The found this article through a reference -
The author Ruth N. Davidar is a nutritionist and a food writer. Explains how vegetarian indian cooking compensates for the nutrition the body needs as compared to meat based cooking.
Some excerpts from the article:
Experts will also tell you to watch your intake of iron and calcium in vegetarian diets. Here again, typically Indian food combinations help with the absorption of these minerals. True, the availability of iron from vegetable sources is never very satisfactory, but vitamin C, for instance, helps to overcome this problem by assisting in the conversion of iron to the form that is readily absorbed. In aloo aur palak ki bhaaji the iron that is trapped in spinach is released by the vitamin C found in potatoes. Likewise, substances like oxalates prevent the absorption of calcium (and magnesium) abundant in green leafy vegetables. A traditional Indian recipe like palak paneer circumvents this obstacle. While the calcium in the greens remains in the bound form, the calcium in paneer is readily and easily absorbed.
Interestingly, curds is used extensively in Indian cooking. It could be assumed that milk was allowed to ferment to make it more palatable because of the lack of refrigeration in the old days. However, it has significant nutritional benefits too. When milk sugar or lactose is allowed to ferment naturally, lactic acid is formed by the activity of certain bacteria. This lactic acid promotes the absorption of calcium especially when phosphorus and protein are also available in the same food. Milk that is converted into curds has all these factors - another reason why getting sufficient calcium from a typically Indian diet is not a cause for concern. Further, curds used as a marinade does not just flavour and tenderise foods like meat. It is now known that lactic acid (as found in curds) is an effective antiseptic when heated (as in cooking). Therefore, meat marinated in curds and then cooked would have fewer micro-organisms.