Vitamin A

Vitamin A, the first vitamin to be discovered, is often categorized into two basic forms depending upon which food source they come from.  Animals produce preformed Vitamin A from precursor compounds known as carotenoids, while carotenoids produced from plants and algae are known as known as provitamin A  compounds.  Of the more than 600 different kinds of carotenoids, Beta-carotene is known as the most active precursor to vitamin A.  Both forms of Vitamin A are fat-soluble, and therefore rely on an adequate amount of fat in the diet, as well as bile from the liver, in order to be properly broken down into smaller droplets, known as micelles, and absorbed into the body.

In adequate amounts, Vitamin A has been shown to be essential for the development and maintenance of healthy eyes (vision), skin, digestion, endocrine function, immune function, bones, cellular communication and the overall proper growth, reproduction and repair of the body’s cells and tissues.  Conditions which Vitamin A has been known to help range from night blindness, acne, psoriasis, and leaky gut syndrome to an impaired immune function, frequent infections and even the possible prevention of various forms of cancer.

Factors that can contribute to low levels of Vitamin A in the body include a low-fat diet, excessive consumption of alcohol, smoking, use of cortisone drugs, or sub-optimal levels of the mineral zinc in the body.

Signs of Vitamin A deficiency may include, but are not limited to the following: acne, anemia, brittle nails, skin blemishes, fatigue, impaired growth, mouth ulcers, kidney stones, night blindness or poor ability for the eyes to adapt to the dark, frequent colds and infections, dry/flaky skin, dandruff, thrush, cystitis, diarrhea, and even Vitamin C deficiency.

Good Food Sources of Vitamin A

Rich sources of preformed Vitamin A can be found in cod-liver oil, liver, milk, cheese, butter, eggs and all meats.    

The various provitamin A carotenoids can be found many plant based foods such as apples, apricots, asparagus, avocado, bananas, berries, broccoli, cantaloupes, carrots, cauliflower, cherries, chili peppers, citrus fruits, currants, dates, figs, grapefruit, grapes, honeydew melons, kale, kiwi, leafy greens, mangoes, nectarines, palm fruit, palm oil, papayas, parsley, peaches, pears, peppermint,  persimmons, red and yellow peppers, pineapple, plums, pomegranates, pumpkin, sea vegetables, squash, sweet potatoes, watermelon, yams and yellow corn.            

Supplemental Sources of Vitamin A

Vitamin A can be found in different supplemental forms such as preformed Retinyl Palmitate or Retinyl Acetate and/or provitamin A in the form of beta-carotene or other various carotenoids.  Most, but not all, Vitamin A supplements are offered in soft-gel form as they are mixed with an oil base to improve absorption.  Most supplements are designed to provide a daily dose ranging anywhere from 2,500 IU – 10,000 IU of preformed Vitamin A or 10,000-25,000 IU of Beta Carotene.

What about Toxicity?

Since Vitamin A is a fat-soluble vitamin and is stored in the body, toxicity is possible. Depending on the individual, Vitamin A toxicity may occur after consuming the preformed version of Vitamin A found in animal foods around or above 26,000-100,000 IU per day for an extended period of time, often measured in months.  While there is a risk for Vitamin A toxicity when consumed in the preformed form, there is no known risk of Vitamin A toxicity associated with the consumption of the provitamin A carotenoids since the body has a way of regulating the conversion, if needed, in order to maintain adequate levels.   

 

References:

Holford, P., (2004) The Optimum Nutrition Bible, (p.481)  Crossing Press Inc., Freedom CA

Kirschmann, G. & J., (1996) Nutrition Almanac, (pp.33-41) McGraw-Hill, New York, NY

Balch, P., (2003)  Prescription for Dietary Wellness, (pp. 8, 49-50) Penguin Group Inc.,  New York, NY

Murray, M., (2005) The Encyclopedia of Healing Foods, (pp. 98-100) ATRIA Books, New York, NY

Murray, B. & O’Neill, K., (2002) Power Plants, (pp. 139-147)  Woodland Publishing, Pleasant Grove, UT

Fresh & Natural

Author: Fresh & Natural

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