Vitamin A

Vitamin A is an important nutrient. It is especially helpful in the bodies of infants and toddlers for fighting off the effects of viral infection. It helps maintain the immune system in both children and adults. It plays a critical role in the creation of thyroid hormones and is absolutely necessary for creating the pigments that allow you to see at night. You have to get your vitamin A to have healthy skin.

Here's a list of just some of the reasons the best natural vitamin, vitamin A, is vital:

• A byproduct of vitamin A called retinoic acid helps cells respond to thyroid hormone.
• Among women who have a family history of breast cancer, higher intake vitamin A is associated with lower rates of cancer before menopause.
• Human immunodeficiency virus (HIV) and human papillomavirus (HPV) are transmitted 4 to 200 times more readily when the carrier suffers vitamin A deficiency.
• In the fetus, vitamin A is essential for the formation of the heart, eyes, and ears.
• Mild deficiency in vitamin A increases risk of diarrhea and fevers in children.
• Mild vitamin A deficiency can lead to inflammation at the corners of the eyes.
• Severe vitamin A deficiency can lead to xerophthalmia, a condition of extremely dry eyes.
• The retina uses vitamin A to make rhodopsin, also known as visual purple. This pigment allows the retina to detect very small amounts of light, making night vision possible.
• Vitamin A helps maintain the integrity of the mucosa in the ears, nose, and throat, protecting them against infection.

Amazingly, many natural health experts offer the opinion that you don't need this best natural vitamin at all. Your body can make vitamin A from beta-carotene, they say, or vitamin A is toxic if taken to excess. Still other health experts say that you need this best natural vitamin, that you have to get your vitamin A, but the only way you can get it is from (their particular brand of) fish oil. What's the truth?

For a long time, nutritional researchers didn't know how to measure this best natural vitamin. This vitamin is fat-soluble. When you consume foods or supplements containing vitamin A or beta-carotene, your bloodstream concentrations don't go up. Recent research has found that these vitamins go straight into your fat cells.

That's why a simple blood test can't tell you if your vitamin A levels are going up, down, or staying the same. In rare instances in which people took 60 to 600 times the recommended dosage of this best natural vitamin, there have been serious side effects (night blindness, or in children of mothers who took overdoses of vitamin A in early pregnancy, birth defects). Since nutritionists couldn't tell you how much vitamin A to take, they recommended you take none at all. You could get your nutritional needs from beta-carotene, they said.

The problem is, you can't.

Like its chemical cousin vitamin A, beta-carotene is also fat soluble. The beta-carotene you consume goes to your fat cells, not into circulation.

The more fat you have in your body, the more beta-carotene they soak up, and the less of the best natural vitamin A is made for the rest of your tissues. Your fat cells, however, should be in great shape!

If you're in the minority of people who aren't overweight, beta-carotene can be converted into the best natural vitamin A by your liver, lungs, and kidneys. The tissues, however, can only produce about 20% of the amount of vitamin A your body need, less if you suffer liver, lung, or kidney disease.

Vitamin A can also be produced by beta-carotene in the intestine. If you consumed no supplemental vitamin A and no vitamin A-rich foods at all, this is where your body would get most of the vitamin.

The problem with producing vitamin A in the intestine is obvious. The contents of the intestine are in constant motion. There is a real risk of losing the best natural vitamin A the intestine makes into waste material.

If you get your vitamin A from food rather than supplements, what are the foods you need. Here's the rather short list:

Food	Serving	Vitamin A, measured as retinol equivalents	Vitamin A, IU	Retinol, measured in micrograms	Retinol, measured in IU
Cod liver oil	1 teaspoon	1,350 mcg	4,500 IU	1,350 mcg	4,500 IU
Egg	1 large	91 mcg	303 IU	89 mcg	296 IU
Butter	1 tablespoon	97 mcg	323 IU	95 mcg	317 IU
Whole milk	1 cup (8 fl ounces)	68 mcg	227 IU	68 mcg	227 IU

(Source: The Linus Pauling Institute, Oregon State University, 2005.)

To this list, you could add skim milk, usually packaged with the artificial analog of the best natural vitamin A. There's also vitamin A in many breakfast cereals, and, were you inclined to use it as health food, caviar. Any natural food that's rich in vitamin A is high in fat and cholesterol.

