Vitamins

Question 1

history of vitamins

Answer 1

Purified diets of carbohydrate, protein, fat, minerals and water were not capable of normal growth
“Accessory growth factors”
Casimir Funk, a Polish biochemist, isolated an antiberberi substance from rice polishings
Named it vitamine
An amine
Vital for life

Question 2

what are vitamins?

Answer 2

Essential organic compounds required in very small amounts involved in fundamental functions of the body
Not metabolic fuels or structural nutrients
Regulators (catalysts) of reactions, some of which are involved in energy metabolism

All vitamins are metabolically essential but not all required in the diet
Most mammals can synthesize vitamin C; not humans and primates
Most B vitamins cannot be synthesized by animals but bacteria do make them
Some function as vitamins after undergoing a chemical change

Question 3

classification of vitamins

Answer 3

Based on solubility in the laboratory
Solubility greatly influences how the body absorbs, transports and stores vitamins
Fat-soluble
Vitamins A, D, E and K
Water-soluble
B vitamins and vitamin C

Question 4

bioavailability

Answer 4

Rate and extent to which a nutrient is absorbed from the gastrointestinal tract
Influenced by genetics, aging, nutritional status & other food compounds
Extent to which nutrient is available to cells for metabolic purposes
Poor bioavailability can negate higher abundance in foods

Question 5

regulation and body stores

Answer 5

Absorption
Small intestine & large intestine
Regulation
Kidneys & small intestine

Question 6

increasing intake

Answer 6

Increase diet availability

Fortification

Genetic modification

Question 7

water soluble vitamins

Answer 7

B1
    B2
    B3
    B5 
    B6
    B7

B12

Question 8

vitamin B2- riboflavin

Answer 8

Riboflavin is easily destroyed by light so milk is packaged in cardboard or cloudy plastic containers so little riboflavin is lost before consumption.

Question 9

vitamin B3- Niacin

Answer 9

Forms
Nicotinic acid
Nicotinamide

Body uses both forms to make:
NAD+
NADP

Question 10

bioavailability of niacin/b3

Answer 10

Treating grain products with alkaline substances cleaves protein from niacin
Not limes, lime water (Ca(OH)2)
Destroys other vitamins

1 mg niacin = 60 mg tryptophan

Question 11

vitamin b5- pantothenic acid

Answer 11

Bioavailability
Pantos = everywhere

Not stored in body

Coenzyme form high in liver, kidney, heart, adrenal glands, & brain

Question 12

vitamin B6

Answer 12

Forms
Pyridoxine
Pyridoxal
Pyridoxamine
Forms pyridoxal phosphate (PLP)
Coenzyme form of B6 
Stored in muscle & liver

Question 13

functions of biotin

Answer 13

Catalyzes carboxylation reactions

Use of amino acids & fatty acids in citric acid cycle for synthesis of fatty acids

Question 14

Function of Folate: Single-Carbon Transfers

Answer 14

Coenzyme involved in transfer of single-carbon groups to form organic substances
Homocysteine to methionine

Coenzyme involved in transfer of single-carbon groups to form organic substances
Homocysteine to methionine
Purines & pyrimidines
Normal growth & development

Question 15

dietary sources of folate

Answer 15

Since 1998, all cereal products in U.S. fortified with folic acid
Heat, light, & oxygen destroy folate

Question 16

functions of b12

Answer 16

Coenzyme that catalyzes:
Production of succinyl CoA
Uses amino acids & fatty acids for ATP production
Key for ruminants!!
Conversion of homocysteine to methionine
Allows use of folate

Question 17

functions of vitamin c

Answer 17

Antioxidant

Recharges enzymes

Involved in a variety of redox reactions

Question 18

Vitamin C & Protection from Free Radical Damage

Answer 18

Free radicals
Charged substances that have unpaired electrons in their outer shells
Break DNA & oxidize fatty acids found in cell membranes

Question 19

Regulation of Choline in the Body

Answer 19

Unbound choline absorbed in small intestine
Lecithin
Cleaved from glycerol backbone by pancreatic enzymes
Taken up by intestinal cells & reconstituted into lecithin molecules
Released into lymph
Becomes LDL
Made in body by methionine
Assists FA in crossing membranes

Question 20

water soluble vitamins

Answer 20

Absorbed at the small intestine
Absorption often highly regulated by either other vitamins or binding proteins in the small intestine
Transported away from small intestine in blood
Typically not stored; instead, kidney filters excess into urine
Thus, more important to get these vitamins daily
Toxicities almost unheard of

Question 21

fat soluble vitamins

Answer 21

A, D2, D3, E, K

Stored in body

Key players in:
Cell growth
Maturation
Gene regulation

Question 22

basics of fat soluble vitamins

Answer 22

Absorbed in small intestine
Requires lipids & bile
Circulated in lymph via chylomicrons
Become part of lipoproteins or bound to transport proteins

Question 23

vitamin A

Answer 23

Retinoids (preformed)
Retinol 
Most potent form
Retinal
Retinoic acid
Carotenoids
Provitamin A
β-carotein
Nonprovitamin A
Lycopene, lutein, etc.
Phytochemicals 

Retinol activity equivalent (RAE)
1 RAE = 12 micrograms beta-carotene & 1 microgram retinol

Sensitivity
NO3
Rumen

Question 24

night blindness

Answer 24

Inadequate amounts of retinal to re-form rhodopsin
Compound in retina that consists of the protein opsin & vitamin cis-retinal that is needed for night vision

Night vision becomes difficult

Question 25

vitamin K

Answer 25

Phylloquinone (K1)
Food & supplements
Menaquinone (K2)
Produced by bacteria in large intestine
Menadione (K3)
Produced commercially

Packaged into lipoproteins in liver

Question 26

functions of vitamin K

Answer 26

coagulation