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Fat-Soluble Vitamins
| Question | Answer |
|---|---|
| What are vitamins? | Thirteen essential, organic micronutrients that are needed by the body for normal functions. |
| What are some functions of vitamins. | Vitamins act as coenzymes to help regulate metabolism and assist the body to convert the energy in fat, carbohydrates, and protein into ATP. Vitamins also preserve tissues, promote growth and reproduction, act as antioxidants |
| What is the significance of vitamins? | A deficiency of any vitamin can cause a lack of energy and other serious health problems. |
| How are vitamins classified? | 1. It is an organic, non-energy providing compound that the body can't synthesize but is essential to human health. 2. Chronic deficiency of the compound leads to physical symptoms that disappear after taking the compound. 3. Fat or water soluble |
| Why is the distinction in solubility important? | It influences how the body digests, absorbs, transports, stores, and excretes these essential nutrients. |
| What is the structure of vitamins? | They do not have a uniform structure. They all contain carbon, hydrogen, and oxygen. May contain nitrogen, cobalt, and sulfur. There are no bonds for the body to hydrolyze during digestion. Vitamins are absorbed intact. |
| antioxidants | Vitamin C and E |
| Blood clotting and red blood cell synthesis | Folate, Vitamin B12, Vitamin B6, Vitamin K |
| Bone health | Vitamins A, C, D, K |
| Energy production | Biotin, niacin (B3), pantothenic acid, riboflavin (B2). thiamin (B), vitamin B6, vitamin B12 |
| Growth and reproduction | Vitamin A, vitamin D |
| Protein metabolism and synthesis | Folate, vitamin B6, vitamin B12, vitamin C |
| Provitamins | Substances found in food that are not in a form directly usable by the body, but that can be converted into an active form once they are absorbed. |
| Example of a provitamin | Beta-carotene is split into two molecules of vitamin A in the enterocytes or in liver cells. |
| Preformed vitamins | Vitamins found in foods that are already in the active form and do not need to undergo conversion. |
| Hypervitaminosis | When a person ingests more of a vitamin than the body needs, to the point in which tissues become saturated. |
| Megadose | Amount of vitamin or mineral that is at least 10 times the amount recommended in the DRI |
| Megadoses are especially bad for which vitamins? | Fat-soluble vitamins: A, D, and E which are stored in the body's tissues |
| Bioavailability | Degree to which a nutrient is absorbed from foods and used in the body |
| How may be the bioavailability of vitamins vary | The amount of vitamin in the food; whether the food is cooked, raw, or refined; how efficiently the food is digested and absorbed; the individual's nutritional status and general health; and whether or not the vitamin is natural or synthetic. |
| Which type of vitamin is less bioavailable? | Fat-soluble because fat-soluble vitamins require bile and the formation of micelles in order to be absorbed. Vitamins in plant foods are typically less bioavailable than those in animal foods because plant fiber can trap vitamins. |
| How the body absorbs fat-soluble vitamins. Step 1 | Fat-soluble vitamins are often attached to food components, usually protein, in foods. To be absorbed, the vitamin must be released from the protein with the help of pepsin and hydrochloric acid. |
| How the body metabolizes fat-soluble vitamins. Step 2 | They are packaged with fatty acids and bile in micelles that transport them close to the intestinal mucosa. Once there, the fat-soluble vitamins travel through the enterocytes and are repackaged with fat and other lipids into chylomicrons. |
| How fat-soluble vitamins travels through the body. Step 3 | The vitamins then travel through the lymph system before they enter the bloodstream. |
| Things that can impair and compromise absorption of fat-soluble vitamins. | 1. The absence of adequate fatty acids. 2. Malabsorption diseases such as celiac disease and cystic fibrosis 3. Diseases that impair the synthesis of bile, especially Vitamin D and K |
| Why are fat-soluble vitamins stored in the body? | When dietary intake falls short of the body's needs. Because of this they can also build to large toxic quantities in the body. |
