Chapter 7 Vitamins.

Chapter 7 Vitamins

Key Concepts Vitamins are noncaloric essential nutrients that are necessary in very small amounts for specific metabolic control and disease prevention Certain health problems are related to inadequate or excessive vitamin intake

Key Concepts Vitamins occur in a wide variety of foods that are packaged with the energy- and tissue-building macronutrients (CHO, fat, and protein) The body uses vitamins to make coenzymes required for some specific enzymes to function Vitamin supplementation needs depend on a person’s vitamin status

Objectives Describe what vitamins do in the human body Identify: the nature of vitamins the fat soluble vitamins the water soluble vitamins the B – Complex vitamins food sources of vitamins Describe the issue of vitamin supplementation

Dietary Reference Intake: DRI
4 interconnected categories of recommendations: The Recommended Dietary Allowance (RDA)- The daily intake that meets the needs of almost all healthy individuals in a specific group Estimated Average Requirements (EAR) – Basis for developing the RDA “the intake that meets the needs of half of the individuals in a reference population

Dietary Reference Intake: DRI
4 Interconnected categories (cont’d) Adequate Intake (AI) – Guidelines used when not enough scientific evidence available to establish an RDA Tolerable Upper Intake Level – New guideline that sets the maximum intake of a nutrient that is unlikely to pose a risk of toxicity in healthy individuals

The Nature of Vitamins Early observations: Vitamins were discovered during the search for cures for classic diseases that were initially thought to be associated with dietary deficiencies 1753- British Naval surgeon Dr. James Lind observed that on long voyages, when sailors were forced to live on very limited rations because no fresh foods were available, many of them became ill and died. When Lind gave some fresh lemons and limes, no one became ill. This vital clue led to the discovery that “scurvy” was caused by a dietary deficiency

History of vitamin discovery

The Nature of Vitamins Vitamin Discovery cont. Early Animal Experiments: Dr. Frederich Hopkins of Cambridge University fed a group of rats a diet of a synthetic mixture of protein, fat, CHO, mineral salts and water. All of the animals became ill and died. When he added milk to the purified ration, all of the rats grew normally  discovery: accessory factors present in natural foods that are essential for life

The Nature of Vitamins Vitamin Discovery cont. Most of the vitamins now known were discovered during the first half of the 1900s. 1911 – Casimir Funk, a Polish chemist, discovered a nitrogen-containing substance called amine which he thought was the chemical nature of these vital agents. So he called it “vitamine”

Definition: Vitamin Must be organic, dietary substance that is not a carbohydrate, fat, protein, or mineral and is necessary in extremely small amounts to perform a specific metabolic function or prevent an associated deficiency disease Must perform a vital function It cannot be manufactured by the body in sufficient quantities to sustain life - it must be supplied by the diet

Functions of Vitamins General Functions: 1. Components of coenzymes 2. Antioxidants 3. Hormones that affect gene expression 4. Cell membrane component 5. Component of light-sensitive rhodopsin molecule in eyes

Functions of vitamins Control agent to cell metabolism – Enzymes and coenzymes control specific chemical reactions by acting as necessary catalysts – e.g. B vitamins thiamin, niacin, and riboflavin help turn glucose to energy. Component of body tissue construction – Vit C helps synthesize collagen- Also act as antioxidants to protect cell structure and prevent free radical damage Prevent specific nutritional deficiency disease – e.g. scurvy due to lack of vit C

Vitamin Metabolism Fat-Soluble Vitamins: A,D,E,K Dependant upon fat for absorption and transport -incorporated into lipoproteins along with dietary fat- Then enter lymphatic system for circulation – stored for long periods of time in liver and adipose tissue Absorbed in the GI tract Excess intake can result in toxicity

Vitamin Metabolism Water-Soluble Vitamins: Vit C and most of B vitamins Easily absorbed directly into the blood circulation from GI tract Does not need a carrier With the exception of B12 & B6 body does not store water soluble vitamins- need foods rich in water-soluble vitamins daily

Section 1 Fat-Soluble Vitamins

Vitamin A (Retinol) Functions Vision Major function in the retina of eye. Retinol is a part of rhodopsin, that is the pigment in the eye known as visual purple Enables the eye to adjust to different amounts of available light. Maintenance of vision in dim light. Mild deficiency  night blindness

