Torah Portion: Tzav
“וכל דם לא תאכלו“ (ויקרא ז כו)
It is a negative commandment that we not eat the blood of a beheima (domesticated animals), chaya (non-domesticated animals), or blood of fowl, asit is written, You shall not consume any blood (Vayikra 7:26). This prohibition is repeated in numerous places in the Torah.
Among the roots of the mitzvah is the idea that aside from the fact that blood is a food of bad constitution, consuming it involves a touch of cruelty — that a human should swallow the very life-sustaining, soul-carrying part of living creatures who likewise have physical bodies. For it is known that animals have a [primitive] soul, which the Sages refer to as the “essential soul,” meaning, not one of intellect.
The Ramban wrote in explaining the rational against consuming blood that it is well-known that what one eats is [converted and] becomes part of the one who ate it, so if a person eats the blood, it will introduce coarseness into the soul of the human, akin to the soul of the animal which is course and un-refined.
The laws of the mitzvah include: It is permissible to consume the blood of fish and kosher-species locust, but because of mar’is ayin (a misleading impression), it is necessary to do something that will make it obvious that it is fish blood, such as placing some of the fish scales nearby. However, the blood of non-kosher species of fish is forbidden, because of the rule that whatever is produced from a non-kosher creature is likewise not kosher.
Blood of a human, though not forbidden Scripturally, was prohibited by the Sages because of mar’is ayin (a misleading impression). They therefore said that the blood a person has [from his gums] between his teeth, he may swallow. But if any of the blood became attached to a piece of bread or other food the person was eating [and is now outside the person’s mouth], the blood must be removed before continuing to eat the food.
This mitzvah applies in all places and at all times, to both men and women.