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Value of Vitamins and Multivitamins

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  • Value of Vitamins and Multivitamins

    Dietary Insurance: A Daily Multivitamin
    In the past, experts claimed that if people ate healthy diets, taking vitamins was not necessary. However, research is now showing that it is beneficial for the majority of adults to take a multivitamin each day.

    Scientists have discovered evidence showing that vitamins do not just keep away deficiency diseases such as rickets and scurvy. Taking more than the minimum daily requirements of certain vitamins may avert the onset of chronic diseases including osteoporosis, cancer, and heart disease.

    The purpose of this summary is to offer information on why people should take multivitamins, how to improve your diet to increase vitamin intake, and to show newly suspected or acknowledged roles of certain vitamins in health and disease prevention.

    Vitamin A:
    Vitamin A not only helps you see better in darkness, but it also regulates cell division and growth, stimulates the activity and production of white blood cells, assists in maintaining healthy endothelial cells which line the interior surfaces of the body, and plays a role in remodeling bone. For many years, researchers were trying to discover if vitamin A caused cancer since it regulates cell division and growth. Various studies, including ones using beta carotene, now show this to be a false claim. (1)

    While many people do not get enough vitamin A, it is possible to take too much. Taking twice the daily level recommendations, up to 10,000 IU, is believed to be safe. Nonetheless, some research shows that levels of vitamin A this high could raise risks of hip fracture (2) or various birth defects.(3) Optimal Intake: Vitamin A is found in fortified juices, dairy products, and breakfast cereals. Numerous vegetables, fruits, and supplements contain vitamin A precursors, such as beta-carotene. The body converts these precursors into vitamin A. Up to date recommendations for daily vitamin A intake suggest 4,000 IU for women and 5,000 IU for men.

    The 3 Bs: Vitamin B6, Vitamin B12, and Folic Acid
    Our opinion of vitamins is changing due to the various discoveries in research. Deficiency of a B vitamin, folic acid, is associated with causing birth defects including anencephaly and spina bifida. These birth defects occur when tissue that forms the spinal cord, surrounding tissues, or the brain develops incorrectly. Research conducted in Britain twenty-five years ago discovered low vitamin levels in mothers of children with spina bifida.(4) Two major trials were later performed assigning women at random to take placebos or folic acid. The results showed that taking folic acid can prevent birth defects. Getting too little folic acid caused an increased risk in women of having a baby with anencephaly or spina bifida.(5,6)

    Women in their childbearing years are encouraged to take supplements with folic acid. Suggested daily minimums of 400 micrograms are sometimes difficult to get from food. The US Food and Drug Administration now demands folic acid additives in grain products including pastas, enriched breads, cornmeal, rice, and flour, amongst iron and other micronutrient additives.

    Folic acid and two additional B vitamins are now being linked to fighting various types of cancer and heart disease. It is not yet known if folic acid and the two other B vitamins prevent these diseases.

    B Vitamins and Heart Disease
    After two children died from massive strokes in 1968, a pathologist in Boston began studying whether or not the high levels of a protein breakdown product called homocysteine found in their bodies could have caused the cholesterol clogging in their arteries. Following this initial study, others have been conducted connecting high levels of homocysteine to increased stroke and heart disease risks.

    Vitamins B6, B12, and folic acid help recycle homocysteine into one of the twenty chemicals the body uses to create new proteins. If the body has deficiencies in any of these three vitamins, homocysteine cannot be converted into methionine, and levels in the body increase. Increased levels have been linked in several studies to increased risks of stroke and heart disease. While some studies link increased intake of folic acid, whether through multivitamins or the type of folic acid found in the body called serum folate, to lowered risks of heart disease, other studies do not show any relationship between heart disease and homocysteine. Other studies are being conducted to try to answer remaining questions concerning heart disease, homocysteine, and B vitamins including the Women’s Antioxidant Cardiovascular Study(11) and the Vitamin Intervention in Stroke Prevention Study(12).

