In the previous post dedicated to fat burning diet we have seen that one of the causes of the obesity epidemic in the Western world may be the imbalance between omega 6 and omega 3 taken with the diet. These fatty acids, although both essential to the body, have a different effect, omega 6, indeed, are pro inflammatory and able to stimulate adipogenesis, omega 3 instead counteract inflammation and the production and accumulation of fat. An optimal ratio between omega 6 and omega 3, able to have beneficial effects not only on body weight but also on the health of the cardiovascular system and, more in general, of the body, by protecting it against tumors and degenerative diseases, should be 1-4 / 1. However, what we are observing is an explosion of omega 6 levels introduced with the diet so as to reach the 20 / 1 ratio between omega 6 and omega 3 (Simopoulos et al, Nutrients, Mar 2016). We have seen also that this imbalance is partly due to the feeds given to the animals, from which milk, dairy products and eggs are obtained, and also to the choice to prefer seed oils to the very healthy olive oil. But it doesn’t stop here. Today we’ll see the problem of fish. The fish appears little on our table, however, in some cases, it could be an excellent source of omega 3, but only if appropriately chosen. This is the case of fatty fish such as salmon, sardines, anchovies, mackerel, herring, sea bass and, to a lesser extent, tuna and shrimp (Zhang et al, Biomed Res Int, Jan 2018 - Asif et al, Orient Pharm Exp Med, Mar 2011). Unfortunately, the situation is not as simple as you might think and eating more fish isn’t enough to ensure more omega 3 and more health. The consumption of sardines and anchovies is safe and healthy, because they contain very high amounts of omega 3 and only limited quantities of pollutants. The same applies also to shrimps, even if, in comparison, they contain smaller quantities of omega 3 (Al-Mughairi, J Food Sci, Jul 2013 - Sidhu et al, Regul Toxicol Pharmacol, Dec 2003 - Smith et al, Mar Pollut Bull, Sep 2010 - Hosomi et al, Glob J Health Sci, May 2012). Completely different is the situation for what concerns the other types of fish. In fact, nowadays about half of the salmon that is on the market is farmed, and not wild. The problem of farmed salmon is that, as in the case of cows, goats and hens, the feed rich in oils with a high content of omega 6 has deteriorated the quality of the essential fatty acid profile. The amount of omega 3 is increased, but only slightly, on the contrary the amount of omega 6 has increased significantly, worsening the ratio between omega 3 and omega 6 compared to wild salmon (Strobel et al, Lipids Health Dis, Oct 2012).
Moreover, a study compared the levels of contaminants, such as dioxins and PCBs, between wild Pacific salmon and farmed Atlantic salmon, and noted that the latter has the highest amount of toxic substances (Hamilton et al, Environ Sci Technol, Nov 2015). Among fish from different aquacultures, the least contaminated salmon comes from South America, then from North America and finally, the most contaminated, from Europe (Hites et al, Environ Sci Technol , Oct 2004). So, as a first indication, wild salmon is definitely a better choice for diet for what concerns the intake of omega 3 fatty acids and the smaller amount of toxic substances. In the next post we will talk again about other varieties of fish that are found on the market.