Principles Of Dietetics - topic D: nutrition science Flashcards
energy - sources - the brain
the brain uses glucose exclusively as an energy source; uses ketone bodies during starvation
tissue stores of glucose
- glycogen from muscle and liver
- fat from adipose tissue
- cellular mass (protein stores)
- gluconeogenesis - conversion of non-carbohydrate sources into glucose (from glycerol and amino acids) - creation of new glucose from fat and protein
cellular oxidation
- enzymes - proteins, organic catalysts that control reaction
- coenzyme - enzyme activators; includes some vitamins
a. pantothenic acid, thiamin, riboflavin, and niacin are needed for energy production (the big 4!)
total energy expenditure (TEE) - basal energy expenditure
BEE - minimum amount of energy needed at rest in fasting (amount needed to carry out involuntary work of the body, activity of internal organs, internal temperature)
a. affected by extremes in environmental temperatures
- tropical climate 5-20% increase
b. caffeine, alcohol, nicotine stimulate metabolic rate 7-15%
total energy expenditure (TEE) - energy expended in physical activity
EEPA - highly variable
a. activity thermogenesis (AT)
total energy expenditure (TEE) - thermic effect of food
(TEF) - diet-induced thermogenesis (DIT), or the calorigenic effect of food (about 10% of total energy expenditure)
a. energy needed to digest, absorb and assimilate nutrients
b. greater after consumption of carb and protein than after fat
measures of energy utilization - basal metabolic rate
BMR - affected by sex
- measured in morning when reclining, awake, relaxed, at normal body temp, at least 12 hours after last meal, and several hours after strenuous activity
- highest BMR = 0-2 years of age
- when PBI (protein bound iodine) is elevated, BMR is elevated
- cancer and hypertension increase BMR
measures of energy utilization - resting metabolic rate
RMR - your resting metabolic rate is the amount of energy that your body needs to function while at rest.
- energy expenditure measured under similar conditions, after a short rest and controlled intake of caffeine, alcohol
- of the predictive equations: Mifflin - St. Joer (preferred) predicts within 10% of indirect calorimetry. Use with normal weight and obese individuals. use actual body weight (ABW) for underweight, overweight and obese.
measures of energy utilization - weight control
following changes in weight is the most practical way of measuring energy balance, following their weight over time
measures of energy utilization - calorimetry - direct
direct - measures heat produced in respiration chamber (limited usefulness)
measures of energy utilization - calorimetry - indirect
measures oxygen consumed and CO2 excreted using a portable machine (practical way) of measuring which nutrients are being used for energy and determining caloric needs. useful with athlete, burns
- respiratory quotients - RQ = VCo2 (carbon dioxide expired) / VO2 (oxygen consumed) - depends upon the fuel mixture being metabolized
- lower the RQ, increase the fat intake
carbohydrates (3)
- monosaccharide - glucose, fructose, galactose (simple sugars)
- disaccharides - sucrose (glucose and fructose), lactose (glucose and galactose), maltose (glucose and glucose)
- polysaccharide - complex
carbohydrate - sorbitol
alcohol from glucose; absorbed more slowly than glucose by passive diffusion; converted into fructose; excess may cause diarrhea
proteins - physical properties
carbon, hydrogen, oxygen, nitrogen (16%)**, sufur
complete protein
all essential amino acids in sufficient quantity and ratio to maintain body tissues and promote growth; HBV - high biological value
- low protein diets - give mostly HBV
fatty acids - saturated
w/ hydrogen
- all available bonds of carbon chain are filled with hydrogen; solid and hard at room temp
fatty acids - unsaturated
one or more double bonds
