Chapter 11 fat soluble vitamins

Vitamin A• First fat soluble vitamin • Beta-carotene is its PRECURSOR... Roles of Vitamin A• Protein Synthesis and cell differentiation – Retinoic acid – Acts like a hormone – Regulates

Fat Soluble Vitamins

Fat Soluble Vitamins

• Vitamin A

• Vitamin D

• Vitamin E

• Vitamin K

General Properties

• Soluble in ?

• Excess is stored in the body

• Stored in fatty tissues and in the liver

• Can be toxic

General Properties

• Not excreted in urine

• Deficiencies develop slowly

• More stable to heat and cooking

• Contain C, H, O

Vitamin A

• First fat soluble vitamin

• Beta-carotene is its PRECURSOR

Forms of Vitamin A

Vitamin A

• Animal sources contain retinoids

– Retinyl esters (preformed vit A)

• Plant foods

– Carotenoids: Beta-carotene

(provitamin A)

– Can be converted to retinol

• intestine and liver

Retinoids

Vitamin A

• Each form has specific function

• 90% storage in the liver

Vitamin A

• Cells can convert retinol and retinal

to other active forms

Reversible

Irreversible

Roles of Vitamin A

• Promotes vision

– Retinal

– Also intermediate between retinol

and retinoic acid

Vitamin A and Vision

Roles of Vitamin A

• In DIM LIGHT:

– vitamin A + opsin -> rhodopsin

(visual purple)

• In BRIGHT LIGHT the reverse occurs:

– rhodopsin -> vitamin A + opsin

Roles of Vitamin A

• Protein Synthesis and cell

differentiation

– Retinoic acid

– Acts like a hormone

– Regulates differentiation, growth

and development

Roles of Vitamin A

• Cell differentiation

• Orange pigment of foods

• Vitamin A precursor

• Antioxidant

Vitamin A Deficiency

• Deficiency appear after 1-2 years

(adults)

• Developing world nutrition problem

• Susceptible to infectious disease

and blindness

Vitamin A Deficiency

• Blindness (Xerophthalmia)

– total blindness

– xerosis: cornea dry and hard

– keratomalasia: softening of the

cornea irreversible blindness

Vitamin A Deficiency

• Keratinization

– changes in epithelial cells

– secretion of Keratin (protein in

nails and hair)

– Skin becomes dry and rough

Vitamin A Toxicity

accumulates under skin (yellow

skin), but not harmful

Vitamin A Toxicity

• Excess of vitamin A damage cells

• Beta-carotene from supplements

destroy vit A, and pro-oxidant

Food Sources Vitamin A

Food Sources Vitamin A

• Plants (precursors)

– no active vit A

– Red and yellow pigments from

plants

Food Sources Vitamin A

Vitamin A Recommendations

• Retinol Equivalents (RE)

• 1 mcg = 1 RE

• 12 mcg beta-carotene = 1 RE

• 1 IU = 3 mcg retinol

Vitamin A Recommendations

• RDA: 900 mcg/day (Males)

Vitamin D

Vitamin D

• Makes Calcium available for bone

growth

Vitamin D

Orange

Juice

Supplements Diet

Fatty Fish

Calcium, Muscle Bone Health & Regulation of Blood

Pressure Insulin Production (heart disease and diabetes prevention)

Regulation of Immune

Function (diabetes type 1 and Autoimmune disease prevention)

Regulation of Cell Growth (cancer prevention)

1,25(OH)2D

Prostate Gland, Breast, Colon Immune Cells

(Holick, 2003)

Vitamin D metabolism

• Bone formation and maintenance

• Helps the body to absorb Calcium

• Regulation of cell growth

• Regulation of Immune system

• Regulation of blood pressure

• Insulin production

Other sources?

• Sunlight

Vitamin D deficiency

• Rickets in children

• Osteomalacia in adults

• Osteoporosis

Rickets

Rickets

Vitamin D Toxicity

• Hypervitaminosis D

• Most likely to cause toxicity effects

• Deposits of Calcium in soft tissues

• Kidney stones

Vitamin D Recommendations

Vitamin E

Vitamin E

• Stability

– Destroy by heat and oxygen

Vitamin E Function

• Antioxidant

Vitamin E Food Sources

Vitamin E Deficiency

• Rare

• Associated to fat malabsorption

Vitamin E Toxicity

• Rare

• May increase effect of anticlotting

medication

Vitamin E

• Protect against chronic diseases

Vitamin E Recommendations

• RDA: 15 mg/day

• UL: 1000mg/day

Vitamin K

Vitamin K

• Can be synthesize in the intestine by

bacteria

• Absorbed in the intestine

• Stored in the LIVER

Vitamin K and Clotting

Vitamin K Recommendations

• AI:

– Men 120 mcg/day

– Women 90 mcg/day

Questions?