Diet

In all circumstances they should conduct themselves with moderation; if the meal be only one course this is more pleasing in the sight of God; however, according to their means, they should seek to have this single dish be of good quality.

Bahá’u’lláh, Lights of Guidance, p. 294

Treat disease through diet, by preference.

Bahá’u’lláh, Bahá’u’lláh and the New Era, p. 106

"What will be the food of the future?"

"Fruit and grains. The time will come when meat will no longer be eaten. Medical science is only in its infancy, yet it has shown that our natural diet is that which grows out of the ground. The people will gradually develop up to the condition of this natural food."

‘Abdu’l-Bahá: Ten Days in the Light of 'Akká, p.8- 9

Regarding the eating of animal flesh and abstinence therefrom, know thou of a certainty that, in the beginning of creation, God determined the food of every living being, and to eat contrary to that determination is not approved. For instance, beasts of prey, such as the wolf, lion and leopard, are endowed with ferocious, tearing instruments, such as hooked talons and claws. From this it is evident that the food of such beasts is meat. If they were to attempt to graze, their teeth would not cut the grass, neither could they chew the cud, for they do not have the molars. Likewise, God hath given to the four-footed grazing animals such teeth as reap the grass like sickle, and from this we understand that the food of these species of animal is vegetable. They cannot chase and hunt down other animals. The falcon hath a hooked beak and sharp talons; the hooked beak preventeth him from grazing, therefore his food also is meat. "But now coming to man, we see he hath neither hooked teeth nor sharp nails or claws, nor teeth like iron sickles. From this it becometh evident and manifest that the food of man is cereals and fruit. Some of the teeth of man are like millstones to grind the grain, and some sharp to cut the fruit. Therefore he is not in need of meat, nor is he obliged to eat it. Even without eating meat he would with the utmost vigour and energy. For example, the community of the Brahmins in India do not eat meat; notwithstanding this they are not inferior to other nations in strength, power, vigour, outward senses or intellectual virtues. Truly, the killing of animals and the eating of their meat is somewhat contrary to pity and compassion, and if one can content oneself with cereals, fruit, oil and nuts, such as pistachios, almonds and so on, it would undoubtedly be better and more pleasing.

‘Abdu’l-Bahá, Lights of Guidance, p. 294

In regard to the question as to whether people ought to kill animals for food of not, there is no explicit statement in the Bahá’í Sacred Scriptures (as far as I know) in favor or against it. It is certain, however, that if man can live on a purely vegetarian diet and thus avoid killing animals, it would be much preferable. This is, however, a very controversial question and the Bahá’ís are free to express their views on it.

Shoghi Effendi,

In matters of diet, as in medicine, the Universal House of Justice feels that the believers should be aware that a huge body of scientific knowledge has been accumulated as a guide to our habits and practices.

Universal House of Justice, Compilation of Compilations Vol. I, p. 486