Sri Aurobindo
Letters of Sri Aurobindo
08. Transformation of the Physical
I think the importance of sattwic food from the spiritual point of view has been exaggerated. Food is rather a question of hygiene, and many of the sanctions and prohibitions laid down in ancient religions had more a hygienic than a spiritual motive. The Gita’s definitions seem to point in the same direction – tamasic food, it seems to say, is what is stale or rotten with the virtue gone out of it, rajasic food is that which is too acrid, pungent, etc., heats the blood and spoils the health, sattwic food is 
what is pleasing, healthy, etc. It may well be that different kinds of food nourish the action of the different gunas and so indirectly are helpful or harmful apart from their physical action. But that is as far as one can go confidently. What particular eatables are or are not sattwic is another question and more difficult to determine. Spiritually, I should say that the effect of food depends more on the occult atmosphere and influences that come with it than on anything in the food itself. Vegetarianism is another question altogether; it stands, as you say, on a will not to do harm to the more conscious forms of life for the satisfaction of the belly.
As for the question of practising to take all kinds of food with equal rasa, it is not necessary to practise nor does it really come by practice. One has to acquire equality within in the consciousness and as this equality grows, one can extend it or apply it to the various fields of the activity of the consciousness.