What is the “propylene glycol alginate” found in salad dressings?

Dear Cecil:

Why is "propylene glycol alginate" found in salad dressings? It sounds suspiciously similar to a famous antifreeze.

Cecil replies:

Propylene glycol alginate is used as a thickener and stabilizer in such products as ice cream and candy as well as salad dressing. Originally derived from brown algae and since mixed with a few other goodies, the chemical has been used for almost a century in one form or another. It’s on the government’s GRAS (generally recognized as safe) list, but that just means it’s been around for a long time and hasn’t killed enough people to be conspicuous. As with many additives, little long-term testing has been done. PGA does not accumulate in the body, which is mildly reassuring, but there is some evidence that it inhibits the absorption of whatever nutrients happen to be in the food product it’s mixed in with. On the positive side, it also inhibits the absorption of strontium, one of the more toxic components of nuclear fallout … something to keep in mind if you ever do menu planning the day after the Big One drops.

Send questions to Cecil via cecil@straightdope.com.

Comment on this Column