Vipaka connotes the altered taste of a drug or food consumed, after coming into contact with different digestive juices in the gastrointestinal tract (GIT) during the process of digestion. This is of two types, namely, avastha paka and nishtiha paka.
The former is a temporary change in taste of food or drug consumed in the GIT. The process of digestion in the GIT continues in three stages, namely, in the stomach, in the duodenum and in the large intestine. When the food consumed reaches the above regions successively, it gives rise to a particular taste specific to that region, irrespective of the predominance o the kind of taste of the food. It gets converted into a sweet taste leading to the production of kapha (phlegm) in stomach, and stourness in duodenum, leading to the production of pitta (bile). Sour and pungent are avastha paka in stomach, duodenum and large intestine in respect of any drug or food that passes through the gut.
However, when a drug is stated to have a type of vipaka, it really stands not for the one discussed earlier but for nishtiha paka only. It is the taste inferable by its effect on the process of excretion of urine, stools and semen, as also on the three doshas. It is the final taste of rasa (chyle or a fluid) ‘an ultimate essential product of food, after the process of digestion, which circulates all over the body and nourishes all the tissues.’
There are different opinions as to the number of vipakas. According to some experts, every taste has its own vipaka (six tastes and therefore six vipakas). Some others think of it as innumerable or of three or two types only. The last is accepted by Dhanvantari (Sushruta tradition), while the other three kinds are accepted by Atreya (Caraka) tradition. In respect of the former, vipaka does not directly depend on the taste of the foodstuff or drug consumed but on the properties like heaviness or lightness possessed by the drug, which accordingly leads to either guru (heavy) vipaka or laghu (light) vipaka. In the Atreya (Charaka Samhita) tradition, it is assumed that the taste of the article consumed would get converted into a particular taste after digestion. This general statement has enough exceptions, however, it is a commonly accepted theory of vipaka.
The effects of sweet vipaka are – increase in semen, easy bowl movement, micturition and increase in kapha and reduction of vata and pitta.
The effects of sour vipaka are – reduction in semen, easy bowel movement, micturition and increase in pitta.
The effects of pungent vipaka include the reduction of semen, constipation, obstruction, micturition, an increase in vata and pitta and decrease in kapha.