- one double bond = monounsaturated; two or more double bonds = polyunsaturated
- safflower = most polyunsaturated
- canola = most unsaturated
fatty acids - essential fatty acid - linoleic acid
- linoleic acid (omega-6) - lack creates eczema, poor growth rate, petechiae (red and purple skin spots)
- if linoleic acid replaces CHO: LDL decreases, HDL increases
- if linoleic acid replaces saturated fat: total cholesterol decreases, HDL decreases
fatty acids - essential fatty acid - a-linolenic
- a-linolenic (omega-3) - retinal function and brain development; deficiency results in neurological changes - numbness, blurred vision
- comes mainly from fish oils (EPA eicosapentaenoic acid, DHA docosahexaenoic acid) walnuts, flaxseed, canola)
- decreases hepatic production of triglycerides (inhibits VLDL synthesis); little effect on total cholesterol levels
structure of fatty acids
- straight hydrocarbon chains terminating in a carboxyl group (C00H) at one end and a methyl group (CH3) at the other end
- the location of the first double bond, counted from the METHYL END of the fatty acid, is designated by the omega sign
fatty acids - hydrogenation
reduction process of adding hydrogen (at the double bond) to unsaturated fatty acids to increase saturation and stability
fatty acids - in order of predominance (saturated -> least)
coconut oil - most saturated
canola - least saturated
fatty acids - in order of predominance (monounsaturated -> least)
olive oil - most monounsaturated
coconut MCT oil - least monounsaturated
fatty acids - in order of predominance (polyunsaturated -> least)
safflower - most polyunsaturated
palm kernel - least polyunsaturated
fatty acids - in order of predominance - butter and margarine
butter: SAT, MUFA, PUFA
margarine: PUFA, MUFA, SAT
fatty acids food sources
- butter, oils, nuts, bacon
- most heart-healthy lipids have zero grams of trans fat, no partially hydrogenated oils and are liquid plant oils
fatty acids - functions
- energy, insulation and padding, depresses gastric secretion so delays emptying
- 9 kcal/g
fatty acids - functions - alcohol
alcohol - metabolized as a fat - 7 kcal/g - does not require digestion
- decreases beta-oxidation of fatty acids, promotes triglyceride synthesis
- established risk factor for head and neck cancer, may increase risk of developing breast cancer
fatty acids - functions - winterized oils
- winterized oil - salad dressings
won’t crystallize when cold, clear (not cloudy) - corn, soy and cottonseed oils are winterized
vitamin A
- fat soluble
- toxic level 10,000 IU
- function: skin, vision
- sources: yellow, orange fruits (mango); liver
vitamin A deficiencies
- night blindness, nyctalopia, is reversible (detected using dark adaptation test)
- xerophthalmia - corneal damage, not reversible
- Bitot’s spots on conjunctiva (inner area of eyelid)
- dry, scaly skin (hyperkeratosis)
vitamin D
- fat soluble
- cholesterol is precursor
- UV light
vitamin D deficiencies
- rickets - soft bones
- osteomalacia - adult rickets
vitamin E
- fat soluble
- one of the least toxic vitamins
- sources: vegetable oils (cottonseed), whole grains, green vegetables, almonds
vitamin K
- fat soluble
- synthesized by bacteria in lower intestinal tract
vitamin K deficiencies
- hemorrhage
- affected by: mineral oil, antibiotics, anticoagulants/blood thinners (Waferin) - don’t change intake of vit K be consistent
vitamin B1
- thiamin
- water soluble
- high heat destroys thiamin
- function: carb metabolism
- Sources: pork
vitamin B1 deficiency
- beriberi, muscle weakness, foot drop, memory loss, tachycardia, confusion
- labs: decrease in erythrocyte transketolase, increase in plasma pyruvate
vitamin B2 - riboflavin
- riboflavin
- protein breakdown
- lost in UV light
- milk packaged in opaque containers
- sources: animal proteins
vitamin B2 deficiencies - riboflavin
- growth failure
- cheilosis - cracked lips
