[1:1] In the name of GOD, Most Gracious, Most Merciful
[16:115] He only prohibits for you dead animals, blood, the meat of pigs, and food which is dedicated to other than GOD. If one is forced (to eat these), without being deliberate or malicious, then GOD is Forgiver, Most Merciful.

The vegetarian diet is perfectly acceptable in the light of the Quran.  Please review the following verses:

[5:4] They consult you concerning what is lawful for them; say, “Lawful for you are all good things, including what trained dogs and falcons catch for you.” You train them according to GOD’s teachings. You may eat what they catch for you, and mention GOD’s name thereupon. You shall observe GOD. GOD is most efficient in reckoning.

[5:5] Today, all good food is made lawful for you. The food of the people of the scripture is lawful for you. Also, you may marry the chaste women among the believers, as well as the chaste women among the followers of previous scripture, provided you pay them their due dowries. You shall maintain chastity, not committing adultery, nor taking secret lovers. Anyone who rejects faith, all his work will be in vain, and in the Hereafter he will be with the losers.

[5:93] Those who believe and lead a righteous life bear no guilt by eating any food, so long as they observe the commandments, believe and lead a righteous life, then maintain their piety and faith, and continue to observe piety and righteousness. GOD loves the righteous.

[6:145] Say, “I do not find in the revelations given to me any food that is prohibited for any eater except: (1) carrion, (2) running blood, (3) the meat of pigs, for it is contaminated, and (4) the meat of animals blasphemously dedicated to other than GOD.” If one is forced (to eat these), without being deliberate or malicious, then your Lord is Forgiver, Most Merciful.

[7:157] “(4) follow the messenger, the gentile prophet (Muhammad), whom they find written in their Torah and Gospel. He exhorts them to be righteous, enjoins them from evil, allows for them all good food, and prohibits that which is bad, and unloads the burdens and the shackles imposed upon them. Those who believe in him, respect him, support him, and follow the light that came with him are the successful ones.

[10:24] The analogy of this worldly life is like this: we send down water from the sky to produce with it all kinds of plants from the earth, and to provide food for the people and the animals. Then, just as the earth is perfectly adorned, and its people think that they are in control thereof, our judgment comes by night or by day, leaving it completely barren, as if nothing existed the previous day. We thus explain the revelations for people who reflect.

[16:115] He only prohibits for you dead animals, blood, the meat of pigs, and food which is dedicated to other than GOD. If one is forced (to eat these), without being deliberate or malicious, then GOD is Forgiver, Most Merciful.

[22:30] Those who reverence the rites decreed by GOD have deserved a good reward at their Lord. All livestock is made lawful for your food, except for those specifically prohibited for you. You shall avoid the abomination of idol worship, and avoid bearing false witness.

[23:18] We send down from the sky water, in exact measure, then we store it in the ground. Certainly, we can let it escape.
[23:19] With it, we produce for you orchards of date palms, grapes, all kinds of fruits, and various foods.
[23:20] Also, a tree native to Sinai produces oil, as well as relish for the eaters.
[23:21] And the livestock should provide you with a lesson. We let you drink (milk) from their bellies, you derive other benefits from them, and some of them you use for food.

Thank you and may God guide us,
 M. Irtaza