Chapter 8 Vitamins What are Vitamins n Essential

Chapter 8 Vitamins

What are Vitamins? n Essential organic substances n Produce deficiency symptoms when missing from diet n Yield no energy n Basic functions – Facilitate energy-yielding chemical reactions – Function as co-enzymes n Fat-soluble vitamins n Water-soluble vitamins

Fun Facts n Vitamins were named in order of discovery (A, B, C, D, …) n Other substances found not to be essential were dropped (e. g. , vitamin P) n B-vitamins were thought to be one vitamin; turned out to be many (e. g. , B 1, B 2, B 3, …)

Vital Dietary Components n Megadose (>3 -10 x needs as a starting point) – Proved useful in treating certain conditions n Plant and animal foods provide vitamins n Most synthesized vitamins work equally well in the body vs natural n Scientists believe they have discovered all the vitamins

Storage of Vitamins in the Body n Fat-soluble – Not readily excreted (except vitamin K) n Water-soluble – Generally lost from the body (except vitamins B-6 and B-12) – Excreted via urine n Vitamins should be consumed daily – Occasional lapse is harmless

Vitamin Toxicity n Fat-soluble vitamins (e. g. Vitamin A) – Can accumulate in the body n Water-soluble vitamins – Some can cause toxicity n Mostly likely due to supplementation

Preservation of Vitamins n Decreased vitamin content – Improper storage – Excessive cooking >40*C – Exposure to light, heat, air, water, and alkalinity Eat foods soon after harvest (EAT FRESH) n Freeze foods not consumed within a few days n Blanching destroys enzymes (bacteria) n – Slows down vitamin degradation

Preservation Tips

Fat-Soluble Vitamins Overview Dissolve in organic solvents n Not readily excreted n – Can cause toxicity Olestra Absorbed along with fat n Fat malabsorption (Xenical/Olestra) n – May cause deficiency – Cystic fibrosis (Vit. deficiency) n Transported with fat – In lipoproteins Xenical

Confirming your knowledge What are the fat Soluble vitamins, why (i. e. non polar)? 1 3 2 4

Vitamin A n Narrow optimal intake range n Preformed – Retinoids – Found in animal products (fish/organ meats) n Proformed (pro. Vitamin A) – – – Carotenoids Found in plant products Can be converted to Vit A by the body B carotene

Functions of Vitamin A n Promote vision – Night blindness n Promote growth n Prevent drying of the skin and eyes – Xerophthalmia (figure 8 -1) & macular degeneration n Promote immune function and resistance to bacterial infection n Cardiovascular disease prevention (b/c antioxidant) n Cancer prevention (antioxidants and other) n Acne medication (Retin-A, Accutane)

Challenge Question n What is the name following compound (which has been shown to reduce prostate cancer risk) and what are good sources? Gann et al. , 1999, Cancer Research, 59, 1225

Food Sources of Vitamin A: see: 8 -2

Recommended Amounts for Vitamin A g RAE for men n 700 g RAE for women n Daily Value is 1000 g (RAE) ~ 5000 IU n Upper Level is 3000 g, 10, 000 IU n Much stored in the liver n No separate RDA for carotenoids n 900

Toxicity of Vitamin A n Large intake of vitamin A (preformed) – Over a long period – Use of Accutane and Retin-A ≥ 10, 000 IU or 3000 RAE n Signs and symptoms – Bone/muscle pain, loss of appetite, skin disorders, headache, dry skin, hair loss, increased liver size, vomiting – Fetal malformation (binds to DNA cell develop. ) – Possible permanent damage (infants) – < 3000 IUs/day if pregnant

Vitamin D n Prohormone n Derived from cholesterol n Synthesized from sun exposure – Sunscreen SPF >8 decreases synthesis 95% – Expose hands, face, arms 2 -3 x/week for 5 -10 minutes each time (more for darker skin) n Insufficient sun exposure makes this a vitamin n Activated by enzymes in liver and kidneys n Deficiency can cause disease