Vitamin A (Retinol) Tissue strength and immunity
Function cont. Tissue strength and immunity Maintains epithelial tissue Primary barrier to infection- the vital protective tissue covering the body (skin) and the mucous membranes in the nose, throat, eyes, GI tract, and GU tract Growth of skeletal and soft tissue Influences the stability of cell membranes and protein synthesis

Vitamin A Requirements = 700ug women and 900ug for men
Food forms and units of measure: Vitamin A occurs in 2 forms: Preformed Vit A or Retinol The ‘active’ vitamin A found in foods derived from animals Beta-Carotene a pigment in yellow and green foods that the body converts to Vit. A Body storage – liver can store large amounts of retinol

Vitamin A Food sources – Page 99 (Table 7-1) Fish liver oils, egg yolks, butter, cream, fat part of milk; dark leafy greens, orange veggies and fruits Stability – Retinol is unstable in heat and in contact with air. Cook quickly with little water.

Vitamin A foods

Vitamin A Vitamin A : Deficiency disease Xerosis – itching and burning and red inflamed lids Xerophthalmia –blindness Note: Vitamin A deficiency is the number one cause of blindness in children world wide Epithelial Disorders and compromised immune system

Vitamin A Toxicity symptoms – (Hypervitaminosis A)
joint pain thickening of long bones loss of hair jaundice, liver injury which could result in elevated blood pressure (portal hypertension) or swelling or fluid accumulation in the abdominal cavity (ascites) UL = 3000 mcg / day Toxicity usually results from the Preformed Vit A and not beta-Carotene sources

Vitamin D (Cholecalciferol)
Functions Not a true vitamin because made in our own bodies with the help of the sun’s ultraviolet rays. Mistakenly classified as a vitamin by its discoverers in 1922, because they were able to cure the childhood deficiency disease, rickets, with its only known natural form in fish liver oils.

Function cont. The compound made in our skin by sunlight is actually a “prohormone” – a fat-soluble sterol (cholecalciferol/calciferol) that controls calcium metabolism in bone building Calciferol is then activated by 2 enzymes to become the active Vitamin D hormone form called calcitriol that functions in the body.

Calcitriol performs the following functions: Acts physiologically with the parathyroid hormone (PTH) and the thyroid hormone calcitonin. In balance with these 2 hormones, the Vitamin D hormone (calcitriol) stimulates the absorption of calcium and phosphorus in the small intestine

Vitamin D Bone mineralization – Vit D (calcitriol) works with calcium and phosphorus to form bone tissue, regulating the rate of deposit and resorption of these minerals in bone.  Clinically used to tx. osteoporosis

Vitamin D Requirements: Difficult to establish an RDA because: 1. made in the skin by the sun’s UV rays 2. food sources are limited 3. Vit D requirements vary with individuals exposure to sunlight which is affected by season, latitude, and skin color Adequate Intake is 600 IU/ day UL upper limit is 4,000 IU/day Recommendation: triple dose for persons 70+ years old

Vitamin D Food sources: Only fish liver oils and yeast are natural sources Foods fortified with Vitamin D Stability: Vit D is stable to heat, aging and storage

Vitamin D Deficiency disease Rickets – Malformation of skeletal tissue in growing children- Soft bones will bend with the weight of the child Poorly developed teeth and bone Toxicity symptoms- Hypervitaminosis D Calcification of soft tissue in kidneys and lungs Fragile bones

Vitamin E (Tocopherol)
History Early vitamin studies identified a substance necessary for animal reproduction that was chemically in alcohol This “substance” was named “tocopherol” – Gk. – “tophos” meaning childbirth “phero” meaning “to bring” “ol” from alcohol

Fat –soluble 3 forms display the most biological activity: alphatocopherol, betatocopherol, gammatocopherol. Of these three, alphatocopherol is the most significant in human nutrition and is used for measuring dietary needs

Functions: Antioxidant function – A molecule that prevents cellular structure from being broken down by oxygen (the process of oxidation) Relation to selenium metabolism – Selenium is a trace mineral that works as a partner to help the antioxidant function

