I mentioned previously that I'm becoming more skeptical of vegetable oils. Specifically industrial seed oils. Things like soybean (one of the more significant oils used in food processing), corn oils, sunflower, etc. More specifically these oils are referred to as polyunsaturated fatty acids (PUFA) and depending on the type of fatty acid they can be further classified as n-3 (Omega 3 acids) or n-6 (Omega 6 acids). Typically oils have both types of acids but the prevalent one is sometimes used to describe a particular oil. We'll avoid that laziness.
Science lesson: What is an Omega 3/Omega 6 fatty acid?
Fatty Acids - generally a linear chain of carbon atoms with hydrogen atoms attached to the carbon atoms and on one end a carboxyl group which is (COOH). It looks like this, where R is the carbon chain and can be of various lengths.
Saturated fatty acids - Saturated here refers to the R part of the chain. If the connected carbon atoms have single bonds with each other that leaves 2 spots for hydrogen to attach (- CH2 - CH2 - CH2 -). The molecule is therefore "saturated with hydrogen".
Unsaturated fatty acids - The connected carbon atoms have one or more double or triple bonds which means there are less spots for hydrogen to attach. Monounsaturated means there is ONE double bond. Polyunsaturated means there are MORE THAN ONE double bonds.
Omega-3 fatty acids - These are unsaturated fatty acids. Therefore it has double or triple bond. Omega 3 acids have a double bond in the n-3 postion or the 3rd carbon atom in from the non-carboxyl end (the CH3 end). There may be additional double bonds farther up the chain depending on how long the carbon chains is. These dietary fats are mainly found in seafood, some seeds (flax and walnuts), and to a lesser extent in meats, vegetables and diary.
Omega 3 fatty acids - these acids therefore have a double bond on the 6th carbon atom from the non-carboyxl end. These dietary fats are found in industrial oils (corn, soybean, sunflower, cottonseed, etc.)
In general industrial processed seed oils are high in omega 6 acids. And as food has become more processed we've been ingesting more and more of these types of oils.
This USDA PDF states that polyunsaturated fatty acid intake (omega-3 & -6) increased form 13 grams in 1909-19 to 37 grams in 2004 and went from 11% of our total fat intake in 1909-1919 to 21% in 2004.
That PDF also has some PUFA consumption data that I plotted to just check on the graph above. Looks similar.
Also cited are research articles showing associations between omega-6 and diseases.
This research is cited as showing that omega-6 is associated with inflammatory diseases It does nothing of the sort. What it does is look at various countries and their dietary n-3 intake and compare against coronary heart disease mortality, stroke mortality, cardiovascular disease mortality, total mortality, homicide mortality, postpartum depression, major depression, and bipolar disorder. And it shows that the higher the intake of omega-3 the low incidence of these diseases. In particular Iceland and Japan showed low incidence of most of these diseases (presumably they eat a lot of fish, high in omega-3). It doesn't directly focus on omega-6 fatty acids but infers higher omega-3 consumption will lead to lower omega-6 consumption. Possibly.
Also cite is this god awful page from the NIH. The key chart is this one. That's as big as the chart is. To be honest I'm not entirely sure what we are looking at. Y-axis is CHD mortality. Fine. X-axis is Perent Long 6 in total long. I'm guessing this means the percent of PUFAs in various countries diets that are omega-6. But frankly I'm not sure. It could mean the omega-6 in the blood at time of death. Not sure. The text is as bad as the web design.
What I really hate about this chart though is it has an R^2 of 95% meaning it's amazingly predictive. Man nothing is ever this predictive in science. I'm wondering if the data was cherry picked or something. It has happened before.
Another article with a bizarrely similar but different chart suggests these measurements are of highly unsaturated omega-6 fatty acids (HUFA) in cell tissue. And the measurement in the cell tissue is a good measure of the fatty acids in the diet.
There are also research articles that supposedly look at the n-6 to n-3 ratios and how these protect against heart degenerative diseases. But I can't get a hold of that one either. And the abstract really just recommends eating more Omega-3. In fact there are lots of links to research articles that are either not accessible, don't show what the author claims, or even are completely unrelated at all to what the author says.
So what can I say? Not much. Until the research focuses a little more on a holistic view of omega-6 and omega-3 then I'm not quite convinced.
Meanwhile if you want to avoid high Omega-6 oils these would be safflower, sunflower, corn, cottonseed, walnut, and soybean oils. Basically any oil where you say to yourself, "how the hell did they get oil out of that plant?". Coconut oil (my oil of preference) and flaxseed oil are the only plant oils I'll use. And yes coconut oil is completely saturated. And that's exactly why it is my oil of choice. Because saturated fat is good for you. But that's another post.