| How are water-soluble vitamins absorbed? | Absorbed with water and enter the bloodstream directly from the small intestine. Easily absorbed and must be consumed adequately every day. |
| antioxidants | Nutrients and phytochemicals that act to neutralize free radicals. |
| oxidative stress | Condition whereby free radicals are being produced in the body faster than they are neutralized. |
| Damaging effects of antioxidants | Contribute to cardiovascular disease, cancer, diabetes, arthritis, Parkinson's disease, and Alzheimer's. Can alter DNA and RNA, cause inflammation, and are thought to contribute to aging. Can damage vision |
| age-related macular degeneration (AMD) | Disease that affects the macula of the retina, causing blurry vision and, potentially, blindness. |
| cataract | Common eye disorder that occurs when the lens of the eye becomes cloudy. |
| How can Age-related macular degeneration be mitigated? | Antioxidant supplements containing vitamin A, beta-carotene, vitamin C, and vitamin E, along with the minerals zinc and copper, reduce the risk of AMD and reduce the development of advanced AMD. |
| How can cataracts be mitigated? | Vitamins C and E (and the carotenoids lutein and zeaxanthin) may also reduce the risk of cataract |
| Note for phytochemicals | Some phytochemicals, including carotenoids, are also responsible for the vibrant colors of many fruits and vegetables. Table 9.2 emphasizes the importance of consuming a colorful diet so as to take in an abundance of phytochemicals. |
| What is the best source of vitamins? | Eating whole foods, including fruits, vegetables, and whole grains, remains the best way to meet vitamin needs because these foods are rich in antioxidant phytochemicals and fiber. |
| Fat-soluble vitamins in food when exposed to oxygen | Oxygen can destroy vitamins A, E, and K. Fresh vegetables and fruits should be stored in airtight, covered containers and used soon after being purchased. |
| Fat-soluble vitamins in food when exposed to light | Light, especially ultraviolet light (UV) can destroy vitamins. For example, up to 80 per cent of the riboflavin content of milk stored in clear glass bottles can be destroyed by UV light. |
| Fat-soluble vitamins in food when exposed to water | Water-soluble vitamins leach out of foods when soaked or cooked in liquids, so cooking foods in as little water as possible is recommended. |
| Fat-soluble vitamins in food when exposed to pH changes | Changes in pH can destroy some vitamins, especially thiamin and vitamin C. Adding ingredients such as baking soda to food increases the pH and destroys pH-sensitive vitamins. |
| Fat-soluble vitamins in food when exposed to heat | Vegetables cooked by microwaving , steaming, and stir-frying can have approximately one-and-a-half more vitamin C after cooking than if they were boiled, which involves longer heat exposure. |
| Fortification | The addition of nutrients by manufacturers to enhance the nutrient quality of the food and to prevent or correct dietary deficiencies. |
| Fortified foods | Foods with added vitamins and minerals ; contain nutrients that are not naturally present in the food or that are in higher amounts than the food contains naturally. |
| Fortified foods pros | Pro: It can be a valuable option for individuals whose diet falls short of some nutrients. Good for older adults who are inactive and thus have lower kilocalorie needs. Women in their childbearing years may look to folic acid-fortified cereals. |
| Fortified foods cons | Individuals are more likely to overconsume vitamins from fortified foods than from whole foods. These individuals are at risk for health problems. |
| retinoids | Term used to describe the family of preformed vitamin A compounds. |
| retinol | Alcohol form of preformed vitamin A. |
| retinal | Aldehyde form of preformed vitamin A |
| retinoic acid | Acid form of preformed vitamin A; signals genes to make the proteins needed to begin cell division. |
| retinyl ester | Ester form of preformed vitamin A found in foods and stored in the body. |
| provitamin-A carotenoids | Group of yellow, red, and orange plant pigments that act as precursors to vitamin A. |
| beta-carotene | One of the provitamin A carotenoids. |
| The term vitamin A | refers to a family of fat-soluble retinoids that include retinol, retinal, and retinoic acid. Each contain a ring with a polyunsaturated hydrocarbon chain. |