- angular stomatitis - mouth corner cracks, sore throat, Magenta tongue
vitamin B3 deficiencies
niacin
- pellagra, dermatitis, diarrhea, dementia
- beefy, bright, thickened, red tongue
- symmetrical, pigmented rash in sunlight
vitamin B9 - folate
- folate
- water-soluble
- DNA synthesis
- sources: fortified dry cereal, lentils, beans
vitamin B9 - folate deficiencies
- fatigue
- irritability
- dyspnea - shortness of breath
vitamin B6 - pyridoxine
- pyridoxine
- water soluble
- involved in protein breakdown
- functions: coenzyme in AA metabolism
vitamin B12
- water soluble
- functions: protein synthesis
- sources: animal proteins
- deficiency = rare
vitamin B12 deficiencies
- stomach or illium are prime cases
- macrocytic megaloblastic anemia after gastrectomy, or removal of illeium
vitamin B5 - pantothenic acid
energy release
vitamin C
ascorbic acid
- most easily destroyed, structure like glucose
- functions: aids iron absorption
vitamin C deficiency
- scurvy, poor wound healing, bleeding gums, petechiae
vitamin B7 - biotin
- synthesized by intestinal bacteria
calcium
- most abundant mineral
- calcitonin lowers serum calcium by inhibiting bone resorption
calcium deficiencies
hypocalcemia leads to tetany- stiff muscles, irregular contractions
phosphorus
- second most abundant mineral
- sources: animal proteins
iron
- trace mineral
- iron overload
- hemochromatosis treated with iron chelation therapy
- sources: heme iron: animal foods, meat, fish, poultry
non-heme: cereals, vegetables, poorly absorbed; absorption aided by gastric juice, vitamin C. - needs acid for absorption
iron deficiency
- spoon shaped nails
- pale conjuctivae (mucous membranes lining eyelid)
zinc
- trace mineral
- increase taste acuity
- enhances insulin action
- stabilizes DNA, RNA
- sources: meat, liver, egg, fish
zinc deficiency
- reduced immune function, alopecia, poor wound healing, hypogeusia
- growth retardation and sexual immaturity in adolescents
copper
- attached to protein ceruloplasmin
- functions: hemoglobin synthesis, aids iron absorption
copper deficiency
wilson’s disease: low serum copper, deposited in organ’s and tissues where it doesn’t belong
chromium
functions: aids insulin action, glucose metabolism
sulfur
animal proteins
vitamins - 4 notes
- high doses of vitamin E may antagonize vitamin K
- hypersensitivity to light may be due to deficiency of beta carotene
- infants and adolescents have a higher prevalence of iron deficiency
- calcium deficiencies are associated with vitamin D and magnesium deficiencies
water
- intracellular (within cells) ICW; extracellular (plasma, lymph, interstitial or intercellular) ECW. serves as medium for cell metabolism
- insensible water loss (skin, breathing): .8-1.2 liters/ day - difficult to measure
electrolytes
concentration expressed in milliequivalents
- mEq = mg / atomic weight x valence
- convert to either direction
extracellular electrolytes
- Na+
- sodium chloride is 40% sodium. sodium is reabsorbed by aldosterone, and retained by steroids
intracellular electrolytes
- K+
- potassium sources: meat, fruits, vegetables (banana, orange, tomato, potato, cantaloupe)
- sources low in potassium: apple, cranberry, blueberry, carrot, corn.
- hyperkalemia causes cardiac irregularities
normal ranges for electrolytes
- sodium: Na+ -> 136-145 mEq/L
- potassium: K+ -> 3.5-5 mEq/L
- calcium: Ca++ -> 4.5-5.5 mEq/L (9-11 mg/dl)
- magnesium: Mg++ -> 1.5-2.5 mEq/L (1.8-3 mg/dl)
- urine specific gravity 1.002 - 1.025 (formula uses weight and volume)
fluid balance - osmosis
fluid moves from less to more concentrated side of membrane
fluid balance - diffusion
particles move from more to less concentrated side
fluid balance - effect of protein
exerts colloidal osmotic pressure
fluid balance - misc info
- albumin exerts pressure on blood vessel wall that keeps water within. when albumin drops, the pressure drops, causing fluid to leak out - causing edema.
