Processed Eucheuma seaweed

Processed Eucheuma seaweed is the whole red alga milled rather than carrageenan extracted from it, so it keeps the fermentable fraction that extraction would have removed. That is the difference between this and refined carrageenan on this axis.

Processed Eucheuma seaweed is a thickener made from whole red algae rather than from extracted carrageenan, so it keeps more of what the seaweed absorbed. It is used in small amounts, which holds the level here. Seaweed is the reason nickel is asked about here at all: it concentrates trace elements from seawater, and the review behind this level is about exactly that load in seaweed and in the ingredients made from it.

Processed Eucheuma seaweed is milled red algae used as a thickener, not a fermented product. Seaweed concentrates minerals from seawater, which matters on the nickel axis; it does not make amines.

A seaweed extract used as a thickener. Seaweed is low in salicylate to begin with, and processing lowers it further.

Processed Eucheuma seaweed is milled red algae, used as a thickener at fractions of a percent. Whatever oxalate the source plant held, the amount reaching a portion is too small to register.

Processed Eucheuma seaweed (E407a) is the same red algae as carrageenan, less refined - the cell wall is left in, which is the whole difference. No histamine route. Being the less processed of the two does not change that, and does not make it the safer choice on any axis here. As with carrageenan, the inflammation question comes from animal work, so read it as a question rather than a finding.