The prohibition against eating blood is enumerated numerous times in the Torah and is repeated in Parshas Reeh.
The Torah provides the reason for the prohibition “for the life-force of all flesh is in the blood and I have assigned it to you as an atonement for your lives upon the altar”. The Ramban explains that this is like the forbidden fats (Cheilev) which are prohibited because they are dedicated to Hashem on the altar. Additionally, it is not proper for man to eat the life-force or soul of another living being.
The Rambam in Moreh Nevuchim explains that the Torah forbids us to eat blood as this was a pagan or idolatrous practise.
In Parshas Re’eh, the prohibition on eating blood is repeated in 3 consecutive verses. 23 Only be strong not to eat the blood, for the blood is the life-force and you may not eat the life-force with the flesh. 24 Do not eat it, you shall pour it on the ground like water. 25 Do not eat it, in order that it be good for you and your children after you, when you do what’s right in the eyes of Hashem.
From the repetition, our sages conclude that there are different types of blood, each subject to a different law. The most serious level of prohibition is on the Dam HaNefesh, the life-blood. This is the blood which spurts out at the time of Shechita. Consuming Dam HaNefesh is forbidden on punishment of Kareis - spiritual disconnection. This is the blood mentioned in verse 23 as being the life-force.
The second type of blood, referred to in verse 24, is Dam Tamtzis. This is the blood which slowly ebbs out from the incision after the Shechita. Dam Tamtzis is also Biblically forbidden to be eaten, but not punishable by Kareis.
The final type of blood is referred to as Dam HaEivarim, the blood which remains absorbed within the organs and flesh of the animal after Shechita. Our sages make a further distinction within this category: Only once the blood has separated and moved from the capillaries is it forbidden. This happens when the meat is cooked.
This is why meat that is going to be cooked needs to be Kashered through Melicha (salting) to remove its blood. Additionally, some of the veins in which the blood is trapped need to be removed and some need to be cut open prior to Melicha. Like salting, roasting over fire also removes the blood from the meat.
The prohibition on blood applies to both the blood of a kosher or non-kosher animal. But the Torah limits the prohibition to animals and birds. The sages explain that the prohibition only applies to animals that require Shechita – domesticated animals, venison and birds.
Fish Blood
The blood of fish is Biblically permitted. However, if the blood is collected in a vessel, it is Rabbinically forbidden on account of Maaris Ayin – that someone may believe that it is forbidden blood.
If it is recognisable that the blood is from fish, there is no Maris Ayin. The Shulchan Aruch gives the example of where there are fish scales in the blood, evidencing that it is the blood of fish.
The Gemara only mentions the concern of Maris Ayin in relation to fish blood. There is a dispute whether the blood of grasshoppers is also subject to Maris Ayin. The Pri Chadash rules that the same concern applies. Others suggest that since it is uncommon to collect the blood of grasshoppers in this manner, they were not included in the Rabbinic concern.
Human Blood
Like the blood of fish and grasshoppers, human blood is not subject to the Biblical prohibition. Nonetheless, the Gemara teaches that if a person bit into bread and there was blood on it, the blood must be scraped off or removed because of Maris Ayin. In contrast, blood that is between one’s teeth may be swallowed and the concern of Maris Ayin does not apply.
What is the reason for this distinction? Rashi explains that it is his is because the blood between the teeth is hidden from view. According to Tosfos, the permissibility is because it is evident that it is the blood of a person.
The Poskim draw on this dispute when addressing whether one may suck the blood from a wound elsewhere on the body, such as one’s finger. According to the reasoning of Rashi, the leniency is limited to blood that is in one’s mouth that is hidden from view. Blood from a wound anywhere else on the body would be visible and hence subject to Maris Ayin. However, according to Tosfos, the blood from a wound elsewhere on the body is also evidently human blood and hence permissible.
The Minchas Yaakov leaves the matter unresolved. However other Poskim are lenient. There are also Poskim who rule stringently. This all applies to swallowing the blood. One may suck the blood and spit it out.
The blood of fish, grasshoppers and humans is not intrinsically forbidden. Therefore if they became mixed into other food – for example if one cut there finger while making food, the food will be permissible (as long as know redness is visible).
Raw Meat
Even when discussing the meat of an animal or bird, there is a scenario in which one may eat the meat without having to Kasher it to remove the blood. This is where the meat is eaten raw.
As discussed above, the blood within the flesh (Dam Haeivarim) is only forbidden if it has not separated or moved to come out. This happens once the meat is cooked. It also applies to blood that is trapped in a bruise.
However, when eating raw meat, the blood is considered as not having moved from its place and hence the meat can be eaten raw, provided that it has been thoroughly rinsed to remove any surface blood. Any of the veins in which blood is trapped must also be removed. According to the Rambam22, one may not eat raw meat without salting.
In the laws of Shabbos, the Alter Rebbe writes that on Shabbos, a healthy person may eat the meat that was slaughtered for a sick person if they eat it raw and unsalted, since salting meat is forbidden on Shabbos.
The Chavas Daas questions this permissible ruling, because when one bites into the raw meat, the pressure of biting draws out the blood, which should now be forbidden. He suggests that the permissibility only applies when swallowing a piece whole, but not if one bites or chews it. However, the Shulchan Aruch does not mention any such qualification. The Acharonim explain that the blood that emerges through biting is not considered as Dam Shepiresh.