- anasarca is extreme, generalized edema and widespread swelling of skin due to effusion of fluid into extracellular space. it is associated with heart, liver, renal failure, and extreme protein/kcal malnutrition
dehydration
- most lab values are elevated
- nausea, dizziness, sunken eyes, fever, hyperventilation, excessive sweating, concentrated urine, dry inelastic skin, increase in solutes (BUN), tachycardia, headache, fatigue, decreased appetite, rapid weight loss
- serum sodium is the BEST assessment parameter for fluid status. hypernatremia is associated with dehydration. hyponatremia is associated with over-hydration.
acid-base balance
- regulation of hydrogen concentration
- acid releases hydrogen ions; base takes up hydrogen ions
- buffer - mixture of acid and base components to protect against a strong acid or strong base
- major buffer: carbonic acid (H2CO3) and sodium bicarbonate (NaHCO3) - maintains proper pH level
- body’s pH = 7.4 - bodily functions work well
acid-base balance - role of lungs and kidneys
- regulated components
- lungs control supply of carbonic acid (CO2, water)
- amount altered by rate and depth of breathing
- hypoventilation- retention of acid; hyperventilation(pushing it out) - loss of acid
- kidneys control bicarbonate (base)
- regulate hydrogen ion secretion and bicarbonate reabsorption
- if kidneys retain bicarbonate- level of base increases
- if kidneys excrete excess bicarbonate- level of base decreases
- a change in one side of the buffer brings about a compensatory change in the other side to maintain balance; maintain pH close to 7.4
acidosis
- failure related to pulmonary system: respiratory: acidosis-retention of CO2 by lungs (decreased ventilation). to compensate, kidneys increase absorption of base.
- failure related to renal system: metabolic: acidosis- kidneys either produce to retain too much hydrogen leading to an increase in production of carbonic acid; or the kidneys may excrete too much base. to compensate, respiration increases to remove carbon dioxide to decrease carbonic acid.
alkalosis
- failure related to pulmonary system: respiratory: alkalosis-loss of carbonic acid (increased ventilation). to compensate, kidneys excrete additional base.
- failure related to renal system: metabolic: alkalosis-loss of hydrogen due to loss of acid; or an increased retention of base. to compensate, ventilation decreases to retain CO2 to make carbonic acid
respiratory acidosis
patients with emphysema
- retention of acid from the lungs
- less is excreted through the urine
respiratory alkalosis
- loss of acid through lungs
metabolic acidosis
- kidneys excrete excess base
- lungs will lose acid
evaluating acid-base abnormalities - normal range
- check the pH. is it moving towards acidosis or alkalosis?
- then look for the cause - is it respiratory or metabolic?
normal: pH = 7.4, HCO3 = 24-28 (kidneys), pCO2 = 35-45 (carbonic acid/lungs)
pregnancy weight gain guidelines
weight gain guidelines
- 25-35 lbs for normal weight female BMI 18.5-24.9
- 28-40 lbs for underweight female BMI <18.5
- 15-25 lbs for overweight female BMI 25 - 29.9
- 11-20 lbs for obese female BMI >= 30
- target: at least achieve lower limit
pregnancy misc guidelines
- weight gain - 1lb/ month first 3 months; 1 lb per week thereafter
- at risk: failure to gain 4 lbs (1.8 kg)/month in last half of pregnancy; <16 or >=35 years of age; <12 months between pregnancies
- pregnant adolescent - high risk - needs extra iron, calcium, zinc