If you don't want the fat and cholesterol, you can take beta-carotene:

• Your body needs 2 retinol equivalents (a measurement that takes into account the different weights of molecules of beta-carotene and retinol, the basic form of vitamin A) of beta-carotene in supplements to make 1 retinol equivalent of vitamin A.
• Your body needs 24 retinol equivalents of beta-carotene in food to make 1 retinol equivalent of vitamin A.

You can replace a teaspoon of cod liver oil with a pound of squash. You can replace a teaspoon of butter with two cantaloupes. Whether you use cod liver oil, eggs, butter, and whole milk, or you load up on orange and yellow fruits and vegetables, you can get your body's requirements of the best natural vitamin A from food.

It just takes some work. The simpler approach to vitamin "insurance" is to use a supplement. And natural isn't necessarily best.

Consumers are often cautioned that too much of this best natural vitamin can be toxic. Expectant mothers are warned that too much vitamin A can cause birth defects.

What the experts overlook is that the form of vitamin A that is known to cause birth defects is a pharmaceutical derivative known by its trade name Accutane. This is physiologically the exact opposite of the best natural vitamin A. Too much of this synthetic derivative of vitamin A indeed can cause serious problems. Supplemental vitamin A, whether taken fish oil or synthetic, does not.

Even 300,000 IU a day for a year will not necessarily cause ill effects, but a much lower dose is all you need. When there are urinary or respiratory infections, the best natural vitamin A to support mucosal function can be taken in doses of up to 200,000 IU a day for up to 5 days. People with HIV or chronic viral hepatitis might take up to 25,000 IU a day for up to a year. The rest of us can benefit from up to 5,000 IU a day indefinitely, although lower dosages are also adequate.

Recommended Dietary Allowance (RDA) for Vitamin A as Preformed Vitamin A (Retinol)
Life Stage	Age	Females: mcg/day (IU/day)	Males: mcg/day (IU/day)
Infants	0-6 months	400 (1333 IU)	400 (1333 IU)
Infants	7-12 months	500 (1667 IU)	500 (1667 IU)
Children	1-3 years	300 (1000 IU)	300 (1000 IU)
Children	4-8 years	400 (1333 IU)	400 (1333 IU)
Children	9-13 years	600 (2000 IU)	600 (2000 IU)
Adolescents	14-18 years	700 (2333 IU)	900 (3000 IU)
Adults	19 years and older	700 (2333 IU)	900 (3000 IU)
Pregnancy	18 years and younger	750 (2500 IU)	-
Pregnancy	19-years and older	770 (2567 IU)	-
Breastfeeding	18 years and younger	1,200 (4000 IU)	-
Breastfeeding	19-years and older	1,300 (4333 IU)	-

(Source, US Department of Agriculture, 2004.)

Your key consideration in using vitamin A isn't whether it's "natural" or synthetic, provided, of course, you aren't using the pharmaceutical form of the vitamin called Accutane. Your key consideration in using vitamin A is whether you are using supplements in conjunction with a reasonable program of weight control.

The heavier you are, the more likely you are to suffer the conditions associated with inadequate vitamin A. Vitamin A can help you remain healthy while you are normalizing and stabilizing your weight, but if once normal vitamin A levels are established, the real question for most of us, are we at our proper weights?

Article source :http://www.the-vitamin-and-supplement-guide.com/bestnaturalvitamin.html

