Omega 6 poly-unsaturated fatty acids are contained primarily in vegetable oils, such as sunflower, safflower, canola, soybean oil, etc.
They are predominantly used in processed foods and fried foods.
I’ve written extensively about the dangers of such vegetable oils in the past, and how they are a primary cause of atherosclerosis (a leading factor in heart disease), as well as neurodegenerative diseases such as Alzheimer’s, Parkinson’s, Multiple Sclerosis, and others.
Consumption of high quantities of Omega 6 is a relatively new phenomenon in human history: Omega 6 doesn’t exist in nature, it only appeared on the scene when we started to heavily process foods and extract oils such as those mentioned above.
All forms of fat that exist in nature (from fish, olive oil, avocados, walnuts, dairy, etc) are high in either Omega 3, MUFA (mono-unsaturated fatty acids), or saturated fatty acids.
This study published in the European Journal of Clinical Nutrition raises yet another concern: the impact of Omega 6 consumed by the mother on her children.
What the study revealed is that the Omega 6 consumed by the other ends up in her breast milk, which in turn impacts the health of the children all the way to the age of 5 years old!
The study revealed that the ratio of Omega 3 to Omega 6 had an impact on the amount of fat the child gains at ages 2, 3, 4 and 5. The more Omega 3 (less Omega 6) consumed, the more muscle and less fat the child carries. When Omega 6 is high, the reverse happens.
In conclusion: for your own health (cardiovascular, inflammation, etc) as well as the health of your children, it’s highly advisable to avoid overconsumption of Omega 6 foods (vegetable oils for example) and increase your consumption of high quality Omega 3 (sardines, salmon).
And remember: if you’re using an Omega 3 supplement, you have to make sure it’s of high quality, otherwise it will have the reverse effect on your health. If it smells "fishy" or your breath smells "fishy" after taking it, then it's gone rancid. Throw it away and make sure you purchase a new one that's not exposed to heat in the store and that's been cold processed.