deck_4503545 Flashcards
What are the 4 fat-soluble vitamins?
A, D, E, K
What do fat-soluble vitamins require for abspt?
Bile and dietary fat
How are these vitamins transported?
W/ fats through lymphatic system in chylomicrons
Are these vits stored? Where?
Yes, in body fat (adipose tissue)>Thus intake can vary w/o risk of deficiency
e. Not easily excreted, unlike water soluble vitaminsi. **Increase … ii. Ppl should not take supplements high in these vitamins
FIGURE OUT
What are pre-made/preformed vit A called? Is it active or inactive? Toxic?
Retinoids: retinol, retinal, retinoic acidActive (usable)May be toxic
Where are retinoids found?
Animal foods>Liver, eggs, fortified into dairy, fish
What is the provitamin/precursor form of Vit A)? Is it active or inactive? Toxic?
CarotenoidsInactiveNon-toxic
Where are carotenoids found?
Plants → Yellow, orange, red fruits and veggies>More color, more carotenoids• Frozen and canned > retail fresh»Carrots, red bell peppers, cantaloupe
What is Retinoid fxn?
> Key role in night vision>Cell differentiation (key in fetal development)>Growth regulation”needed for vision (retinal), and for growth and differentiation of cells (retinoic acid)”
What is Retinoic Acid used for?
used topically to treat certain skin conditions (e.g. acne)>Vit A is a key component>Helps cells divide more rapidly, clearing old cells
What is fxn of Carotenoids? How absorbed?
Family of Phytonutrients>Decrease cancer risk and prevent macular de-generation»>In eye, (yellow) carotenoids have been shown to decrease risk of macular degeneration>Need dietary fat to be absorbed (absorbed in chylomicron)
(???) How are preformed and precursor forms of Vit A transformed in digestive tract?
> Preformed → Retinol transformed into Retinal >Precursor → Beta-carotene transformed into Retinal in liverand intestinal mucosa»_space;Retinal is converted to Retinoic Acid, can’t covert back
What is Vit A role in Visual Cycle?
> Vit A is a component of Rhodopsin (retinal + opsin) >When light hits, Retinal molecule changes molecular form»>Bent (cis) → straight (trans)»>Signals to brain that there’s light>Retinal breaks away from opsin → brain perceives light»>Retinal is lost in cycle»>Need more to form Rhodopsin»>If insufficient Retinal, eyes have difficulty adjusting to dark”- Retinal binds to opsin in the eye to form rhodopsin. After light strikes rhodopsin to begin the visual cycle, a nerve impulse is sent to the brain so the light is perceived.- When vit A is deficient, there is a delay in the regeneration of rhodpsin that causes difficulty seeing in dim light (night blindness).”
What is Vit A role in Gene Expression and Cell Differentiation ?
> Vit A has a role in directing which genes are transcribed and translated to create diff kinds of proteins»>Impt in early development and growth”- In order to affect gene expression, retinoic acid enters the nucleus of specific target cells, where it binds to retinoic acid receptor proteins; the retinoic acid-protein complex then binds to the regulatory region of DNA.”
What is relationship btwn Vit A and Keratin?
> Vit A helps w/ turnover of cells in eye that help w/ moisture and lubrication»>W/ insufficient Vit A, body creates Keratin, which leads to a hard and dry layer in the eye
Causes and symptoms of Vit A Deficiency?
Caused by insufficient intake of Vit A, fat>Night blindness>If severe: permanent blindness>Xerophathalmia – lack of mucous synthesis»>Keratin on the eye”More severe deficiency interferes w/ cell differentiation. This impairs immune fxn and growth and causes epithelial surface of eye to become hard and dry, leading to infection and blindness.”
Causes and symptoms fo Vit A Toxicity?
Retinoids – can be toxic and can increase risk of bone fractures and birth defects»_space;>Supplements (including multivitamin) have Vitamin A in multivitamins has been related to hip fractures in postmenopausal womenCarotenoids – not toxic, but high intake can cause»_space;>Hypercarotenemia: orange hue in skin, benign»_space;>Birth defects
What are dietary and other sources of Vit D? Essential?
Vit D = “sunshine vitamin” → Produced in the skin by exposure to UV light>Not found in many foods, mostly eggs, fatty fish (salmon), and milk (fortified dairy products)>Only conditionally essential in diet if you’re not producing enough through skin
What is active form of Vit D?
Vit D3, or Cholecalciferol>Modified in liver and then activated in kidney
Vit D toxicity?
