Vitamins

1. Vitamins Brought to you by the Flintstones

2. C.5.1 Define the term vitamin.

3. So, what exactly is a vitamin? • Here’s the technical definition: An organic molecule that is required in only trace amounts and can only be obtained through the diet since it cannot be synthesized.

4. In other words… • Vitamins are “Vital amines” that we need to survive, but can’t make ourselves. • Most vitamins are coenzymes or are precursors to coenzymes, and many are antioxidants. • Your body can’t differentiate between synthetic and natural vitamins. • Fun Fact: 1g of B12 is enough for 500,000 people! Crazy right??

5. C.5.2 Deduce whether a vitamin is water or fat soluble from its structure.

6. Water Soluble Vitamins • There are nine total water soluble vitamins. and are found in aqueous environments inside cells, where most are needed as components of coenzymes. • Excess of these vitamins is excreted by urine, so it needs to be constantly replenished in small amounts. • These are carried by the blood-stream.

7. How do you recognize them? • Water soluble vitamins all have –OH, -COOH or other polar groups to make them water soluble. (more on this later…) • Example: Vitamin C and Vitamin B

8. Fun Fact • Ever wondered where the names B and C came from? They are the names of the test tubes where the vitamins were first recognized. Scientists later realized that test tube contained more than one type of vitamin, which resulted in vitamins B1, B6, B12 etc.

9. Fat Soluble Vitamins • These are stored in the body’s fat deposits and cell membranes. • Because they are not continuously excreted by the body, excess of fat soluble vitamins is more hazardous than water soluble since they can accumulate in body fats. • None has been identified as a coenzyme.

10. What do they look like? • The structures of fat soluble vitamins are more hydrocarbon-like and have less functional groups. • Nonpolar • Examples: Vitamins A, D, E & K

11. C.5.3 Describe the structures and major functions of retinol (vitamin A), calciferol (vitamin D) and ascorbic acid (vitamin C)

12. Retinol/Vitamin A • Fat Soluble • It has 3 active forms: retinol, retinal, and retinoic acid • It is produced by cleavage of (b) carotene (this is the molecule that gives carrots their orange color), so it is required for the synthesis of visual pigments • It is an antioxidant! How does it work? • Hint: Look at the functional groups at the end of each hydrocarbon chain...more to come!

13. What is Vitamin A used for? • It is essential for night vision (particularly rhodopsin), healthy eyes, normal development of epithelial tissues, formation of bone, reproduction and more! • Required for the production of rhodopsin (light-sensitive material in the rods of the retina). • Rhodopsin: a pigment of the retina that is responsible for both the formation of the photoreceptor cells and the first events in the perception of light.

14. Forms of Vitamin A http://www.vivo.colostate.edu/hbooks/pathphys/misc_topics/vitamina.gif

15. Vitamin A Deficiency • Deficiency can cause night blindness and xerophthalmia. • Xerophthalmia: is a medical condition in which the eye fails to produce tears; it may be caused due to a lack of vitamin A • Macular degeneration: a medical condition in which the light sensing cells in the macula (part of the retina) malfunction and, over time, cease to work (blindness).

16. Xerophthalmia http://www.milesresearch.com/eerf/images/xerophthalmia1.jpg http://www.milesresearch.com/eerf/images/bitot-step0.jpg

17. Calciferol/Vitamin D • Fat Soluble • It is related in structure to cholesterol. • It is synthesized when UV light from the sun strikes a cholesterol derivative in the skin. • In your kidney, vitamin D is converted to a hormone which regulates calcium absorption and bone formation.

18. Vitamin D Structure

19. Function and Deficiency of Vitamin D • Required for the uptake of calcium from food. Deficiency can cause weak bones (rickets). • Rickets: softening of the bones in children potentially leading to fractures and deformity; results from severe malnutrition and is predominant in developing countries • Osteomalacia is used to describe a similar condition occurring in adults. • Sufficient vitamin D levels can also be achieved through dietary supplementation. • Most dermatologists recommend vitamin D supplementation as an alternative to unprotected UV exposure due to the increased risk of skin cancer associated with sun exposure.

20. Rickets http://www.dinf.ne.jp/doc/english/global/david/dwe002/dwe002g/dwe00215g01.gif http://www.e-radiography.net/radpath/r/Rickets_wrist_healing.jpg

21. Ascorbic Acid/Vitamin C • Water Soluble • It is biologically active without any change in structure from the form it has in food. • It has been proven to be a valuable anti-oxidant (you will get to see this for yourself today!) • We are one of the few species that obtain it from our diet, most others synthesize it from glucose.

22. Structure of Vitamin C

23. Function of Vitamin C • Its most characteristic role is to function as a co-substrate in the formation of structural collagen • It makes up much of skin, ligaments, tendons, and also serves as matrix on which bone and teeth are formed.

24. What is Collagen? • Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% of the total protein content. • Fibrous structural protein • Bundles of collagen are called collagen fibers • Support most tissues • Gives cells structure inside and out • Main component of cartilage, ligaments, tendons, bone, teeth • Responsible for skin strength and elasticity

25. Collagen http://www.3dchem.com/imagesofmolecules/Collagen2.jpg

26. Deficiency of Vitamin C • Deficiency can cause scorbutus (scurvy). • Scurvy leads to the formation of liver spots on the skin, spongy gums, and bleeding from all mucous membranes.

27. Scurvy http://www.med.uc.edu/departme/cellbiol/Image7.gif http://www.faqs.org/nutrition/images/nwaz_02_img0214.jpg

28. Antioxidants and Preservatives • A substance that prevents oxidation by reacting w/ an oxidizing agent and gets oxidized itself. • Many foods get spoiled because they get oxidized, so they are protected by “phenolic” additives. • A naturally occurring phenolic antioxidant is vitamin E.

29. Antioxidants Continued… • Rancidity: it is when fats and oils develop an odor/flavor upon exposure to moist air, which is the result of the oxidation of the carbon-carbon double bonds in the fatty acid chains in the tri-glycerols. • So, antioxidants prevent rancidity in foods by preventing them from getting oxidized, by getting oxidized themselves. • Our principal dietary antioxidants are vitamins C, E, B, and selenium. These work by defusing the potentially harmful free radicals in the body

30. C.5.4 Describe the effects of food processing on the vitamin content of food.

31. Effects of Cooking on Vitamin Contents • Vitamins containing carbon-carbon double bonds and hydroxyl groups are easily oxidized and thus can be destroyed by prolonged cooking and high temperatures (which speeds up oxidation).

32. Vitamin C • Vitamin C is water soluble and readily oxidized. So boiling vegetables can deplete a lot of Vitamin C content. • Scurvy, from lack of vitamin C, was common in sailors because they spent long periods without fresh foods. • Solutions: • Keeping food refrigerated can slow the oxidation process. • Steaming foods instead of boiling

33. Vitamin C Oxidation http://online.redwoods.cc.ca.us/depts/science/chem/chem1A/Labs/VitaminC/VitaminC.gif

34. Other Vitamins • Vitamin D can be destroyed through oxidation by some bleaching agents used in manufacturing purified flour. • Vitamin A is not readily broken down by cooking.

35. Genetic Modification • Does not lower nutrition value/destroy vitamins • Increases food productivity • Food more resistant to disease/toxins • Better flavor texture, nutritional value and shelf life • May contaminate DNA or increase risk of a disease- long term effects are unknown

36. Genetically Modified Tomato

37. And Now for the Lab…