Chapter 12 Nutrition Notes PDF

Preview

Summary

Chapter 12 Lecture Outline ...

Description

Vitamin 1. Compound needed in very small amounts in the diet to help regulate and support chemical reactions in the body 2. Named in alphabetical order 3. Not a source of energy, but aid in energy metabolism, growth and development, and maintenance in body tissue 4. Carbon bidden to hydrogen 5. 13 vitamins are essential

Fat-Soluble vitamins 1. Vitamins that dissolve in fat and such substances as ether and benzene are NOT water 2. Vitamins A, D, E, K 3. Dissolve in organic substances

Water-Soluble vitamins 1. Dissolve in water 2. Has 8 3. B-vitamins (Thiamin, Riboflavin, Niacin, Panthothenic acid, Biotin, Folic acid, Vitamin B6, and B-12) 4. Vitamin C

Can vitamins be synthesized? Answer: Vitamins cannot be synthesized in the body or in insufficient qualities

Are all substances vitamins? Answer: No, a substance is NOT a vitamins merely because the body can't make it

Absorption of Vitamins 1. Require efficient use of bile and pancreatic lipase in the small intestine to digest dietary fat and intestinal absorption 2. Fat-soluble vitamins are absorbed along with dietary fat 3. 40-90% of fat-soluble vitamins are absorbed when consumed in recommended amounts 4. Vitamin B and C is at 90-100% and happens in the small intestine and independent of dietary fat

Absorption steps 1. (All vitamins) in stomach begins release of vitamin in food 2. (All vitamins) Digestive enzymes produced by the pancreas aid in release of vitamins from food 3. (Fat-soluble) Bile produced in the liver and stored in the gallbladder and aids in fat-soluble vitamin absorption 4. (Fat-soluble) Absorbed in the small intestine along with dietary fat, and carried by chylomicrons into the lymphatic circulation 5. (Water-soluble) Absorbed in the small intestine and released directly into blood 6. (Vitamin K) Small amounts are made by bacteria in the ileum of the small intestine and large intestine

Synthetic and natural forms of vitamins 1. Synthetic and natural forms are similar minus most natural vitamin E which is 2x potent 2. Synthetic folic acid is 2x as natural form

Malabsorption of vitamins 1. If the absorption of a vitamin is decreased, a person much consume larger amounts to avoid deficiency 2. Vitamins must be consumed in food and must be absorbed from the small intestine 3. Alcohol abuse, intestinal diseases, and absorption of some B-vitamins

Transport of Vitamins 1. Once absorbed, fat-soluble vitamins (FSV) are packaged for transport through the lymphatic system and delivered by the bloodstream to target cells in the body by chylomicrons and other blood lipoproteins (Circulates triglycerides removed by blood cells) 2. Liver repackages FSV with new proteins for transport in blood or adipose tissue/liver for later and the rest stays in liver (has FSV) from diet

Storage of Vitamins in the Body

1. Vitamins are not readily excreted from the body, but are stored in the liver and or adipose tissue 2. Water soluble vitamins (WSV) are excreted quickly by the body resulting in limited stores 3. Exceptions are vitamin B-12 and B-6 which are stored to a greater extent than the other WSV's 4. Vitamins should be consumed daily because of limited storage 5. Symptoms of deficiency usually occur several weeks later and when storage is completely depleted

Vitamin Toxicity 1. Caused by excess intake of a vitamin 5-10x greater than DRI guideline 2. Most likely to occur in FSV's A and D because they usually supply less than twice the DV of components

Vitamin A 1. Known for more than 3500 years as a factor needed to prevent night blindness 2. Refers to the preformed retinoids and provitamin A carotenoids that can be converted to vitamin A activity

Retinoids 1. 2. 3. 4.