- no alcohol
- progesterone: hormone that develops placenta after implantation
- recommend 1.4 g/day linolenic acid (300 mg DHA), 1.3 g/day (lactation). needed for development of fetal nervous system
- avoid excess intake of preformed vitamin A (supplements > 5000 IU)
- avoid shark, swordfish, king mackerel, limit albacore, raw fish
infancy normal birth weight
normal birth weight 2500 - 4000 g
infancy average kcal/kg
0-6 months - 108
7-12 months - 98
lactation - human milk
- 20 kcal/ounce
- maternal hormones from pituitary; prolactin stimulations milk production; oxytocin moves milk through ducts
- recommend exclusive breast-feeding for first 6 months, then supplemented by weaning foods for at least up to 12 months
- milk supply is adequate if infant gains weight and length, has frequent stools and 6-8 wet diapers per day
baby friendly hospital initiative
global effort to increase incidence and duration of breast feeding (measurable outcomes)
infant formula
- 20 kcal/ounce; need 2 1/2 oz/lb/day
- hyperbilirubinemia - unconjugated bilirubin levels elevated within first week of life as a result of increased breakdown of red blood cells or decreased intestinal mobility. encourage 9-12 feedings per day of human milk or formula to promote hydration and intestinal motility
- introduce vegetables before fruit. add solids at 4-6 months, when sitting posture can be sustained and extrusion reflex diminishes. begin with iron-fortified cereal (rice), then strained vegetables or fruit
- 6-8 months of age add large finger foods (teething biscuits) that can be secured with a palmar grasp
- 9-12 months of age, add small finger foods (dry cereal: cheerios) as pincer grasp (thumb and forefinger) develops
- no whole cow’s milk during first year of life, no fruit juice until age 1
- low fat and non-fat milks are inappropriate during the first two years of life
- for those who cannot tolerate cow’s milk-based or soy products, use formulas made from a casein hydrolysate (Pregestimil)
- sunken fontanel may be due to dehydration or protein malnutrition
childhood
- limit fruit juice to 4 ounces each day up to age 6
- 2002 RDA protein: males 14-18 = 52 g; females 14-18 = 46 g
- age 14, female adult need for protein
WHO growth charts from birth - 2 years old
CDC growth charts from 2 - 20 years
- weight for length/stature - detects short term changes in nutritional status
- stature / length for age - length to long, defines shortness/tallness
- BMI for age percentiles starting at age 2 years: age and sex specific - overweight= 85th - 94th, obese >= 95th. best measure to assess weight in children (includes height, weight, age)
failure to thrive in infants
- weight for age that falls below the 5th percentile on multiple occasions or weight deceleration that crosses two major percentiles on a growth chart.
other factors: - measure head circumference (OCF occipital frontal circumference) until three years of age
- until age two, measure supine length (lying down)
- look for change in rate of growth as potential risk
- FTT in children may result from: acute or chronic illness, restricted diet, poor appetite, lack of fiber leading to chronic constipation, diminished intake
- lead poisoning - irritability, lethargy, anorexia, vomiting, constipation, anemia
adulthood RDA protein and fluid
- protein: >= 19 males - 56 g; females - 46 grams
- fluid: 35 ml/KG or 1 ml/kcal ingested; AI 3.7 L/day men; 2.7 L/day women >19
elderly kcal, fluids, etc.
