nutritional biochem

what is the estimated avg requirement, (EAR)?
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)
what is the recommended dietary allowance, (RDA)?
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%)
what is the adequate intake, (AI)? when is it used?
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.
what is the tolerable upper intake level, (UL)? what is it useful for?
the highest avg daily nutrient intake level w/no adverse effects. it is useful in assessing fortified foods and dietary supplements, like vitamin A
what does the dietary reference intake, (DRI) consist of?
EAR, RDA, AI, and UL
what is the BMI? how does it correlate mortality risk?
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
what % of adult americans are overweight? obese?
2/3 adult americans are overweight, 36% obese
what is the BMR?
BMR (basal metabolic rate) = REE + AT, where REE is resting energy expenditure, and AT is adaptive thermogenesis
how are the calories for BMR calculated?
calories for BMR = weight (kg) x 24 kcal/kg/day
what is the REE?
REE = resting energy expenditure, 50 – 70%, digesting food, respiration, blood flow, ion transport
how does energy expenditure occur?
through BMR, physical activity, and adaptive thermogenesis
what is thermogenesis? are there differnt kinds?
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
what is adaptive thermogenesis? where is it localized?
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
how is dietary thermogenesis proposed to correlate with the fat mass set point?
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
what is temperature induced thermogenesis based on?
uncoupling proteins
what tissue does the generation of heat occur in via thermogenesis and what does it function to do?
thermogenesis occurs particularly in brown adipose tissue and it provides necessary warmth as well as aiding the body burning excess food & avoid weight gain
how do uncoupling proteins generate heat?
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

what disease is the most common reason for death in the US? can dietary adjustment decrease risk of this disease?
heart disease, yes
what are dietary recommendations for avoiding heart disease? what is expected with application of these?
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
what does “diet” refer to as comparted to “nutrition”?
diet=what you ingest, nutrition=chemicals necessary for proper functioning
what is the acceptable macro-nutrient range for fat, protein and carbohydrates?
fats 20 – 35 % of energy source, (~10% LCFAm or omega 3,6)
carbohydrates 45 – 65 % of energy source
proteins 10 – 35 % of energy source
what is more important than the amount of fat in the diet?
what kind of fat it is
what strongly influcences the incidence of coronary heart disease?
dietary fats
is there strong evidence for linking dietar fat and CA or obesity?
no
what food are more saturated fats found in? how does it affect cardiovascular health?
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
what food is PUFA omega 6 found in? what is it a precursor for? how does it affect cardiovascular health?
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
what food are more mono-unsaturated fats found in? how does it affect cardiovascular health?
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
what food is PUFA omega 3 found in? what is it a precursor for? how does it affect cardiovascular health?
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
where are trans fatty acids found? how do they affect cardiovascular health?
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
how much does dietary cholesterol affect plasma cholesterol?
not much, the type of fat is more important than the amount consumed
how does consumption of SFAs affect cardiovascular health?
raise LDL, little effect on HDL, and increased risk of CHD, prostate, colon CA
what are the “simple sugars?
monosaccharides, (glucose, fructose – > corn syrup, honee) and disaccharides, (sucrose, lactose, maltose -> maple syrup, molasses, table sugar, milk, beer)
what are complex carbohydrates?
polysaccharides, (starches found in plants, wheat, grains, potatoes, dried peas/beans, vegetables)
what compose nondigestible carbohydrates?
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)
what do soluble fibers help with?
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
what do insoluble fibers help with?
increased bowel motility, reducing exposure of gut to carcinogens, reduces constipation+hemorrhoid formation, softens stools
what is AI for males females of dietary fibers, (nondigestible CHOs)?
male:38,female:25 g/d, (american diet is ~11)
what are added sugars?
sugars and syrups added to foods during processing or preparation
what is the glycemic index?
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).
how is the glycemic index calculated?
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
what is considered low, medium and high glycemic index?
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)
what is the glycemic load? how is it calculated?
(glycemic load) GL = GI x CHO (g)
consideration of amount of carbohydrates
how do the 20 most consumed CHO sources in the american diet rate in terms of GI?
most are >69, (high)
what happens in the early postprandial period after consuming high GI/GL load meal?
significant increase in blood glucose->increase in insulin secretion->increased anabolism, (esp glycogenesis/lipogenesis), decreased blood glucose due to increased insulin)-> HUNGER
what happens in the middle postprandial period after consuming high GI/GL load meal? (2-4 hrs later)
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
what normally happens in the late postprandial period, (4-6 hrs later), how does consumption of high GI/GL change this?
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)
what are benefits of CHO consumption?
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)
low GI food is good for?
high GI food is good for?
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
what are proteins in the diet necessary for? how does this need change from infancy->20 yrs old?
needed for essential amino acids, need decreases steadily over development
what are the essential amino acids?
arginine
histidine
isoleucine
leucine
lysine
methionine
phenylalanine
threonine
tryptophan
valine
where are high quality proteins found? low?
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)
what pseudocereal has all essential amino acids and high quantity of vitamins & minerals?
quinoa
what is PEM? who does it more commonly affect? what are causes of morbity and more mild/moderate forms?
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
what is marasmus like PEM?
what is kwashiorkor like PEM?
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
what is cachexia?
consequence of chronic, systemic inflammatory/neoplastic condition, characterized by muscle wasting. regulation involved cytokines and hormones suchs as tumor necrosis factor and interleukins
what do animal protiens carry high amounts of? what are better sources of protein?
saturated fats, (red meat). poultry, fish, nuts, and legumes are better sources, or leaner cuts of red meat.
what happens to excess protein?
urinated out as nitrogen along with calcium, increasing the risk of nephrolithiasis/osteoporosis
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