Vitamin B-12 assists in the formation of red blood cells and the normal functioning of your nervous system and is required for the synthesis of DNA (your genetic resumé). Because B-12 is only found in foods of animal origin, strict vegetarians might need to take a supplement to avoid a deficiency. Furthermore, this unique vitamin needs the help of another substance called intrinsic factor to be absorbed. Because intrinsic factor is made by the lining of the stomach, people with gastrointestinal disorders (especially found in the elderly) might need to get B-12 shots directly into the bloodstream. Symptoms of B-12 deficiency include nervous disorders and pernicious anemia.
Because a good amount of vitamin B-12 can be stored in the liver, it might take years for a deficiency to be recognized. As a result, people should have their B-12 levels checked starting at age 60 and every decade thereafter.
Foods rich in cobalamin (B-12) include meat, fish, poultry, eggs, milk products, and clams.
Food for Thought
Folic acid has been shown to decrease your risk for colon cancer. If you have ulcerative colitis or feel that you are at a high risk for colon cancer—speak to your physician about supplementation. Folic acid can also reduce the risk of heart disease by lowering the levels of a harmful substance called homocysteine in the blood.
Scurvy is a disease resulting from a deficiency of vitamin C, characterized by bleeding and swollen gums, joint pain, muscle wasting, and bruises. Scurvy is now very rare, except among alcoholics, and can be cured by as little as 5 to 7 milligrams of vitamin C.
Folic Acid (Folacin, Folate)
Folic acid appropriately gets its name from the word foliage because it's primarily found in leafy, dark green vegetables. In addition to playing a vital role in cell division and red blood cell formation, this vitamin is needed to make the genetic material DNA.
In recent years, folic acid has gained a lot of attention for its ability to reduce neural-tube birth defects in newborn babies. Needless to say, it is imperative that pregnant mothers and women of childbearing years get the appropriate amounts of folic acid by both foods and supplementation. For this reason, folic acid is a key ingredient in most prenatal vitamins. Because this nutrient is involved in cell division, a deficiency will leave you vulnerable to anemia and an abnormal digestive function because your blood cells and cells of the intestinal tract divide most rapidly. Foods rich in folic acid include spinach, liver, beans (all types), peas, asparagus, lima beans, oranges, brussels sprouts, collard greens, and avocadoes.
Pantothenic Acid and Biotin
Pantothenic acid and biotin are both part of the “B-vitamin gang” that participates in the metabolism of energy. In addition, pantothenic acid also plays a role in the formation of certain hormones and neurotransmitters. Although both vitamins are vital for normal functioning, as of today there isn't a set RDA for either one. This is because deficiencies are so rare, and they are both found in a wide variety of plant and animal foods.
For reasons that are unclear, cigarette smokers seem to require 50 percent more vitamin C than nonsmokers. Instead of popping more vitamin C, why not just quit smoking?
Food for Thought
There's no need to megadose on vitamin C because it turns out that young, healthy, nonsmokers can only absorb about 400 mg per day. Even the Linus Pauling Institute now recommends only 400 mg vitamin C per day for this group, although they caution that older people and those suffering from certain diseases may need more.
Vitamin C (Ascorbic Acid)
Now the million-dollar question, “Can vitamin C ward off the common cold?” The scientists say no. To date, there is no documented evidence supporting this notion. Interestingly enough, this vitamin might lessen the severity of those lousy symptoms experienced during a cold because vitamin C has a mild antihistaminic effect.
What else can vitamin C do? Let's just say if all the vitamins and minerals were on a pay scale according to the jobs they perform, vitamin C would be rolling. Vitamin C wears many hats, from helping to keep your bones, teeth, and blood vessels healthy to healing wounds, boosting your resistance to infection, and participating in the formation of collagen (a protein that helps support body structures). Another benefit from eating foods rich in vitamin C is that you increase the absorption of the mineral iron— good news for people with greater iron requirements
Although vitamin C deficiency is uncommon, it can cause a lowered resistance to infection, sore gums, hemorrhages, and in severe cases, the disease scurvy.
Foods rich in vitamin C include melons, berries, tomatoes, potatoes, broccoli, fortified juices, guava, kiwi, mangos, papaya, yellow peppers, and citrus fruits (oranges, grapefruits, etc.)
More on: Children's Nutritional Needs
Excerpted from The Complete Idiot's Guide to Total Nutrition © 2005 by Joy Bauer. All rights reserved including the right of reproduction in whole or in part in any form. Used by arrangement with Alpha Books, a member of Penguin Group (USA) Inc.
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