Chapter 11 Fat Soluble Vitamins: ADEK

Chapter 11 - FSV Characteristics of fat-soluble vitamins Do not dissolve in water, but dissolve in fat or organic solvents. Dietary fat soluble vitamins need bile for absorption. The fat-soluble vitamins include vitamins A, D,E and K Found in the fats and oils of foods. Stored in the liver and fat tissue until needed not readily excreted from the body. Risk of toxicity.

Storage of vitamins in the body Vitamins A, D and E: These three fat-soluble vitamins can accumulate in the liver and fat tissue of the body and are not readily excreted. Long-term intakes more than the RDA can be toxic, particularly vitamins A and D. Vitamin K: The other fat-soluble vitamin, vitamin K, is readily excreted from the body.

Absorption & transport The fat-soluble vitamins, like lipids are absorbed with dietary fat. Bile aids in the absorption of fat-soluble vitamins. The GI must function adequately for efficient uptake of fat-soluble vitamins. Under normal conditions, healthy individuals will absorb 40-90% of fat-soluble vitamins.

Absorption & Transport Fat malabsorption interfere with the absorption of FSV. Unabsorbed fat is excreted as feces. The following conditions adversely affect the uptake of fat-soluble vitamins: Cystic fibrosis Crohn’s disease Celiac disease Certain medications

Vitamin A Family of compounds called Retinoids: Retinol – supports reproductive functions Found in animal foods and nutrient supplements. Can converted to retinoic acid and retinal in the body. Retinal – Aid in vision Retinoic acid – regulates growth ~90% of retinoids are absorbed These are preformed Vitamin A – form that the body readily uses. Found only in animal sources

Provitamin A = carotenoids Found in plant sources Not biologically available until they are changed into one of the retinoids in the body There are over 600 different carotenoids only 3 can be converted to vitamin A Beta carotene (most common form) Alpha carotene Beta- cryptoxanthin Accounts for 25 – 35 percent of dietary vitamin A consumed in the US

Essential for healthy eyes Promotes cell differentiation Functions of Vit A Essential for healthy eyes Promotes cell differentiation Determines what cell becomes in your body Supports reproductive system, development of limbs, heart eyes and ears Promotes bone and teeth growth Play a role in immunity and preventing infections by creating white blood cells Carotenoids, which act as antioxidants, decrease the damaging effects of free radicals.

Sources of Vitamin A Sources Preformed Vit A Organ meats (liver), milk, cereals, cheese and eggs are the most popular sources of Provitamin A (carotenoids) Fruits: peaches, apricots, cantaloupes, mangoes, papaya Vegetables: tomatoes, carrots, winter squash, sweet potatoes, broccoli, romaine lettuce, collard greens and spinach. Adding as little as 1 tablespoon of vegetable oil to your diet can increase absorption of carotenoids by as much as 25%

Vitamin A RDA – can be measured in micrograms of retinoic activity equivalents (RAE) or in international units (IU). 1 RAE = 3.3 IU 900 microgram for men 700 microgram for women Upper limit 3,000 microgram/day Deficiency Night blindness – difficulty seeing at dusk, can’t adjust from day light to dark Vitamin A deficiency is the main cause of non-accidental blindness (Xerophthalmia) Many die after blindness as a result of infection. The eye becomes prone to infections when the conjunctiva is damaged. Infections can spread systemically throughout the body.

Figure 11.5: Vitamin A–Deficiency Symptom—Night Blindness. These photographs illustrate the eyes’ slow recovery in response to a flash of bright light at night. In animal research studies, the response rate is measured with electrodes.

