursor for? how does it affect cardiovascular health?
answer

omega 3 is found in fish, flaxseed and walnuts. it is a precursor for ESSENTIAL FA, linolenic acid, it has little effect on LDL or HDL, but it does lower serum TGs and lower the risk of CHD. its ANTIARRHYTHMIA effect is strongest
question

where are trans fatty acids found? how do they affect cardiovascular health?
answer

they are found in small amounts in animals, mostly in partially hydrogenated vegetable oil. they raise serum SFA, blood cholesterol, LDL and the risk of CHD. HDL levels are decreased
question

how much does dietary cholesterol affect plasma cholesterol?
answer

not much, the type of fat is more important than the amount consumed
question

how does consumption of SFAs affect cardiovascular health?
answer

raise LDL, little effect on HDL, and increased risk of CHD, prostate, colon CA
question

what are the “simple sugars?
answer

monosaccharides, (glucose, fructose – > corn syrup, honee) and disaccharides, (sucrose, lactose, maltose -> maple syrup, molasses, table sugar, milk, beer)
question

what are complex carbohydrates?
answer

polysaccharides, (starches found in plants, wheat, grains, potatoes, dried peas/beans, vegetables)
question

what compose nondigestible carbohydrates?
answer

dietary fibers divided into soluble, (forms a viscous gel when mixed w/liquid like oatmeal), and insoluble, (woody structure like celery, good for bowel movements), and functional fibers, (synthetic that delay gastric emptying – makes you feel more full faster)
question

what do soluble fibers help with?
answer

decrease absorption of dietary fat, cholesterol, (increases cholesterol loss by feces). also generates feeling of fullness, (delays gastric emptying), and reduces postprandial blood glucose conc
question

what do insoluble fibers help with?
answer

increased bowel motility, reducing exposure of gut to carcinogens, reduces constipation+hemorrhoid formation, softens stools
question

what is AI for males females of dietary fibers, (nondigestible CHOs)?
answer

male:38,female:25 g/d, (american diet is ~11)
question

what are added sugars?
answer

sugars and syrups added to foods during processing or preparation
question

what is the glycemic index?
answer

the level to which blood glucose spikes then falls after eating a carbohydrate meal. low glycemic indexed foods create a sense of satiety over a longer period of time, (can help lower caloric intake).
question

how is the glycemic index calculated?
answer

GI = (%total CHO) x (GI value)
GI value of various food is determined based on blood glucose measurements after consumption of 1 g of particular food compared to that of 1 g white bread
question

what is considered low, medium and high glycemic index?
answer

low is <55, (most fruit & vegetables, pasta, cheese, milk & nuts, except watermelon & potatoes)
medium 56-69, (sucrose, candy bar, basmati rice, croissant, sweet potato, some brown rice)
high >70 (glucose, corn flakes, baked potato, white rice, white bread, watermelon)
question

what is the glycemic load? how is it calculated?
answer

(glycemic load) GL = GI x CHO (g)
consideration of amount of carbohydrates
question

how do the 20 most consumed CHO sources in the american diet rate in terms of GI?
answer

most are >69, (high)
question

what happens in the early postprandial period after consuming high GI/GL load meal?
answer

significant increase in blood glucose->increase in insulin secretion->increased anabolism, (esp glycogenesis/lipogenesis), decreased blood glucose due to increased insulin)-> HUNGER
question

what happens in the middle postprandial period after consuming high GI/GL load meal? (2-4 hrs later)
answer

most all nutrients are completely absorbed from the intestinal tract->high insulin, low glucagon->decreased blood glucose, (hypoglycemia)->increased HUNGER->high insulin creates a state similar to fasting condition
question

what normally happens in the late postprandial period, (4-6 hrs later), how does consumption of high GI/GL change this?
answer

normally, low levels of glucose and FFA stimulate release of the counter regulatory hormones, (epinephrine, glucagon, and cortisol), however these actions are blocked by high insulin levels, (such those stimulated by high GI/GL meals)
question

what are benefits of CHO consumption?
answer

high in B vitamins, (important in metabolic pathways, correlate w/high energy levels). products made w/whole grain, have high fiber/iron. and starchy vegetables, (beans, peas, lentils) have avg of 3 g fiber, (low fat, high protein)
question

low GI food is good for?
high GI food is good for?
answer

low GI food is good for slow and steady release of glucose. high GI food is good for energy recovery after endurance exercise, or for pts with diabetes experiencing hypoglycemia
question

what are proteins in the diet necessary for? how does this need change from infancy->20 yrs old?
answer

needed for essential amino acids, need decreases steadily over development
question

what are the essential amino acids?
answer

arginine
histidine
isoleucine
leucine
lysine
methionine
phenylalanine
threonine
tryptophan
valine
question

where are high quality proteins found? low?
answer

high quality proteins are found in meat, fish, milk. low quality proteins are found in plants, (need to combine beans and wheat for example to get all necessary amino acids)
question

what pseudocereal has all essential amino acids and high quantity of vitamins & minerals?
answer

quinoa
question

what is PEM? who does it more commonly affect? what are causes of morbity and more mild/moderate forms?
answer

protein-energy malnutrition, it affects children more, morbidity is due to fluid, electrolyte imbalances, opportunistic infections and anemia. mild and moderate forms of PEM cause weight loss, (arrested growth/muscle wasting), diarrhea, lethargy, and decreased subcutaneous fat
question

what is marasmus like PEM?
what is kwashiorkor like PEM?
answer

marasmus like PEM is common in chronic illness, missing all sorts of nutrients. kwashiorkor like PEM is more related to low protein diets, related to catabolic illnesses, (acute), trauma, burns, sepsis. -> present with large belly, fatty liver
question

what is cachexia?
answer

consequence of chronic, systemic inflammatory/neoplastic condition, characterized by muscle wasting. regulation involved cytokines and hormones suchs as tumor necrosis factor and interleukins
question

what do animal protiens carry high amounts of? what are better sources of protein?
answer

saturated fats, (red meat). poultry, fish, nuts, and legumes are better sources, or leaner cuts of red meat.
question

what happens to excess protein?
answer

urinated out as nitrogen along with calcium, increasing the risk of nephrolithiasis/osteoporosis

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