NSC 170C1 1st Edition Lecture 16 Outline of Last Lecture I. Vegetarian Diets Outline of Current Lecture I. What is a vitamin? A. Water Soluble and fat soluble II. Types of Vitamins Current LectureI. What is a vitamin?A. Vitamins are tasteless, organic compounds needed by the body in small amounts for growth, reproduction, and good health.i. Vitamins are antioxidants ii. Vitamins are either fat soluble or water soluble iii. Vitamins Can Be Destroyed by Air, Water, and Heata) Don’t Expose Produce to Airb) A Little Water Is Enoughc) Reduce the Cooking Timed) Keep Food Cooliv. 13 Vitamins a) Found in most foods i. Vitamins D and K, niacin, and biotin can also be synthesized in the body or by microorganisms in the intestinal tractii. Chronic deficiency will cause physiological symptomsiii. Consuming too much of some vitamins may cause adverse effectsII. Vitamins Are Either Fat Soluble or Water SolubleA. Fat Vitamins: Vitamins A,K,D,E i. Require dietary fiber to be absorbed a) Absorption begins at the small intestine b) Packaged with fatty acid and bile in micelles and absorbed through the intestinal liningc) Once absorbed, packaged into chylomicrons and transported through the lymph systemii. The liver is the main storage site for vitamin A and to a lesser extent vitamins K and E. Vitamin D is stored in fat and muscle tissue.iii. Large quantities of some fat-soluble vitamins (particularly A and D) can build up and cause toxicityB. Water Soluble: Vitamin B and Ci. Absorbed in water and enter the bloodstream directlya) Most are absorbed in the upper part of the intestine, except for vitamin B12, which is absorbed in the lower partii. Not stored in the body; excess amounts are excreted in urineiii. Important to consume adequate amounts of them dailyiv. Dietary excesses can still be harmfulIII. Digesting and absorbing vitamins A. Some Vitamins Are Antioxidantsi. Antioxidants: compounds including vitamins E and C, the mineral selenium, and certain phytochemicals that counteract oxidation reactionsB. Free radicals: oxygen-containing molecules that damage cells by altering their structure, proteins, and DNAi. Normal by-products of metabolic reactions, but increased levels result from exposure to environmental pollutants or UV rays from the sunii. Attack molecules in the body in a chain reaction fashionC. Antioxidants are your body’s natural defense against free radicalsD. Normal and Impaired VisionIV. Vitamin AA. Daily needs i. Males: 700 mcg RAE Females: 900 mcg RAEii. A daily recommended intake for beta-carotene has not been established, but 3 to 6 mg/d from foods is recommendedB. Food Source i. Organ meats (liver), milk, cereals, cheese, and eggsii. Carrots, spinach, and sweet potatoes are popular favorites for carotenoids (fat increases absorption)C. Too much or Too little vitamin Ai. Excessive amounts (usually due to taking supplements) can accumulate to toxic levels.a) UL: 3,000 microgramsii. Carotenoids from foods are not toxic.a) Can cause carotenodermia, a nonserious condition resulting in orange-tinted skiniii. Chronic deficiency of vitamin A can lead to night blindnessa) If prolonged, can lead to permanent vision damageb) Vitamin A deficiency is the #1 cause of preventable blindness in children.iv. Deficiency is also associated with stunting of bonesV. Vitamin E A. What Is Vitamin E?i. Alpha-tocopherol is the most active form in the bodyB. Functionsi. Acts as a powerful antioxidant to neutralize free radicalsii. Protects cell membranes and prevents oxidation of LDL cholesteroliii. Acts as an anticoagulant, inhibiting damaging blood clotsC. Daily Needsi. Adults: 15 mg vitamin E (alpha- tocopherol equivalents) per dayD. Food SourcesVegetable oils, nuts, seeds, fortified cereals, and some green leafy vegetablesE. Too Much or Too Littlei. No known risk of consuming too much vitamin E from food sourcesii. Overconsumption of synthetic form in dietary supplements and fortified foods may increase risk of hemorrhageiii. UL: 1,000 mg/dayiv. Although rare, chronic deficiency can cause nerve problems, muscle weakness, and free radical damage to cell membranesVI. Vitamin K A. What Is Vitamin K?i. Menaquinone: synthesized by bacteria in the intestinal tractii. Phylloquinone: found in green plantsB. Functionsi. Plays a major role in blood coagulation (clotting)ii. Involved in synthesis of four clotting factorsiii. Important to bone healtha) Enables the bone protein osteocalcin to bind to calciumC. Daily Needsi. Amount contributed by intestinal synthesis unknown; recommendationsare based on consumption by healthy adultsii. Men: 120 mcg/d Women: 90 mcg/dD. Food Sourcesi. Green vegetables such as broccoli, asparagus, spinach, salad greens, brussels sprouts, and cabbageii. Vegetable oils and margarineE. Too Much or Too Littlei. No known adverse effects of consuming too much from foods or supplements (no UL set)ii. People taking anticoagulant medications such as warfarin (Coumadin) need to keep vitamin K intake consistentiii. Vitamin K deficiency severe enough to affect blood clotting is extremely rare in healthy individualsVII. Vitamin DA. What Is Vitamin D?i. The “sunshine vitamin”ii. Made in your body with the help of ultraviolet (UV) rays from sunlighta) Cholesterol-containing compounds in skin converted to inactive form of vitamin Db) Inactive form converted to an intermediate form in the liver,then the active form in the kidneysiii. People with insufficient sunlight exposure must meet needs through diet (vitamin D in foods is also in the inactive form)iv. SterolsB. Functionsi. Regulates the bone minerals calcium (Ca) and phosphorus (P)ii. Stimulates intestinal absorption of Ca and P to maintain healthy blood levels and build and maintain bonesiii. When dietary Ca is inadequate, vitamin D and parathyroid hormone cause Ca to leave bones to maintain necessary blood levelsiv. Vitamin D may prevent diabetes and some cancersv. Lower levels of breast, colon, and prostate cancers in regions with amplesunlightvi. Low blood levels of vitamin D observed in people with type 2 diabetes and insulin resistanceC. Daily Needsi. Sun exposure cannot meet everyone’s vitamin D needsii. Skin pigmentation and sunscreens reduce vitamin D productiona) Sunlight intensity during the winter months in northern latitudes is not sufficient to make vitamin Diii. Needs are based on dietary sources onlya) DRI for adults: 5 to 15 mcg (200 to 600 IU), depending on ageD. Food Sourcesi. Fortified milk