Biologically active forms of vitamin A, including retinol, retinal, and retinoic acid. Do not need to be converted to be active Exist in 3 forms: Retinol (an alcohol), Retinal (an aldehyde), and retinoic acid Tail segment of vitamin A structure terminates in 1 of these 3 chemical groups (alcohol, aldehyde, or acid) and determines name or classification 5. Can be interconverted, BUT retinoic acid CANT be converted to other forms 6. Ability to interconvert forms helps maintain adequate amounts of each retinoid form for its unique functions 7. The tail of vitamin A molecule can vary from cis to trans configuration which influences the function of retinoid

Carotenoids 1. Pigmented materials in fruits and vegetables that range in color; 3 types yield vitamin A activity in humans and thus are called provitamin A; Many have antioxidant properties 2. A carotenoids is a tool for converting the amounts of vitamin A and carotenes expressed in a particular unit of measure into another unit of measure 3. 1 RAE 1 IU Vitamin A activity (Used to be based upon carotenoids making bigger impact than vitamin A) 4. 1 ug retinol 0.3 ug retinol

5. 12 ug beta-carotene 3.6 ug beta-carotene 6. 24 ug alpha-carotene 7.2 ug

Provitamin 1. Substance that can be made into vitamin A 2. Only alpha-carotene, beta-carotene, and beta-cryptoxanthin can be converted to biologically active forms of vitamin A 3. Found mainly in dark green and yellow-orange fruits and vegetables

Vitamin A in Foods 1. 2. 3. 4.

Found in fish, liver, fish oils, milk, eggs, and margarine (Preformed vitamin A foods) 70% of vitamin A comes from animal products Beta-carotene has the greatest amount of provitamin A activity Measured in milligram (1/1000 g) or microgram (1/1000000 g)

Dietary vitamin A 1. Dietary vitamin A activity is expressed in Retinol activity equivalents (RAE) to account for the different biological activities of retinol and provitamin A carotenoids 2. 1 RAE= 1 ug of retinol 12 ug beta-carotene and 24 ug of 2 provitamin A

Absorption, Transport, Storage, Exceretion Vitamin A 1. Retinyl esters don't have vitamin A activity until the retinol and fatty acid are separated in intestinal tract (Requires bile and pancreatic lipase enzymes) 2. (Packaged into chylomicrons before entering lymphatic circulation) 3. 90%+ of retinol is absorbed into cells of small intestine via specific carrier protein 4. Dietary carotenoids often are attached to proteins that must sppit off by digestive enzymes prior to absorption (Once freed, carotenoids are absorbed primarily by passive diffusion (rates from 5-60% of intake) 5. Provitamin ---> Retinal cell----> Retinol----> Can have fatty acid chain and be retinyl ester for lympathic system as chylomicrons (Can be cleared to form retinal acid) 6. Chylomicrons deliver vitamin A to tissues for storage or cellular use 7. Retonic acid can enther the bloodstream directly for transport to the liver 8. Carotenoids also can enther blood stream 9. Over 90% of vitamin A are found in liver with small amounts of adipose tissue, kidneys, bone marrow, testicles, and eyes (Liver has enough vitamin A in form of retinyl esters to last to several months to protect against vitamin A deficiency)

Absorption, Transport, Storage, Exceretion Vitamin A Steps 1. Vitamin A as a retinoid is released from liver into bloodstream bound to retinol binding protein (RBP) 2. On release, vitamin A enters the target cell 3. Vitamin A binds to RBP 4. Once released from RBP with vitamin A enters nucleus and binds to nuclear-retinoid receptors (RAR and RXR) 5. Complex binds to DNA activating gene transcription 6. Resulting mRNA has the code for the protein 7. Protein ultimately produces cellular responses Primary means to excrete vitamin A is via urine Carotenoids excrete via bile eliminated with feces

Functions of Vitamin A (Retinoids) 1. Growth and Development 2. Cell Differentiation 3. Vision 4. lmmune System

Growth and Development 1. Embryonic development (eyes, limbs, cardiovascular and nervous system) 2. Retinoic acid necessary for production, structure, normal function of skin cells in lungs, trachea, skin, & GI tract

Cell Differentiation 1. 2 main retinoid receptors RXR and RAR 2. Bind to specific DNA sites that regulate formation of mRNA and formation of proteins via gene expression 3. Gene expression directs cell differentiation (making stem cells specialized)

Vision 1. Vitamin A essential to retina of the eye to turn light into nerve signals to brain Rods: A light-sensitive cell of one of the two types present in large numbers in the retina of the eye, responsible mainly for monochrome vision in poor light Cones: A light-sensitive cell of one of the two types present in the retina of the eye, responding mainly to bright light and responsible for sharpness of vision and color perception Opsin: A group of light-sensitive proteins found in photoreceptor cells of the retina

