There are three qualities of Maya (nature’s deluding power) and they are present in varying quantities within one’s mind:
Satva: qualities like tranquility, restraint, forgiveness, purity and peace of mind
Rajas: qualities like passion, aggression & pleasure
Tamas: qualities like anger, resent, arrogance, excessive lust and destruction.
Various foods can influence the state of one’s mind by altering the levels of above listed qualities, in other words these qualities are simulated by the food we take. Onions and garlic increase tamasik qualities.
Now if there are rajasik and tamasik qualities present within religious people minds then they will not remain calm and can not adhere to his duties (worshiping god, meditation and things like that). Hence tamasik and rajasik foods are prohibited for brahmins or religious people.
(Note: These things are of little importance now a days as caste system is on the verge of extinction and very few people follow these rules as they either consider it superstition or they simply can’t follow it due to present lifestyle.)
But let us consider the following points:
Think about the person slicing an onion, tears roll down through eyes. It’s due to the presence of sulphur, and human body naturally is not acquainted with such chemicals, so it resists by activating tear gland. Now, you are eating the whole thing, that’s too much for our body to bear. The organo-sulphuric compounds in onion and garlic certainly have disquieting/exciting effects on the brain. Therefore it was recommended that intellectuals (priests, teachers and spiritually inclined people) not eat them as it would adversely affect their thinking process.
It’s also due to the strong smell, which is a sign of impurity and non-serenity, and people finally end up hating this smell. Those who eat already know.
People constantly argue, that they have a good medicinal value. But when you are talking about medicine, you must also know that medicines are taken in a limited quantity and we usually do not make chutneys, curries and sabjis of our medicines.
If you are a Hindu, or know something about Hindus, you may know that, we do not offer Onion & Garlic to our deities, neither you will be served with them at any temples.
They are considered as “Tamsik” food, which arouse qualities like anger, laziness, and divert us from the correct path of spiritual knowledge.
As per Ayurveda (& some say it is not related to Health and hence is Yogic concept than Ayurveda), food is classified into 3 categories Satvic, Rajasic and Tamasic.
Sattvic foods lead to clarity of mind and physical health.
Rajasic foods have a stimulating effect on the mind and body.
Tamasic foods have a sedative effect on the mind and body.
Being a Brahmin or religious person or a spiritual person, doesn’t mean to be a priest (and/or a teacher) as perceived by many. Brahmin was supposed to be much more than that. In short, they are expected to be torch bearers of the society and hence are supposed to maintain their consciousness in equilibrium all the time.
Rajasic and Tamasic foods could lead to aggressiveness or even worse dullness (mentally & physically – especially Tamasic foods).
So, it is advised for Brahmins to avoid Rajasic, strictly avoid Tamasic foods and Satvik to be consumed only to alleviate any suffering.
Onion and Garlic are classified as Tamasic foods, hence avoided by Brahmins or religious people.
During Kruti (Kreta) yug there was a king named Hiranyakashyapa, better known as the father of Baktha Prahlada,who also had a daughter named Simhika(Simhita). Simhika was married to Viprachitti. They had 100 sons and one daughter. First born was named Swarbhanu.
Devas and Asuras were churning ocean for a nector called Amruthawhich would give immoratality on drinking it (well There were other reasons as well).
Devtas were lead by Indraand Asuras were lead by Bali who was the son of Baktha Prahladaand also the uncle of Swarbhanu.
After They got amrutha from churning, Vishnu took form of a woman(mohini) and convinced the asuras and devas to sit apart.
Swarbhanu the nephew of Bali found something fishy about it and sat amongst devas(Surya and Chandra in particular). With no intention of giving the amrutha to Asuras, Vishnu poured it all to the devas and Swarbhanu drank it along with the devas. Surya and Chandra found something odd about Swarbhanu’s attire and complained about him to Vishnu. Vishnu realizing that he is an asura, quickly released his sudarshana chakra to decapitate him. Bali went to Lord Shiva for justice for which shiva condemned vishnu’s action and asked his son Ganesha to deal with Swarbhanu’s situation as he had an experience with his own encounter of similar type.
Ganesha Replaced Swarbhanu’s Head With A dragon’s Body to be called as Rahu and torso with Dragon’s head to be called as Ketu. The blood that droped from the head and torso on Earth grew up into plants- ONION and GARLIC, just like the drops of Amrutha fell from tumblr that devas and asuras were carrying off shore to grow up into GANJA an herb with negative energy (Which Lord Shiva Consumed as he could not drink amrutha, since he was storing poison in his throat).
Since onion and garlic were not of god’s direct creation and it was also born through blood (of an Asura) it is of pure TamasikNature.
Scriptures advise everyone to avoid Onion and garlic on Thursdays, Amavasya, Tarpana, Srardh and festival days for achieving both material and spiritual benefits
Bramhins or spiritual people are of sathvik nature and they have to maintain that nature at all cost for which they have to eat only Sathvik Food and avoid Rajasik (Extreme spices, deep fried..) and Tamasik (Meat, rotten..) food at all cost.
Consumption of onion and garlic might trigger higher physical excitation in spiritual minds who otherwise intend to devote their physical and mental attention to spirituality. Spirituality demands calmness of body and mind and that relates a lot to abstinence from his/her physical desires. In a way to increase nearness to spiritual excellence while inculcating Sat gunas and its application for a balanced life, Spiritual people tend to avoid onion and garlic.