Vitamins are vital organic nutrients essential to over all health and are needed for cells and fluids in the body. They are found in all the foods that we eat, and must be consumed in small quantities since our bodies cannot make them. They are also available in dietary supplements, but those are only suggested if necessary, like if the body is not getting enough vitamins from food. Even though vitamins do not supply energy as carbohydrates, fats and proteins do, they are vital because they regulate the body chemistry and body functions. Vitamins assist the body in functioning and healing properly. They help prevent diseases, help brain function, and play a big role in feeling well every day. There are fat soluble vitamins, and water soluble vitamins. They are classified by their solubility, which affects how much the vitamin is stored, and how easily it is excreted. (Wiley & Sons, 2013, Ch 8.1).
As stated before, vitamins need to be consumed and digested by foods. Vitamins are metabolized through a process that involves the mouth, stomach, pancreas, intestines, and liver. Many people do not realize the importance of chewing food. It helps break apart the fiber in foods and release the vitamins. Digestion in the stomach also releases vitamins, where some niacin is absorbed. Digestive enzymes are released by the pancreas to further the release of vitamins. When entering the small intestine, water-soluble vitamins are absorbed by simple diffusion, facilitated diffusion, and active transport. The micelles in the small intestine absorbs most fat-soluble vitamins, along with dietary fat. Vitamin B-12 and vitamin C are absorbed later in the small intestine. Bacteria in the large intestine absorbs a small amount of vitamin K, biotin, and pantothenic acid. Bile produced by the liver also helps absorb fat-soluble vitamins. Any vitamins not absorbed are considered waste. (Wiley & Sons, 2013, Ch 8, Sec 1).
Fat-soluble vitamins are vitamins that are absorbed along with dietary fat in the body. Fat-soluble vitamins include vitamin A, D, E, and K. They are stored in the liver and fatty tissues, and excess amounts cannot be released from the urine. Fat-soluble vitamins are stored longer, so it takes longer to build a deficiency to them when they are no longer provided in the diet. Sources of vitamin A are liver, fish, milk, margarine, better, eggs, carrots, leafy greens, sweet potatoes, broccoli, apricots, and cantaloupe. The functions of vitamin A include healthy vision, reproduction, immunity, and cell differentiation. It is needed to maintain epithelial tissue, which makes up the skin and tissues around the eyes, intestines, lungs, vagina, and bladder. People who do not get enough vitamin A may have a weak immune system, dry skin, stunted growth, xeropthalmia (which causes blindness), and even night blindness. Too much vitamin A can cause headaches, vomiting, hair loss, liver damage, skin changes, bone pain, and birth defects. Vitamin D is found in egg yolk, liver, fish, oils, tuna, salmon, milk, margarine, and even from sunlight. It plays an important role in the absorption of calcium and phosphorous, and maintains the bones. Not enough vitamin D can cause abnormal growth, rickets in children, misshaped bones, bowed legs, and soft bones. It also causes osteomalacia in adults, or weak bones and bone pain. Too much vitamin D causes growth retardation, kidney damage, and calcium deposits in soft tissues. Sources of vitamin E include vegetable oils, leafy greens, seeds, nuts, and peanuts. Vitamin E functions as an antioxidant and protects cell membranes. It is rare to get too much or too little of vitamin E, but too much can cause inhibition of vitamin K activity, and too little can cause nerve damage and broken red blood cells. Vitamin K is found in vegetable oils, leafy greens, and synthesis by intestinal bacteria. Its function is synthesis of blood clotting proteins, or in other words, it helps the blood clot. Not...
References: Wiley & Sons, John. (2013). Nutrition: Everyday Choices. Chapter 8: The Vitamins. Retrieved September 27, 2013. From http://edugen.wiley.com/edugen/student/main.uni
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