Polyunsaturated fat oxidation page

[Stabby]

So we all know that when polyunsaturated oils like canola and soybean are heated they go from fairly poisonous to super-ultra death oil due to the oxidation of the polyunsaturated fats; that's a given. But then that begs the question that if oils oxidize so easily when heated, wouldn't nuts and seeds that contain huge amounts of polyunsaturated fats also be terribly unhealthy when cooked? That would mean roasted, baked into bread, used in a frying pan, etc. I believe this to be the case because before I went primal I was into the granola-and-nut-soy-munching hippie stuff and had bad acne from all of the insulin and inflammation. Roasted nuts would undoubteably cause harsh and inflammed pimples just the same as heated vegetable oil. Just my anecdotal observations.


So if this is true, aside from the fact that they're eating bread, all of this flaxseed bread that people are buying is ironically undermining their efforts at eating healthier. But then again I suppose that's the case with a lot of CW.

[Steve-O]

"wouldn't nuts and seeds that contain huge amounts of polyunsaturated fats also be terribly unhealthy when cooked?"


Yes. High heat applied to any type of fat causes oxidation. Obviously deep frying foods in PUFA is the worst extreme.


What you have to weigh is the benefits vs. the costs.


Baking a piece of wild salmon will result in some of the fat to oxidize, but not enough so that it outweighs the benefits of eating it.


The costs of eating deep-fried breaded mozzarella every day definitely outweigh any benefit it may provide.

[MELANIE]

does that mean you shouldnt cook with almond meal or heat olive oil or coconut oil?

[Steve-O]

Again, it's not all or nothing. Some increased oxidation is going to be a fact with any cooking. That doesn't mean all the benefits are stripped from those foods.


Unfortunately, I don't have a fat oxidation chart to measure the amount of oxidation that occurs to different fats in different foods exposed to different temperatures for specific periods of time.


Not sure one exists. Science project, anyone?

[Stabby]

Ooer! That would be helpful.


Without any actual empirical measurements I would assume that PUFA content vs antioxidant content would be a decent marker. Saturated fat content would most definitely be a factor too (the small amount of PUFA get protected in coconut oil).

[ani]

I've been recently wondering about this as well. I used to bake with flaxseed and almond meal but I've recently stopped realizing I was just putting into my body the same substances I try so hard to avoid. I even (mostly) stopped eating any nut that has been roasted due to fear of oxidation. Am I right in doing this?

[grokka]

I've been recently wondering about this as well. I used to bake with flaxseed and almond meal but I've recently stopped realizing I was just putting into my body the same substances I try so hard to avoid. I even (mostly) stopped eating any nut that has been roasted due to fear of oxidation. Am I right in doing this?

I'd guess that the cell walls would protect most of the fats from being oxidized in the whole nut, but not so when ground up. That being said, I'd still avoid most nuts because they won't be protected in your body!

[Stabby]

Whoa, old thread. Nuts do offer some protection, definitely more than would be found in oils, but the best policy is to just not eat anything high in PUFAs in any significant quantity, cooked or raw.

[rayout]

does that mean you shouldnt cook with almond meal or heat olive oil or coconut oil?

Olive oil is pretty high in poly unsaturated fat (around 20%) so I would not cook with it.

Coconut oil is around 1.6% poly unsaturated fat. Ghee and beef tallow is around the 3% range. These are your best options.

Lard is around 10%

As far as taste goes I am looking for a good source of duck fat and that is in the 12% range from what I could find on google. It's so good....

[peril]

Don't have references, but I believe that whole food sources of PUFA are more stable than extracted forms (ie oils and flours). Also, combining them with significant amounts of SFA helps to stabilise them. Safest thing, especially if you are treating diseases of inflammation, is to eat whole, raw nuts and seeds in moderation and avoid their oils and flours. Eat fish and brains rather than take fish oil