If one prefers can one receive communion under only the blood of Christ?
Yes. EIther species contains the Body, Blood, Soul and Divinity of Our Lord.
Yes. Each species is the Body, Blood, Soul & Divinty of Jesus.
Many who have wheat intolerances recive from the Cup only. If both species are not usually offered to the congregation, you would need to make prior arrangements with your priest.
You should mention this to the priest beforehand so he can tell you how he wants you to process. He may still want to give you a blessing or something like that so people aren’t confused by your actions in the communion line.
***Unless communion is being offered under both species (body & blood) I doubt that you will find a priest that will give you only the blood just because *that is what you prefer. If you have a good reason not to receive under the appearance of bread (gluten allergy, radiation tx. to the throat, difficulty or unable to take solid foods, etc.) then there shouldn’t be any problem. But, just because that is what you prefer - probably not.
If communion is being offered under both species, then you can get in line and just receive from the cup. If this is your regular parish, then I would speak to the pastor first, so he knows you reason and to make sure you are doing so for a justified reason.