Before adopting a low carb diet, the only canned fish I ever ate was tuna, mostly in the form of the classic tuna-salad sandwich. I still eat canned tuna, minus the bread, but because of two concerns, I restrict the amount.
First, there is my concern about mercury in tuna. I’m not in one of the government’s “high risk” groups for mercury consumption (pregnant women, nursing mothers, children), but I figure, why take chances? I buy only light tuna, which tests significantly lower for mercury than white (or albacore) tuna, and I limit myself to two or three tuna meals a week.
Second, there is my concern about the fat content of tuna; namely, it has no fat content. A four-ounce serving provides only one gram of fat. That’s fine if you are on a low-fat diet and seek a source of lean, relatively cheap protein. But on a LCHF (low-carb high-fat) diet — well, you need fat! So I always add fat to the tuna I eat, usually in the form of mayo or olive oil.
(Yes, I could just buy tuna packed in oil, but the type of oil used is often problematic; the same is true for sardines packed in oil. See below.)
Two fattier fish I now eat are salmon and sardines. I’ve always eaten salmon steaks as an occasional restaurant option and more rarely as a grilling option. But I never ate sardines at all, and I never ate canned or smoked salmon. I do now.
Sardines make a great (if smelly) snack or salad topper. In his book Living Low Carb, nutritionist Jonny Bowden calls sardines a “quick, easy, inexpensive source of first-class protein and omega-3 fats.” Bowden recommends buying sardines packed in their own oil, and avoiding those packed in soy or other vegetable oil. (He objects to these oils because of their high omega-6 content, which cancels out the beneficial effects of the omega-3 in the salmon; I object to soy in particular because there is way too much of it in the modern American diet. Take a look at almost any food label.)
I haven’t found any sardines packed in sardine oil around here, so I buy them packed in water. Ounce for ounce, canned sardines have about twice the fat of canned tuna. I keep a tin or two of sardines in the back of a file drawer at work where I used to keep my microwavable soups.
Salmon is a wonderful food. Wild-caught salmon has a better reputation for cleanliness than farm-raised, and it turns out that most canned salmon in the U.S. is wild-caught Alaskan fish. Fresh, frozen or smoked salmon may be wild or farmed, so you need to check labels. I use canned and smoked salmon in salads, and I also use canned to make salmon patties.
Four ounces of canned salmon without the skin and bones has three or four times the fat of four ounces of canned tuna, and salmon packed with the skin and bones (traditional) has even more fat. That size serving of salmon contains over 1000mg of omega-3, plus lots of protein and calcium.
As for mercury contamination, both sardines and salmon are relatively clean compared with tuna. The FDA has published tables showing the parts of mercury per million found in various fish (1990-2010). The mean ppm of mercury found in samples of salmon, sardines and tuna are
- Salmon (canned) 0.008
- Sardines 0.013
- Salmon (fresh/frozen) 0.022
- Tuna (canned, light) 0.128
- Tuna (canned, albacore) 0.350
Canned salmon has one of the lowest levels of mercury contamination of any fish or seafood; only scallops, shrimp and crab rival it. But even albacore tuna isn’t bad compared to swordfish (0.995) and shark (0.979). Of course, you don’t see much canned shark or swordfish on supermarket shelves.
Among canned fish, salmon is more expensive than sardines or tuna, and doesn’t seem to go on sale as often. But in terms of nutrition and taste, salmon’s worth the extra money.