Dear Dietitian,

I read your response about the nutritional value of canned salmon and thought it was informative. I'm allergic to fresh fish, but I can eat crab, scallops, shrimp, and canned salmon without any reactions such as blisters, throat tingling, and sneezing. I've always been able to eat canned tuna without reaction, but fresh fish will cause lip swelling, eye-watering, and hives.  

My questions are: How much canned salmon is too much in a week?  Is there a risk? Is there a limit? Is it more nutritious in a salad, baked, or fried? What other foods contain omega 3-fatty acids?

Gretchen

Dear Gretchen,

Fish and seafood are great choices for a healthy diet. Oily fish such as salmon, mackerel, rainbow trout, and tuna are excellent sources of omega-3 fatty acids. Scientists are studying the effects of omega-3s in preventing heart disease and stroke.

Most of the studies that link omega-3s to heart health and stroke prevention are EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Another omega-3 is ALA (alpha-linolenic acid). Small amounts of ALA (2-5%) can be converted to DHA and EPA. ALA is found in plant foods, like flax seeds, edamame, chia seeds, tofu, and plant oils.

As many as 2.6 million Americans are allergic to finfish. Symptoms include hives and swelling of the lips, tongue, face, or throat. The most serious allergic reaction is anaphylaxis, which may result in death. Although these reactions can be severe and even life-threatening, it has been reported that patients with fish allergies “appear to be able to safely eat canned tuna because of a loss of allergenicity in processing.” (1)

It is not uncommon to be allergic to finfish (tuna, halibut, salmon, etc.) but not shellfish (shrimp, crab, lobster, etc.), and vice versa. It is also possible to be allergic to certain types of finfish but not others. To explore specific allergies, consult an allergist, a medical doctor specializing in treating allergies.

As for the safety of fish consumption, there has been concern about mercury levels in fish. Mercury is a heavy metal that, if consumed in large amounts, can build up in the blood and cause health problems. The FDA regulates the mercury levels in fish, so it is safe to eat for the general population. Women who are pregnant, may become pregnant, or breastfeeding are encouraged to limit their fish intake.

Finally, the American Heart Association recommends consuming oily fish (3 ounces cooked) twice a week to get your omega-3s (2). Adding tuna or salmon to a salad brings a filling protein source. Baked, broiled, or grilled fish are always healthy options. Fried fish is a tasteful alternative once or twice a month.

Disclaimer: This column is for educational purposes only and is not a substitute for medical treatment. Talk to your doctor if you think you have any type of allergy.

Until next time, be healthy!

Dear Dietitian

References

1. Bernhisel-Broadbent J, Scanlon SM, Sampson HA. “Fish hypersensitivity II: Clinical relevance of altered fish allergenicity cause by various preparation methods.” J Allergy Clin Immunol. 1992; 90:622-629
2. “Fish and Omega-3 Fatty Acids” https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/fish-and-omega-3-fatty-acids. 1 Nov 2021