Vitamin A is a nutrient that is obtained through food in two different forms. Food sources of Vitamin A com as Retinal, the functional form of vitamin A is found in meat, dairy and other animal sources. Carotenoids, which are changed by the body into vitamin A, is found in most fruits and vegetables, most famously carrots. Once in the body, Vitamin A from animal products and vitamin A from plants function the same way. Vitamin A performs many important functions in the body, but it’s function in vision often leads to the most notable side effect of deficiency, that is poor vision especially in dim lighting. The recommended daily allowance of Vitamin A is 900ug per day in males, and 700ug per day in females.
Obtaining the recommended daily allowance of vitamin A is not difficult, however, keeping track of how much you consume in a day is. There are a couple of reasons for this. First, Beta Carotene is not all converted to Vitamin A. The actual amount of Beta Carotene that becomes vitamin A depends on how much vitamin A you already have in your body. People who have vitamin A deficiency will convert much more Beta Carotene into Vitamin A then people who already have plenty of vitamin A in their systems. The second reasons is because cooking the active Vitamin A form which is found in meat and dairy products results in the the destruction of some of the Vitamin A depending on the type and length of cooking done. So in both the source of plant and animal forms of vitamin A, there is difficulty determining the usable amount of vitamin A. The good news is that most meat sources like liver that provide vitamin A, provide it in huge amounts, so even after some is destroyed by cooking, a single serving can yield a full days supply of vitamin A. And with Beta Carotene, people who have a deficiency will utilize more than people without a difficiency.
Vitamin A as a nutrient is found in almost all meat and dairy sources, however, many of these become poor sources of vitamin A after cooking has been done. The major exception to this rule are liver (beef, pork or chicken) which will supply more than the recommended daily allowance with even a small serving. Other meat and dairy products that are a good source of vitamin A in their edible forms include eggs, butter and cheese. Milk is a poor source of vitamin A because pastuerization destroys most of the vitamin A. One supplement worth mentioning is Cod liver oil, which contains large amounts of vitamin A.
Carotenoids, especially Beta Carotene, are a source of vitamin A that comes from plants. Most nutritionists recommend that the majority of vitamin A should come from carotenoids because the fruits and vegetables that contain the carotenoids also contain a large number of other beneficial nutrients. At the same time, animal sources of vitamin A such as eggs and cheese contain a large number of undesirable things such as cholesterol and saturated fat. Carotenoids are found in almost all vegetables in large amounts as well as many fruits. Carrots, spinach, brocolli and mangos are all a good source of Vitamin A. There are two things that can be done to increase the amount of carotenoids absorbed by the body. The first is to use a blender. Breaking the cell walls of vegetables, especially carrots, will allow the body to aborb more of the nutrient. The second way to help absorb vitamin A is to include some fat with the meal. While this sounds absurb, it is important to note that fat is needed by the body for certain functions, and also that fat is required for the transport of many nutrients, including carotenoids through the walls of the small intestines. Any easy source of small amounts of fat is 2% milk, which can be consumed with each meal to improve nutrient absorption.
Vitamin A can be consumed in two forms. The active form of vitamin A can come directly from animal products such as liver, cheese and eggs. Cooking will reduce the amount of vitamin A these foods provide, but they will still give large amounts. Because these foods contain other things that are not helpful to good nutrition like cholesterol, it is usually recommended that the majority vitamin A come from plant sources. Plants provide Carotenoids, which are transformed inside the body into the active form of vitamin A. Carrots, brocolli, leafy vegetables and dark colored fruit are all a good source of beta carotene and vitamin A.