Our body gets the omega 3 and omega 6 fatty acids from diet, for this reason, our food choices are responsible for the intake of these important substances, both essential to our health but with different actions. In fact, omega 3 fatty acids act by counteracting inflammation, adipogenesis and fat accumulation, on the contrary, omega 6 fatty acids stimulate the inflammation processes and the fat production. The scientists Gerard Ailhaud and Pierre Weill were the first ones who understood that one of the reason of the increasing obesity epidemic in the Western World could be the imbalance between omega 3 and omega 6, in favor of the latter (Ailhaud et al, Obes Rev, Feb 2004 – Ailhaud et al, Prog Lipd Res, May 2006). In order to guarantee us more health and also … the right body weight a good choice may be to include in the diet a higher quantity of omega 3. We have seen that fish is a source of these essential fatty acids but it should be chosen with some attentions. Now we go on talking about different types of fish in order to understand the best fish to take on the table. Among the omega 3 rich fishes we can find tuna. However, tuna shows also the highest contamination for what concerns substances such as dioxin and methylmercury, this depends on the fish diet and on the pollution of our seas (Maqbool, Public Health Nutr, Nov 2011). Generally, according to the scientists and the experts, it is better to eat small fishes, where the mercury accumulation is smaller, moreover, canned tuna is considered safer, at least for what concerns the levels of mercury, than fresh and big tuna. The difference is given indeed by the fishing area and the canned tuna comes generally from less polluted seas. However, a study has observed that the 55% of all the analyzed canned tuna found on the shelves of US supermarkets exceed the reference values (Gerstenberger et al, Environ Toxicol Chem, Feb 2010). For this reason, tuna is a fish that should be eaten very carefully and not too often. Then, for what concerns mackerel, it is considered a fish with a high intake of omega 3 and low levels of toxins, although there are some types of mackerel, of large size and fished in particular countries such as Malaysia and Mexico, that have high levels of mercury (Ramírez-Islas et al, Environ Sci Pollut Res Int, May 2018 – Hajeb et al, Environ Monit Assess, Dec 2010), for this reason it is important to know exactly the origin of the fish. Another source of omega 3 may be herring, however in this case the risk comes from the contamination of dioxin and PCB, a string pollutant. Herring results indeed one of the most contaminated but these values depends on the fishing area. In fact, it has been demonstrated that the herring from the Baltic sea is more polluted than herring from other countries (EFSA Journal 2010; 8(3), 1385). Be always informed about the origin of the herring, but, in any case, it is better to limit the consumption of this fish. Finally, the sea bass, a largely known and eaten fish. Sea bass is a source of omega 3, however its consumption should be limited because it may present contamination, although in a lower quantity than tuna, of mercury. Also the levels of PCB, although below the threshold considered safe, may result a problem if accumulated in time. Generally, farmed sea bass is more contaminated than wild sea bass and the advice of scientists is not to exceed the 8 servings per month of this fish (Carubelli et al, Chemosphere, Aug 2007 – Report of the American Pregnancy association). To sum up, for a healthy diet and in order to get an intake of omega 3 by limiting the dosage of pollutants in our body a good choice may be to serve anchovies, sardines, wild salmon, mackerel and shrimps, as we have seen in the previous post, but in any case it is important to change the type of fish on the table because there isn’t any fish, even the smallest, completely without toxins.
Fat burning diet Part 11, keeping on talking about fish
Tuna, mackerel, herring and sea bass are fishes with a high intake of omega 3 but may be contaminated by mercury and dioxin