Jutians are a group that have abilities that includes utilizing blood magic. Which requires the expenditure of their own blood as "fuel" for the magic.

Assume they are 100% biologically human except when it is pointed otherwise.

To them it is not much magic and just a thing they are born with.

So the way they can use it is very close to how a human moves their body.

You can move your hand, and think about moving your hand.

Now to the actual magic and the part that concerns is it is as following:

Once the person decided to do something magical they have to give away a measure of their blood. The amount changes based on the required effect, also can be called spell, so the bigger the effect the more blood is required.

The "size" aspect is not so complicated. For example lighting 2 meters on fire is easier than 10 meters.

The blood is then magically focused on one part of the body, usually the palm of the hand, then that parts opens and the required amount of blood is expelled from that point and the spell happens.

Basically think of it as a wound or donating blood.

The better and more experienced the Jutian the more they can utilize the amount of blood they use and get better results.

Now such a system means that the theoretical maximum amount of blood they can use is roughly the same amount of blood we have which is around 5 liters, a quick google search gives 4.5-5.6 liters, but that is not reasonable as that would mean instant death.

Anyway most of the time the amount of blood magic is few millimeters and expending a full liter is problematic as they will suffer as much as as humans would.

Anyway google again supplies me with an answer of how much blood people can replace in a day with numbers in a range of 40-70 ml per day.

To simplify things lets take an average of 55 ml per day. But since those people always had this blood magic thing I though to up their numbers as their bodies are constantly having to reproduce blood to replenish the lost blood. So say an average of 25% of 55 so around 68 ml per day.

Anyway I'm not sure if it related but I just thought to provide it.

And there are actual limitations on their magic.

They can't get a random bucket of blood to use as fuel, it has to be their own magic from their own veins. They can't just drink a lot of blood to use it. They can't try to store their blood in a container. DNA matching or blood type matching is not a thing. This is magic. Anemia or other medical conditions are not a problem. Blood is still blood. And since this is pre blood transfusion setting they can't use blood packs or get transfusion. No magic means can increase their blood or enhance their recharging.

Lastly blood here is the dictionary definition of blood. No plasma complication.

So all they have is their bodies and their natural body's ability to recharge the blood.

So what can they do to quickly replenish their blood and enhance their recharging abilities?

Like what food? What exercise?

I know that for example red meat, beans, dried fruits...etc are good for people who suffer from anemia but honestly my medical knowledge is awful so will that translate to overall blood recharging or just improving the quality of the blood?

It is not purely medical thought as I'm also interested in knowing what is the general tricks and overall methods would such a race use to always be full of blood.

This is important as if you just used a lot of blood you want to recharge it quickly but not concerned with the quality of the blood so the type of food you look for can be different.

They are not idiots and trial and error insures that even without access to our advanced medical knowledge they can still figure out foods and other things that helps them.

So that's why the question is here I'd say. I mean you can replace the blood magic part with just someone just someone who wants to know the science behind it and it would remain the same. I just provided the context.

Without modern medicine or supplements what can they do to always be replenishing blood as fast as possible assuming their are human, like I detailed before, and have no technology or medical knowledge above the renaissance period.

Edit: I don't get the close votes. This is just a medical question with magic for context. Like just what would a human do in that situation. Human biology and knowledge of the time applies. Just that.

It's like asking how can this guy build a pyramid about 147 meters high with a base of 230 meters in 2580 BC.

The whole plasma and blood components and transfusion thing is simply off limits because of the scientific limitation of the time.

They don't have knowledge about plasma and so they themselves don't know exactly what part of their blood is consumed in magic.

Even if I decide the it is iron in the blood that is consumed, then it is pretty much useless as they don't know that.

Bringing 2020 medical knowledge to a setting roughly equaling 1600 just seems absurd in the context of the world. I know you are scientifically right but those people simply don't know that much like our actual ancestors.

Even if they attempt transfusion without know about blood types of the dangers of diseases in the blood. So again they fail.

I appreciate the input but when dealing with worlds with less science things are complicated.