Function cont. Requirements- Expressed in terms of alpha-tocopherol in mg./day. Men and women age 14 years + : 15mg/day UL = 1000mg/day Food sources – vegetable oils: wheat germ, soybean, safflower oil: nuts, fortified cereals, and avocados Stability- stable to heat and acids but not to alkalis (Table 7-3 p. 101)

Vitamin E foods

Vitamin E Deficiency Disease Hemolytic Anemia – preemies: infants who miss the final 1-2 months of gestation when tocopherol stores are normally built up, are vulnerable to hemolytic anemia – the lipid membranes of RBCs are easily oxidized by oxygen and the continued loss of RBCs leads to anemia

Vitamin E Deficiency Disease cont. Decreased myelin synthesis – In older children and adults, a deficiency of tocopherol disrupts normal synthesis of myelin, the protective fat covering of nerve cells that helps them pass messages along to specific tissues. The main nerves involved are: 1) spinal cord fibers that affect physical activity (eg. walking) and 2) the retina of the eye that affects vision Toxicity symptoms – no toxicity from food source; mega doses of supplemental tocopherol may interfere with Vitamin K activity and blood clotting UL 1000 mg/day

Vitamin K History: Henrik Dam, a biochemist at the University of Copenhagen, discovered a hemorrhagic disease in chicks that were fed a fat –free diet He determined that the factor responsible was the absence of a fat-soluble, blood-clotting vitamin that he called “koagulationsvitamin”, or Vitamin K Several forms of Vitamin K compose a group of substances with similar biologic activity in blood clotting. The major form found in plants, is named “phylloquinone” .

Vitamin K Phylloquinone is our dietary form of Vitamin K Menaquinone: synthesized by intestinal bacteria Contributes about ½ of our daily supply of Vit K

Vitamin K functions Blood clotting -The basic function of Vit K is in the blood clotting process. The most familiar of these Vitamin K-dependent blood factors is Prothrombin. Thus phylloquinone can serve as an antidote for the excess effects of anticoagulant drugs. Used in the control and prevention of certain types of hemorrhages. Bone development – specific proteins in bone and bone matrix are dependent on Vitamin K for their synthesis and are involved with calcium in bone development

Vitamin K Requirements : AI value 120 ug/day men and 90 ug/day for women Gradual increase from birth-adulthood Food sources: green leafy vegetables, spinach, turnip greens, broccoli (note: a diet assessment should be made when a person is started on anticoagulation therapy to help determine therapeutic dose. Also, ongoing intermittent evaluation of diet when concern arises about therapeutic control or stability.)

Vitamin K Deficiency disease: Uncommon except in clinical conditions related to blood clotting, malabsorption, or lack of intestinal bacteria to synthesize the vitamin E.g. Vitamin K shot given to newborns to prevent hemorrhage from the cutting of the umbilical cord (a newborn’s intestine is sterile at birth) Toxicity symptoms – none known No UL exists

Water-Soluble Vitamins
Section 2 Water-Soluble Vitamins

Vitamin C (ascorbic acid)
Functions – Vitamin C acts as a protective agent (antioxidant), and enzyme cofactor, and plays a role in many metabolic and immunologic activities. Connective tissue – needed to build and maintain strong tissue by involvement with collagen synthesis – esp. bone, cartilage, tooth dentin, and strong capillary walls in blood vessels

Vitamin C (ascorbic acid)
General body metabolism – a greater concentration of ascorbic acid in the more metabolically active tissues such as adrenal glands, brain, kidneys, liver, pancreas, thymus, and spleen. Also helps in the absorption of iron, and for clinical needs such as wound healing, fevers, infection, and growth periods

Vitamin C foods

Vitamin C Antioxidant function – Vit C protects from free radical damage which is associated with increased risk of cancer and heart disease. May prevent the development of chronic disease Requirements : (RDA) Men (18 years +) 90 mg/day Women (18 years +) 75 mg./day Smokers – increase by 35mg/day Increased needs during pregnancy and lactation UL = 2000mg /day

Vitamin C Stability – oxidizes to air and heat. Not stable in alkaline substances such as baking soda which destroys the ascorbic acid content. When extra water is added to cook with, vitamin C leaches out into the water.

