Water soluble Vitamins Chapter 7 1 Water Soluble

Water soluble Vitamins Chapter 7 1

Water Soluble Vitamins • • • Readily excreted from the body focus on regular intake B vitamins and Vitamin C Table 7 -4 Summary B vitamins – often found together in foods – lack of one, may indicate others are low – function as coenzymes fig 7 -1 – key roles in metabolism – breakdown and synthesis 2

B vitamins • Many B vitamins are inter-dependant in metabolism (Fig 7 -6) • after ingestion, broken down into free vitamins in stomach and SI absorbed in SI 50 -90% – reformed into coenzymes in cells as needed • Intake is plentiful in our society – fortification and availability – other areas - public health concern – elderly / alcoholics • long term deficiency - not clear • short term - fatigue, other physical symptoms 3

B vitamins • Grains and seed modified by processing - milling – crushed - germ , bran and husk removed leaving starch containing endosperm – flour, bread and cereals – enrich flour with thiamin, riboflavin, niacin folate and iron – still lack B-6, and minerals • choose whole grains 4

Thiamin (B 1) • Release energy from carbohydrate • deficiency - beri (I cant) – weakness, loss of appetite, irritability, – occurs when rice (white) is staple – glucose poorly metabolized - primary fuel for brain and nerve – occurs after only 10 days on thiamin free diet • Thiamin in Food – pork, whole grains, soy milk, fortified cereals, enriched flour – RDA 1. 1 -1. 2 mg / day – average 150% (M) 100% (F) • poor and elderly at risk • supplements non toxic - lost in urine 5

Riboflavin (B-2) • • Many energy yielding pathways vitamin and mineral metabolism antioxidant Deficiency – inflammation of mouth and tongue – dermatitis, cracking of skin around mouth – develop after 2 months – occurs with niacin , thiamin and B-6 deficiency • Riboflavin in food – – milk, enriched grains, fortified cereal, RDA 1. 1 -1. 3 mg / day alcoholics at risk no toxic indications 6

Niacin (B-3) • Pair of related compounds – energy utilization and synthetic pathways (fat) – broad use - widespread symptoms • pellagra - deficiency syndrome – rough or painful skin, dementia, – early symptoms - poor appetite, weak • Niacin in foods – poultry, fortified cereal, wheat bran, tuna, asparagus – niacin is heat stable – RDA 14 - 16 mg / day – risk with alcoholism and disorders of tryptophan metabolism • toxic > 35 mg/day - headache, itchy 7

Pantothenic Acid • Energy release from carbohydrate, fat and protein • forms coenzyme A • deficiency - rare - burning/tingling in feet or hands • Pantothenic acid in foods – present in all food – sunflower seeds, mushrooms, peanuts, eggs – AI 5 mg/day – alcoholism - poor diet – symptoms masked by other deficiencies 8

Biotin • 2 forms - active in fat and carbohydrate metabolism – synthesis of glucose, Facids, DNA – breakdown of AA • deficiency - scaly inflammation of skin – dec. appetite, nausea, anemia, depression • Biotin in food – – cauliflower, egg yolk, peanuts, cheese intestinal bacteria synthesize biotin antibiotics raw egg whites - avidin - binds biotin not absorbed – AI 30 mg/day – relatively non toxic 9

B-6 • Family of three compounds • coenzyme metabolism • deficiency - widespread symptoms – depression, vomiting, skin disorders, nerve irritation, impaired immunity • metabolism of AA - needs B-6 – split N from AA - synthesis on nonessential AA • synthesis of neurotransmitterscommunication – 1950’s infant formula - heat destroyed B-6 - convulsions • synthesis of hemoglobin (O 2) and white blood cells (immunity) • role in recycling homocysteine 10

B-6 in foods • Animal products, fortified cereal, potatoes, milk • animal sources are more absorbable • measurement in food is difficult • RDA 1. 3 - 1. 7 mg/day • set high due to high protein intake • high protein breakdown • Athletes - may need slightly more – increased glycogen and AA use as fuel – higher protein intake – sufficient intake from inc food and protein intake in athletes 11

B-6 • Alcoholism -metabolites formed in ethanol - inc destruction – dec. absorption, and synthesis of coenzyme – liver disabled (cirrhosis and hepatitis) • B-6 toxicity – – – 2 - 6 g/day for 2 months irreversible nerve damage also with long term 200 mg/day abuse in bodybuilders symptoms - difficulty walking, hand foot numbness • upper limit 100 mg/day 12

Folate • Formation of DNA • Metabolism of AA (homocysteine) • deficiency - early phases of red blood cell synthesis - immature cells can not divide - DNA not formed • megaloblasts - enlarged cells • macrocytic anemia - dec O 2 carrying • after 7 -16 weeks • Cancer therapy - hampers folate metabolism • affects rapid cell division of cancer – intestine and skin as well 13

Folate in foods • Green leafy veg. , organ meats, sprouts, orange juice • food processing and preparation destroys 50 -590% of folate in food (heat) • RDA 400 ug/day DFE-Dietary Folate Equivalent) • synthetic foalte absorbs a lot better than natural folate • Folate enrichment now mandatory • women, pregnant of concern • elderly and alcoholism 14

B - 12 • Family of compounds - cobalt – synthesized by bacteria and fungi • complex means of absorption – B-12 released by digestion - stomach acid – free B-12 binds with intrinsic factor – B-12 / intrinsic factor complex absorbed in SI – 30 -70% of dietary B-12 absorbed • without I Factor, 1 -2% absorbed – 95 % of deficiencies – decline in intrinsic factor with age 15

B-12 functions • Variety of cellular processes – conversion of folate to active form – maintenance of myelin sheaths that insulate nerve fibers – patchy degeneration -paralysis…. . death • Pernicious Anemia - weakness, sore tongue, back pain, apathy, tingling in extremities – 3 years for nerve destruction irreversible – starts after middle age -10 -20 % • infants of vegan mothers – long term nervous system problems – brain growth, spinal cord, intellectual development 16

B - 12 in food • Meat, milk, eggs • RDA 2. 4 ug/day • takes 20 years without B-12 to exhibit nerve destruction • Vegan, elderly • non toxic 17

Vitamin C • • • Most animals make from glucose absorbed in SI - 80 -90% 20 % absorbed when mega dose role in synthesizing collagen (protein) connective tissue, bone, teeth, tendons, blood vessels, wound healing deficiency - scurvy - 20 -40 days water soluble antioxidant nitrosamines (cancer) folate, vit. E 18

Vitamin C • Enhances iron absorption – toxicity of vit. C due to over absorption of iron • vital for function of immune system • Dr. Linus Pauling - 1 g – common cold? – Large dose eliminated – absorption saturated at 200 mg/day • Vit C in Food – green pepper, cauliflower, brocolli, cabbage, fruits – lost in processing - heat, iron, copper, O 2 – RDA 60 mg/day (smokers -100) 19

Toxicity of Vitamin C • Probably not toxic below 1 g • regular consumption • stomach inflammation, diarrhea, iron toxicity • hemochromatosis • mega-dose - alert physician – can alter medical results • Fig 7 -12 review- vit in foods – functions, deficiency, toxicity, absorption 20