Immune function: Prevent infection Vitamin A Analysis in Dermatology: Used for oral medication and prevent acne Carotenoid Functions: Diets high in carotenoid (Maeula degeneration) decrease risk for eye diseases, cancers, and cardiovascular disease

Vitamin A Toxicity 1. Occur when RDA is exceeded by 5-10x 2. Acute, chronic, and tetogenie

Vitamin D: "Conditional" vitamin prohormone (Precursor of a hormone)

Vitamin D2 in Food 1. Fatty fish, cod liver oil, fortified, milk, fortified cereals 10 ug (400 IU) per quart 2. Contain form of eryocalciferol or D2 found in natural form of foods 3. Has vitamin D activity in humans, but in lower amounts than provided by D3 formed in the body

Vitamin D3 Formation in the Skin 1. Synthesis of D3 begins with a compound called 7-dehydrocholestorol, a precursor of cholesterol synthesis located in the skin 2. Via sunlight exposure, 1 ring on the sunlight on the molecule undergoes a chemical transformation, forming the more stable D3 and this allows D3 to enter the bloodstream for transport to the liver and kidneys where conversion to its bioactive form of calcitriol

3. Sun exposure provides 80-100% of D3 needed by body (Depends upon time, location, season, age, color, and sunscreen)(D3 decreases by 70% at age 70)

Previtamin D3: Precursor of 1 form of vitamin D, produced as a result of sunlight opening a ring on 7-dehydrocholesterol in the skin

Vitamin D Needs 1. North Americans need 10 ug (400 IU) 2. RDA to 15 ug 1 day (600 IU/day) 1-70 and 20 ug (800 IU) for 70+ (Based upon minimum sun exposure

Absorption, Storage, Transport, and Excretion of Vitamin D 1. 80% of vitamin D2 is incorporated (along with other dietary fats) into micelles in the SI, absorbed and transported to the liver by chylomicrons through lymphatic system

Absorption, Storage, Transport, and Excretion of Vitamin D Steps 1. UV light from sun converts 7-dehydrocholestorol to vitamin D3 (cholecalciferol) in skin 2. Dietary vitamin D is absorbed with dietary fat in the intestine 3. Vitamin D from both dietary sources and synthesis in skin is bound to carrier proteins and transported to the liver 4. Vitamin D is converted in the liver to 25-OH D3 (calcidiol) 5. Vitamin D is converted in the kidney to 125 (OH2) vitamin D3 (calcitriol)

Functions of Vitamin D 1. Calcitriol is most active form of Vitamin D 2. Maintains body concentration of calcium and phosphorus maintaining skeletal health 3. Intestinal absorption of calcium and phosphorus from food and minerals 4. Low blood calcium levels cause PHH and 1,25 (OH2) vitamin D3 to mobilize calcium from bone 5. PTH also reduces calcium excretion by kidneys and stimulates kidney synthesis of 1,25 (OH2) vitamin D3 6. 1,25 (OH2) vitamin D3 stimulates intestinal calcium absorption 7. High blood calcium levels cause increased synthesis of the hormone calcitonin, which promotes calcium deposits in bones to help blood calcium levels return to normal

Vitamin D Deficiency 1. Weak bones because skeleton will not mineralize without adequate calcium 2. 20-25 ug (800-1000 IU) of vitamin D each day until concentration 3. Once normal 10 ug (400 IU/day) is good

Rickets: Disease by inadequate mineralization of bones caused by poor calcium deposition during growth (infants and children) Osteeomalacia: Weakening of bones that occurs in adults as a results of poor bone mineralization linked to inadequate vitamin D states

Vitamin D Toxicity 1. UL is 1000-3000 for infants- 8 years old 2. 4000 IU's per day for 9+

Vitamin E 1. 2. 3. 4.

