Dietary sources

All natural sources of vitamin A in the diet are derived ultimately from provitamin A carotenoids. For much of the world's human population, and particularly in parts of the developing world, vegetables and fruits provide the main dietary sources of vitamin A in the form of P-carotene and other provitamin carotenoids. In other parts of the world, milk, butter, cheese and eggs are important dietary sources of vitamin A. The liver of meat animals is a particularly rich source as this organ stores the vitamin for the body's use. Preformed vitamin A is present in animal tissues and in milk as a consequence of the enzymatic conversion of ingested provitamin carotenoids in the intestinal wall of the animal. Dietary preformed vitamin A consists mainly of retinol esterified with long chain fatty acids, particularly palmitic acid. Retinyl esters are also found in processed foods supplemented with vitamin A.

Lose 10 Pounds Naturally

Lose 10 Pounds Naturally

Studies show obesity may soon overtake tobacco as the leading cause of death in America. Are you ready to drop those extra pounds you've been carrying around? Awesome. Let's start off with a couple positive don't. You don't need to jump on a diet craze and you don't need to start exercising for hours each day.

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