The various characteristics of food can be identified by their tastes. Food can be classified according to tastes. Taste is the most important characteristic of any food substance. The nutritional and medicinal value of food is known by its tastes. There are six tastes in nature: Sweet, Sour, Salt, Bitter, Pungent and Astringent. All food substances are contained in these six tastes. For example – Milk and Ghee (clarified butter) are Sweet, Curd is Sour, Salts are Salty ,Bitter Gourd is Bitter, Pepper is Pungent (hot), Indian Gooseberry and Betel Nuts are Astringent. The first three tastes – Sweet, Sour and Salt are mostly in common food substances and Bitter, Pungent and Astringent tastes are mostly important for medicinal substances. All these six tastes have a close relationship with the three Doshas or factors of health - Vata (wind), Kapha (water/cold) and Pitta (fire/heat) which if vitiated cause disease. Vata is increased by Pungent, Bitter and Astringent tastes. Kapha is increased by sweet, Sour and Salt. Pitta is increased by Pungent, Sour and Salt. These are hot in nature. Consuming cold substances increases Vata and Kapha but they decrease Pitta. Conversely, consuming hot substances increase Pitta but decrease Vata and Kapha. All substances, are either heating or cooling depending on their action. This is termed efficacy of the substances according to Ayurveda. Traditional Indian cooking is based on the principles of Ayurveda. It is according to specific areas. If we are affected by a disease due to vitiated Vata, the food ought to be Sweet, Sour and Salty in taste and hot in efficacy. This helps to reduce the vitiated Vata. For reducing the aggravated Pitta, we should eat Sweet Bitter and Astringent food. If we are affected by vitiated Kapha then we should eat Bitter, Pungent and Astringent food which is hot in efficacy. This diet plan is called Pathyam by Ayurveda. There is need to adopt a diet according to the change of seasons. It is most important for digestion. This is essential for maintaining health. Sweet tastes are the ones which nourish the body the most .The way to good health is through adopting proper food habits based on factors which interfere with digestion, different food substances and their properties, rules of dietetics and the concept of incompatible food. It is common sense that we consume food which is cold in efficacy in summer and we eat food which is hot in efficacy in the winter season. If food is consumed in accordance with instructions of Ayurveda then the life of living beings will be balanced. Therefore, one should plan one's diet according to one's own situation and the seasons. Here is a website that classifies all food according to its effect on the Doshas - http://www.holistic-online.com/ayurveda/ayv-food-classification.htm
The ancient system of medicine in India called Ayurveda or knowledge of life, lays great stress on following a correct diet for maintaining health. Here I will briefly detail the various principles of Ayurvedic diet.