I have been with some Brahmins, and I was told that along with meat, they are also prohibited from eating onions and garlic.
I can understand the meat prohibition because of cows, but what is the reason for the prohibition on onions and/or garlic?
There are many beliefs about it:
According to Ayurveda, foods are grouped into three categories - sattvic, rajasic and tamasic - foods in the modes of goodness, passion and ignorance. Onions and garlic, and the other alliaceous plants are classified as rajasic and tamasic, which means that they increase passion and ignorance.
Ahinsa - In Hinduism, killing is prohibited (even of microbes). So ground food needs proper cleaning, which causes the death of micro-organisms.
Some even say that meat, onion, and garlic can cause behavioural changes if consumed in high quantity. It's also related to Ayurvedic categorization.
As per the scripture, garlic, onion and mushroom are prohibited for Brahmins because they are considered impure as they generally grow in the place of impurity. Brahmins need to maintain purity as they worship gods who are sattvic (pure) in nature.
Garlic, leeks and onions, mushrooms and (all plants), springing from impure (substances), are unfit to be eaten by twice-born men. [Manu Smriti - 5.5]
Brahmins are the ones who do the rituals, so they need goodness in their souls; no passion for money (raja guna); very reduced, controlled involvement in sex (only for child birth) (reduction of raja guna); no fighting or hatred (tama guna).
Onions and garlic cause tama guna. God (supreme god) and Dev-Devis don't take offerings by humans who have uncontrolled raja and tama gunas. So, onions are prohibited for Brahmins, or anyone who wants to become a Brahmin (Brahmacharis).
Found useful answer on Quora:
As per ancient Indian knowledge Ayurveda, All kind of food is divided into three categories viz namely Sattvik (are those that lead to clarity of mind and physical health), Rajasic (are those that have a stimulating effect on the mind and body), Tamasic (are those that have a sedative effect on the mind and body).
In fact all kind of food including meat is considered and put into these categories. The basic concept is whatever you eat will affect your body and mental health. Bhagvad Gita chapter 17 (verse 7 to 10) explain it.
āhāras tv api sarvasya tri-vidho bhavati priyaḥ yajñas tapas tathā dānaṁ teṣāṁ bhedam imaṁ śṛṇu
Even the food each person prefers is of three kinds, according to the three modes of material nature. The same is true of sacriﬁces, austerities and charity. Now hear of the distinctions between them.
āyuḥ-sattva-balārogya- sukha-prīti-vivardhanāḥ rasyāḥ snigdhāḥ sthirā hṛdyā āhārāḥ sāttvika-priyāḥ
Foods dear to those in the mode of goodness increase the duration of life, purify one’s existence and give strength, health, happiness and satisfaction. Such foods are juicy, fatty, wholesome, and pleasing to the heart.
Sattvic diet places emphasis on lacto-vegetarian ingredients that is fresh, seasonal, and naturally sourced. Oils and spices are considered sattvic, if naturally sourced and used in moderation. Examples include: water, cereal grains, legumes, vegetables, fruits, nuts, unpasteurized and unhomogenized fresh milk and all fresh milk derivatives (mostly ghee, but also butter, cream, fresh or cottage cheese (paneer), and yogurt (lassi)), and raw honey. Sattvic foods are considered as those that help restore and maintain harmony and balance in one's body and mind. Sattva is Calm, Saintly. Sattvic food brings up quality that allows humbleness, forgiveness.
kaṭv-amla-lavaṇāty-uṣṇa- tīkṣṇa-rūkṣa-vidāhinaḥ āhārā rājasasyeṣṭā duḥkha-śokāmaya-pradāḥ
Foods that are too bitter, too sour, salty, hot, pungent, dry and burning are dear to those in the mode of passion. Such foods cause distress, misery and disease.
Rajasic foods lead to aggressiveness and irritability. If a person or thing tends to be extremely active, excitable, or passionate, that person or thing could be said to have a preponderance of rajasic. Rajasic food should be consumed to attain above qualities. But like everything these have side effects too Such foods cause distress, misery and disease. Examples include: caffeinated drinks (such as coffee, tea (both black and green), cola drinks, and energy drinks), brown or black chocolate, paan, ginkgo biloba, overly spicy food, over salty food.
yāta-yāmaṁ gata-rasaṁ pūti paryuṣitaṁ ca yat ucchiṣṭam api cāmedhyaṁ bhojanaṁ tāmasa-priyam
Food prepared more than three hours before being eaten, food that is tasteless, decomposed and putrid, and food consisting of remnants and untouchable things is dear to those in the mode of darkness.
Tamasic foods are those that have a sedative effect on the mind and body. In general, they are considered detrimental. According to yoga, these foods are to be avoided as they can cause mental dullness and physical numbness. However, in times of pain they are allowed to alleviate suffering. Tamasic food promotes dissolution, death, destruction, ignorance, sloth, and resistance. Examples include: meat of an animal, fish, the fertilized egg, onion, garlic, scallion, leek, chive, mushroom, alcoholic beverages, durian, blue cheese, eggplant, opium, and any food which has been kept overnight before consumption. In Chapter 14 verse 8 of Gita Krishna also says
You should know, O Arjuna, tamas as the cause of delusion enslaving all embodied beings born of nescience; by negligence, listlessness and somnolescence
Onions and Garlic lead to ignorance, lethargy, anger, aggression, over stimulation of the senses, increase in sexual desire and anxiety. Root vegetables like carrots, beets, sweet potatoes, and turnips are not considered tamasic in Hinduism way of classification. botanical members of the alliaceous family (alliums) are not considered pure in Jainism based on the principle of nonviolence, which is different from Hinduism reason.
śrī-bhagavān uvāca paraṁ bhūyaḥ pravakṣyāmi jñānānāṁ jñānam uttamam yaj jñātvā munayaḥ sarve parāṁsiddhim ito gatāḥ The Supreme Personality of Godhead said: Again I shall declare to you this supreme wisdom, the best of all knowledge, knowing which all the sages have attained the supreme perfection.
Q: Why not to have garlic & onion?
A: Garlic & onion make you little dull. Creates tamogun. For meditators it’s not very good. For gastric problem- garlic, for heart problem- onion. But as a regular diet, take everyday I would not advise. It makes consciousness dull. This universe is filled with Prana, life energy. If you area good meditator, nothing can make you unhappy. Even if you are unhappy, it immediately gets removed.
From a Q&A with Sri Sri Ravi Shankar:
Every food which covers other food fragrance was regarded as non-deity. This can be easily understood by observing that the presence of Garlic in a dish would rectify almost completely the fragrance offered by other spices or a vegetable. Same goes with Onion. Due to this property, these were discarded as impure in our scriptures.
According to ayurveda, foods are classified by their rasa (taste), vipak (aftertaste), virya (energy) and prabhava (specific qualities). The specific qualities of onion and garlic are that they carry the energy of anger. Anger pollutes memory and therefore increases bodily consciousness (Bhagavad-gita 2.63).