Our choice of a vegetarian or non-vegetarian diet depends on four main factors. The first is a matter of habit, conditioning and taste. Generally, the body responds best to those things to which it has been habituated since childhood. Hence generally unless the situation demands it, such as a change in outer conditions of living or the necessity of profession, it is best to keep to the diet one has got accustomed to since childhood. Surely sometimes when one is ill, a high protein diet as is provided by certain non-vegetarian or rather quasi non-veg diet such as eggs can be helpful to recover faster.
The second aspect is the biological and physiological aspects of the human body. Biologically we are designed by nature more towards a vegetarian diet. As to the importance of meat to provide us with certain nutrients such as certain Vitamins, Iron etc is much exaggerated. In general, a wholesome and balanced vegetarian diet can provide everything in enough quantity as any non-vegetarian diet can. On the other hand, there is increasing evidence that certain types of non-vegetarian diet are harmful to the heart and colon whereas a vegetarian diet with high fibre can be preventive for some of these diseases.
The third reason why certain people take to a vegetarian diet is a religious and ethical one. It is based on inflicting pain to sentient creatures. While this is a good practice since it trains us to be kind and teaches us to extend our sensitivities to those creatures who belong to other species. However, as is the case with most such habits that one adopts on conventional religious and moral grounds simply as part of one’s religious and social inheritance that one follows them instinctively without giving it a conscious thought.
The fourth aspect is rather subtle and relates to the kind of consciousness that is there in everything. When we eat and drink something it is not just the outer food and matter alone but all that is imprinted and contained within it. Seen thus we can easily understand that the plant life contains largely the first stir of life that enlivens matter and helps it live and grow. On the other hand, animal food contains certain aspects of the vital that we find in an animal such as fear and rage and lust. This is especially so when animals are butchered in certain ways. That is when they scream and feel the pain in prolonged ways. All this consciousness goes in with the food we take. Its other side is when we partake food that is offered to the Divine. Then what we receive along with it is bhakti, faith, the touch of Grace.
These are but mostly outer aspects of food. More important is the occult atmosphere in which it is prepared and taken, the inner state and attitude, and the stage of evolution. It is known that attachment to certain kinds of food such as non-vegetarian and even vegetarian food with strong spices tends to automatically drop as we grow in our consciousness. But the reverse is not necessarily true. There is certainly a difference when things are done through conscious choice and when merely through habit and circumstances.