Retinol is another name for vitamin A. You can find yellow or orange carotenes in some vegetable and milk and they can be converted into retinol. So, they are seen as food sources of vitamin A. However in most cases, Retinol is found in animal products. Beta-carotene is definitely the most essential substance.
To define vitamin A activity of a diet in the most convenient way is by referring to the following formula: 1 µg retinol equivalent = 6 µg beta-carotene or 6 µg retinol. When compared with retinol in general diet, there is some conversion losses and non-absorption. And this average value takes all these into account.
Vitamin A contained in foods is generally quite little. Animal liver, kidney eggs and dairy produce contains high levels of retinol, but the most concentrated source is found in fish liver oils. However, there is none found in lard and dripping. Yellow and dark green vegetables together with carrots contain beta-carotene of different amount, with the darker ones contain higher amount. Therefore, spinach has more compared to cabbage, and cabbage heart has less compared to its outer leaves.
Butter has been used as a guideline for manufacturers to produce margarine with quantity of vitamin A as high. This has been enforced by law. To follow the law, synthetic beta-carotene and retinol are added.
Our diet generally provides twice as much vitamin A (includes one part of carotene and two parts of retinol) compared to the recommended intake.
Effects of Retinol Deficiency or Excess
Vitamin A helps prevent night blindness and is essential for people who work in dim light. Lacking of it causes many children around the world having xerophthalmia and keratomalacia. For a healthy skin, the presence of sufficient vitamin A in your body is very important.
Too much vitamin A, nevertheless, will stay in your liver for a very long time and can be poisonous to your body.
To recap, vitamin A is important to our body, especially when it comes to eyes protection. However, too much intake can cause some bad side effects as well. It is essential to know the food sources of retinol as the nutrient is not easy to obtained from what we eat.