In last week’s Dear Mark  I took up a reader question about trans fats . While we’re on the fat subject, I figured it was a good time to keep the conversation going and cover an email I got last week about polyunsaturated fatty acids (PUFAs). Thanks to Brent for this one.
I loved your posts on trans fats last week, but now you have me wondering about all the other truths I know but can’t explain. How about polyunsaturated fat? When I was reading the Definitive Guide to Oils , I was having a rough time remembering exactly why PUFAs aren’t recommended. Can you jog my memory, Mark?
Let me take this one apart – separate out the good PUFA from the bad from the downright ugly. We’re talking everything from grains to nuts, corn and canola oil to fish oil. When it comes to PUFAs, it truly is a mixed bag.
What Are They?
Chemically speaking, polyunsaturated fats have more than one (hence the “poly”) double bond in their carbon chain. They’re further determined by the position of these double bonds in relation to the end of the molecule. For example, omega-3s sport a double bond three “links” down from the “methyl” end of the molecule.
These double-bonded carbon links are in essence missing their hydrogen atoms. (As you recall, if all the links have their hydrogen, you’re looking at a fully saturated fat .) Because they’ve got multiple “incomplete” double bonds to their name, polyunsaturated fats are, as a class, chemically unstable and prone to oxidation.
What Do They Do?
PUFAs can be a real Jekyll and Hyde. On the one hand, PUFAs include the essential fatty acids, including our favorite omega-3s . But when oxidation comes into play, we’re looking at a whole different animal. Heating in particular sets a bad course in motion , but simply exposure to air, light and even moisture can incite the process. We’re now looking at lipid peroxides, which initiate a free radical free-for-all. The free radicals make their way through the body pillaging at every turn. Their damage takes a toll on everything from cell membranes, to DNA/RNA strands, to blood vessels (which can then lead to plaque accumulation). The harm adds up over time in the organs and systems of the body and can cause significant impact, including premature aging and skin disease , liver damage , immune dysfunction, and even cancer .
What’s a Good Primal Type To Do?
Grok – and even Grandma – got their fat intake mostly in saturated forms. (Who among us doesn’t love butter , lard, tallow , and the like?) These days, we drown ourselves in PUFAs with all the vegetable oils (typically corn, canola, soybean, sunflower and safflower) we use. It’s a completely unnecessary response to the saturated fat scare that CW  has drummed up over the last several decades. Those clowns that think Canola oil , no matter how rancid it’s gotten sitting in a hot warehouse for 10 months, is somehow still preferable to Grandma’s fresh rendered lard.
On the other side of the spectrum, some strict paleo followers, for example, choose to forgo nuts and seeds and their oils. I agree that avoiding PUFAs in general is a good rule of thumb, but I straddle the line – with a little extra time and care – in order to take advantage of what I deem valuable nutrient (PUFA) sources.
I like my nut butter  (which I make myself) and occasional seeds  for my salads. I buy them raw and as fresh as possible from sources I research. I’m a stickler for proper storage. Opaque containers. Refrigeration. Although I enjoy some nut oils on salads or other dishes now and then, I rarely buy them because I don’t want the remainder going bad in my frig. (Besides, I’d rather eat the whole foods in most cases than bother with a lineup of oils  that had to go through at least some processing. I keep a couple good bottles of great quality cold-pressed olive oil (which, as you’ll remember, is mostly monounsaturated anyway) around and use them up quickly. Look for the darkest bottles you can find. Dated products are even better.
As for fish oil , I use and suggest the same basic principles. Buy the freshest products you can find. Buying direct from a reputable manufacturer offers the advantage of minimizing storage and transport time/scenarios. Some research suggests that taking fish oil with vitamin E reduces oxidation within the body. Refrigerate fish oil supplements to prolong freshness, but use them up in a timely manner.
Finally, I make sure my diet is chock-full of antioxidants (including vitamin E) and minerals to counter any oxidative stress from PUFAs or any other source. As careful as I try to be with PUFAs, there’s nothing wrong with a little extra insurance.
Now it’s your turn. Let me know your take – and intake (or not) – of PUFAs. Thanks as always for the questions and comments, and keep ‘em coming!