    Folic Acid and Cancer
    Folate also assists in the building of DNA, the intricate compound that creates our individual genetic code. Some observational studies indicate that higher intake of folic acid can reduce the risk of colon (13) and breast cancer (14). This information is critical for alcohol drinkers because alcohol hinders the body’s use of folic acid and stops folate moving through the body. The Nurses’ Health Study shows that higher intake of folic acid in women who drink over one alcoholic drink daily can help decrease risks of breast cancer .(14)

    Optimal Intake: Although the optimal daily intake is not known for sure, researchers believe that very few adults get the amounts of B vitamins needed through their diet. The use of a multivitamin is suggested and further research in the next few years will most likely stress the importance of taking these supplements.

    Folic Acid: 400 micrograms of folic acid daily is suggested. Folic acid can be found in fortified grains, beans, and breakfast cereals.Vitamin B6: Presently, research suggests a daily intake of 6 micrograms of vitamin B12. In the past, deficiencies in this vitamin were the cause of pernicious anemia, a fatal disease with symptoms including disorientation, tingling in the extremities, memory loss, and hallucinations. Today those who are diagnosed with disease are generally elderly people who have trouble absorbing vitamin B12. The vitamin B12 deficiency is thought to sometimes be mistaken for Alzheimer’s disease or dementia.

    Vitamin C:
    The actual vitamin itself was not discovered until 1932. However, for many generations preceding the discovery, people knew that something found in citrus fruits prevented scurvy. This disease was responsible for the deaths of up to 2 million sailors from 1500 to 1800.(15) Today, because of the Nobel laureate Linus Pauling, high doses of vitamin C are thought to prevent chronic diseases and colds.

    Not only can vitamin C help manage infections, but it aids in the production of the tissue collagen required for healthy gums, teeth, bones, and blood vessels and is a strong antioxidant that helps counteract harmful substances(16). The debate is over the amount of vitamin C required to maintain health.It is now believed that extra high doses of vitamin C are not needed. Research supports the amounts of vitamin C found in multivitamins can minimize cold symptoms; however, no research supports that high doses prevent or alleviate colds.(17) No association has been found in studies between eye diseases, cancer, and heart disease and vitamin C.

    Optimal Intake: 90 mg of vitamin C is recommended daily for men and 75mg is recommended for women. Those who smoke should intake an extra 35 mg daily. Although high intake of vitamin C hasn’t proved to increase good health, amounts between 200 and 300mg are suggested to be helpful. Taking a multivitamin daily and eating a balanced diet can provide these amounts. Vitamin C is found in foods including spinach, tomatoes, red and green peppers, broccoli, fortified cereals, and citrus fruits and juices.

    Vitamin D:
    Those living in the northern half of the country rarely intake enough vitamin D. Others who typically have deficiencies are those who spend less than fifteen minutes each day in sunlight. A study conducted on patients of a hospital in Boston revealed a vitamin D deficiency in 57 of those tested.(18)

    Vitamin D helps the body build strong bones by assisting in the retaining and absorption of phosphorus and calcium. Studies conducted in laboratories show that vitamin D stops the division and growth of cancer cells.

    An association between an amplified risk of bone fractures and vitamin D deficiency has been found in various preliminary studies. Taking vitamin D supplements is thought to prevent the increased risk of fractures.(19) Deficiency of vitamin D has also been linked with increased risks of cancers including breast, prostate, and colon in other studies.

    Optimal Intake: Before the age of 50, 5 micrograms or vitamin D are recommended daily. Those between 50 and 70 should increase their intake to 10 micrograms; those over 70 should increase intake to 15 micrograms. Vitamin D is not found naturally in many foods. Fortified cereals and dairy products and some fish including tuna and salmon contain vitamin D. Taking a daily multivitamin is the easiest way to get enough vitamin D.