- young old 65-74; aged 75-84; oldest old 85+
- kcal needs decrease, protein needs remain same (1 g/kg)
often lack calcium and iron (decreased absorption due to decreased HCL) - encourage folate-rich foods; supplements of B6 and B12 may be needed
- more vulnerable to toxicity of vitamin A (increase liver storage, decrease clearance from blood
nutrition and athletics
- athletes need water during physical activity: 16 oz. water for every 1 lb/ body weight lost
- at rest and during normal activities, fats are the primary energy source (80-90%); carb 5-18%; protein 2-5%
- during prolonged exercise, reliance on carb to provide pyruvate for continued lipid oxidation
- creatine supplements to NOT enhance endurance (not helpful for marathon runner, soccer player)
nonnutritive sweeteners
provide minimal to no energy and must be approved by the FDA
sugar alcohols: sorbitol, mannitol, xylitol
- can be labeled “sugar-free” but not “calorie-free”
- more slowly absorbed than other sugars causing diarrhea, abdominal pain, gas
- consuming more than 30 g sorbitol is not recommended
herbals & botanicals to avoid pre-surgery
black cohosh, garlic, ginger, ginkgo biloba, ginseng, st. john’s wort
- issue = blood clotting and presurgical patients need to avoid
digestion - chemical or enzymatic activity
mainly in small intestine
- in stomach: start of proteolysis by protease pepsin-protein digestion begins in the stomach- and HCL; limited continuation of starch hydrolysis by salivary amylase
- hormone gastrin stimulates gastric secretions and motility
- hormone CCK cholecystokinin (released from duodenum when fat enters) contracts gallbladder releasing bile, stimulates pancreas
- hormone secretin (duodenum)-stimulates pancreas- stimulates flow of pancreatic juice (bicarbonate) and water into the duodenum, inhibits gastric acid secretion
- hormone glucagon-like peptide 1 (GLP-1)- insulin synthesis , hormone glucose-dependent insulinotropic polypeptide (GIP), released from intestine in presence of glucose and fat, stimulates insulin synthesis and release
digestion - mechanical or muscular activity
- rhythmic contractions of esophagus force food into the stomach where it is mixed with gastric juice and reduced to chyme (acidic) - helps neutralize stomach acid
digestion - bacterial digestion (colon)
- colonic salvage: anaerobic fermentation and absorption of end-products of carbohydrate, fiber and AA breakdown
- converts malabsorbed CHO and fibers into:
-> SCFA (short-chained fatty acids)
-> gases
absorption and metabolism - carbohydrates
- simple sugars: small intestine -> liver -> converted to glucose or glycogen
- sources of glucose: dietary, liver glycogen, products of intermediary carbohydrate metabolism (conversion of lactic acid and pyruvic acid)
- 58% protein - glucogenic AA (yield glucose following deamination- remove nitrogen)- can be converted to glucose
-> alanine is the most glucogenic AA (alanine-glucose cycle). catabolized to pyruvate or to Kreb’s cycle intermediates
-10% fat - glycerol - can be converted to glucose - fatty acids and muscle glycogen-only used by muscle do not contribute to the body’s supply of glucose
energy metabolism
- glucose in cell is oxidized to produce energy, CO2, water (end products of metabolism)
where does glycolysis occur and the pupose
in cytoplasm
- purpose is to produce pyruvate for the Kreb’s cycle by breaking down glucose, with or without oxygen, into pyruvate or lactate
aerobic glycolysis end product
pyruvate
anaerobic glycolysis end product
lactate
glucose during glycolysis
glucose enters cell aided by insulin; combines with phosphorus in presence of magnesium to form glucose-6-phosphate; proceeds to pyruvic acid
glycose-6-phosphate during glycolysis
may lead to the synthesis of glycogen
- liver glycogen releases glucose to blood to maintain normal blood glucose levels; process requires glucose 6-phosphatase. muscle cells do not have this enzyme (muscle glycogen is only used by that muscle)
- glucose-6-phosphate also proceeds through the pentose shunt (side-channeling of glucose)
pyruvic acid during glycolysis
pyruvic acid can proceed to form lactic acid, used for muscle contractions when energy needs exceed supply of oxygen (oxygen debt)
what is the cori cycle
- cori cycle - lactate is released from tissue, transported to liver, and converted back to glucose as pyruvate
pyruvate is the main substrate for energy production within Kreb’s cycle - what else is required?
