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    Beta carotene

    Carotenes, especially beta-carotene, occurs abundantly in the natural plant world. It is estimated that nearly more than 500 different carotenoids such as ?-carotene, α -carotene, lutein, cryptoxanthins, zeaxanthins, etc distributed throughout the plant and algae kingdoms. Although many of these have proven independent functions, around 50 or more can be metabolized to vitamin-A inside the human body. ?-carotene is the most prevalent carotenoid in the plant sources of the food chain and, for the same reason, is also known as pro-vitamin A.

    Roughly, 6 μg (range varies widely 6-18 μg) of ?-carotene is equal to 1 RE (Retinol equivalents) or 3.33 IU of vitamin-A.

    fruit and vegetables rich in carotenes
    Fruits and vegetables rich in ?-carotene.

    Health benefiting role of beta carotene

    • Being an important flavonoid compound, beta-carotene has powerful antioxidant functions that help the body scavenge free radicals, and thereby limiting damage to cell membranes, DNA and protein structures in the tissues.

    • Research studies suggest that dietary intake of foods high in ?-carotene has a positive association with decreased risk of cardiovascular disease as well as oral cavity and lung cancers.

    • Up on conversion to vitamin-A by the enzymes in the intestinal wall, it performs all the functions of vitamin-A such as visual cycle, reproduction (gametes production), maintenance of epithelial functions, growth and development.



    Natural sources of beta-carotene

    Almost all the green-yellow-orange (GYO) vegetables and fruits are rich sources of beta-carotene. Some of the common vegetables/fruits/herbs/nuts per 100 g of weight with the highest content of ?-carotenes are:

    Vegetables: ?-carotene/100 g
    Brussel sprouts 450 μg
    Butternut-squash 4226 μg
    Carrots 8285 μg
    Collard greens 3842 μg
    Endive 1500 μg
    French beans 379 μg
    Kale 9226 μg
    Lettuce 5226 μg
    Mustard greens 6300 μg
    Pumpkin 3100 μg
    Spinach 5626 μg
    Sweet potato 8509 μg
    Swiss chard 3647 μg
    Tomato 449 μg
    Watercress 1914 μg
    Fruits:
    Apricots 1,094 μg
    Cantaloupes 2,020 μg
    Guava 374 μg
    Mango 445 μg
    Orange 71 μg
    Papaya 276 μg
    Persimmon fruit 253 μg
    Plums 190 μg
    Watermelon 303 μg
    Herbs:
    Basil 3,142 μg
    Cilantro 3,930 μg
    Parsley 5,054 μg
    Thyme 2,264 μg
    Nuts and seeds:
    Pistachio 332 μg
    Walnuts 12 μg

    (Source: USDA National Nutrient Database).

    Beta carotene supplements?

    The benefits of beta carotene supplements, however, has surprisingly unexpected results. Two large-scale prospective randomized studies on high-risk cigarette smokers; 1. ?-carotene (α-tocopherol, ?-carotene (ATBC) Cancer Prevention Study and, 2. the ?-carotene and retinal efficacy trial (CARET) found that ?-carotene supplementation indeed increased the rate of lung cancer in the group.

    On the contrary, as mentioned above, high dietary intake of foods rich in ?-carotene is associated with decreased risk of cardiovascular disease and cancers. However, ?-carotene supplementation appears harmful to health, especially in high-risk smokers.


    Carotenemia

    The consumption of excess plant sources of beta-carotene result in the deposition of carotenes in the skin, and tissues could lead to a harmless condition known as carotenemia. The state recedes in itself once foods rich in carotenes withdrawn from the diet. (Medical disclaimer:)


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    Further reading and References:

    Stanford School of Medicine Cancer information Page- Nutrition to Reduce Cancer Risk.



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