Chapter 11 HUN

Water-soluble

• Vitamin C/ Ascorbic Acid

• B1  Thiamin

• B2 Riboflavin

• B3 Niacin

• Biotin

• Folate/ Folic Acid

• B6 Pyridoxine

• B12 Cobalamin

• Pantothenic Acid

Fat-soluble

• Vitamin A -Retinol

• Vitamin D-Calciferol

• Vitamin E- Tocopherol

• Vitamin K- Phylloquinone

 Vitamins

• Support nutritional health

• Vitamins differ from energy-yielding nutrients

  • Structure

    • Individual units

  • Function

    • No energy yielded

  • Food contents

• Similarities to energy-yielding nutrients

The Vitamins – An Overview

• Bioavailability

  • Quantity provided by food

  • Amount absorbed and used by body

  • Factors influencing bioavailability

    • Efficiency of digestion

    • Nutrition status

    • Method of food preparation

    • Source of nutrient

    • Other foods consumed at same time

The Vitamins – An Overview

• Precursors

  • Provitamins

    • Converted to active form in body

• Organic nature

  • Can be destroyed during storage and in cooking

Minimizing Nutrient Losses

The Vitamins – An Overview

• Toxicity

  • More is not necessarily better

  • Excessive intakes

    • Levels higher than UL

Dose Levels and Effect

The B Vitamins

• Vitamins do not provide the body with fuel for energy

• Coenzymes

  • Assist enzymes with release of energy

    • Without coenzyme, an enzyme cannot function

• RDAs and AIs

Coenzyme Action

Figure 10-14

 Thiamin (B1)

• Part of coenzyme thiamin pyrophosphate (TPP)

• Energy metabolism

  • Conversion of pyruvate to acetyl CoA

  • TCA cycle

• Nerve activity and muscle activity

• RecommendationsThe B Vitamins – Thiamin

• Deficiency

  • Malnourished and alcoholics

  • Beriberi

    • Indonesia

      • Polished rice

Thi

• Beriberi

  • Wet, with edema

    • cardiovascular system

  • Dry, with muscle wasting

    • nervous system

• Deficiency symptoms

  • Enlarged heart, cardiac failure

  • Muscular weakness

  • Apathy, poor short-term memory, confusion, irritability

  • Toxicity symptoms: none reportedmins – Thiamin

  • Food sources

• Prolonged cooking destroys thiamin

• Leaches into water when boiling or blanching foods

• Cooking methods that conserve thiamin

• Pork

• Soy milk

• Squash, acorn

Riboflavin (B2)s – Riboflavin (B2)

• Serves as coenzyme in energy metabolism

  • Flavin mononucleotide (FMN)

  • Flavin adenine dinucleotide (FAD)

• Recommendations

• Deficiency

  • Inflammation of membranes

• Toxicity

  • No UL

• Deficiency disease: ariboflavinosis

• Deficiency symptoms

  • Inflamed eyelids and sensitivity to light, reddening of cornea

  • Sore throat

  • Cracks and redness at corners of mouth

  • Painful, smooth, purplish red tongue

  • Inflammation characterized by skin lesions covered with greasy scales

• Toxicity symptoms: none reportedoflavin

• Food sources

  • Milk and milk products

  • Other sources

• Destruction of riboflavin

  • Ultraviolet light

  • Irradiation

  • Not destroyed by cooking

• Liver

• mushrooms

The B Vitamins – B₆

• Three forms

  • Pyridoxal, pyridoxine, and pyridoxamine

  • Conversion to coenzyme PLP

    • Amino acid metabolism

    • Urea metabolism

    • Conversion of tryptophan to niacin or serotonin

    • Synthesis of heme, nucleic acids, & lecithin

• Stored exclusively in muscle tissue

• Recommendations

  • Large doses

• Deficiency

  • Symptoms

  • Alcohol & isoniazid

• Toxicity

  • Irreversible nerve degeneration

• Food sources

  • Broccoli

  • Tomato juice 

  • Banana

  • watermelon

n Selected Foods

  The B Vitamins – Folate

• Known as folacin or folic acid

• Primary coenzyme form – THF (tetrahydrofolate)

  • Transfers single-carbon compounds during metabolism

    • Convert vitamin B12 to coenzyme form

    • Synthesize DNA

    • Regenerate methionine from homocysteine

• Neural tube defects

• Supplement use

  • 1 month before conception

  • Through first trimester

• Fortified grain products

• Congenital birth defects

• Safety concerns with fortification

  • Mask a vitamin B12 deficiencytamins – Folate

• Deficiency

  • Impairs cell division and protein synthesis

  • Red blood cells and GI tract cells falter

    • Pernicious Anemia

  • Primary deficiencies

  • Secondary deficiencies

    • Drugs

  • Food sources

    • Broccoli

    • Tomato juice

    • Pinto beans

    • Lentils

    • Asparagus

    • Vitamin B12 and folate depend on each other for activation 

Interactions among the B Vitamins

• Each B vitamin coenzyme is involved in energy metabolism

  • Directly

  • Indirectly

• Deficiencies

  • Single B-vitamin deficiencies seldom show up in isolation

    • Beriberi and pellagra

• Toxicities

  • Excess eliminated through urine excretion

  • Homeostasis disruption

    • Toxicities develop

• Food sources

  • First choice should be foods rather than supplementsf Vitamin c

 Vitamin C – Roles

• Antioxidant

  • Defends against free radicals

    • Loses electrons easily

  • Vitamin C recycling

  • Protects tissues from oxidative stress

    • Disease prevention

  • Enhances iron absorption Roles

• Cofactor in collagen formation

  • Matrix for bone and tooth formation

  • Conversion of proline to hydroxyproline

• Cofactor in other reactions

  • Hydroxylation of carnitine

  • Conversion of tryptophan to serotonin

  • Conversion of tyrosine to norepinephrine

  • Making hormones

  • Prevention and treatment of common cold

• Conflicting and controversial research

• Deactivates histamine

• Disease prevention

• Deficiency disease: 

• Scurvy: below 10mg

• Deficiency symptoms

  • Anemia (small-cell type)

  • Atherosclerotic plaques

  • Pinpoint hemorrhages, bone fragility, joint pain

  • Poor wound healing, frequent infections, bleeding gums, loosened teeth

  • Muscle degeneration and pain, hysteria, depression, rough skin, blotchy bruisestions

• Prevent overt symptoms of scurvy

• Absorption maximum

  • 200 mg

• Higher vitamin C levels for smokers

• Notable signs of deficiency

  • Gums bleed easily around teeth

  • Capillaries under skin break spontaneously

• Scurvy

• Other physical signs

• Psychological signs

• Sudden death

• Toxicity

• Supplementation side effects

  • Diarrhea

  • GI distress

• UL

• Interference with medical regimens

• Medical conditions in which high doses of vitamin C should not be consumed

• Food sources

  • Broccoli 

  • Strawberries

  • Red bell pepper

  • Kiwi

  • Brussels sprouts