It’s common knowledge among nutrition nerds that Omega-3 fats, such as those from fatty fish, are healthy, and that Omega-6 fats, such as those in processed vegetable oils, are unhealthy. In other words, a high Omega-3 to Omega-6 ratio is good and a low Omega-3 to Omega-6 ratio is bad. Unfortunately, our modern food environment has pushed most of our Omega-3 to Omega-6 ratios down 10 to 20 times lower than what’s considered ideal, potentially contributing to the development of chronic inflammation and disease.
But two big questions remain. (1) Does a low Omega-3 to Omega-6 ratio actually contribute to chronic disease or is this simply a “correlation without causation?” After all, in order to alter your Omega-3 to Omega-6 ratio, you must eat different foods, and it is possible that other compounds in these different foods contribute to disease, rather than the Omega fat ratio itself. (2) Even if a low Omega-3 to Omega-6 ratio does cause inflammation and disease, how does it do so?
A brand-new Harvard study published in the top journal Nature Communications Biology sheds light on both these questions. In this study, the scientists genetically engineered mice using genes taken from worms so that the mice could make Omega-3 and/or Omega-6 fats within their own bodies. What this means is that the mice could eat the exact same diets and end up with different Omega-3 to Omega-6 ratios, thus eliminating the confounding variable of different diets (question 1 above). The scientists then did a complex set of analyses, called “a multi omic analysis” that allowed them to examine and disentangle the relationships among the mutant mice’s genetics, microbiomes, and metabolites (question 2 above).
This powerful and comprehensive study produced a library of results, but the quick and dirty is this: The mice with the low Omega-3 to Omega-6 ratio were fatter, had a negative change in their microbial ecosystems, i.e. their “gut bugs,” and got more diseases, including cancer. These and other data presented in this paper suggest a model in which a low Omega-3 to Omega-6 ratio (which is the same as a high Omega-6 to Omega-3 ratio, as shown in the paper’s culminating figure) cause a distinct set of changes that are directly linked to damaging inflammation and contribute to chronic diseases, like obesity and cancer.
So how does this relate to you? Indirectly, this study advises that you remain conscious of your Omega-3 to Omega-6 ratio. Try to eat more Omega-3-rich foods like salmon, mackerel, anchovies, sardines, herring, flaxseeds, pastured eggs, and even grass-fed and grass-finished meat, and try to avoid Omega-6-rich foods, particularly processed vegetable oils like soybean sunflower and corn oils, as well as low quality grain-fed poultry and meat. You don’t need to go crazy or be obsessive, but it’s always best to be informed. Thank you, Omega mice!
The study can be found here: https://www.nature.com/articles/s42003-019-0521-4.pdf