  • 1
    $\begingroup$ Be like Popeye the Sailor Man: Endless spinach. $\endgroup$
    – Joe Bloggs
    Sep 17, 2020 at 6:48
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    $\begingroup$ In ye olde days (like 30 years ago) I was forced to eat a lot of beets (because they're red and look like heart) and half-fried livers for my anemia. Liver is rich is in iron and beets juice is (from what I read) stimulating production of blood (but is not treatment for anemia). $\endgroup$ Sep 17, 2020 at 8:33
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    $\begingroup$ This sure is an interesting variation on the phrase 'sweating blood' as a means to accomplish something. It is more a medical question than a science question. Does the 'hard science' tag apply to 'hard medicine'? The question seems to be asking 'How does the body replenish blood, and what does it need to do so?' Seems to me that is strictly factual. $\endgroup$ Sep 17, 2020 at 22:26
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    $\begingroup$ @JeffZeitlin, There is an answer. Only ours using modern medicine is more detailed. we know for a fact that certain foods improve iron levels and so on. I have a connection which is basically based on their knowledge and limits of a human like body. They don't know about plasma and can't make blood transfusion so stop trying to force your view on it. It's just a general medical question: how can a human replenish blood faster. I think medicine can answer that. I basically said you can ignore the magic part. Only added it for context $\endgroup$
    – Seallussus
    Sep 17, 2020 at 22:47
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    $\begingroup$ @Seallussus - Modern medicine may have drugs that cause the body to replenish blood faster in emergency situations; that's actually something of a staple of SF. However, there are no such routine practices in use; there are no specific dietary practices that enhance the replenishment of blood any faster than normal healthy eating - we rely only on the natural function of the body to complete the replenishment - it is because of this that there are limitations on the frequency of permitted blood donations. more... $\endgroup$ Sep 18, 2020 at 13:10

4 Answers 4


It'll require more than just food and rest

Blood consists of a lot of components. According to my own blood donor company, you'll have the following recovery times:

  • Blood plasma volume is restored to normal levels in about twelve hours.
  • Blood plasma itself and the platelets recover in a few days.
  • Red blood cells recover in a few weeks.
  • The iron level in the blood is restored in about two months.

This last one is also a reason to only allow people to donate again after two months (at least where I live). This all is for 500 ml of blood. Food intake and the right exercise/rest can probably improve these numbers, but apparently it's not well enough to start suggesting these to donators. Only no intensive workouts or using dangerous stuff (heavy machines, driving) is recommended some time after. It seems that food and exercise/rest aren't improving it in the amounts you're looking for.

Extrapolating from this I can surmise that your daily users either have a different and faster way to replenish, or they use incredibly small amounts at a time. Leaving the iron in the blood alone would already do wonders though.

Edit: foods that can help:

  • Iron-holding food such as spinach, fish, chicken, whole grain products, eggs and red meat.
  • Iron uptake can be assisted by a lot of vitamin C. This is in citrus and many fruit juices.
  • Drinking a lot of fluid after donation/spell.
  • 1
    $\begingroup$ I thought the iron is contained in the haemoglobin inside the red blood cells. So how come it takes longer to regenerate the iron than to regenerate the red blood cells? $\endgroup$
    – Daron
    Sep 17, 2020 at 19:35
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    $\begingroup$ Iron is contained in other parts of the body as well. $\endgroup$
    – Mary
    Sep 17, 2020 at 23:34

Magically-Induced Hemochromatosis

This is a disease where you store too much iron in your body. This would greatly help with the regeneration of blood.

However, you not only can use blood more frequently, you must. The only known treatment for hemochromatosis is blood-letting to this day. See the link for more details on the symptoms if they are negligent about this.


Mutant Molecules:

I think the heart of the question is well answered by Trioxidane's answer, but I thought I'd add a few elements to expand it a little. First, it depends on what portion of the blood is used in the magic. I'm not sure what you mean by no plasma complication, since blood is a colloid of cellular material in plasma, so plasma IS part of blood (this is a hospital blood banker talking). Unfortunately for witchcraft, female Jutians would start out with a disadvantage over males, because female blood supply suffers loss and reduced iron reserves as a result of menstruation, nursing, etc. Men also tend to consume more iron, but Jutians would likely be acutely aware of their foods and how it would affect magic levels.

Scenario one says a certain volume of blood is consumed. In this case, the negative effects of blood loss will be cumulative, but recovering fluids will increase blood volume, so the caster may get progressively weaker the more they cast, but diligent consumption of fluids will mean they can keep casting till they no longer can stay conscious.

Scenario 2 is the one I think fits your question the best. The casters have a mutant form of heme that can bind magic particles ("magic-nesium" or MGN) found (semi-abundantly?) in the environment. Only those who can actually bind these particles are able to use them to cast. MGN can behave several ways depending on your desires. It can be an alternative oxygen binder, with as much affinity for oxygen as you want, or it can compete with iron for binding.

  • Oxygen binding MGN can be substituted for iron in whole or in part in the mutant heme, and it can bind oxygen as well or as poorly as you want. Your Jutians can have as much or as little as you want. If it completely replaces iron, then foods rich in MGN are more important than iron in recovering blood. They are certainly more important for casting. If MGN merely can replace iron, then your Jutians will want as much of this as possible, because their blood would literally be more potent magically than normal Jutians. Iron would actually compete with MGN in the blood. They might want to be vegetarians and avoid iron rich foods.
  • If MGN does not bind oxygen, or if it does so poorly, then your Jutians are in a bit of a pickle. The more MGN they get, the weaker physically they will be, but the stronger magically. The more Iron they consume the stronger they will be physically, but weaker magically. Jutians will have a Faustian choice between health and magic. They will still lose blood cumulatively, but would need to choose between consuming MGN-rich foods to recover magic, or iron-rich foods to protect their health.
  • Another possibility is that MGN behaves like carbon Monoxide, binding more tightly to iron in mutant heme than oxygen does. Jutians in this scenario might smoke or burn MGN-containing products in preparation to do magic. The more charged up they got with MGN, the sicker they would become. They would be more severely affected by blood loss because however much MGN they still had would be displacing oxygen in their remaining blood.