List of vitamins

Vitamin	Dosage	Functions	Natural Sources
Vitamin A Retinol and/or Beta Carotene	5000 - 50,000 IU	Helps build healthy eyes, required for growth and bone development. Beta Carotene is a good antioxidant. Helps healing of infections.	Carrots, yams, pumpkins, yellow or orange fruits, beet greens, fish, eggs, tuna
Vitamin B1 Thiamine	25 - 300mg	Helps in carbohydrate metabolism and energy production. Required for normal nerve function.	Whole grains, rice bran, lean meats, fresh peas, beans, wheat germ, oranges, poultry, fish, enriched pastas
Vitamin B2 Riboflavin	25 - 300mg	Helps in production of energy from foods and the formation of red blood cells.	Fortified grains & cereals, leafy green vegetables, poultry, fish, yogurt, milk, cheese
Vitamin B3 Niacin	25 - 300mg	Assists in release of energy from carbohydrates, fats and proteins; helps promote healthy skin.	Fortified breads and cereals, brewer's yeast, broccoli, carrots, cheese, dandelion greens, dates, eggs, fish, milk peanuts, potatoes, tomatoes, tuna, veal, beef liver, chicken breast
Vitamin B5 Pantothenic Acid	10 - 300 mg	Helps release energy from foods; required for synthesis of many substances.	Lean meats, whole grain cereals, fish, legumes
Vitamin B6	2 - 300 mg	Essential for protein metabolism and nervous system function; participates in synthesis of hormones and red blood cells.	Whole grain breads and cereals, fish, chicken, bananas
Vitamin B9 Folic Acid	400 - 1,200 mcg	Essential for red blood cell formation and synthesis of DNA and protein	Fortified cereals, pinto beans, navy beans, green leafy vegetables, beef, brown rice, bran, cheese, lamb, liver, milk, mushrooms, oranges, split peas, pork, tuna, whole grains
Vitamin B12 Cyanocobalamin	25 - 500 mg	Helps maintain healthy nervous system, required for normal growth and for production of red blood cells. Helps breakdown fatty acids.	Ham, clams, cooked oysters, king crab, herring, salmon, tuna, lean beef, liver, low fat diary products
Vitamin C	60 - 5,000 mg	Required for formation of connective tissue, bones and teeth; assists in utilization of other vitamins, acts as an antioxidant.	Citrus fruits, strawberries, broccoli, melons, peppers, collards, dandelion greens, onions, radishes, watercress
Vitamin D	400 - 800 IU	Aides in normal bone growth and tooth function; facilitates calcium and phosphorus absorption.	Sun exposure, sardines, salmon, fortified milk, fortified cereals, herring, liver, tuna, margarine, cod liver oil
Vitamin E	30- 1,200 IU	As an antioxidant it protects body cells and helps maintain normal red blood cells.	Whole grains, wheat germ, nuts, spinach, sunflower seeds
Vitamin H Biotin	0.3 - 1 mg	Assists in metabolism of carbohydrates and synthesis of fats and proteins.	Legumes, nuts
Vitamin K	80 mcg	Essential in the blood clotting process.	Green leafy vegetables like kale, spinach, broccoli, cauliflower

Article source :http://www.the-vitamin-and-supplement-guide.com/listofvitamins.html

vitamins

The term "vitamin" is used to describe certain organic compounds that are needed by the body but that cannot be manufactured by the body. They mainly serve as catalysts for certain reactions in the body. If these catalysts are missing, as in a vitamin deficiency, normal body functions can break down amd make a person more susceptible to disease. The amounts of vitamins required are very small, perhaps hundredths of grams. Vitamins are mainly obtained from our foods, but there are some special cases. Vitamin K is manufactured in our bodies in certain bacteria in our intestines, and vitamin D is produced with the help of ultraviolet radiation on our skin.

Vitamins are classified as either fat-soluble (lipid soluble) or water-soluble. Vitamins A, D, E and K are lipid-soluble and accumulate within the fat stores of the body and within the liver. The lipid-soluble vitamins are often associated with toxicity when taken in large amounts.

Vitamin C and the B vitamins are water soluble. When water-soluble vitamins are taken in excess, they are readily excreted in the urine and not usually associated with toxicity. There is some storage of vitamins C and B in the liver.

Common Vitamins and Their Functions
Vitamin	Chemical Name	Function
A1	retinol	Necessary for protein synthesis
A2	3-dehydroretinol	Prevents night blindness
B1	thiamine	Necessary for carbohydrate metabolism, prevents beri-beri
B2	riboflavin	Acts as an oxygen carrier to the cell; prevents lesions of the mouth, eyes and skin.
B6	pyridoxine	Takes part in the decarboxylation of amino acids; alleviates dermatitis, irritability, and apathy
B12	cobalamin	Synthesizes certain amino acids; prevents pernicious anemia.
C	ascorbic acid	Needed in the formation of tissue, prevents scurvy
D2	calciferol (activated ergosterol)	Increases the absorption of calcium and phosphorous from the small intestine.
D3	activated 7-dehydrocholesterol	Prevents rickets
E	alpha-tocopherol	Antioxidant; no known therapeutic use
K	...	The anti-hemorrhaging vitamin.

From Shipman & Wilson, Intro to Physical Science

The word vitamin comes from the word "vitamine" which was coined by researchers in 1912 to describe this recently discovered class of substances. At that time they were thought to be all amines which were essential to life. But not all of the vitamin are amines, so the "e" at the end was dropped to retain the now common term for these nutritional supplements.

Article source :http://hyperphysics.phy-astr.gsu.edu/HBASE/Organic/vitamin.html