Salmons that swim upstream, free and healthy, thanks also to the crustaceans with which they feed and that give their flesh a natural pink color ... unluckily, this image is no longer so truthful. In fact, with the increase in salmon consumption all over the world, the need to meet this demand has caused also the growth of several salmon farms. Nowadays, more than half of the salmon served on our tables comes from farms.
Salmon, properties and benefits
The strength of the salmon is due to its undoubted healthy benefits. In fact, salmon brings precious omega 3 fatty acids with a protective action on the heart, and this action is well documented. Not only that, salmon is also a source of vitamin D (Jakobsen et al, Nutrients, 2019). But what happens with farmed salmon? You should consider that these fish are no longer free to move and to feed as they like, that they are crammed into tanks, often injured and sick and that to give to their flesh a pink color food coloring are now used in their food. Do the benefits of omega 3 contained in salmon outweigh the risks of pollutants and toxic substances that are very abundant in farmed fish? Let's try to understand.
The problem of farmed salmon, risk-benefit analysis
The problem of salmon is summarized in the benefit-risk analysis that appears in an article published in the prestigious journal Science (Tuomisto et al, Science, 2004). The point is that salmon, both wild and farmed, provides omega 3 fatty acids, which have been shown to reduce mortality by 20% in people with coronary heart disease. Wild salmon however has a high cost while farmed salmon is much cheaper. By contrast, however, salmon, especially farmed salmon, also contains toxic and carcinogenic substances, such as dioxin (Foran et al, Environ Health Perspect, 2005). And the omega 3 that it is rich in does not act against cancer. Some scientists, as reported in the Science article, believe that the benefits of omega 3 intake would outweigh the risks but the reality is that this claim is based on an analysis that does not take into account all the repercussions, even indirect, that consuming foods rich in toxic and carcinogenic substances can have. For example, the possible brain damage that these toxic substances may have on children exposed to these substances when they are still in the mother's womb should also be considered.
Wild salmon, more expensive but ...
Wild salmon is certainly more expensive than farmed salmon. It is true that wild salmon contains slightly less omega 3 fatty acids than farmed salmon, but it is also true that farmed salmon also provides a significant amount of omega 6 fatty acids, which are already very abundant in our western type diet. In case of an excess in omega 6 fatty acids, in the long run, they can cause chronic inflammation in the body. In particular, the ratio between omega 3 and omega 6 in wild salmon is 10, in the farmed salmon 3 (Hamilton et al, Environ Sci Technol, 2005). Not only that, wild salmon also contains higher amounts of vitamin D (Jakobsen et al, Nutrients, 2019). Finally, farmed salmon also has antibiotics, often used massively and that can develop antibiotic resistance in some pathogenic organisms for humans (Higuera-Llantén et al, PLoS One, 2018).
Wild and farmed salmon, conclusions
Given all these considerations, the advice of scientists is not to eat farmed salmon more than once a month (Foran et al, J Nutr, 2005). In fact, the benefits would not outweigh the risks. To this is added that there are other sources of omega 3, not contaminated, such as flax seeds and walnuts and, to a lesser extent, dried fruit, such as cashew nuts, and legumes. Another valid alternative is also given by wild salmon, less contaminated than farmed salmon.