jimtrue.com : school : HS1322 : CH06: Vitamins

Posted by Jim True on November 24, 2009 9:10 PM. Last Updated November 24, 2009 9:10 PM

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CH06: Vitamins

Characteristics of Vitamins

• All vitamins are similar because they made of the same elements: carbon, hydrogen, oxygen, nitrogen and some cobalt
• Vitamins are different in two ways: 1) arrangement of the elements, 2) different in their functions

Water-soluble vs Fat-Soluble Vitamins

• Water-Soluble: A, D, E & K
• Fat - Soluble: Vitamin C, B-complex such as thiamin, folate and B12

Fat Soluble Vitamins

• General found in foods containing fats and are stored in the body either in the liver or in adipose tissue until needed
• Excessive intake of A or D causes them to be stored and can be undesirable
• Vitamin D is the MOST toxic of all the vitamins
• Absorbed and transported around the body like other fats
• Any interference with fat absorption may prevent these vitamins to be absorbed
• Low intake of Vitamin A and E is a concern for adults, children may have low intakes of Vitamin E
• RDA of Vitamin A: 900microg for Men/ 700mg for Women: UL (Upper Level): 3000microg

Forms of Vitamin A: Retinoids

• Retinol: will convert to Retinal and Reinoic Acid in your body
• Retinal
• Retinoic Acid
• Carotenoids: Yellow vegetables (carrots and sweet potatoes) or deep green vegetables (spinach), make Beta-Carotene converts to Retinol

Functions of Vitamin A

• Essential for health of the cornea (clear membrane surrounding the eye); deficiency causes xerosis (dry eye) and eventually xerophthalmia (no tears)
• Essential for retina of eye: deficiency causes night blindness
• Needed to make and maintain the epithelial cells that form the protective linings of your lungs, GI tract and urinary tract
• Also essential to make and maintain epithelial cells that produced mucus (protects cells)
• Role in reproduction, growth and development, bone growth and teeth development in children
• Proper functioning of the immune system

Beta Carotene

• A precursor of vitamin A
• Functions as an antioxidant in the body; a compound that combines with oxygen to prevent oxygen from oxidizing or destroying important substances
• Rich sources: Deep green vegetables, deep orange fruits and vegetables

Retinol

• Preformed Vitamin A
• Found in animal products such as: liver, vitamin a fortified milk, eggs, fortified cereals, butter and margarine

Measurements of Vitamin A

• Measured in retinol activity equivalents (RAE)
• One RAE =
• - 1 microgram retinol
• - 12 micrograms beta-carotene
• - 24 micrograms of other vitamin A precursors

Vitamin A Deficiency & Toxicity

• Deficiency is of most concern in developing countries where it causes night blindness, blindness, poor growth and other problems
• Prolonged use of high doses of preformed Vitamin A may cause hypervitaminosis A: hair loss, bone pain, skn problems, liver damage, nausea/diarrhea

Vitamin D

• When ultraviolet rays shine on your skin, a cholesterol like substance is converted into a precursor of Vitamin D and aborbed in the blood
• Over the next few days, the precursor is converted to vitamin D3 (cholecalciferol)
• Vitamin D3 is converted into its active form a hormone by enzymes in the liver and then the kidney
• 2 FACTS: can be most toxic vitamin in the body and acts like a hormone
• A racist vitamin because light skinned people can expose themselves 2-3 times a week to the sun and get enough Vitamin D; dark skinned need more exposure, because they have pigmentation, melanin which acts like sunscreen
• Body will store Vitamin D during periods of no sun exposure

Functions of Vitamin D

• Maintains blood calcium levels by:
• Increasing calcium absorption in the intestine
• Decreasing the amount of calcium excreted by the kidney
• Pulling calcium out of the bones
• Blood calcium levels must be kept high so there is enough calcium to build bones and teeth, contract muscles, and transmit nerve impulses
• Bone growth

Sources of Vitamin D

• Vitamin D fortified milk and cereals
• Fatty fish

Vitamin D: Deficiency and Toxicity

• Deficiency in children: rickets - children disease in which bones do not grow normally, results in bowed legs and knocked knees
• Deficiency in adults: osteomalacia - adult disease result in legs and spinal bones are softened and maybe bend
• Toxicity: Vitamin D is the MOST toxic of all vitamins
• About 4 to 5x the Adequate Intake: symptoms will include nausea, vomiting, diarrhea, fatigue, and confusion; can lead to calcium deposits in the heart, blood vessels and kidneys

Functions of Vitamin D

• Antioxidant - especially helps the red blood cells and cells in the lungs and brain
• May protect against heart disease by preventing the oxidation of LDL

Food Sources for Vitamin E

• Widely distributed in plant foods:
• Vegetable oils, margarine and shortening
• Salad dressing made from vegetable oils
• Seeds and nuts
• whole-grain breads and cereals
• Most Americans don't consume enough Vitamin E

Vitamin K

• Essential role in producing blood clotting factors, such as prothrombin
• Needed to make an important protein used form bone
• Bacteria in the intestines produce a form of Vitamin K
• Food sources: liver, green leafy vegetables, broccoli, vegetable oils

Water-Soluble Vitamins

• Includes Vitamin C and B-Complex vitamins
• B vitamins work in every cell as coenzymes
• Only small amounts of water-soluble vitamins are stored in body (except B6 and B12)
• American adults take in too little vitamin C
• Excessive supplementation of certain water-soluble vitamins can cause toxic effects

