Re: Vitamin X About To Crack Zip Fil
Hercules Montero
Vitamins are organic substances that are generally classified as either fat soluble or water soluble. Fat-soluble vitamins (vitamin A, vitamin D, vitamin E, and vitamin K) dissolve in fat and tend to accumulate in the body. Water-soluble vitamins (vitamin C and the B-complex vitamins, such as vitamin B6, vitamin B12, and folate) must dissolve in water before they can be absorbed by the body, and therefore cannot be stored. Any water-soluble vitamins unused by the body is primarily lost through urine.
In the U.S., the National Academy of Medicine (formerly the Institute of Medicine) develops nutrient reference values called the Dietary Reference Intakes (DRIs) for vitamins and minerals. [1] These are intended as a guide for good nutrition and as a scientific basis for the development of food guidelines in both the U.S. and Canada. The DRIs are specific to age, gender, and life stages, and cover more than 40 nutrient substances. The guidelines are based on available reports of deficiency and toxicity of each nutrient. Learn more about vitamins and minerals and their recommended intakes in the table below.
A diet that includes plenty of fruits, vegetables, whole grains, good protein packages, and healthful fats should provide most of the nutrients needed for good health. But not everyone manages to eat a healthful diet. Multivitamins can play an important role when nutritional requirements are not met through diet alone. Learn more about vitamin supplementation.
Vitamins were obtained only from food until the 1930s when commercially made supplements of certain vitamins became available. The U.S government also began fortifying foods with specific nutrients to prevent deficiencies common at the time, such as adding iodine to salt to prevent goiter, and adding folic acid to grain products to reduce birth defects during pregnancy. In the 1950s, most vitamins and multivitamins were available for sale to the general public to prevent deficiencies, some receiving a good amount of marketing in popular magazines such as promoting cod liver oil containing vitamin D as bottled sunshine.
This page specifically discusses the use of multivitamins, which typically contain about 26 different vitamins and minerals, and often provide 100% of the Recommended Daily Allowance of these micronutrients. We will explore situations that a multivitamin may be health-promoting, as well as if there is a benefit or harm in taking extra nutrients from a pill if the diet is already adequate.
For those who eat a healthful diet, a multivitamin may have little or no benefit. A diet that includes plenty of fruits, vegetables, whole grains, good protein sources, and healthful fats should provide most of the nutrients needed for good health. But not everyone manages to eat a healthful diet. When it comes to specific vitamins and minerals, some Americans get less than adequate amounts, according to criteria set by the National Academy of Medicine. For example, more than 90% of Americans get less than the Estimated Average Requirement for vitamin D and vitamin E from food sources alone. [2]
Multivitamins come in various forms (tablets, capsules, liquids, powders) and are packaged as a specific combination of nutrients (B-complex, calcium with vitamin D) or as a comprehensive multivitamin.
If you are unsure about taking a multivitamin, you may wish to consult with a registered dietitian who can evaluate your current diet to determine any missing nutrients. At that time, suggestions to improve your food intake of those nutrients will be provided, or one or more supplemental vitamins may be prescribed if that is not possible. Always inform your doctor of all supplements you are taking in case of potential interactions with medications.
Mega-doses (many times the Recommended Daily Allowance) of vitamins are not recommended. This can potentially interfere with the absorption of other nutrients or medications, or can even become toxic if too much is taken for a long period.
There is no arguing that multivitamins are important when nutritional requirements are not met through diet alone. [4] The debate is whether vitamins are needed when the diet is adequate to prevent deficiency in nutrients, as some research has shown no benefit or even harmful effects when taking supplemental vitamins and minerals.
For many diseases, but especially for cancer, only long-term trials are informative. The following studies looked at the effect of multivitamins on specific diseases and included healthy people as well as those with chronic diseases at the start of the study:
A randomized double-blind placebo-controlled trial provided a multivitamin or placebo to more than 14,000 male physicians, some with a history of cancer. After 11 years, the men taking a MVI had a significant 8% reduction in total cancers, compared with men taking a placebo. The results did not differ among men who had a history of cancer at the start of the study and men who were healthy at baseline. [6]
Some research has suggested that the rates of death appear higher in people using multivitamins. However, one major flaw in these studies was that many of the participants had already developed some type of serious illness. They may have started using vitamins after their health deteriorated, hoping for a benefit. But in those cases, taking a multivitamin might have been too late.