| How to differentiate retinol, retinal, and retinoic acid. | Attached at the end of the hydro carbon chain is either an alcohol group (retinol), an aldehyde group (retinal), or an acid group (retinoic acid). The alcohol form is the most usable. |
| Vitamin A in food form | In foods, vitamin A is found as retinol or as a retinyl ester, which has an ester group (a compound derived from a carboxylic acid) attached at the fatty acid tail. |
| Vitamin A's significance in epithelial tissues | They stimulate cell division and cell differentiation of epithelial cells as they grow and development |
| How does Vitamin A support vision | Light that passes the eyes and hits the retina is translated into visual images with the help of two vitamin A-dependent proteins, rhodopsin and iodopsin. These proteins are found in the tips of light-absorbing cells in the retina called rods and cones. |
| Vitamin A absorption | All forms of preformed vitamin A are absorbed by active transport in the small intestine with the help of bile and micelles. |
| Effect of vitamin A on mucus | Columnar epithelial cells are tall, moist, secrete mucus, and are lined with cilia. Vitamin A deficiency can cause these cells to become hard, flattened, and unable to produce mucus. |
| Vitamin and Bone Health | Both excessive intake and insufficient intake of Vitamin A have negative impacts on bone density. |
| Carotenoids as antioxidants | Nonprovitamin A compounds (compounds that the body doesn't convert into vitamin A) are the carotenoids lycopene, lutein, and zeaxanthin. They stabilize free radicals. |
| Food sources of vitamin A | Milk, cereal, cheese, egg yolks, organ meats, carrots, spinach, and sweat potatoes, |
| Hypervitaminosis A | Serious condition in which the liver accumulates toxic levels of vitamin A |
| carotenodermia | Presence of excess carotene in the blood, resulting in an orange color to the skin due to excessive intake of carrots or other carotene-rich vegetables. |
| night blindness | inability to see dim light or at night due to a deficiency of retinal in the retina |
| xerophthalmia | permanent damage to the cornea causing blindness; due to a prolonged vitamin A deficiency |
| keratinization | accumulation of the protein keratin in epithelial cells, forming hard, dry cells unable to secrete mucus; due to vitamin A deficiency |
| calciferol | Family of vitamin D compounds |
| ergocalciferol (vitamin D2) | form of vitamin D found in plants and dietary supplements |
| cholecalciferol (vitamin D3) | Form of vitamin D found in animal foods, supplements, and formed from precalciferol in the skin; absorbed from the skin into the blood |
| parathyroid hormone | hormone secreted from the parathyroid glands that activates vitamin D formation in the kidney |
| prohormone | physiologically inactive precursor to a hormone |
| 1,25-dihydroxycholecalciferol | active form of vitamin D that leaves the kidney and enters the cells; also known as calcitriol |
| Vitamin D2 and Vitamin D3 metabolism | Absorbed into the small intestine as part of a micelle. Each is repackaged into chylomicrons and circulates through the lymph system before arriving at the liver for storage |
| 1,25-dihydroxycholecalciferol metabolism part 1 | Provitamin D3 is converted to precalciferol when UV rays hit the skin. Precalciferol is changed to cholecalciferol. |
| 1,25-dihydroxycholecalciferol metabolism part 2 | It's transported by a binding protein to the liver and it gets a hydroxyl group to the 25th carbon. Then the kidneys add another to the first carbon. |
| When blood calcium levels drop, | the parathyroid hormone travels to the kidneys to activate vitamin D. This increases the intestinal absorption of calcium, increases kidney's reabsorption of calcium, and mobilizes calcium from bone. Blood calcium returns to normal. |
| Vitamin D help... | ...regulate the growth of cells (reduced risk of cancer), regulates the immune system (reduces the risk of autoimmune disorders), regulate blood pressure (reduces hypertension). |
| Variable impacts on vitamin D synthesis | Dark skin individuals need a longer period of sun exposure. Cloudy day reduces synthesis by 50%. 60% if smoggy and sit in the shade. Sunscreen by more than 95%. |
| Food sources of vitamin D | Fortified milk, soymilk, breakfast cereals, yogurt, fatty fish |
| hypervitaminosis D | Condition resulting in excessive amounts of vitamin D in the body; only results from too much vitamin D supplements |