Activation of Vitamin D

Functions of Vitamin D n Regulates blood calcium – Along with the parathyroid hormone – Regulates calcium + phosphorus absorption – Reduces kidney excretion of calcium – Regulates calcium deposition in bones n Influences normal cell development – Linked to reduction of breast, colon, and prostate cancer

Role in Bone Formation n Causes calcium + phosphorus to deposit in the bones n Strengthens bones n Rickets is the result of low vitamin D – Breastfed infants with little sun exposure n Osteomalacia (soft bones) – Rickets-like disease in adults – Bones lose minerals and become porous

Challenge Question n According to the USDA and ODS – Vitamin D is now considered a deficiency in N. American diets – what are the two major reasons? n 1. n 2.

Food Sources of Vitamin D n Fatty fish (salmon, herring) n Fortified milk (N. fat, Low fat or Whole) n Some fortified cereal

Adequate Intake (AI) for Vitamin D g/day (200 IU/day) for adults under age 51 n 5 g/day (400 - 600 IU/day) for older adults n 10 -15 n Supplement if a breastfed – (See physician for details) infant

Toxicity Warning n Vitamin D can be very toxic, especially in infancy and childhood n Upper Level is 50 µg/day n Results in – Over-absorption of calcium (hypercalcemia), increase calcium excretion – Calcium deposits in organs (kidneys) & blood vessels – Growth retardation

Vitamin E Fat-soluble antioxidant n α β δ gamma tocopherol forms n n Resides mostly on cell membranes

Other Functions of Vitamin E n Protects double bonds in unsaturated fats n Improves vitamin A absorption n Deficiency – Breakdown of cell membranes – Hemolysis – Nerve degeneration n RDA for adults is 15 mg/day – Many adults are not meeting this goal

Food Sources of Vitamin E

Toxicity of Vitamin E Upper Level is 1, 000 mg/day (supplementary alphatocopherol) n Upper Level is 1500 IU (natural sources) or 1100 IU (synthetic forms) n n Adivse mixture of natural tocopherols (vs synthetic sources) (400 IUs) n Toxic effects – – – Inhibit vitamin K metabolism and anticoagulants Possible hemorrhage Muscle weakness, headaches, nausea

Vitamin E n SHOW Vit E video

Vitamin K (“Koagulation”) n Synthesized by bacteria in the colon (10%) and absorbed (diet) Frequent anti-biotics deficiency. . . n Role in coagulation process (fig 8 -10) n Role in calcium-binding potential

Food Sources of Vitamin K n Liver n Green leafy vegetables n Broccoli n Peas n Green beans n Resistant to cooking losses n Limited vitamin K stored in the body (<24 hr)

Adequate Intake for Vitamin K 90 µg/day for women n 120 µg/day for men n Excess vitamins A and E n – Interferes with vitamin K – May cause hemorrhage and fractures n Newborns – Routinely injected with vitamin K – Breast milk is a poor source Toxicity unlikely; readily excreted n High Levels CVD, prevent reduced clotting n

Overview of Water-Soluble Vitamins n n n n Dissolve in water Generally readily excreted from body Subject to cooking losses Function as coenzymes Participate in energy metabolism 50 -90% of B vitamins are absorbed Marginal deficiency more common U. S. Enrichment Act (grains milled loose vitamins. . ) – Must be added back (enriched) to products (cereals) n Why experts recommend whole grains/brown rice vs Refined grain products

Confirming your Knowledge Overview of Water-Soluble Vitamins n What are the water soluble vitamins and why (i. e. polar) ? (3) (2) (1) (5) (4) (6) (9) (7) (8)

Overview of Water-Soluble Vitamins Participate in energy metabolism

Thiamin n Sensitive to alkalinity (base) and heat n Coenzyme form used in energy metabolism n Deficiency: Beriberi (severe muscle weakness n RDA – 1. 1 mg/day for women – 1. 2 mg/day for men – Most exceed RDA in diet n Surplus is rapidly lost in urine; non-toxic

Food Sources of Thiamin, fig. 8 -14

Riboflavin n Coenzyme forms participate in energyyielding metabolic pathways n Deficiency – Cheilosis, inflammation of mouth and tongue, dermatitis, sensitivity to sun n RDA – 1. 1 mg/day for women – 1. 3 mg/day for men – Average intake above RDA n Non-toxic

