Chapter 10 water soluble vitamins

Vitamins Characteristics• Organic components of food, but distinct from carbohydrates, fat, and protein • They are present in foods in small amounts... Vitamins Characteristics• When la

Vitamins

• Apo-enzyme: protein portion of an enzyme system

• Co-enzyme : Vitamin portion of an enzyme system

Co-Enzyme Action

Vitamins Characteristics

• Organic components of food, but distinct from carbohydrates, fat, and protein

• They are present in foods in small amounts

– regulating body processes

– in very small amounts

Vitamins Characteristics

• When lacking in tissues, they result in a specific disease or syndrome (combination

of symptoms and signs)

Vitamins Characteristics

• Not synthesized in tissues in sufficient quantities to meet the body's needs

• Non energy yielding nutrients

Vitamin Classification

• Water Soluble

• Fat Soluble

Water soluble vitamins

Water soluble vitamins

• Must be supplied in diet every day

• Stability varies

• Generally do not have precursors

Primary deficiency caused by inadequate diet

General Functions of Water Soluble Vitamins

• Energy Release

• Metabolism of AA

• Cell Replication: DNA - RNA synthesis

Metabolism of AA

• Piridoxine (B6)

• Pyridoxal

• Pyridoxamine

Cell Replication

• Folate

• B12

• All these vitamins function as a Co-Enzymes in chemical reactions, so

• They can be called regulators of body processes

Vitamin C

• Does not function as a Co-Enzyme but is water soluble

• Antioxidant

• Collagen synthesis

Enrichment vs Fortification

• Enrichment: process of restoring

nutrients that were lost during

refining processes to levels present

in the original whole grain

• Fortification process of adding nutrients to a product that may have never been present or are added in amounts greater than what should

be found

Husk, bran and germ are

all lost in refining

B Vitamins

• Excretion

– Excess excreted in urine, mainly

as thiamin

– decreased thiamin excretion with a

thiamin-load test may be indicative

of deficiency

Thiamin Functions

• Energy Metabolism

– Part of coenzyme TPP (thiamin

pyrophosphate in the Krebs cycle (TCA)

– Necessary for decarboxylation

• Supports nervous system functioning

• Supports appetite

• Deficiency diseases

• Common in rice eating areas of the world

• Thiamin is in the bran \ polished rice has less thiamin

Thiamin Deficiency

• Beriberi

– Signs and symptoms vary with

age, severity of deficiency and diet

– Elderly, alcoholics, some athletes

– Symptoms include mental

confusion, muscle wasting, edema, peripheral paralysis

Thiamin Deficiency

• Beriberi

– Wet : with edema

– Dry: with muscle wasting

Edema of Beri-Beri

Thiamin Recommendations

• Functions

- Energy metabolism

• Essential for metabolism of carbohydrates,

amino acids, and lipids

• FAD part of respiratory chain; energy

production

• Essential for a number of metabolic actions

- Normal vision

- Skin health

• Sources

- Dairy

- Green leafy vegetables

- Enriched, fortified and

whole grains

- Liver

• Deficiency (ariboflavinosis)

– Early symptoms: photophobia,

burning and itching of eyes,

soreness of mouth

– Later symptoms: magenta tongue,

dry cracked mouth

Riboflavin Recommendations

• RDA:

– 1.3 mg/day (Male)

– 1.1 mg/day (Females)

• NO TOXIC Effects

• Absorption

- small intestine

- little storage

Niacin Functions

- Functions as coenzymes in all cells

- NAD (nicotinamide adenine dinucleotide), NADP

- Energy metabolism

Dermatitis of PELLAGRA

Niacin Toxicity

• Megadose levels of niacin have recently been shown to be toxic and may cause:

– Liver damage and jaundice

– Painful Skin rash and flush

– Pancreatic damage (elevated serum

glucose)

– Altered fat metabolism in the heart

Niacin Recommendations

• Deficiency and toxicity are highly unlikely

• Deficiency was created in rats and chicks by feeding large doses of avidin

BIOTIN Recommendations

• AI: 30 mcg/day

• Toxicity not reported

Pantothenic Acid

• Absorption: Small intestine

• Stability: Destroy by heat

Pantothenic Acid

Requirements

• AI: 5mg/day

• RDA: None

VITAMIN B 6 Pyridoxine, Pyridoxal,

Pyridoxamine

VITAMIN B 6 Pyridoxine, Pyridoxal,

VITAMIN B 6 Pyridoxine, Pyridoxal,

Pyridoxamine

• Functions

- Metabolism of tryptophan

- Lineoleic to arachidonic acid

– Almost all reactions use pyridoxal phosphate (PLP)

VITAMIN B 6 Pyridoxine, Pyridoxal,

Metabolic roles of B 6

B 6

Tryptophan -> Brain amines(serotonin)

B 6

Tryptophan -> Niacin

B6 Recommendations

• RDA: 1.3mg/day 19-50 yr

• UL: 100mg/day

• Functions

- Transfers C during cell formation

- Role in DNA and RNA formation

- Essential to cell division and

maturation

- Works with B 12

Anemic Blood Cells

• Who is at risk?

- Infants

- Alcoholics

- Women of childbearing age

- NTD: spina bifida, anencephaly

Anencephaly

Decrease of NTD since

Folate Fortification

What about folate and

heart disease?

B 12

met

homocys

met synthase

proteins

S-Adenosyl Methionine (SAM)

Folate Recommendations

• RDA: 400 mcg/day

• UL: 1000 mcg/day

VITAMIN B 12 (Cobalamin)

• Unique characteristics:

- requires Calcium for absorption

Cyanocobalamin Structure

H 3 C

H 2 C C O

N

H

H 2 C C

NH 2 O

CH 2 CH 2 CNH 2

O H N

H 3 C

H 3 C CCH 2

C O

NH

CH 2 CH O

B 12

- Functions

- cell replication and growth

- digestive tract health

- synthesis of myelin

B 12

• Toxicity

• apparently low

• RDA: 2.4 mcg/day

VITAMIN C (Ascorbic acid)

VITAMIN C (Ascorbic acid)

VITAMIN C Food Sources

– Mild- easily bruised, pain in

muscles, bleeding gums

– Scurvy - bleeding gums, teeth

loosen, muscles degenerate, dry skin, wounds fail to heal, joint

pain, bones soften, anemia and infections are common

Vitamin C Recommendations

• RDA: 90 mg (Males) 75 mg (Females)

• UL: 2000 mg/day

For each vitamin you have