Toxic at high lvls>Flynn – toxicity not thought to be issue, even w/ supplementation, but widespread use of vit D as supplement is relatively newBook info:»>High blood and urine Ca2+ concentrations»>Depositing of Ca2+ in blood vessels and kidneys, cardiovascular damage and possibly death
Vit D fxns?
> Bone health → maintains lvls of Ca2+ and P in blood that favor bone mineralization w/ calcium phosphate>Normal fxning of parathyroid gland>Regulation of immune system
How is Vit D synthesized? Where is it activated?
Light causes 7-dehydrocholesterol to be converted to Vit D3 → Needs to be activated in liver and then kidney
Is dietary Vit D3 active or inactive?
Inactive
How does Vit D affect Ca2+ Abspt? PTH?
> Increases abspt of dietary Ca2+ through normalizing parathyroid gland>Vit D works w/ parathyroid hormone (PTH) to increase Ca2+ retention at kidney, increase release at the bone, and increase abspt at the intestine
Causes and symptoms of Vit D deficiency?
> Dietary Ca2+ can’t be absorbed efficiently>Improper bone mineralization>Abnormalities in bone structure>Cancer potential for all ages
Vit D deficiency in CHILDREN?
RICKETS=Bowed legs and abnormal ribs»>Has increased overtime bc children wearing more sunscreen and covered up
Vit D deficiency in ADULTS?
OSTEOMALACIA=Bone pain, muscle aches, increase in bone fractures
How does Vit E exist in food?
In 8 forms/isomers – we’re not able to absorb in all of those forms
What form of Vit E is the only form we can absorb and USE in the body?
Alpha-tocopherol
What is needed for Vit E to be absorbed and why?
FAT – bc packaged in chylomicron and then delivered throughout body
Why is Vit E requirement so high?
> Req is based on amount needed to maintain plasma concentrations of alpha-tocopherol that protect RBC membranes from rupturing>Requirement assumes vegetable oil intake»>Vit E is added to keep vegetable oils (high in polyunsat fats) from oxidizing
Causes and symptoms of Vit E deficiency in premature infants?
> Mother doesn’t transfer Vit E to fetus until 37weeks»>Can result in hemolytic anemia (rupture of RBCs)»>Same symptoms as iron and Vit B6 deficiency>Deficiency is rare bc vit E is plentiful in food supply and stored in many body tissues
What are some dietary sources of Vit E?
EVOO, Soybean oil, Nuts and seeds
What are some fxns of Vit E?
> Antioxidant»> Protects against cell damage by neutralizing free radicals that cause oxidative damage»>Neutralization Process: Vit E donates one of its e- to free radical → impairs further Vit E activity → Vit C can restore Vit E by replacing e-(replenishes its antioxidant potential)
Vit E in supplements vs in food?
> Supplement–no benefit, and some studies show Vit E supplements increase disease and hemorrhagic stroke risk>In food–not toxic»>Vegetable seed oils contain Vit E → used to decrease oxidation of oil
Benefits of Vit E in EVOO?
EVOO is highest in alpha tocophorol and monounsat fat >More Vit E available to body than in other veg oils bc its low in polyunsat fat
Primary fxn of Vit K?
Blood clotting (“Koagulation”/coagulation)
1st form of Vit K? Dietary sources?
> Phylloquinone>Plants: Leafy greens (spinach, kale, broccoli)
2nd form of Vit K? Dietary sources?
> Menaquinone >Animal foods (and synthesized by gut bacteria): Liver, salmon
Symptoms of Vit K deficiency?
Rare>Major symptom: Abnormal blood coagulation»> Discovered when cattle were given fat-free diet, cows bleeding to death bc couldn’t absorb Vit K w/o fat»>Almost no Vit K is transferred from mother to fetus → newborns are routinely given Vit K injections at birth to prevent blood clotting disorders»>Very rare in US
What is Vit K blood clotting process?
**Vit K is part of clotting cascade→Series of rxns involving clotting factors, several of which require Vit K for formation Vit K is coenzyme needed for produxn of prothrombin, other blood-clotting factors, and several proteins involved in bone formation and breakdown>Prothrombin (requires Vit K for its formation and subsequent conversion to Thrombin) → Thrombin → Fibrinogen (requires Thrombin for conversion to Fibrin) → Fibrin
Vit K Toxicity
primarily a problem if you take supplements, less risk in diet- Bc vit K fxns in blood clotting, high doses can interfere w/ anticoagulant drugs, e.g. Coumadin
What is Vit K impt for, excluding coagulation?
Bone health»>Used in laying down healthy, new bone»>Unlike other fat-soluble vitamins, the body uses vit K rapidly, so a constant supply is necessary
What is relationship btwn Vit K and Coumadin?
