Why beta-carotene from plant sources is important for making Vitamin A in human body?

Info Source:

http://www.nlm.nih.gov/medlineplus/ency/article/002400.htm

Vitamin A comes from animal sources, such as eggs, meat, fortified milk, cheese, cream, liver, kidney, cod, and halibut fish oil. However, all of these sources -- except for skim milk that has been fortified with Vitamin A -- are high in saturated fat and cholesterol.

Sources of beta-carotene include:

• Bright yellow and orange fruits such as cantaloupe, pink grapefruit, and apricots
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• Vegetables such as carrots, pumpkin, sweet potatoes, and winter squash
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• Other sources of beta-carotene include broccoli, spinach, and most dark green, leafy vegetables.

My Note: By far the most important provitamin A carotenoid is beta-carotene; other provitamin A carotenoids are alpha-carotene and beta-cryptoxanthin. The body converts these plant pigments into vitamin A.

The more intense the color of a fruit or vegetable, the higher the beta-carotene content. Vegetable sources of beta-carotene are fat- and cholesterol-free.