| hypercalcemia | chronically too much calcium in the blood |
| rickets | vitamin D deficiency in children resulting in soft bones |
| Osteomalacia | the adult equivalent of rickets |
| Osteoporosis | such a decrease in bone density that it increases the risk of a fracture |
| Vitamin E | 8 different forms but the most active form is the alpha-tocopherol. It has a long side chain of saturated carbon. |
| Vitamin E absorption | through biles and micelles into the enterocytes |
| Vitamin E transportation | Transported as part of chylomicrons through the lymph fluid into the blood and arrives at the liver. |
| Vitamin E storage | 90%+ stored in adipose tissue. Excess is excreted through bile, urine, feces, and pores of the skin |
| Vitamin E as an antioxidant | It is a powerful antioxidant. They neutralize free radicals before they can harm cell membranes |
| Vitamin E as an anticoagulant | inhibits platelets from unnecessarily clumping together and creating a damaging clot in the bloodstream. Lessens the stickiness of the cells that line the blood vessels. Reduces risk of heart attack and stroke. |
| Food sources of vitamin E | Vegetable oils, avocados, nuts, and seeds. Some green leafy vegetables and fortified cereals also contribute |
| Toxicity of Vitamin E | Too much can cause hemorrhage which is excessive bleeding and loss of blood; results from too much vitamin E supplements |
| Vitamin E deficiency | Can cause nerve problems, muscle weakness, and uncontrolled movement of body parts and can increase the susceptibility of cell membranes being damaged by free radicals |
| Vitamin K | in plants, phylloquinone. Phylloquinone is primary source of vitamin K in the diet. in animals' large intestine, menaquinone |
| Vitamin K absorption and transport | 80%+ absorbed in the jejenum. 10% produced by bacteria in the large intestine. Incorporated into chylomicrons and transported to the liver. When diet is deficient, storage form is transported by VLDL, LDL, and HDL. |
| Vitamin K and blood clotting | There are four vitamin K-dependent clotting factors which are each necessary in the process of blood clotting |
| clotting factors | substances involved in the process of blood clotting |
| Vitamin K and strong bones | Vitamin K participates in the carboxylation (enables protein to bind to calcium ions) of other proteins necessary in bone formation |
| Food sources of Vitamin K | Think green. Vegetables like broccoli, asparagus, spinach, salad greens, brussels sprouts, and green cabbage. Vegetable oils and margarine are also good |
| Vitamin K toxicity | Individuals taking anticoagulant medication need to make sure they maintain a consistent intake of Vitamin K. No known adverse effects of too much. |
| Vitamin K deficiency | Babies are born with low levels of vitamin K and are routinely supplied right after birth. Rare in healthy individuals unless you have a condition where you can't absorb fat properly |
| Are supplements beneficial? | Risks tend to outweigh benefits. They do not reduce risk of CVD, Cancer, or cognitive decline |
| Are supplements a substitute for healthy eating? | Research says no. They tend to have adverse side effects. They tend to be the reason for vitamin toxicity in the body. |
| Are supplements useful for people in rare cases? part 1 | Women of child-bearing age that need to consume synthetic folic acid to prevent birth defects, pregnant and lactating women, older individuals, individuals who do not meet their vitamin D needs, vegans, and people on low-kilocalorie diets |
| Are supplements useful for people in rare cases? part 2 | individuals with food allergies, individuals who abuse alcohol, individuals who are food insecure, infants who are breastfed |
| Supplements are not regulated like drugs | Dietary supplements do not need approval from the FDA before they can be marketed to the public. FDA cannot remove it from the marketplace unless it has been shown to be unsafe and harmful |
| An ideal supplement would have... | ...a USP Verified Mark and must have a supplement facts panel that lists the serving size, the number of capsules or tablets in the bottle, the amount of the vitamin in each capsule, and the percentage of the daily value. Ingredients must be listed. |
Created by:
bsauveur
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