Toxicity Hypervitaminosis A - is a condition that results from excessive intake of vitamin A from supplements Cause defective physical development during early development of the fetus resulting in birth defects Even 3X RDA vitamin A is considered risky during pregnancy. Accutane is associated with congenital malformations result involving the head and brain. FDA has recommended that women of childbearing years limit their vitamin A intake to 100% RDA

Toxicity High consumption of vitamin A has been linked to osteoporosis and increased risk of fractures Provitamin A carotenoids in foods are not toxic Extra carotenoids are stored in the liver and in the fat under the skin, causing carotenodermia

Figure 11.7: Symptom of Beta-Carotene Excess—Discoloration of the Skin. Fig. 11-7, p. 375

Vitamin D/calceferol Also called the “sunshine vitamin” because it is made with the help of ultraviolet (UV) rays from sunlight Vitamin D enters your body in an inactive form The kidneys convert dietary vitamin D into the active form Precursor = body’s cholesterol

Vitamin D/ calceferol Functions of Vit D Sources of vit D Helps bone health by regulating calcium and phosphorus concentration in the blood When blood concentration of calcium is low, vitamin D and parathyroid hormone signals the kidney to decrease excretion of calcium and phosphorous Sources of vit D Fortified milk, cereals, yogurt, fatty fish

Vitamin D Adequate Intake: 5 micrograms/day for 19-50 yr Upper level: 50 micrograms/day

Vitamin D Deficiency Rickets in children (soft bones) poor bone mineralization Bowed legs Unable to hold up their own weight when standing up Recently researchers have found a rise in rickets among children, linked to increase consumption of soft drinks Limited outdoor activities Fear of skin cancer Air pollution reduces ultraviolet rays of the sun by as much as 60%

Vitamin D Osteomalacia - adult form of rickets Occurs in women with decreased calcium and phosphorus intake Causes bone weakness and pain Can lead to osteoporosis

Vitamin D Toxicity Hypervitaminosis D – associated with over-consumption of supplements Increased calcium withdrawal in bones and intestines Increased calcium and phosphorous concentrations in the blood (hypercalcemia) Increase calcium deposits in kidneys, lungs, blood vessels and heart

Vitamin E Vitamin E is an effective antioxidant Prevent oxidation of lipids, vit A and LDL to prevent build-up in the arteries Neutralize free radicals before they damage cell membranes Prevents blood clotting in the blood by acting as anticoagulant There are 8 different forms, only one is active in the body (alpha- tocopherol) The synthetic is only half as active as the natural

Vitamin E Sources Polyunsaturated plant oils (vegetable oils) Nuts and seeds Leafy green vegetables Fortified cereals RDA: Adults need 15 milligrams/day Upper limit is 1,000 milligrams

Vitamin E Deficiency Erythrocyte hemolysis in premature infants (red blood cell destruction causing anemia) Toxicity from synthetic form or fortified foods increase risk of hemorrhage A deficiency of vitamin K can increase the anticoagulant effect

Vitamin K There are two forms of vitamin K: Menaquinone – synthesized by the intestinal tract Phylloquinone – found in green plants Functions Essential for blood clotting Vitamin K plays a role synthesizing clotting factors Without vit k a simple cut on the finger would cause uncontrollable bleeding Synthesis of bone protein (osteocalcin) that regulates blood calcium.

Vitamin K Inadequate amount of vitamin K may contribute to osteoporosis, associated with increased risk of hip fractures Sources Intestinal bacteria can make vitamin K but not enough to meet all of the body’s needs Leafy green vegetables Cabbage family vegetables Vegetable oils and margarine

Vitamin K Deficiency Toxicity Newborn infants receive a single dose of vitamin K at birth because of a sterile intestinal tract to prevent hemorrhagic disease Rare in healthy individuals Toxicity No known adverse effect from consuming too much vitamin K from food or supplement Interferes with anticlotting medication (coumadin)

Recommendation for Vitamin K Adequate Intake (based on amount that is consumed on average) Infants: 2 – 2.5 microgram Children: 30 – 55 microgram Men: 60 – 120 microgram Women: 60 – 90 microgram

Homework/extra credit 5 points Complete the vitamin/mineral evaluation form posted on the course website