Fat Soluble Vitamins Fat soluble vitamins include: A and carotenoids, E, K, D Associated with fat absorption Needed in small amounts Stored in fatty tissues Excess intake has toxic consequences

Fig. 10-1a, p. 327 Retinol and caroteinoids Lipid-soluble red, orange, and yellow pigments produced by plants Fewer than 10% have vitamin A activity B carotene,  carotene,  cryptoxanthin Others also have physiological importance Lycopene Canthaxanthin Zeaxanthin

Fig. 10-1b, p. 328

Fig. 10-2, p. 329 Specfic protein carrier- vitamin A Passive diffusion - carotenoids 70-90% vitamin A absorption if fat is present <5% to 60% for carotenoids; vitamin E interferes CRBPII = cellular retinol binding protein LRAT = lecithin retinol acyl transferase

Outer of photoreceptor (rod) cell Segment Inner segment Photoreceptor (rod) cell Outer segment Capillary Pigment epithelium Nucleus ‘‘Outer limiting membrane’’ Müller cell Fig. 10-7, p. 334 Functions: Vitamin A Vision Cell differentiation, growth, reproduction Bone development Immune system

Fig. 10-8, p. 334

Fig. 10-9, p. 335 Functions: Vitamin A Vision Cell differentiation, growth, reproduction Bone development Immune system

Functions: Vitamin A Vision Cell differentiation, growth, reproduction Bone development Immune system

Functions: Vitamin A Vision Cell differentiation, growth, reproduction Bone development Immune system Function: Carotenoids Antioxidants for singlet oxygen; Lycopene > vitamin E >  carotene >  cryptoxanthin > zeaxanthin,  carotene > lutein (also work better when used together) Antioxidant for lipid peroxides (works with vitamin E) Lower incidence of atherosclerosis through prevention of oxidation of LDLs

Fig , p. 339 Interaction with other nutrients: Vitamins E and K (inversely related; high A, low E and K) Zinc and iron Protein Excretion: most in urine as oxoretinoic acid, small amounts in expired air, some in feces

Deficiency: increased morbidity in children under age 5 with no evident clinical signs of deficiency Signs, when present include xeropthalmia, anorexia, retarded growth, increased susceptibility to infections, enlargement of hair follicle, and keratinization of epithelial (mucous cells) of the skin. Toxicity: Hypervitaminosis A Nausea, vomiting, double vision, headache, dizziness, and desquamation of the skin Teratogen

Fig , p. 344 Vitamin D (a seco-steroid) plants animals

Table 10-2, p. 345

Fig , p. 346 Dietary Vitamin D is absorbed from a micelle, along with other fats. About 50% of dietary D3 is absorbed. Most absorbed in distal small intestine. Incorporated into chylomicrons Cholecalciferol from the skin is bound to DBP and travels primarily to the liver, but can be picked up by other tissues as well (muscle and adipose) Blood is the major storage site; half-life of days Hydroxylases generate the active form of the vitamin (25-OH cholecalciferol) Release by the kidney of active forms; a half-life of 4-6 hours in the blood

Fig , p. 347 Functions: Acts as a steroid hormone in calcium homeostasis Intestinal effects Effects on the kidney Effects on bone

Fig , p. 348

Fig , p. 349

Deficiency: rickets, osteomalacia Interaction with other nutrients: Calcium, phosphorus, vitamin K Excretion: Bile > feces > urine Toxicity: Not possible from excess exposure to sunlight Few cases; calcification of soft tissues, hypertension, anorexia, renal dysfunction

Fig , p. 353 Only form with biologic activity

Table 10-3, p. 354 Digestion and Transport: Synthetic forms are de- esterified Free alcohol forms are absorbed passively in micelles; non-saturable 20-80% absorption; better with fats Incorporated into chylomicrons in intestinal cell and sent out into lymph Transfer between chylomicrons, HDLs and LDLs occurs in the blood. HDLs and LDLs contain highest concentration of the vitamin Half-life of about 48 hrs. Some stored in adipose, liver, lung, heart, muscle, adrenals

Fig , p. 356 Functions: Maintenance of membranes - prevents oxidation of unsaturated fatty acids contained in the phospholipids (includes membranes of mitochondria and ER) Reduced LDL oxidation; decreased plaque formation Reduction in cataract formation Reduced oxidation in diabetics Suppression of activity of HMGcoA reductase (cholesterol synthesis) 1 2

Fig , p. 356 Regeneration Nutrient Interactions: Function closely linked to selenium (needed for GSH peroxidase), vitamin C, sulfur containing amino acids, Inhibits carotene absorption and conversion to retinol; may impair vitamin K absorption; may cause vitamin -D dependent bone mineralization problems Deficiency: Rare except in populations with fat malabsorption (cystic fibrosis) myopathy and weakness, croid pigment accumulation, and degenerative neurologic problems Toxicity: one of the least toxic; bleeding problems

Fig , p. 361 Vitamin K Absorption: in micelles; incorporated into chylomicrons, then chylomicron remnants, then VLDLs, then HDLs and LDLs. Found mainly in liver and heart. Turnover is once every 2.5 hrs. From green plants Synthesized by bacteria Synthetic form

Table 10-4, p. 361

Fig , p. 363 Functions: blood clotting and bone mineralization

Fig , p. 364 Vitamin K cycle Needed for protein carboxylation Vit. K usually only present in this form in the body Osteocalcin or Bone Gla protein Matrix Gla protein

Deficiency: rare in adults; newborns, chronic antibiotic administration, and malabsorption can result in deficiency Bleeding episodes Osteoporosis Toxicity: none known

Table 10-1, p. 326