Chapter 8 Vitamins Flashcards
Vitamins
Two Classes-
Fat-soluble- A,D,E,K need fat to be absorbed
Water-soluble- B vitamins, C
B vitamins
thaimin, rinoflavin, niacin, pantothenic acid, biotin, vitamin B-6, folate, B-12
B-12 & B-6- stored in liver, not easily excreted in urine- water soluble but can accumulate to toxic levels
Two qualifications to be a vitamin
1) Body is unable to synthesize
compound to maintain health
2) absence from diet for a period of time produces deficiencies, unless reversed by re-introducing
Megadoses
intake of nutrient above estimated needs to prevent deficiency or for aid in certain treatments
Fat- Soluble Vitamins
Absorbed with dietary fat
Efficient absorption yields 40-90% intake
Unabsorbed fat carries fat-soluble vitamins with it to be excreted through feces (Deficiency risk)
Water-Soluble Vitamins
B Vitamins- broken down into free form by stomach & small intestine- absorbed by small intestine- 50/90% absorption rate by small intestine- then transported to liver via hepatic portal vein distributed to body tissues
Factors that can destroy vitamins
heat, light, exposure to air, cooking in water, alkalinity
Benefits of frozen veggies
Vegetables are harvested and immediately frozen- blanched in boiling water as part of freezing process- blanching destroys enzymes in food that degrade vitamins overtime
Functional Foods Definition
Two Categories:
foods that have health benefits beyond basic nutrition needs
Zoochemical- health-promoting chemicals found in animal foods
Phytochemical- health promoting compounds found in plant foods- also serve as environmental protection for plants against UV’S, insects, predators
Phytochemical funtions
-Stimulate immune
-Reduce inflammation
prevent DNA damage and aid in DNA repair
-Reduce oxidative stress on cells
-Regulate intracellular signaling of hormones and gene expression
-Activate insulin receptors
-Inhibit initiation and proliferation of cancer and stimulate spontaneous cell death
-Alter absorption,production, metabolism of cholesterol
-Mimic or inhibit hormones and enzymes
-Decrease the formation of blood clots
Vitamin A Fun Facts
- 90% stored in liver & 10% stored in adipose tissue, kidneys, lungs
- 3 active forms: Retinol, retinal, retinoic acid- exist only in animal products
- Retinol is stored by way of joined to a fatty acid and becomes retinyl
Carotenoid Fun Facts
- Precursors of Vitamin A found in plant foods
- Categorized as phytochemicals
- 3 forms allotted to be converted to retinol in the body: alpha-carotene, beta-carotene, beta-cryptoxanthin (all three termed: provitamin A)
Vitamin A Functions (Immune & Epithelial Cells)
- Maintains health of epithelial cells (line the external surface of the lungs, intestines, stomach, vagina, urinary tract, bladder, eyes, skin)
- Retinoic acid: required for immature epithelial cells to mature
- Vit A supports activity of T-Lymphocytes
Vitamin A Functions (Vision)
- Cones & Rods in the eye(retina) require Vit A to function properly- retinal (form) allows eye to adjust to dim light
- Progressive deficiency- cells in cornea lining decrease mucus production- dry eye
- Vitamin A deficiency- leading cause of blindness worldwide
- Macula- part of eye responsible for most detailed, central vision- contains carotenoids: lutein & zeaxanthin- riches sources: green leafy vegetables- higher % consumed in diet lead to lower risk for age-related macular degeneration
- Carotenoids from whole foods are preferred vs supplementation to reap health benefits- studies generally conducted on carotenoid consumption through food rather than supplementation
Vitamin A Functions (Growth, Development, Reproduction)
