Kosher and the Soul: The Science and Spirituality Behind Jewish Dietary Laws

From a spiritual perspective, non-kosher food causes great harm to the soul of a Jew, whose very nature is rooted in belief in God. Non-kosher food creates timtum ha-lev — a spiritual dullness or blockage of the heart, which weakens the soul’s natural clarity and its deep, inherent faith in the reality of the Creator. Of course, there are many reasons a person may struggle with faith besides eating non-kosher food, but we will focus specifically on the spiritual effect of non-kosher food on the Jewish soul.

God created the world and all of nature; therefore, He knows what is spiritually healthy and what is not. Spiritually — and even physically, we now see that mixtures such as meat and milk can be harmful in various ways. Even pork, which does not appear drastically different from other non-kosher animals, has been found to contain components linked to certain cancers. It is no coincidence that non-Jews are choosing to consume kosher food, even though they are not required to.

The real reason for keeping kosher is not found in the simple, surface explanation but in the deeper mystical layers — the spiritual dimension. The Jewish soul is built in a way that when it comes into contact with the spiritual structures of animals forbidden by the Torah, significant spiritual harm is created. This harm cannot be felt physically, but it causes a subtle dullness toward belief in God and even makes it harder to truly understand and connect to Torah learning.

God knows exactly what each food contains and what it contributes to the body. There are foods that are permissible but not ideal to eat in excess — such as liver, and foods that only the very pious avoid, such as brain and heart, which contain the strongest expression of the animal’s nature. Because of this, their spiritual impact is greater:

• The brain – seat of thought

• The heart – source of life

• The liver – filters the blood

Many people therefore avoid eating liver, heart, and brain even from kosher animals because of their stronger spiritual effect.

What Do the Sages Say About Non-Kosher Animals?

According to the Rambam, all non-kosher animals forbidden by the Torah have inferior diets and therefore negatively impact a person’s physical health (Guide for the Perplexed 3:48). The Abarbanel agreed (Sefer HaChinuch, mitzvah 73). Rabbi Yitzchak Arama, however, believed the damage is primarily psychological: "They dull the intellect, distort thinking, and awaken crude and animalistic desires" (Akeidat Yitzchak, Shemini).

The Ramban combines both opinions and says that non-kosher foods harm both physically and spiritually (Ramban, Vayikra 11:13).

Rebbe Nachman on the spiritual harm of non-kosher food

Rebbe Nachman writes in Likutei Moharan: "When eating is kosher and proper, the spiritual husks (klipot) are subdued… one gives them only the minimal vitality they must receive. Therefore, through kosher eating, foolishness is subdued and the intellect rises." (LM I:17)

The opposite is also true: eating non-kosher food, God forbid, strengthens the forces of foolishness and weakens the mind. And who would want that?

Environmental Insight

Some sages offered an additional perspective: limiting consumption to domesticated, kosher animals helps prevent the extinction of wild species — an interesting ecological viewpoint found in early sources.

Eating Blood

Eating blood exposes a person to contamination and disease. The Torah’s requirements of checking the lungs and sinews, salting and soaking the meat, and thoroughly cleaning poultry, are not merely ritual, but also carry significant health benefits. These steps are not typically observed in standard non-kosher meat processing.

Insects and Creeping Creatures

Y. Roth, a food-technology expert at the Ministry of Health in Be’er Sheva, published an extensive article listing numerous diseases caused by insects in food — not only from eating them, but also through contact, inhalation, their eggs, discarded skins, hairs, and droppings. He cites nine different types of illnesses linked to insect contamination.

Thus, care for kosher food is connected not only to spiritual purity but also to physical health.

Kosher Living and the Design of Creation

A Jew avoids insects not for health reasons alone, but because God commanded it. Today we see additional layers of wisdom in these laws — both physical and spiritual.

As the Zohar says: “God looked into the Torah and created the world.” Creation mirrors the Torah, and one who guards the Torah’s laws is protected from much harm.