    Vitamin E:
    Initial studies, such as the Nurses' Health Study (20) and Health Professionals Follow-up Study,(21) showed the possibility that taking vitamin E supplements for at least two years, caused a 20 to 40 reduction in heart disease.(22)

    Further studies have not shown the same positive results. A study conducted by the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto miocardio (GISSI Prevention Trial), did not find that vitamin E had any effect on the prevention of strokes, heart attacks, or deaths in 11,000 heart attack survivors. However, the study did find that vitamin E seemed to lower the death rate and number of sudden deaths caused by heart disease.(23) The Heart Outcomes Prevention Evaluation (HOPE) trial studied 9,500 women and men previously diagnosed with high risk of or actual heart disease. The patients were given vitamin E supplements for four years; the study found no benefits from the intake of vitamin E. (24)

    Researchers believe that further trials could prove that drugs including beta blockers, aspirin, and ACE inhibitors lower the effectiveness of vitamin E and that the vitamin may prove to be more helpful in those with good health. Currently trials are being conducted, including the Women's Health Study (25), to find more about the potential benefits of vitamin E.

    Optimal Intake: The intake of 15 milligrams of vitamin E daily is currently recommended. This amount is equal to 22 IU from foods or 33 IU from supplementation. Studies are now suggesting that a minimum of 400 IU of vitamin E daily might be necessary to maintain the best health. A vitamin E supplement is recommended in addition to a multivitamin, which only provides about 30 IU.

    Vitamin K:
    Vitamin K is responsible for helping to create six out of the thirteen proteins used to clot blood. Because of the vitamin’s critical role in blood clotting, patients taking anticoagulants such as Coumadin have to closely watch their levels of vitamin K.

    Vitamin E is now being linked to building bone. Those with low bone density have shown low levels of vitamin K circulating their body. Vitamin K supplementation seems to help improve the overall health of bones.(26) The Nurses’ Health Study reports a 30 less chance of hip fractures among women who intake a daily minimum of 110 micrograms of vitamin K. (27) The study suggests a 50 reduction in risk of hip fracture among those who eat a serving of green leafy vegetables daily versus those who only eat one serving weekly. The Framingham Heart Study has also linked a reduction of hip fracture risk with increased intake of vitamin K.(28)

    Optimal Intake: Men should intake 80 micrograms of vitamin K daily and women should intake 65. Many adults get the daily recommendations through diet alone because this vitamin is found in numerous foods including cooking oils and green leafy vegetables. However, many young adults and children do not get the recommended intake of vitamin K. (29)

    Antioxidants
    Free radicals are harmful substances our cells must continually fight. They can cause damage almost any body tissue or substance including artery walls, DNA, and proteins found in the eye. Free radicals come from our food, the air we breathe, and are sometimes formed as byproducts inside the body.

    Antioxidants help our bodies fight free radicals and are found in the food we eat. Antioxidants are found in plant-based foods such as vegetables and fruits and include beta-carotene, related carrotenoids, vitamin E, and vitamin C. Enzymes in the body also use minerals found in foods, such as manganese and selenium, to fight against free radicals.

    In the 1990’s, antioxidants were promoted to prevent cataracts, cancer, memory loss, and heart disease and became a popular commodity in the nutrition.The combination of fiber, minerals, antioxidants, in addition to other substances found in a healthy diet can prevent various diseases. It is still in question whether high intake of vitamin E, vitamin C, or other antioxidants can individually prevent disease.

    Present research has not shown beta-carotene, vitamin E, or vitamin C to have any affect on the prevention of age-related diseases, cancer, or heart disease. Antioxidants including zeaxanthin and lutein are being researched to see if they have any affect on macular degeneration. Lycopene is being studied to find affects on prostate cancer.

    The Bottom Line
    An unhealthy diet cannot be simply replaced by taking a daily multivitamin. Multivitamins only provide a handful of vitamins needed to remain healthy and are thought of as a nutritional backup. A diet full of whole grains, fruits, and vegetables will help maintain a healthy lifestyle.

    Deficiency diseases are not a problem for the majority of people in today’s society. However, most people do not intake enough of five important vitamins thought to help prevent a variety of serious diseases. These five vitamins are:

    * Folic acid
    * Vitamin B6
    * Vitamin B12
    * Vitamin D
    * Vitamin E

    For less than $40 each year, people can take regular generic RDA-level multivitamins to acquire the recommended levels of these vitamins.

    PUBLISHED BY HARVARD SCHOOL OF PUBLIC HEALTH
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