A third scenario 3 is that MGN is present in plasma, bound to mutant globulins (plasma proteins), antibodies, or the like. In THIS scenario, the plasma is consumed, severely dehydrating the Jutian, but the red blood cells are left mostly intact. In this case, consuming iron-rich foods is irrelevant, because they don't need it. Consuming water will replace much of the blood volume, but the lost MGN and mutant globulins will take time or MGN-rich food to replace. Plasma also contains clotting factors, so consuming large amounts of plasma in casting could lead to bleeding disorders like factor deficiencies. Here, your Jutians are less physically affected, but could still dehydrate themselves to death, or suffer effects similar to people with iron overload or polycythemia vera.

despite your desire not to have transfusions, I will mention a consequence of this. Plasma (or serum, after it clots) is less likely to have complications of transfusion than red cells, and is easier to transfuse. If serum were to concentrate MGN-binding antibodies/globulins, then it could be given as an injection (which was possible long before transfusions) or consumed as an MGN-rich food, either of which would allow quicker restoration of MGN in the same way as you were avoiding by the limitation against transfusion. There would be complications long term, but it could be done.

  • $\begingroup$ @Seallussus This answer doesn't require any advanced knowledge by your Jutians, it merely lays out the likely scenarios that would affect the recovery & loss of blood and magic based on hematology. I give you the science so you know HOW various options would work. Understanding of basic medical techniques as laid out by the ancients like Hippocrates and Galen would give understanding of blood, essential essences, and the like (well before 1600). Sorry, I can't help feel that edit was directed at this answer. $\endgroup$
    – DWKraus
    Sep 17, 2020 at 23:50
  • $\begingroup$ Appreciated. It is a good idea. I think maybe I'll incorporate a crop or animal as an overall good blood replenish option. This fits the history of the people and how they became what they are today. Scenario 1 is the most fitting I think. They also don't like to use magic anyway. Mostly used when really needed. True the point about women. Can't do anything there. The edit was to generally clarify the reasoning behind why I don't want to consider plasma or iron...etc. Since it is your field I think to expand on what I'm figuring out. Basically the process of blood spending... $\endgroup$
    – Seallussus
    Sep 19, 2020 at 4:51
  • $\begingroup$ blood spending is totally random. I have 0 idea of how bleeding or transfusion work so that's why I'm asking. When they want to do magic just a measure of the blood, proportional to the spell, is spent. So imagine a magical hand going into the body and grabbing a set amount of blood, spell dependent, and then removing that amount of the liquid. First does that break any rules? Like there is no targeting process to go after plasma or iron. Just the random amount of blood. I think the effects is how I like it. You can spend a full liter of plasma and suffer or a liter of mixed blood. $\endgroup$
    – Seallussus
    Sep 19, 2020 at 4:55

The first spell they learn in youth is how to grow their canine teeth into fangs and through them, channel another's blood into their veins. They rarely do this in public so over the ages, the few sightings have been written off as vampires.

An additional aspect of that first spell is that it enhances their sense of smell so far that they can differentiate a potential victim's blood type from a distance. This allows them to only choose victims who have compatible blood types or are universal donors.

The second spell they learn allows them to retract the canines so that they don't look like unusual between refuelings.

  • 1
    $\begingroup$ "No magic means can increase their blood or enhance their recharging." AND "Without modern medicine or supplements what can they do to always be replenishing blood as fast as possible assuming their are human, like I detailed before, and have no technology or medical knowledge above the renaissance period." $\endgroup$
    – IT Alex
    Sep 17, 2020 at 17:14
  • $\begingroup$ @ITAlex, I thought that I had gotten past both of those requirements by making it a mechanical increase of the blood stream via the large canine teeth with tunnels leading into their blood supply; along with the enhanced sense of smell so that they could detect the donor victims which were compatible. No magic is needed to make the teeth work after they have been lengthened and no scientific knowledge of blood types is needed to know which potential victim smells like a good source of replenishment. $\endgroup$ Sep 17, 2020 at 17:34
  • $\begingroup$ still doesn't cover the core of the question which is how to help them regenerate blood. Unless you are doing a frame challenge in which you should specify that as part of the post. $\endgroup$
    – IT Alex
    Sep 17, 2020 at 17:59
  • $\begingroup$ I was simple offering "replacement" as an alternative to "regeneration". If that is a challenge to the original state of the question, then it was unintentional. I also thought that the vampire link fit nicely with the early-scientific time period of the question. $\endgroup$ Sep 17, 2020 at 18:10

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