Food Sources of Riboflavin n Milk/milk products n Enriched grains/cereals n Eggs n Liver n Spinach n Oysters n Brewer’s yeast

Niacin n Coenzyme forms used in energy metabolism n Deficiency – Pellagra: rough/painful skin (epidemic US < 1930 s) – Dementia, diarrhea, dermatitis, n RDA – 14 mg/day for women – 16 mg/day for men n Toxicity – Upper Level is 35 mg/day

Food Sources of Niacin n Enriched grains (breakfast cereals) n Beef n Chicken/turkey n Fish n Heat stable; little cooking loss n 60 mg tryptophan (Amino acid) can be converted into 1 mg niacin

Pantothenic Acid n Part of Coenzyme-A – Essential for metabolism of carbohydrate, fat, and protein n Deficiency rare – Usually in combination with other deficiencies

Food Sources of Pantothenic Acid n n n n Meat Milk Mushrooms Liver Peanuts Adequate Intake = 5 mg/day Average intake meets AI

Biotin n Free and bound form n Co-enzyme – Metabolism of carbohydrate and fat – Helps breakdown certain amino acids n Deficiency–rare – Scaly, inflamed skin – Changes in tongue, lips – Decreased appetite, nausea, vomiting

Food Sources of Biotin n Cauliflower, egg yolk, liver, peanuts, cheese n Intestinal synthesis of biotin contributes very little (10%) n Avidin egg protein inhibits absorption – More than a dozen raw egg whites a day to cause this effect

Biotin Needs n Adequate adults n No intake is 30 µg/day for Upper Level for biotin n Relatively nontoxic

Vitamin B-6 n Coenzyme forms – Activate enzymes needed for metabolism of carbohydrate, fat, and protein – Synthesize nonessential amino acids via transamination – Synthesize neurotransmitters – Synthesize hemoglobin and WBC

Food Sources of Vitamin B-6, fig. 8 -22

RDA for Vitamin B-6 n 1. 3 mg/day for adults n 1. 7 mg/day for men over 50 n 1. 5 mg/day for women over 50 n Daily Value set at 2 mg n Average intake is more than RDA n Athletes may need more n Alcohol increases vitamin B-6 destruction

Vitamin B-6 As a Medicine? n 50 -100 mg/day therapy – Questionable treatment of PMS – May treat pregnancy hypertension n Carpal tunnel syndrome n Morning sickness – (100 mg/day may help; see Ch. 13) n Toxicity potential – > 200 mg/day can lead to irreversible nerve damage n Upper Level set at 100 mg/day

Folate n Coenzyme – DNA synthesis – Homocysteine metabolism – Neurotransmitter formation n Sensitive to: – Heat, oxidation, ultraviolet light

n Megaloblastic Anemia n 10% N. Americans- genetic defect to process Folate Deficiency folate (req. 2 X RDA), need genetic testing. . n Neural tube defects n Women need ample Folic acid: – Neural tube closes w/i 28 days of pregnancy spinal bifuda

n. Megaloblast cells -Req. ample Folic acid

Child bearing Women need ample Folic acid: Neural tube closes w/i 28 days of pregnancy spinal bifuda

Food Sources of Folate n Liver n Fortified breakfast cereals n Grains, legumes n Foliage vegetables n Orange juice

RDA for Folate n 400 µg/day for adults n 600 µg/day for pregnant women n Excess intake can mask vitamin B-12 deficiency n Upper Level 1 mg (synthetic form) – Synthetic form 1. 7 X more potent. . . – Folate in food has limited absorption (synthetic form) (Natural form)

Vitamin B-12 Synthesized by bacteria and fungi n Coenzyme n – – – n Role in folate metabolism Maintenance of the myelin sheaths RBC formation Deficiency (absorption problems) – Pernicious anemia (weakness, sore tongue, back pain) – Nerve degeneration and paralysis