- Binds to receptors on DNA to increase synthesis for certain proteins associated with growth- fetal growth- functions in the differentiation and maturation of cells that form tissues & organs
- Bone growth during childhood- assists with breakdown and formation of healthy bone tissue
- Aids in sperm production
- Needed for normal reproductive cycle in women
Sources of Preformed Vitamin A
liver, fish, fish oils, forified milk, butter, yogurt, eggs
- 70% of American diet includes these sources
Sources of Proformed Vitamin A (carotentoids)
Dark green vegetables, yell-orange vegetables, carrots, winter squash, broccoli, mangos, sweet potatoes, peaches, apricots
Vitamin D Two Unique Qualities
1) Only nutrient that is also a hormone
2) Only nutrient that can be produced in the skin from UV rays
7- dehydrocholesterol
Found in skin- a precursor to vitamin D- form of cholesterol that is then made into vitamin D3 (cholecalciferol) when exposed to uv rays on skin
Vitamin D3 (Cholecalciferol)
previtamin form found naturally in some animal sources- fish egg yolks
How Vtamin D3 is made in active hormone form in the body
Skin: UV rays from sun activate 7-Dehydrocholesterol > makes Vitamin D3 (cholecalciferol) > liver: activates cholecalciferol to make 25-hydroxyvitamin D3 (calcidiol) > Kidneys: in turn make biologically active for of Vitamin D3 (calcitrol)
Factors that affects UVB ray absorption
dark skin pigment, geographic latitude, time of day, season of year, weather conditions, amount of skin covered by clothing
- UVB absorption and synthesis of vitamin D decreases with old age > 70% by age 70
- Dark skin pigment need 3-5x the amount of time in the sun (approx. 3-5x longer than avg. > 45 min/ 1hr)
Functions of Vitamin D (Blood Calcium regulation)
- Calcitrol: maintains normal levels of calcium and phosphorus in the blood > Pairs with PTH (parathyroid hormone) to regulate blood calcium
- Regulates in 3 ways:
1) influences calcium & phosphorus absorption from small intestine
2) Works in combo with PTH & Calcitonin to regulate calcium exretion via kidney
3) Affects deposition/withdraw of minerals from bones
Functions of Vitamin D (Gene Expression and Cell Growth)
- Involved in gene expression and cell growth > binds to and affects cells of the immune, nervous, parathyroid, pancreas, skin, muscles, reproductive organs
- Considered most important regulator of cell growth influencing normal development of certain cells (skin, colon, prostate, breast) adequate vitamin D can reduce risk for these cancers
Vitamin D Deficiency
- Low levels- small intestine only able to absorb around 10-155 calcium from diet
- Deficiency can be traced by poor dietary intake, malabsorption, altered metabolism (e.g liver or kidney disease), inadequate sun exposure
Rickets
- When referenced in children, will present itself as bowed legs, thick wrists and ankles, curvature of spine, pigeon chest (protrutes above the sternum), skull malformations, pelvic deformities
Osteomalacia
- Adult form of rickets
- Can result from low calcium intake, insufficient calcuim absorption in small bowel, poor conservation of calcium by the kidneys
- Most common in people with liver, gallbladder, stomach, intestinal disease or cirrhosis of the liver
- 400-800 IU/ day of Vitamin D supp in conjunction w/ adequate calcium from diet proves to reduce fracture risk in older adults
Two Forms of Vitamin D
Vitamin D3 Vitamin D2 (ergocalciferol) - synthetic product from irradiation of plant sterols and used in some supps
Food sources of Vitamin D
- Fatty fish: richest source > wild-caught salmon 600-1000 IU/ 3.5 oz > farmed salmon 100-250 IU/ same amount
- Tuna > 6oz/ 300 IU approx.
