It's okay to use aluminum pots for canning; in fact, the top of the line All American pressure canners are aluminum.

Raw aluminum can react with certain foods, but that won't happen if the food is in jars. Are you talking about cooking the marmalade in the aluminum pot, or are you talking about using the aluminum pot as a water bath canner?

Large aluminum stockpots make excellent water bath canners. Much better than those old thin, blue, speckled rustbuckets.

Aluminum has been linked to Alzheimer's. I think it would be ok to cook the sealed canning jars in an aluminum pot but I'd recommend not cooking any food in the pot by itself.

Not causally linked. Circumstantially linked. Nevertheless I wouldn't cook in aluminum for canning, as many home-canned foods (i.e. jams, tomato products, fruits, pickles) are high-acid and there can be flavor and color impairments due to interactions with the aluminum.

Carol