> Coumadin (warfarin) =anticoagulation medicine>Vit K interferes (role in clotting)»>In past: patient told not to eat Vit K containing veggies»>Newer thought: Vit K containing veggies daily, adjust med to diet
Why is too much clotting dangerous?
Risk of heart disease and strokeClots can break off and»>travel to brain → cause stroke»>travel to heart → cause heart attack
How much of the blood is composed of water? Blood fxns?
90%-Transports O2 and nutrients to cells-Removes CO2 and waste products
What are direct fxns of water in the body?
> Lubricant, cleanser, cushion against shock»>Tears: wash away dirt in eye»>Synovial fluid: lubricates joints»>Saliva: assists in chewing, tasting, swallowing»>Spinal fluid: protects again shock>Assists in regulating body temp (e.g. sweat)»>Can hold onto heat and changes body temp slowly>Part of metabolic rxns: we make water at end of ETC>Helps maintain acid-base balance
Water deficiency (dehydration) vs. intoxication (overhydration)?
> Dehydration – thirst is a late signal>Intoxication – less common»>Can lead to hyponatremia (low sodium in blood), which can result in abnormal fluid accumulation in body tissues»>Marathon concern>If water intake is low, antidiuretic hormone will cause kidney to conserve water>If water intake is high, more water will be excreted in urine
Our need for water is dependent on what 3 dietary factors? How?
> Protein, sodium, and fiber in diet»>higher consumption increases water needs>[Waste product from protein = urea]
What are the 3 principle electrolytes?
Sodium (Na+), potassium (K+), chloride (Cl-)>Positively and negatively charges ions → conduct an electrical current in water
What is distribution of principle electrolytes relative to cell?
[remember: 3Na out/2K in]>Na—main mineral OUTSIDE cell>K—main mineral INSIDE cell>Cl—exists w/ Na+ outside cell as salt, NaCl»_space;>If eat a lot of sodium food (high Na+ outside of cell), you draw water out of cell = raises BP (pressure on heart)
What are causes and symptoms of deficiency of Potassium?
> Usually caused by supplements or renal disease>”The electrolytes are found in plentiful amounts in the diet, and the kidneys of a healthy individual are efficient at regulating amounts in the body.”>”- Low levels can occur when water and electrolyte losses are increased due to excessive sweating, chronic diarrhea or vomiting, or kidney disorders.”
Toxicity of K+?
> Caused by supplements>Leads to renal disease»>Can shut down heart
Toxicity of Na+?
> Leads to high BP (hypertension/HTN)»>Rare (bc fluid usually compensates when you consume too much Na+)>Most of dietary sodium comes from packaged/ processed foods, not adding salt to food
What is HTN? Dangers?
Increase in the pressure of the blood against the arterial walls (too much pressure on arteries)>No outward symptoms but can lead to heart and kidney diseases>Can damage arteries >Atherosclerosis >CVA → stroke
Risk factors for HTN?
> Obesity>Aging>Diabetes – (bc insulin affects kidney)>Lack of physical activity>Poor diet (high Na+, low K+)>Genetics, ethnicity, smoking, heavy alcohol consumption, stress
Treatment of HTN?
Conventional: decrease Na+ in diet**Main food sources of Na+ in diet: -Processed food-Packaged food (canned)-Fast food
What is the DASH diet?
DASH=Dietary Approaches to Stop Hypertension**Increasing K+ intake by eating fruits and vegetables to lower BP
What is 1 serving of fruits or vegetables?
1/2 cup
How many servings of fruits and veg recommended for lowering BP?
9
What would a typical day on DASH diet look like?
> Fruit at breakfast>Vegetables at lunch and dinner
Definition of minerals
Nutrients needed by the body in small amounts for health and maintenance
Sources of minerals?
unprocessed foods, some processed foods (fortified) and dietary supplements>Soil and water mineral concentration affects nutrition quality/content of some foods
Why do some minerals have upper limits?
> Correct proportions of mineral intake is essential to health>ULs (upper limits) have been established for certain minerals due to toxicity, which often results from environmental pollution or excessive use of supplements
What is bioavailability?
Amount of minerals in a food that is ABSORBED and AVAILABLE to the body
What influences bioavailability?
Phytates, tannins, oxalates, and fiber ⇒Tend to be high in plant products>Minerals from plant foods are LESS available v. animal
What are major sources of tannins? How do tannins affect bioavailability?
> Black tea and red wine>Hinder abspt of Ca++
What are major sources of oxalates? How do oxalates affect bioavailability?
