The Vitamin That Does It All
1. What is it and where does it come from?
Vitamin A is fat-soluble, stored in body fat. Although not necessary to intake every day, Vitamin A is vital to the body. 90% of it is stored in the liver. Vitamin A is found in two forms – Retinol (preformed Vitamin A) or Retinoids (beta-carotene).
Beta-carotene is a precursor to Vitamin A, formed in the intestine, liver, and kidneys. Betacarotene is found in deep-yellow and deep-green leafy vegetables. Vitamin A is found in fish liver oils, egg yolk, liver, and fortified foods such as milk or margarine.
2. What does it do and what scientific studies give evidence to support this?
Vitamin A is required for synthesis of photoreceptor pigments of rods and cones, the integrity of skin and mucosae, normal tooth and bone development; normal reproductive capabilities; and has important antioxidant properties. It helps form the substance rhodopsin, which is necessary for good vision (particularly night vision). Vitamin A also helps keep the membranes, inner linings, tissues, the skin, and eyes in good health. It also helps to energize cells in the immune system and acts as an antioxidant. It’s a good idea to stop free radicals before they stop you.
3. How much should be taken? Are there any side effects?
The RDA for males is 5000 IU (1.5mg), females 4000 IU. Vitamin A in excess of 50,000 IU can be toxic, causing damage to the body. Stick to the RDA and you’ll better off than if you take to much or too little. Beta-Carotene is not toxic even in large doses because the body converts only what it needs to Vitamin A. The optimal level of Beta-Carotene intake is 17,500 IU. Drug interactions include the reduced effectiveness of Phenytoin and increasing effects of Oral anticoagulants.