Why are onions and garlic considered aamish (non-veg) among Hindus? Is there a scientific / religious reason for it?
Conversations between a devotee and Bhagavan Ramana Maharshi from the book Letters from Sri Ramanasramam
Devotee: There is a saying amongst us that the good which garlic can do, even a mother cannot do. That verse expresses the same sentiment.”
Bhagavan: “Such a saying is prevalent in this part of the country also. People say it is very good for health. Really it is so. It removes rheumatism and gives strength to the body. For children it acts like amrit (nectar). Garlic is also known as amrit.”
Devotee: “How did it get that name?”
Bhagavan: “There is a curious story about it. As is well known, when gods (devas) and demons (rakshasas) churned the ocean, amrit came out of it. When the rakshasas were running away with the vessel containing amrit, devas appealed to Vishnu. Vishnu came on the scene in the shape of Mohini (Enchantress), and offered to resolve their quarrel by serving amrit to them all. They agreed. While serving it to the gods first, it appeared that there might not be enough to go round for the demons and so one of the latter got into the line of the gods unobserved by Mohini and was swallowing the amrit, when the Sun and the Moon noticed it and gave her the hint. She threw the ladle, with which the amrit was being served, at the demon. The ladle became the Chakra (an invincible lethal weapon of Vishnu) and cut off his head, but as amrit had already gone down his throat, the head became a graha (planet) and has since been taking vengeance on the Sun and the Moon at the time of an eclipse. That is the story. Now, when the head of the demon was severed, the trunk fell down and, in the process, a few drops of amrit also fell on the ground, and it is said that those drops became the garlic plant. That is why it is said that garlic has some of the properties of amrit. It is very good for the body. But since it also has the touch of the demon, it has tamasic qualities too, which affect the mind, if eaten. Hence it is forbidden for sadhakas.”
Devotee: “Are not horseradish (mullangi) and drumsticks also forbidden for sadhakas?”
Bhagavan: “Yes. Watermelon, horseradish, drumsticks, onions and other similar vegetables are forbidden. The mind will be clear and pure depending on the sort of food one eats, sattvic or otherwise.