- Egg yolk > approx 41 IU/ one large yolk
Adolescence intake of Vitamin D
- Recommended by American Academy of Pediatrics- all infants to small adolescent children take up to a minimum of 400 IU/ day
- breast milk- poor source of vitamin D
Symptoms of Vitamin D Toxicity
- Weakness, loss of appetite, diarrhea, vomiting, mental confusion, increased urine output
Vitamin E Functions
- 8 total forms > most potent/ biologically active : alpha- tocopherol
- Antoxidant > principle function in humans
- Found mainly in adipose tissue & lipid bilayers of cell membranes (mainly polyunsaturated fats)
- Aids free radical neutralization in cell membrane by donating electrons or hydrogen to the free radical> important function for organs highly exposed to oxygen (lungs, red blood cells)
Other functions:
- Important for muscle & nervous system development in early human development
- Improves Vitamin A absorption when Vitamin A dietary intake is low
- Functions in metabolism of iron in cells
Vitamin E Deficiency
- Higher risk for pre-term infants > have low Vitamin E stores > mother transfers to baby during late stages of pregnancy
- Smokers high risk for deficiency
Vitamin E Drug Interactions
- Insufficient blood clotting (prolonged bleeding) risk if taken in conjunction w/ Vitamin E while taking anticoagulant medications (e.g Coumadin, heavy aspirin use)
Vitamin K General Facts
- Found in plants, plant oils, fish oils, animal products
- Synthesized by bacteria in the colon > fulfills 10% of human requirements
- 3 forms;
1) phylloquinone (most abundant form from green plants)
2) menaquinone (made by gut bacteria)
3) menadione (synthetic form found in supps but 2x biologically available as other two forms
Vitamin K Functions
- Life and death blood clotting > serves as a cofactor in chemical reactions that add CO2 to various proteins that enables calcium to bind to those proteins
- Bone health > osteoclasts depend on vitamin K for bone mineralization
Vitamin K Deficiency
- Newborns have sterile gut (insufficient bacteria in intestinal tract) > cannot produce enough vitamin K for effective blood clotting
- Extended use of antibiotics > deficiency risk
- Chronic antibiotic use destroys naturally occurring bacteria that produce vitamin K that is absorbed and used by the body
- When fat absorption is limited
3 Forms of Vitamin K
1) phylloquinone- most abundant form
2) menaquinone- synthesized by gut bacteria
3) menadione- synthetic form found in supplements
Food sources of Vitamin K (phylloquinone)
green leafy veggies, broccoli, asparagus, peas
Anemia
- A decreased oxygen-carrying capacity of the blood. Caused by many factors like iron deficiency and major blood loss
Thiamin (B-1) Functions
- aids in releasing energy from carbs
- coenzyme form (TPP) participates in reactions in which carbon dioxide (CO2) is released > important in the process of the body to produce ATP by the breakdown of carbohydrates/amino acids
- aids in chemical reactions that make RNA, DNA, and neurotransmitters
BeriBeri
Thiamin deficiency disorder is characterized by weakness, loss of appetite, irritability, nervous tingles throughput body, poor leg/arm coordination, deep muscle pain in the calves
- results when glucose can’t be metabolized to release energy due to lack of thiamin > thiamin coenzyme participates in glucose metabolism
Riboflavin (B-2)
Functions
- Coenzyme forms:
(FAD) flavin dinucleotide & flavin mononucleotide (FMN)
> participate in the metabolic, energy-yielding breakdown of fatty acids
Niacin (B-3)
Functions
- Functions as two compounds:
nicotnic acid & nicitinamide - Niacin coenzyme: nicotinamide adenine dinucleotide (NAD) & nicotinamide adenine dinucleotide phosphate (NADP) is used in ATP generation (energy production through breakdown of carbohydrates or fats )
- Used for over 200 enzymatic reactions in the body
Vitamin B-6
Functions
- coenzyme in over 100 reactions for amino acid and protein metabolism
- PLP pyroxidal phosphate (B-6 coenzyme) participates in synthesis of nonessential amino acids> splits nitrogen group from an amino acid >makes available to another amino acid
- synthesis of neurotransmitters > serotonin & gamma aminobutyric acid > tryptophan into niacin > breakdown storage of glycogen into glucose > production of white blood cells
- plays role in homocysteine metabolism
Megaloblastic Anemia
Anemia, characterized by abnormally large red blood cells
Clinical Indications of Folate Deficiency
- disrupts blood cell division> blood sample may indicate abnormally large blood cells
- inflammation of tongue, poor growth, mental confusion, depression