Functions of Vitamin C

• Needed to make collagen, a fibrous protein that is part of skin, bone, teeth, ligaments, and other connective structures (vitamin C acts like Cement)
• Needed to make some hormones, such as thyroxine
• Needed for immune system
• Antioxidant (like Vitamin E and beta-carotene)
• Helps iron to be absorbed

Vitamin C as an Antioxidant

• Ascorbic Acid <-> DehydroAscorbic Acid
• OH - Hydroxic Group

Food Sources of Vitamin C

• Citrus fruits, Bell peppers, kiwi fruit, strawberries, tomatoes, broccoli, potatoes, fortified juices and cereals

Vitamin C: Deficiency and Toxicity

• Deficiencies resulting in scurvy are rare (bleeding of the gums, loose teeth)
• Situations that require additional Vitamin C: pregnancy, lactation, growth , fever, infections, burns, surgery and smoking
• UL is 2 grams: Over 2 grams causes gastrointestinal symptoms. HIgh levels interfere with certain medical tests: Men 90mg, 75mg; UL 2000mg

Thiamin(B1), Riboflavin (B2) and Niacin(B3)

• All play key roles as part of coenzymes in energy metabolism: they are essential to release energy from carbohydrates, fats, and proteins
• All are needed for normal growth
• Thiamin also plays a role in nerve function
• Riboflavin is needed to help form Vitamin B6 coenzyme and to make niacin in the body
• RDA Thiamin B1: Men 1.2 Mg, Women 1.1 mg: UL None
• RDA B2: Men 1.3, Women 1.1, UL None
• B3: Men 16 Mg, Women 14mg, UL 35 mg

Food sources For B1-3

• Thiamin (B1) - pork, sunflower seeds, wheat germ, peanuts, dry beans, whole-grain and enriched breads/cereals
• Riboflavin (B2) - Milk & Milk products, organ meats, whole-grain & enriched bread/cereals
• Niacin (B3) - Meat, poultry, fish, organ meats, whole-grain and enriched breads and cereals, peanut butter

Tryptophan found in protein foods is converted to niacin in the body

Functions of Vitamin B6

• Important role as part of coenzyme involved in carbohydrate, fat and ESPECIALLY protein metabolism
• To make hemoglobin
• Import to the immune system, WBC's
• Also used to break down glycogen to glucose and to make neurotransmitters
• RDA for B6: 1.3 mg for both men/women: UL: 100mg

Sources of Vitamin B6

• Meat, poultry, fish, not as well absorbed from plant foods, potatoes, some fruits (bananas and watermelons), some leafy green vegetables (broccoli/spinach), fortified ready-to-eat cereals

Vitamin B6: Deficiency and Toxicity

• Deficiency: May occur in women and older adults, fatigue, depression, irritability
• Toxicity: more than 2 grams daily for 2 months or more than 200 mg daily for longer can cause irreversible nerve damage and symptoms such as numbness in hands and feet and difficulty walking
• B6 is stored in the muscles

Functions of Folate (B9)

• Part of coenzymes required to make DNA the genetic material contained in every cell
• therefore folate is needed to make all new cells, especially those that need to be replenished frequently: RBC, WBC and Digestive tract cells
• Needed for amino acid metabolism
• RDA: 400 microgram Men/Women, UL: 1000 micrograms

Sources of Folate (B9)

• Green leafy vegetables, legumes, orange juice, fortified breads and ready-to-eat cereals, much folate is lost during food prep and cooking

Dietary Folate Equivalents (DFEs)

• RDA for folate is measured in micrograms of DFEs
• DFEs take into account the amount of folate absorbed from natural and synthetic sources
• Synthetic Folate is used in fortified foods such as breads and in supplements
• Synthetic folate is absorbed at 1.7 times the rate of naturally occuring folate

Folate Deficiency

• Deficiency causes megaloblastic anemia: RBC are large and immature
• Other deficiency symptoms: digestive tract problems such as diarrhea, mental confusion and depression
• During earliest weeks of pregnancy, women need folate because a deficiency can caues neural tube defects
• Some medications interfere with the normal use of folate in the body

Functions of B12

• Convert folate (B9) into its active forms so that it can make DNA
• B12 removes the methyl group; both coenzymes are now active
• RDA: 2.4 microgram Men/Women: UL- None
• Also functions as part of a coenzyme needed to make new cells and DNA
• Helps in the normal functioning of the nervous system by maintaining the protective cover around nerve fibers
• Bone cells depend on Vitamin B12

Sources of Vitamin B12

• Only Animal foods: meat, poultry, fish and shellfish, eggs, milk and milk products
• Vegetarian concerns

Vitamin B12 Deficiency

• Deficiency is usually due to problem with absorption - lack of intrinsic factor or lack of hydrochloric acid, both are more so problems as you get older
• Pernicious anemia: develops when B12 is not properly absorbed. Symptoms: macrocytic anemia, weakness and fatigue, nervous system problems: blaance, numbness, confusion

Pathothentic Acid and Biotin

• Parts of coenzymes involved in energy metabolism
• Pantothenic acid is also neededto make lipids, neurotransmitters, and hemoglobin
• biotin is also involved in the metabolism of carbohydrates, fats and protein

Sources of Pantothenic Acid & Biotin

• Both are widespread in foods
• Panto: fortified cereals, beef, pultry, mushrooms, potatoes, tomatoes
• Biotin: egg yolks (intestinal bacteria make considerable amounts of biotin

Choline

• Choline can be made in the body in small amounts
• Needed to make the neurotransmitter acetylcholine and the phospholipid lecithin (Major component of cell membranes)
• Widespread in foods
• Choline is a conditionally essential nutrient

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