Key to reproduction Vitamin E later named tocopherol Deficiency noticed with fat malabsorption diseases Family naturally occurring compounds- 4 tocopherols (alpha, beta, gamma, delta) & 4 tocotrienols (same as above) 5. Long carbon chain tail attached to a ringed structure (isomer forms) 6. Most active is alpha-tocopherol

Vitamin E in Foods: Plant oils, wheat germ, avocado, almonds, peanuts, and sunflower seeds Depending upon harvesting processing, storage, and cooking can be destroyed by oxygen, metals, light, and heat via frying

Vitamin E Needs 1. RDA is 15mg/day of alphartocopherol 2. Based on the amount needed to prevent a breakdown of red blood cell membrane by hemolys (Equivalent to 22 IU of natural and 33 IU synthetic) 3. On average, we get 2/3 4. IU= 0.45 mg and 1 IU= 0.67 mg

Absorption, Storage, Transport, and Excretion of Vitamin E 1. Absorption depends upon amount of dietary fat via pasive diffusion (20-70% dietary intake) 2. Must incorporated into micelles in SI a process dependent on bile and pancreatic enzymes and once taken up by the intestinal cells, vitamin E is incorporated into chymocrions for transport in the lymph and eventually blood 3. As chylomicrons are broken down, most of vitamin E to the liver as chylomicron remnants and some goes to other tissues 4. Liver prepackages with lipoprotein (VLDL, LDL, and HDL) for delivery to body tissues (FSV E does not have specific protein in blood lipoproteins and most goes to adipose tissue and not liver) 5. Can be excreted via bile, urine, and skin

Functions of Vitamin E 1. Important part of the body's antioxidant network (maintain integrity of cell membranes by stopping chains reacting to free radicals 2. Antioxidants function in a variety of ways to regulate FR's and prevent damage 3. Lipid peroxidation reactions break apart fatty acids and create lipid peroxyl radicals (LPR) 4. Superoxide dismutase enzymes eliminate superoxide radicals that form when oxygen reacts with other compounds (2 require cu and zinc)(3 require mineral mg in mitochondria) Free radicals 1. Compounds with an unpaired electron which causes it to seek an electron from another compound Strong oxidizing agents and can be very destructive to electron dense cell components 2. Destroy invading pathogens, generate leukocytes, destroy bacteria and viruses

Lipid peroxyl radicals 1. Peroxide compound containing a free radical, designated R-O-O, R is a carbonhydrogen chain broken off of a fatty acid chain and the dot is an unpaired electron 2. Vitamin E is most effective at stopping LPR by donating a hydrogen to lipid radicals stopping the peroxidation chain 3. Vitamin E keeps cell integrity by limiting oxidiative stress

Glutathione peroxidase: Selenium containing enzyme that can destroy peroxides acts in

conjunction with vitamin E to reduce FR damage to cells

Catalse: Enzyme that breaks down hydrogen peroxide (H2O2) to water

Vitamin E Deficiency 1. Found in Chrons disease, smokers, and preterm infants 2. Premature breakdown of red blood cells and development of hemolytic anemia

Vitamin E Toxicity 1. Excessive amounts interfere with vitamin K in blood clotting and cause hemorrhaging 2. UL is 1000 mg (1500 IU) of alpha-tocopherol for natural and 1100 for synthetic sources

Vitamin K 1. Role in blood clotting 2. Named after koagulation (formation of blood clot) 3. Family compound of vitamin K are phylloquinones (Come from plants K and most biologically active form) and memaquione (Found in meat (K2) and synthesized by bacteria in colon)

Sources of Vitamin K: 10% from bacterial synthesis in colon and 90% is in diet (Veggies and is destroyed by heat) Vitamin K Needs: 90 ug/day (For women) and 120 ug/day (For men)

Absorption, Storage, Transport, and Excretion of Vitamin K 1. 80% of vitamin K is taken by SI and incorporated into chylomicrons and requires bile and pancreatic enzymes 2. The menaquinones synthesized by bacteria in colon are via passive diffusion 3. Can be incorporated into the lipoprotein VLDL in the liver for storage or carried by HDL and LDL to cells throughout the body 4. Excretion via bile by feces and small amount by urine

Function of Vitamin K

1. Synthesis of blood clotting factors by liver and conversion of preprothrombin bin to the active blood clotting factor called prothrombin (Co2 is added to a glutamic acid in preprothrombin, yielding prothrombin and then vitamin K is converted to an inactive form once it has inactive form once it has activated the clotting factors

Deficiencies of Vitamin K: Occur in newborns; Antibiotics mess with vitamin K Dietary supplements: Dietary supplements are used when diet...