Thursday, July 18, 2013

Colour of life .Antioxidants.- part 2

Our eyes are special, they can see a range of colours and anthropologist today believe that we may owe this ability to leaves and fruits! Other than some tropical forest dwelling primates, we are the only animals who can distinguish red from green. Our ancestors like the primates had to detect their food against the green of the forest canopy. They had to distinguish the light green tender leaves from the difficult to digest older leaves. Without red vision, the carotenoid- coloured red fruits would have been difficult to find. The pleasure we enjoy today, of a colourful world was shaped by fruits and leaves. Today these pigments still play a vital role in our body and they are a key to a healthy life.
Green Chlorophyll, is probably the most well known of the pigments. ‘Chlorophyll  a’ is bright blue-green and ‘chlorophyll b’ is olive green in colour. In most leaves, the ‘a’ form is 3 times more than the ‘b’ form and as the leaves age; the ‘a’ form degrades faster, changing the colour of the leaves. Chlorophyll, is an antioxidant and protects the body from harmful effects of “free radicals.”
Yellow, red and orange carotenoids. The first member, of this large family of pigments, was first isolated from carrots, hence the name. They are responsible for most of the yellow and orange colours of fruits and vegetables (Zeaxanthin, xanthophylls and beta-carotene). The reds in watermelons, chillies and tomatoes are by capsanthin, capsorubin and lycopene respectively. The red colour of plants is due to anthocyaninis. These are fat soluble, stable molecules and hence stay bright when food is cooked in water. One of their main jobs is to protect the DNA and photosynthetic system of the plant during photosynthesis. Therefore, plants have one carotenoid molecule for every five or so chlorophyll molecules. Hence, dark green vegetables have lots of carotenoids. Eating a variety of colourful fruits and vegetables therefore douses our body with their goodness and protects us from various free radicals. About ten different types of carotenoids, are converted into Vitamin A in our intestine, the most well known among them is beta-carotene.
Red and purple Anthocyaninis and Pale yellow Anthoxanthins. The red, purple and blue colour of many berries, cabbage, potatoes, apples and radish are due to anthocyaninis. Anthoxanthins colour potatoes, onions and cauliflower, with their pale yellow hue. There are about 300 known anthocyaninis, and any given fruit and vegetable will have at least a dozen of them. These are water soluble and easily get diluted in water while cooking, so vegetables coloured by these pigments lose their colour while cooking. These pigments too have antioxidant properties
Red and Yellow Betains. About 50 types of red betains and 20 types of yellow betaxanthins are found in only a few vegetables. Some of the common ones are Beets, chard, amaranth and prickly pear. Our body cannot metabolise them efficiently, hence in large doses, like when eating beetroots, the excess is harmlessly passed off in urine, giving it a red tinge. The red betains are good antioxidants.
Nature is a riot of colours and incorporating it in our diet, will definitely go a long way in protecting us from the dangers that are lurking around us.     

1 comment:

  1. Aarina9:36 am

    Feeling nice having all of this refreshed in my mind!