I would have been all over canned salmon for it's oils, but I've not seen it without added salt.

I do know that mayonnaise has added sugar, but if you do the math, it's a tiny amount and should be ok on the diet. Anywhere else you turn (like nuts, etc), you're going to get at least as much or more carbs anyway. Vinegar ought to be ok on the diet. It's basically alcohol at it's end stage of being metabolised (FYI alcohol is broken down to acetaldehyde and then to acetic acid, which is vinegar). There's only one issue about store-bought mayonnaise that bothers me - see below.

Two issues with tuna and mayonnaise that I can think of:

1. Mercury: all fish contains methylmercury to some degree. Although tuna contains least (because they use smaller fish, and the mercury is accumulated over the fish's lifetime), it's still presumed to be a hazard for a developing nervous system. For this reason they caution pregnant/nursing women and children away from eating too much fish. Whether this applies to me (not pregnant, not woman, not child, and had fried my brain with all sorts of things in the past anyway), I don't know. I decided that it's not as bad as the steroids and antibiotics in canned salt-free chicken.

2. Phytoestrogens: most mayonnaises are prepared with soybean oil. Soybeans are known to contain high levels of phytoestrogens. Maybe not high enough so that men grow boobs, but still - I've already posted some references on this. However, it's less clear to me whether phytoestrogens make it into the oil - apparently at various stages of processing the beans the phytoestrogens are either destroyed or discarded. Either way, it's possible to get safflower oil mayonnaise if you're willing to spend the buck, or prepare your own mayonnaise if you're culinary-gifted enough. But that may knock out most males out of the race, so then you might be stuck with issue #1...