It is important to remember that a multivitamin cannot in any way replace a healthful well-balanced diet. The main purpose of a multivitamin is to fill in nutritional gaps, and provides only a hint of the vast array of healthful nutrients and chemicals naturally found in food. It cannot offer fiber or the flavor and enjoyment of foods so key to an optimal diet. However, multivitamins can play an important role when nutritional requirements are not met through diet alone. When this is the case, an expensive brand name is not necessary, as even standard store brands will deliver results. Look for one that contains the Recommended Daily Allowance amounts and that bears the United States Pharmacopeia (USP) seal of approval on the label.
Water-soluble vitamins do not stay in the body for long and cannot be stored. They leave the body via the urine. Because of this, people need a more regular supply of water-soluble vitamins than fat-soluble ones.
A balanced, varied diet that contains plenty of fruits and vegetables should be the primary source of vitamins. The Department of Health and Human Services provide up-to-date guidelines detailing the best ways to get enough nutrients from the diet.
Aim to get vitamins from a balanced, varied diet that contains plenty of fruits and vegetables. If a person is pregnant or has a health issue or a restricted diet, a doctor or nutritionist may recommend supplements.
Vitamin A is a fat-soluble vitamin that is naturally present in many foods. Vitamin A is important for normal vision, the immune system, reproduction, and growth and development. Vitamin A also helps your heart, lungs, and other organs work properly. Carotenoids are pigments that give yellow, orange, and red fruits and vegetables their color. Your body is able to convert some carotenoids into vitamin A.
The amount of vitamin A you need depends on your age and sex. Average daily recommended amounts of preformed vitamin A and provitamin A carotenoids are listed below in micrograms (mcg) of retinol activity equivalents (RAE).
Vitamin A is available in dietary supplements, usually in the form of retinyl acetate or retinyl palmitate (preformed vitamin A), beta-carotene (provitamin A), or a combination of preformed and provitamin A. Most multivitamin/mineral supplements contain vitamin A. Dietary supplements that contain only vitamin A are also available.
Vitamin A deficiency is rare in the United States because most people get enough vitamin A from the foods they eat. However, vitamin A deficiency is common in many developing countries, especially in young children.
A long-term deficiency of vitamin A can also lead to a higher risk of respiratory diseases (such as pneumonia) and infections (such as measles and diarrhea). It can also cause anemia (a condition in which the red blood cells do not supply enough oxygen to the body). In severe cases, not getting enough vitamin A can increase your chances of dying.
People who eat a lot of foods containing vitamin A or beta-carotene might have a lower risk of certain kinds of cancer. However, studies do not show that vitamin A or beta-carotene supplements help prevent cancer or lower the chances of dying of cancer. In fact, some studies find that in people who smoke or used to smoke, high doses of beta-carotene supplements can increase the risk of lung cancer and death.
In developing countries where vitamin A deficiency is common, children with measles are more likely to have severe symptoms and may die from the disease. In these children, taking supplements with high doses of vitamin A might help prevent new cases of measles and might lower their risk of dying of measles.
Getting too much preformed vitamin A (usually from supplements or certain medicines) can cause severe headache, blurred vision, nausea, dizziness, muscle aches, and problems with coordination. In severe cases, getting too much preformed vitamin A can even lead to coma and death.
If you take too much preformed vitamin A while pregnant, it can cause birth defects in your baby, including abnormal eyes, skull, lungs, and heart. If you are or might be pregnant or breastfeeding, you should not take high-dose supplements of preformed vitamin A.
High intakes of beta-carotene do not cause the same problems as preformed vitamin A. Consuming high amounts of beta-carotene can turn the skin yellow-orange, but this condition is harmless and goes away when you eat less of it. However, several studies have shown that smokers, former smokers, and people exposed to asbestos who take high-dose beta-carotene supplements have a higher risk of lung cancer and death.
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