I have a character in my story who is both a vampire and a practicing Muslim. I have another who is also a vampire and she subsists off menstrual blood. [Nutritious :>] However, I imagine Sam (the vampire I mentioned first) would have some objections to this, and it is also a tad weird. Asking your friends to donate their period blood is a lot weirder than asking your girlfriend. However, I´ve heard that things like coconut water can be used for blood transfusions. So can vampires live off those as well? In addition to or instead of blood? Secondary question, if vampires are well-known, would the practice of feeding off period blood be accepted or kind of ignored?

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    $\begingroup$ Isn't the answer already in your head? Being a fictional character it's entirely up to you what it can feed on. Why not tomato juice? By the way, I suspect for a practicing Muslim any blood is not halal. $\endgroup$
    – L.Dutch
    Feb 21, 2022 at 5:31
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    $\begingroup$ "Vampires" are a very nebulous concept that span cultures, and nearly every story that features a vampire has different rules for them. If you, as an author, think they should be able to drink coconut water, they can. If you think they can't, they can't. Could you narrow down the scope of your question to help us answer it? Give us some rules for your vampire, some explanations on how you want them to work, and then we can help you stay consistent within your world. $\endgroup$ Feb 21, 2022 at 5:54
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    $\begingroup$ Coconut water is . . . mostly water. It does contain a little bit of carbohydrates, but the character would need to drink some 3 liters (0.8 U.S. gallons) per day to get enough carbohydrates to satisfy their modest energy requirements. It does not contain any fats or proteins to speak of. $\endgroup$
    – AlexP
    Feb 21, 2022 at 9:55
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    $\begingroup$ I suspect that coconut water is substituting for saline. If all your blood was replaced with coconut water (or saline) you'd die, because it can't do most of the useful things that blood does. $\endgroup$ Feb 21, 2022 at 10:08
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    $\begingroup$ Anecdotal evidence suggests coconut water was used as an emergency substitute for blood plasma (not blood) during the WW2 in the Pacific by the British &/or Japanese when blood plasma wasn't available. That same evidence reported 'mixed' results. In other words if the choice was between death or coconut water you used coconut water - just until you could scrounge up real plasma or the patient died. Those results don't bode well for your Vampire i.e. in an emergency it might act as a substitute for real blood (for a short period of time). But the vamp won't be 'live' for long on it. $\endgroup$
    – Mon
    Feb 21, 2022 at 11:20

2 Answers 2


As several commenters have pointed out, vampires vary a lot between different works so it's really up to you.

Coconut water doesn't work as a whole blood substitute because it lacks blood cells. There is an urban legend about it being used as a blood plasma substitute, but that is largely a myth. Coconut water has been used intravenously as a way to hydrate a patient in an emergency. In those cases it was an isotonic saline substitute rather than a plasma substitute. It is usually sterile until the coconut is cracked, and contains useful minerals and carbohydrates, but is not very similar to blood plasma. So if your vampires need blood partly for nutritional purposes, they're out of luck.

On the plus side, coconut water has to be extracted from a relatively fresh coconut, so you could argue that it somehow contains the life force of the coconut, in the same way that blood is said to contain peoples' life force in many vampire stories. You'd need a lot of handwavium to explain why other types of seed wouldn't work - especially if fresh farm animal blood isn't good enough either (which seems likely if one of you vampires needs to use menstrual blood).

  • $\begingroup$ Is there a reason why you had made this a community wiki? $\endgroup$
    – L.Dutch
    Feb 21, 2022 at 12:23
  • $\begingroup$ @l-dutch Yes, but not an especially good one. I've seen more answers done this way lately, and hadn't tried it myself. Going by the early comments it seemed likely this question would be voted down (but I was interested enough to write a reply), so I didn't think it would make much difference either way. $\endgroup$ Feb 21, 2022 at 13:18

That really depends on how vampires work in your universe.

Every worldbuilder makes up their own rules for vampires in their world, depending on what is required for the stories they want to tell. Explanations for vampirism in fiction vary from "it's magic" (which means you can make up pretty much any rules you want as long as they are internally consistent) to various scientific explanations of varying degree of detail and plausibility. There is certainly precedent for vampire stories exploring "what if vampires could survive on something else than blood" (like True Blood). But there are even more vampire stories where having no other options than to drink fresh human blood or perish is an integral part of being a vampire (classic Dracula vampires). So don't feel pressured to get your vampires "right". Create the vampires you need for your world.

So the real question is: Do you want vampires in your world to be able to survive on coconut water? Would that enable a certain plot you have in mind? Then do it. Or would that ruin a certain plot you have in mind? Then don't do it.

Or as TVTropes writes: Our Vampires Are Different.


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