Vitamin C S/S ascorbic acid deficiency are: Tissue bleeding (easy bruising, pinpoint skin hemorrhages, etc.) Bone and joint bleeding Poor wound healing Easy bone fx Soft bleeding gums with loosened teeth Extreme deficiency produces scurvy: a hemorrhagic disease characterized by bleeding in joints, other tissues, & breakdown of fragile capilaries

Vitamin C Toxicity symptoms – excessive levels may cause diarrhea; kidneys will usually excrete excess Vit C Food sources – Citrus fruit, tomatoes, cabbage and other leafy vegetables; berries, melons, broccoli, potatoes, and other green and yellow veg., green and red bell peppers, kiwi

Vitamin C deficiency Scurvy teeth Petechiae

Thiamin (Vitamin B1) Thiamin is a coenzyme factor that relates to the production of energy from glucose and the storage of energy as fat Especially necessary to maintain 3 body systems: Gastrointestinal system- lack of  poor appetite, indigestion, constipation, poor stomach function and decrease HCL secretion

Thiamin (Vitamin B1) Nervous system – Depends on glucose for energy. Without sufficient thiamin  inability of nerves to do their work -> decreased alertness, decreased reflex response, apathy, fatigue, and irritability. Cardiovascular system – Without constant energy ->Heart muscle weakens -> heart failure; circulation becomes a problem, and fluid accumulation in the lower part of the legs

Thiamin (Vitamin B1) Requirements are directly related to energy and CHO metabolism: For healthy persons: RDA for 18yrs. + Men 1.2 mg Women 1.1 mg Increase need during pregnancy and lactation; when treating infection, and alcoholism No UL Food sources – Pork, Beef, Liver, Whole or enriched grains, legumes, wheat germ, eggs, fish Stability- Fairly stable but is destroyed by alkalis and prolonged heat

Vitamin B1 Thiamin Deficiency disease: Beriberi – a paralyzing disease Associated with chronic ETOH abuse and poor diet Alcohol inhibits the absorption of Thiamin Wernicke’s encephalopathy: a disease affecting mental alertness and coordination Toxicity symptoms – No evidence of toxicity from oral intake Kidneys clear excess

Vitamin B1 Thiamin deficiency
Beriberi

Riboflavin (Vitamin B2)
“Riboflavin” comes from the Latin word “Flavus” meaning yellow; and “ribose”, a sugar A yellow-green fluorescent pigment Functions – Vital coenzyme factor in both energy production and tissue protein building Requirements: RDA 18 yrs. + Men 1.3 mg Women 1.1 mg Increase during pregnancy and lactation

Food sources Milk and milk products, meat, enriched cereals, green vegetables Stability Destroyed by light, milk is now sold in plastic or cardboard cartons instead of glass containers

Deficiency disease rarely occurs alone; usually occurs with a deficiency of other B vitamins and protein. Cracked lips, mouth Swollen tongue Eyes burning, itching, or tearing from extra blood vessels in the cornea Scaly, greasy dermatitis in skin folds Toxicity symptoms – None known; no UL

Niacin (Vitamin B3) Functions Coenzyme role: partners with riboflavin and thiamin to help in the cell -metabolism system that produces energy A necessary part of important chemical reactions involved in DNA repair and calcium mobilization in the body

Niacin (Vitamin B3) Requirements Expressed in terms of “niacin equivalents” (NE). Because the body can make some of its niacin from the essential amino acid tryptophan, the total niacin requirement is stated in terms of “niacin equivalent”. 60mg tryptophan = 1mg niacin = 1NE RDA : for adults age 14 yrs. +: Men 16 mg NE and women 14 mg NE per day Increase dose during pregnancy and lactation

Niacin (Vitamin B3) Deficiency disease: Pellegra: dermatitis, diarrhea, dementia, death corrected with supplemental Niacin Other s/s of general niacin deficiency: Weakness, poor appetite, indigestion, skin and nervous system disorders Extended deficiency may result in CNS damage with resulting confusion, apathy, disorientation, and neuritis. Such CNS s/s seen in chronic alcoholism

