Food and Nutrition zone

Water-Soluble Vitamins Like fat-soluble vitamins, water-soluble vitamins are essential organic substances needed in small amounts for the normal function, growth, and maintenance of body tissues. For example, thiamin, riboflavin, niacin, pantothenic acid, and biotin are especially important for energy metabolism. Vitamin B-6, folate, and vitamin B-12 are important for amino acid metabolism and red blood synthesis. Vitamin C participates in the synthesis of numerous compounds, including collagen, and choline is required for nervous system function and aids amino acid and lipid metabolism.  In contrast to the fat-soluble vitamins, only small amount of water-soluble vitamins are stored in the body. The risk of water-soluble vitamin toxicity tends to be low because, unlike fat-soluble vitamins, water-soluble vitamins are readily removed by the kidneys and excreted in the urine. In fact, Tolerable Upper Intake Levels have been set only 4 of the water-soluble vitamins and choline. ...

 Vitamin K Vitamin K food sources Vitamin K appropriately gets its name from the Danish word koagulation ("coagulation" or "clotting"). Its primary action s blood clotting, in which its presence can make the difference between life and death. Blood has a remarkable ability to remain liquid, but it can clot within seconds when the integrity of that system is distributed.  It has other names such as Phylloquinone (vitamin K1), menaquinone (vitamin K2), and menadione (in supplements). Roles in the Body: More than a dozen different proteins and the mineral calcium are involved in making a blood clot. Vitamin K is essential for the activation of several of these proteins, among them prothrombin, made by the liver as a precursor of the protein thrombin. When any of the blood-clotting factors is lacking, hemorrhagic disease results. If an artery or vein is cut or broken, bleeding goes unchecked. Of course, this is not say that hemorrhaging is always caused by vitamin K de...

Vitamin E Vitamin E The vitamin E family consists of to subgroups __the tocopherols and the tocotrienols __each containing four members designated by letters of the Greek alphabet (alpha, beta, gamma, and delta). All consist of a complex ring structure with a long saturated (in tocopherols) or unsaturated (in tocotrienols) side chain. The positions of methyl groups (CH3) on the side chain and their chemical rotations distinguish the four members within each subgroup. Of all the members of the vitamin E family, only alpha-tocopherol is maintained in the body and can meet the body's needs for the vitamin. The others are not converted to alpha-tocopherol in the body, nor are they recognized by its transport protein. For these reasons, the RDA is based only on alpha-tocopherol. Most vitamin E research has focused on alpha-tocopherol, but recent studies suggest that the other tocopherols and tocotrienols have unique antioxidant and anti-inflammatory roles that better protect against ...

 Vitamin D Vitamin D food sources Vitamin D differs from the other nutrients in that the body can synthesize it, with the help of sunlight, from a precursor that the body makes from cholesterol. Therefore, vitamin D is not an essential nutrient; given enough time in the sun, people need no vitamin D from foods.  Also known as calciferol , vitamin D comes in two major forms. Vitamin D2 derives primarily from plant foods in the diet. Vitamin D3  derives from animal foods in the diet and from synthesis in the skin. These two forms of vitamin D are similar and both must be activated before they can fully function.  To make vitamin D, ultraviolet rays from the sun hit a precursor in the skin and convert it to pre-vitamin D3, which is converted to vitamin D3 with the help of body's heat. To activate vitamin D _whether made in the body or consumed from the diet _two hydroxylation reactions must occur. First, the liver adds an OH group, and then the kidneys add another OH gr...

 Vitamin A Vitamin A; most essential vitamin Vitamin A refers to the performed retinoids and provitamin A carotenoids that can be converted to vitamin A activity. Retinoids is a collective term for the biologically active forms of vitamin A. They are called performed vitamin A because, unlikely carotenoids, they do not need to be converted in the body to become biologically active. Retinoids exist in 3 forms; retinol, retinal and retinoic acid. The tail segment of the vitamin A structure terminates in 1 of these 3  chemical groups and determines the name or classification. To some extent, these can be interconverted . However, retinoic acid cannot be converted back to the other forms. the ability to interconvert forms helps maintain adequate amounts of each retinol form for its unique functions.  Carotenoids are yellow-orange pigmented materials in fruits and vegetables, some of which are provitamins __that is, they can be converted into vitamin A. Of the 600 or more kno...

  Vitamins: Essential Dietary Components Vitamins are essential, organic substances needed in small amounts in the diet. They are not a source of energy. Instead, they aid in energy metabolism as well as in the growth, development, and maintenance of body tissues.  During the first half of the 20th century, scientists identified each of the 13 vitamins now recognized as essential. For the most part, as the vitamins were discovered, they were named alphabetically: A, B, C, D and E. Later, some substances originally classified as B-vitamins were dropped from the list because they were shown to be non-essential substances. The B-vitamins originally were thought to have a single chemical form but turned out to exist in many forms. Thus, the label "vitamin B" now comprises 8 B-vitamins. Vitamins A, D, E and K dissolve in organic solvents, such as ether and benzene, and are referred as fat-soluble vitamins .  The B-vitamins and vitamin C, in contrast, dissolve in water and refe...

Triglycerides T riglycerides are the most common type of lipid found in foods and in the body. About 95% of the fats we eat and 95% of the fat stored in the body are in the form of triglycerides.  Structure: Triglycerides are built from a glycerol backbone and 3 fatty acids. Glycerol has 3 carbons in its chain. A triglyceride forms when each hydroxyl group on the glycerol backbone bonds with the hydrogen atom from the acid (carboxyl) end of a fatty acid. The bond between a fatty acid and glycerol is called an ester bond. One molecule of water forms each time an ester bond forms (this is called esterification), Thus, when a diglyceride (2 fatty acids attached to a glycerol backbone) forms, 2 molecules of water form. Similarly, forming a triglyceride will generate 3 water molecules. Esterification is a condensation reaction. A molecule of water is used when a fatty acid breaks away from a glycerol backbone (this hydrolysis reaction can be thought of as "de-esterification"). R...