thiamin (TDP), niacin (NAD), riboflavin (FAD), pantothenic acid (CoA), magnesium, lipoic acid
TCA tricarboxylic acid cycle / Kreb’s cycle / citric acid cycle
- in mitocondria
- acetyl CoA comes from pyruvic acid (CHO), oxidation of fatty acids, and degradation of carbon skeleton of certain AA. acetyl CoA is the intermediate breakdown product of carb, protein and fat. fatty acids enter as a two-carbon fragment
- cycle produces 90% of body’s energy as ATP; (also CO2, water)
- lack of carb can lead to ketosis
energy metabolism - MISC
- occurs in every cell during your life
- EMP = glycolysis (just glucose)
- glycogen = stored glucose
- thiamin - elevated plasma pyruvate = deficiency, shows up in blood
- acetyl CoA - starts Kreb cycle
- oxaloacetate = carb fuel
- acetyl CoA is the intermediate breakdown product of CHO, protein and fat
protein metabolism
- pyridoxine is needed for the transport of AA
- branched chain AA - valine, leucine, isoleucine
nitrogen balance - measures body equilibrium
- compares intake to output
0 balance - maintenance, nitrogen equilibrium - healthy adult
+ balance - net gain in body protein (infant, teen, pregnancy, healing) - tissue growth - balance - erosion of body protein, inadequate intake of protein
nitrogen balance formula
nitrogen in minus nitrogen out
protein intake (grams)/6.25 [nitrogen in]- (urinary urea nitrogen (UUN) + 4 [nitrogen out] [compensates of skin and stool]
catabolism (pyridoxine is involved)
- first step is deamination - splitting off of NH2 by hydrolysis in liver
- NH2 converted into ammonia (NH3) which is toxic
- most of the ammonia is converted into urea and excreted by the kidneys
- the remaining carbon chain is a ketoacid; it can be oxidized for energy
fat metabolism
- end products of fat digestion: monoglycerides, diglycerides, glycerol, fatty acids
- monoglycerides, diglycerides, long chained fatty acids combine with help of bile salts (acting as wetting agents) to form micelles
- bound to protein to form lipoproteins (chylomicron); penetrate intestinal mucosa, travel through lymph before entering the blood, into the thoracic duct into the blood
- most dietary fat enters blood as chylomicron
lipogenesis (synthesis, deposition)
- insulin is anabolic hormone
- adipose - most active site: fatty acids + glycerol -> triglycerides
- liver - synthesizes fat, but should not store fat
ketosis
normal fat metabolism - requires adequate carb for complete fat oxidation
- acetoacetic acid and beta-hydroxybutyric acid enter the blood and are taken to the peripheral tissues, converted back to acetyl CoA and oxidized as fuel
abnormal fat metabolism
- inadequate CHO (starvation, uncontrolled diabetes) results in incomplete fat oxidation and buildup of ketones (which serve as fuel for muscle and brain, but disturbs acid/base balance)
- high amounts of acetoacetic acid, and beta-hydroxybutyric acid in starvation and uncontrolled diabetes
mechanisms of absorption - active transport
- most nutrients (glucose, AA, Na, K, Mg, Ca, Fe)
- sodium pump - uphill pumping from lower to higher concentration, across a membrane against an energy gradient; needs energy from ATP
mechanisms of absorption - simple diffusion
- some water and electrolytes
- higher to lower concentration: intestine to blood to lymph
mechanisms of absorption - passive diffusion
- carrier-facilitated: water-soluble nutrients
- higher to lower concentration
factors that aid vitamin and mineral absorption
- vitamin D - hydroxylated in liver, then in kidney; needs bile salts, acidity of chime; accompanies Ca, P absorption
- folate: zinc dependent, cleaves polyglutamate to monoglutamate
- folic acid in fortified foods and supplements is present as monoglutamate
hypothalamus hormones
- serononin is a neurotransmitter. low levels increase carb appetite
- leptin produced by fat cells in response to food intake, induces satiety (suppresses appetite) and enhanced energy expenditure
- ghrelin produced in the stomach and intestine stimulates appetite and growth hormone secretion from the pituitary. decreases fat utilization in adipose
- low leptin and high ghrelin promote excess food intake
social determinants of health
factors - conditions in the places where people live, learn, work, and play that affect a wide range of health risks and outcomes: economic stability, education, social and community context, access to healthy foods and safe neighborhoods, and health care
nutritional genomics
- a genome is the sum of the organism’s genetic material
- nutritional genomics focuses on diet and lifestyle-related disorders resulting from the interaction between the genome and environmental factors, such as nutrients, toxins, physical activities, sleep and stress
- it provides a greater understanding of how to use nutrition therapy to promote health and prevent disease