Niacin deficiency

Niacin (Vitamin B3) Toxicity symptoms – excessive supplementation can cause reddened skin with burning, itching, and tingling UL 35mg/day Food sources – Meat (Most common source), peanuts, legumes, enriched grain Stability – Stable to acid and heat; lost when cooked with excess water

Vitamin B6 Vitamin B6 is the collective name of a group of six related compounds. Known also as “pyridoxine” Function: protein metabolism and cell reactions involving amino acids Aids neurotransmitter synthesis for brain activity and CNS function As a coenzyme it is active in CHO and fat metabolism Extensively stored in tissues throughout the body – particularly muscle

Vitamin B6 (Pyridoxine)
Requirements : RDA up to 50 years old: Men and women mg / day Older adults: men 1.7 mg/day; women 1.5mg/day Increased need during pregnancy and lactation UL 100m/day Deficiency disease – Abnormal CNS, hyperirritability, neuritis, and possible convulsions and certain types of anemia

Vitamin B6 (Pyridoxine)
Toxicity symptoms – large supplemental doses can cause lack of muscle coordination and nerve damage Food sources – Grains, enriched cereals, liver and kidney and other meats. Stability – Stable to heat but sensitive to light and alkalis

Folate Folate – from Latin “folium” meaning “leaf”; was used because a major source for it was in dark green leafy vegetables Chemical form: folic acid Functions – a coenzyme which is used in: the formation of body cells and creation of DNA The formation of hemoglobin and synthesis of amino acids Adequate amt reduces neural tubal defects in the unborn Requirements - RDA age 14 yrs. + = 400 ug of DFE (dietary folate equivalent) per day UL 1000 mcg/day

Folate Deficiency disease Megaloblastic anemia (esp. during pregnancy, and rapidly growing adolescents esp. ones following fad diets or those who smoke) Neural tubal defects in unborn infant if maternal intake is inadequate Toxicity symptoms – none noted from excessive intake of folate from foods. Some evidence that excess intake of folate from supplements may have toxic effects.

Folate deficiency – neural tube defect

Folate Food sources – chicken and beef liver, dark green leafy vegetables, legumes, yeast, orange juice, fortified grains Stability – easily destroyed by heat and leaches into cooking water

Cobalamin Vitamin B12 Functions: Normal blood formation and synthesis of the heme portion of hemoglobin Essential for proper nervous system function Requirements: RDA 19yrs.+ for men and women = 2.4 ug/day Increased need during pregnancy Older than 50, some have trouble absorbing Vitamin B12.

Cobalamin Vitamin B12 Deficiency disease: Pernicious anemia – reduced secretion of “ intrinsic factor” that comes from the cells lining the stomach ->poor absorption of Vit B12. Nervous disorders, sore mouth and tongue, amenorrhea, and neuritis Toxicity symptoms – none known Food sources – Beef/chicken livers, lean meat, clams, oysters, herring, crab Stability – Stable in ordinary cooking process

Cobalamin Vitamin B12

Pantothenic Acid Functions : In its coenzyme role, it is essential to the synthesis and functioning of coenzyme A which controls many cell metabolic reactions involving fat and cholesterol, heme formation and amino acid activation Requirements - No RDA; AI = 5 mg/day for 14yrs + Deficiency disease – unlikely. The only cases are people fed synthetic diets with virtually no pantothenic acid Toxicity symptoms – none; excreted in urine Food sources – Meat, eggs, milk, whole grains, legumes and vegetables Stability – Stable to acid and heat but sensitive to alkalis

Biotin Functions – Partners with co enzyme A; also involved with synthesis of fatty acids and amino acids Requirements – no RDA; AI 30 ug/day in persons 18yrs. + Deficiency disease – no known natural deficiency; induced deficiency may occur in patients on TPN without biotin supplementation; occasional inborn errors of metabolism r/t biotin Toxicity symptoms – none known Food sources – cornmeal, soy meal (flour), liver, egg yolk, cereals that aren’t wheat based, meat, tomatoes, and yeast

Biotin foods

Choline Functions: A water-soluble nutrient associated with B-Complex Vitamin Helps maintain the structural integrity of cell membranes Insufficient data to determine whether essential to human diet Active in the synthesis of acetylcholine which is a neurotransmitter involved with memory storage, muscle control, and other functions