B-12 Absorption -aging n Requires a protein from salivary gland n Requires stomach acid (declines w/ age) n Requires the intrinsic factor (declines w/ age) n Absorbed in the last part of the small intestine n About 50% of B-12 is absorbed n Vegetarian/Vegan diets – low in Vit. B-12 – (need supplement or specified rich source)

Therapy for Ineffective Absorption n Many factors can disrupt this process n Monthly injections of vitamin B-12 n Vitamin B-12 nasal gel n Megadoses of vitamin B-12 – Allow for passive diffusion

Food Sources of Vitamin B-12 n n n n n Synthesized by bacteria, fungi and algae (Stored primarily in the liver of animals) Animal products Organ meat Seafood Eggs yogurt Milk Corn flakes cereal (w/ soy milk)

RDA for Vitamin B-12 n 2. 4 µg/day for adults – Over age 50 recommended take synthetic form – Not bound to foods (no require low stomach acid) n Average intake exceeds RDA n B-12 stored in the liver (> 3 years before deficiency) n Non-toxic

Vitamin C n Synthesized by most animals – Not by humans n Decreased absorption with high intakes > 250 mg n Excess excreted – Diarrhea common n Sensitive to – Cooking/heat (high temp) ~ use medium setting – Iron, copper, oxygen

Functions of Vitamin C n Synthesis of collagen (connective tissue) – Stretch marks n Iron absorption n Immune functions – Prevents duration of common cold? – Interacts with w/ oxidized Vit. E ~ recycles? – Anti-cancer agent and cataracts n Antioxidant? n Req. for syn. Of hormones

Challenge Question What has more Vitamin C/gram and is the best dietary choice for combating the common cold and why? n 1 medium orange n 1 medium red pepper

Deficiency of Vitamin C n Scurvy – Deficient for 20 -40 days – Fatigue, pinpoint hemorrhages – Bleeding gums – Weakness – Fractures – Associated with poverty

Food Sources of Vitamin C n Citrus fruits n Potatoes n Green pepper n Cauliflower n Broccoli n Strawberries n Romaine lettuce n Spinach

RDA for Vitamin C n n n n 90 mg/day for adult males 75 mg/day for adult females (enhances Fe absorptn. ) Daily Value is 60 mg +35 mg/day for smokers Average intake 70 -100 mg/day Upper Level is 2 g/day (inflammation diarrhea) Better to take low doses (250 mg) more frequent vs Mega. DOSE 1 Gram (1000 mg) / day

Choline n Essential nutrient, though not a vitamin n All tissues contain choline n Precursor for acetylcholine (neurotransmitter) n Precursor for phospholipids

Food Sources of Choline n Widely distributed in foods – Fruits/vegetables n Milk n Liver n Eggs n Peanuts n Lecithin added to food n Deficiency rare

Needs for Choline n Adequate Intake is 550 mg/day for males n Adequate Intake is 425 mg/day for females n Average intake is ~700 -1000 mg/day n High doses – Associated with fishy body odor, vomiting, salivation, sweating, hypotension, GI effects n Upper Level is 3. 5 grams/day

Vitamin-like Compounds n Choline n Carnitine n Inositol n Taurine n Lipoic acid n Synthesized in the body at the expense of amino acids and other nutrients

Vitamins-SUMMARY Functions in the Body With a balanced diet – no need for supplements?

Dietary Supplements $21 Billion

Dietary Supplements –Classified as n Vitamins n Minerals Fe 2+ n Herbs n Amino Acids n A dietary substance to supplement the diet n Try a case study?

Vitamins, Supplements SUMMARY n n If going to experiment. . . Make sure < (upper limit) of toxic level Min. 6 weeks for evaluation. . . ANY SUPPLEMENT QUESTIONS? See below n Check any of the following 6 websites for validity – 1. www. acsh. org – 2. www. quackwatch. com – 3. www. ncahf. org – 4. http: //dietary-supplements. info. nih. gov – 5. www. eatright. org – 6. www. usp. org/USPVerified/dietary. Supplements/ **7. “web of science”- (use UCSC Lib login, § http: //oca. ucsc. edu/login (22200 -0230485 -15)