Fat-soluble Vitamins دكتر حيدرپور متخصص طب ورزش استاديار دانشكده پزشكي

Overview of Vitamins  Are essential organic substances needed in small amounts in the diet for normal function, growth, and maintenance of body tissues  Vitamins A, D, E, and K dissolve in organic solvents whereas the B vitamins and vitamin C dissolve in water

Vitamin A retinoids Vitamin A is a generic term for a class of compounds called retinoids Types of retinoids: retinol, retinal, and retinoic acid Carotenoids: pigment in fruits and vegetables used in forming vitamin A Alpha & Beta-carotene are examples of provitamins converted into vitamin A (retinol) The release of vitamin A from food requires bile, digestive enzymes (lipase) from the pancreas and intestinal tract, and integration into micelles 90% of vitamin A absorbed in small intestine Retinoids stored in liver and carotenoids stored in liver and adipose Cellular Retinoid-Binding Proteins (CRBP or RBP) - needed for the transport of retinoids into cell

Functions: Visual – Retinal in retina of the eye turns visual light into nerve signals to the brain – Retinoic acid maintains normal differentiation of the cells that make up the various structural components of the eye Cell differentiation – nuclear retinoid (RAR and RXR) receptors bind to DNA and cause gene expression Used in growth and differentiation of epithelial, nervous, bone tissues Immunity – increases cell differentiation – produce cells involved in specific (e.g., lymphocytes) and nonspecific immunologic defenses (e.g., mucosal surfaces)

Deficiency Xerophthalmia Bitot’s spots (keratin deposited in conjunctiva; associated with night blindness) Follicular hyperkeratosis (protein keratin deposited around hair follicle) Xerosis (very dry, rough skin) Immune suppression (decreased resistance to infections) Anemia Impaired tissue growth (slower bone growth, faulty tooth development )

Dietary Sources Liver sweet potato( سيب زميني شيرين ) Carrots( هويج زرد ) spinach Mango( انبه ) Acorn( بلوط ) squash( كدو ) broccoli( كلم ) margarine peaches( هلو ) Apricots( زرد الو ) Cantaloupes( طالبي - گرمك ) papaya ( انبه هندي )

RDA The Recommended Dietary Allowance (RDA) for vitamin A is 900 mcg(micrograms )/ day for adult males and 700 mcg/day for adult females.

Toxicity Hypervitaminosis A caused by excess dosages (100 times RDA) Can be fatal (13,000 times RDA) Chronic: liver damage, hair loss, bone/muscle pain, loss of appetite, dry skin and mucous membranes, hemorrhages, coma Acute: gastrointestinal upsets/nausea, headaches, dizziness, muscle contraction

Vitamin D

Two nutritionally important forms: vitamin D 2 (ergocalciferol) which is found in plants and vitamin D 3 (cholecalciferol) which is synthesized in the body from cholesterol Conversion in skin: provitamin D (a form of cholesterol) is converted to previtamin D 3 is converted to vitamin D 3 D 3 must be metabolized in the liver before becoming the active form of vitamin D 80% of vitamin D is absorbed in small intestine Carried by proteins in blood stream Formation of hormone form (Calcidiol and Calitriol) of vitamin D occurs in the liver and kidneys

Functions of vitamin D Maintains serum calcium and phosphorus concentrations within the range that supports neuromuscular function and bone calcification – Calcitriol causes calcium to be absorbed by kidneys and intestines and also causes calcium to be released from bone

Food Sources for Vitamin D milk The primary food sources of vitamin D are milk and other dairy products fortified with vitamin D. oily fish Vitamin D is also found in oily fish (e.g., salmon and sardines) we obtain vitamin D through our skin which produces vitamin D in response to sunlight.

Deficiency Rickets (children) Osteomalacia (adults) Decreased calcium and phosphorus levels and thus soften/weakens bone tissue

Dietary sources Fortified milk, margarine, butter, cereals, egg yolks, liver, fatty fish AI (adequate intake) 5 ug/day (19-50yrs) 10 ug/day (51-70yrs) 15 ug/day (>70yrs)

ToxicityToxicity Hypervitaminosis D 5 times the AI is dangerous for infants, 10 times the AI for adults Calcification of soft tissue, growth retardation, excess calcium excretion via the kidneys (kidney stones), headaches, muscle weakness, fatigue, excessive thirst

Vitamin E

Family of eight antioxidants, four tocopherols, alpha-, beta-, gamma- and delta-, and four tocotrienols (also alpha-, beta-, gamma- and delta-) Alpha-tocopherol is most active form The release of vitamin E from food requires bile, digestive enzymes from the pancreas and intestinal tract Vitamin E is stored in liver and adipose tissue

Functions Antioxidant Prevents propagation of free radicals Protects other substances from oxidation by being oxidized itself Also protects polyunsaturated fatty acids and vitamin A

Dietary sources Polyunsaturated plant oils ( ( مارگارين leafy green vegetables, سبزيجات برگدار سبز wheat germ, سبوس گندم whole-grains, غلات كامل liver, egg yolks, nuts آجيل ها seeds تخمه افتابگردان

Deficiencies Hemolysis of red blood cells, anemia, degeneration of sensory neurons RDA 15mg/day

Toxicity nausea, fatigue, blurred vision, augmentation of anti-clotting medications

Vitamin K

Two forms: – Vitamin K 1 Phyllaquinones (plant source) – vitamin K 2 menaquinone (fish oils and meats) 80% of dietary vitamin K is absorbed The release of vitamin K from food requires bile, digestive enzymes from the pancreas and intestinal tract, and integration into micelles Functions: – Contributes to the synthesis of seven blood clotting factors – Cofactor for enzymes

Dietary sources – Liver, milk, green and leafy vegetables, broccoli, and green beans( لوبيا سبز ) Deficiencies – May occur as a result of inadequate fat absorption and/or antibiotic consumption – Excessive bleeding may occur

RDA Men 120 ug/day Women 90 ug/day Toxicity May interfere with anti-clotting medication