> Tree nuts, soy, chocolate>Bind Ca++
How does fiber affect bioavailability?
Traps minerals
How does body’s need of a mineral affect abspt?
The more deficient, the greater the abspt of that mineral
What is mineral to mineral competition?
Calcium, magnesium, iron, and copper all complete for same transport mechanisms**This competition problem is w/ supplements
What is fxn of minerals?
> Help regulate body processes, often as cofactors>Mineral cofactor combines w/ inactive enzyme to form active enzyme (???)[missed a lot → FIG]
What is Calcium? Dietary sources?
> Most abundant mineral in body, 1-2% of adult body weight>Provides structure to bones and teeth and has impt regulatory roles>Dair, fish w/ bones, leafy green veggies, fortified foods
How is Ca2+ absorbed?
> Passive diffusion → need high concentration gradient of Ca2+>Active trnspt → W/o gradient, active form of Vit D is critical to help transfer Ca2+ across cell membranes>abspt is highest pre-puberty
What factors increase and decrease bioavailability of Ca2+?
Increase—presence of vitamin D, acidic foods, lactose, and fat Decrease—iron, tannins, fiber, phytates, and oxalates
What is role of Ca2+ in the body?
> 99% is found in solid mineral deposits in the bones and teeth»>Pre-puberty is time of greatest Ca2+ deposition>Remaining 1% is found in intracellular fluid, blood, and extracellular fluid»>Role in cell communication, nerve transmission, mscl contractions, blood pressure regulation and release of hormones
What is osteoporosis? Reversible?
a condition in which loss of bone mass increases the risk of bone fractures>Loss of bone (protein and mineral content)>Not reversible
Risks factors for osteoporosis?
- risk is related to lvl of peak bone mass and rate of bone loss>older age>gender (women greater)>diet»>Ca2+ is main mineral in bone, but no data showing that intake after pre-puberty will prevent or treat osteo>low physical activity
What factors increase Ca2+ loss in urine?
> Meat/poultry/seafood metabolism>High sodium intake (???)>Low plant product intake (K+ in diet prevents loss)
Problems w/ Ca2+ Supplements
Flynn: usefulness is questionable>Has been related to kidney stones in women (17% increase in risk)>Blocks abspt of other minerals: iron, magnesium, copper
What is Phosphorus (P)? Component in body?
> Makes up about 1% of an adult’s body»>85% of P in body is found in bones and teeth>More readily absorbed than Ca2+>Impt component of molecules w/ structural or regulatory roles
Symptoms of phosphorus deficiency?
Bone loss, weakness, and loss of appetite>Rare bc it’s abundant in most foods and more easily absorbed than other minerals
Phosphorus toxicity?
Toxicity thought to be rare, can lead to bone reabspt>Daily cola (high intake of soda) = increase in bone fractures in adolescent girls, hip fractures in post-menopausal women
What is Magnesium (Mg)? Component in body?
> 50-60% in the body is found in bone»>Essential for maintenance of structure>Present inside cells, where it’s 2nd most abundant intracellular ion, after K+>Cofactor for over 300 enzymes»>Metabolism of energy-yielding nutrients>affects metabolism of calcium, sodium, and potassium
Dietary sources of Mg?
> Component of chlorophyll»>Leafy greens, nuts, seeds, bran
What are risk factors for Mg deficiency?
Deficiency is rare, but risk is high w/ high alcohol consumption or general malnourishment
What are symptoms of Mg deficiency?
-Nausea-Mscl weakness and cramping-Mental derangement -Changes in BP and heartbeat
What is Mg toxicity?
Rare>No adverse effects have been observed from food>Some toxicity from supplements observed, esp among elderly»>UL for adults has been set at 350mg from nonfood sources
What are sources of sulfur? Recommended daily intake?
> Protein-containing foods and sulfur-containing AAs in vitamins (THYMINE, BIOTIN) >Nonfood additives, e.g. sulfur dioxide, sodium sulfite, and sodium bisulfite>No recommended daily intake
What is sulfur’s role in body?
Sulfur-containing AAs, such as methionine and cysteine, are needed for protein synthesis>need in energy metabolism and in the regulation of the pH balance
Cause and symptoms of Ca2+ deficiency?
> Low intake or high loss in urine >Normal blood lvls are maintained by resorbing Ca2+ from bone, resulting in Ca2+ loss from bone- Deficiency can reduce bone mass and increase risk of osteoporosis
Symptoms of excessive Ca2+?
Kidney stones, constipation, raise blood Ca2+ lvls, interfere w/ abst of other minerals, like iron