Choline Requirements : No RDA; AI = for persons over 18yrs: Men: 550mg/day; Women: 425mg/day UL 3.5g/day Deficiency disease – Liver damage Toxicity symptoms - low blood pressure, fishy body odor, sweating, increased salivation, and reduced growth rate Food sources – Milk, eggs, liver, peanuts

Section 3 Phytochemicals

Phytochemicals Plant compounds Bioactive molecules with health benefits A nutrient but not a vitamin or mineral Research believes that there are 25,000 of these phytochemicals found in fruit and vegetables Act as either antioxidant or hormone

Phytochemicals Function: Diets high in phytochemicals induce a protective lipid profile to protect against coronary heart disease, improve overall colon function, help prevent age-related macular degeneration and cancer, and increase the body’s antioxidant status Multiple studies are exploring the possible link between increased intake of phytochemical and reduced risk of developing chronic disease

Phytochemicals Recommended intake – A dietary intake of g/day of fruits and vegetables reduces one’s risk of various forms of cancer Food sources: Color categories: Red foods – lycopene Yellow green – zeaxanthin Red purple – anthocyanins Orange – beta carotene Orange yellow – flavonoids Green – glucosinolates White green - allyl sulfides

Phytochemicals Red foods – lycopene Yellow green – zeaxanthin

Phytochemicals Red purple – anthocyanins Orange – beta carotene

Phytochemicals Orange yellow – flavonoids Green – glucosinolates

White green - allyl sulfides
Phytochemicals White green - allyl sulfides

Phytochemicals Food Sources cont. By consuming one fruit or vegetable from each of the 7 color categories daily, can meet you dietary recommendation. Grains, soybeans, legumes, and nuts also contain phytochemicals

Vitamin Supplementation
Ongoing debate – Most commonly bought over the counter item in America Biochemical individuality - The body’s chemical composition is not the same for everyone. Everyone is different and has different needs. This pattern chances within a given person at different times, under different circumstances during normal life-cycle and with disease.

Individual approach based on needs assessment: Life cycle needs Pregnancy and lactation- Folic acid to prevent birth defects Infancy- Vit D, K, Iron (Fe) and Fluoride Children and adolescents – Multi vitamin for rapid growth period Aging- decrease food intake and impaired nutrient absorption

Lifestyle needs: choices and habits influence the need for supplements Oral contraceptive use – reduces serum levels of several B vitamins and Vit C Restricted diets – E.g. a wise weight-reduction program should meet all nutritional needs. E.g. A strict vegan diet may need Vit B12 supplementation Smoking – need Vit C

Vitamin supplementation
Exercise programs – Need more riboflavin Alcohol – Chronic or abusive use of alcohol can interfere with absorption of B-complex vitamins; esp. Thiamin and may destroy folate Caffeine – in large quantities, it flushes water-soluble vitamins out of the body faster than usual Disease states – require careful nutritional assessment

Megadoses Persons taking megadoses of vitamins are using them as a drug for therapeutic treatment; no longer operating as a nutritional agent Toxic effects: (in megadoses) Fat-soluble vitamins are stored in the liver and may lead to liver and brain damage B6 – nerve damage and reduced muscular coordination Vit C – may cause GI pain, increase the risk for kidney stones; reduce the action of leukocytes against bacteria

Megadoses “Artificially induced” deficiencies: above-normal blood levels of one nutrient may increase the need for the other nutrients with which it works in the body, creating deficiency symptoms. Deficiencies may also occur when a person suddenly stops taking the large amounts and a “rebound effect” results. E.g. infants born to mothers who took megadoses of ascorbic acid during pregnancy have developed scurvy when their high nutrient supply was cut off at birth

Supplementation Principles
Read labels carefully Vitamins can be harmful in large amounts Professionally determined individual needs govern specific supplement use All nutrients work together to promote good health Food is the best source of nutrients Evaluate the information for safety and efficacy of nutrition supplementation

Chapter 7 Vitamins.

Similar presentations

Presentation on theme: "Chapter 7 Vitamins."— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

Chapter 7 Vitamins.

Similar presentations

Presentation on theme: "Chapter 7 Vitamins."— Presentation transcript:

Similar presentations

About project

Feedback