Cucumber along with raw carrots, radish, and tomatoes has been a part of salad for the time immemorial. Cucumber is also consumed as cooked and pickled form in many parts of the world. People on diet for weight control eats this vegetable as it is often regarded as a health food because of its low calorie content and its high vitamins and minerals content.
Common cucumber varieties are white to greenish inside and are of low nutritional quality. On the other hand, orange fleshed cucumber is rich in carotenoids. India, being the centre of origin for cucumbers, is known to be the treasure-house of cucumber diversity. Mostly the first variety is used as it is abundantly grown.
But in the Mamit district of Mizoram, two varieties are found which are very rich in carotenoids as high as 6.5 μg/100 g as compared to 1.17 μg/100 g in the best check variety Himangi.. They have yellow to orange mesocarp and endocarp; an extremely rare trait.
Previously orange-flesh cucumber was reported to be derived from a land race named Xishuangbanna Gourd from a Prefecture Xishuangbanna of the Yunnan Province in the South-west China, which is closer to north-eastern part of the India. Studies indicate that orange fleshed cucumber of China (Xishuangbanna Gourd) is closely related to Indian cucumber found in Mizoram. This suggests that orange-fleshed Indian cucumber might have migrated to China from northeastern parts of the country; which is the primary centre of its origin.
All this information is from ICAR.