What are your thoughts on Barry’s suggestion that there is some sort of problem in cooking O-3 enhanced eggs? I’ve seen similar things related to flax seed oil and roasted & toasted walnuts, etc. What is the bottom line on cooking with omega-3s?
Polyunsaturated fats (which include omega-3 fatty acids) are, indeed, very prone to oxidation when exposed to heat, light or oxygen. This oxidation essentially renders them rancid to some extent, and this will result in less appealing taste (and smell) as well as decreased nutritional value. Add to that the damage imposed by the resulting free radicals, and that “healthy” food has now become a health hazard.
I would never use a polyunsaturated oil for cooking, and I don’t recommend eating roasted nuts because of the oxidation risk. Polyunsaturated oils, like flaxseed oil, should be properly stored (refrigerator or freezer) and added to cold food (like my daily salad) or cooked food only after reasonable cooling. Additionally, I recommend buying polyunsaturated oils, for example, in opaque or dark bottles and using them quickly.
As to the question that came up last week about cooking foods with omega-3 content like fish or enriched eggs, the answer is more complicated. Most research on omega oxidation has been done with straight oils themselves rather than whole foods (e.g. fish oil versus fish fillet). One interesting study showed the bulk of omega-3s were lost when fish oils were heated to 150 degrees Fahrenheit for 30 minutes (only 15.9% of DHA and 18.5% of EPA retained); however, that oxidation was slashed when rosemary or oregano extracts were added to the oils (65.9% of DHA and 69% of EPA retained). Both herbs significantly decreased oxidation, but rosemary proved more effective than oregano.
And this strategy has applications beyond our own kitchens. Egg farmers who enrich their hens’ diets with omega-3 fatty acids are using the herbal principle to reduce oxidation in high omega-3 eggs. (Note about the study (PDF): the authors are Greek and the English is a bit garbled in sections, but the research itself is compelling.) This particular study observed the effects of herbal (as well as vitamin and mineral) supplementation in chicken feed and the eggs’ relative susceptibility toward oxidation. (By the way, this same study showed that chickens fed flax meal produced eggs that were high in both ALA and DHA. The digestion of the feed apparently allowed for the synthesis.) So, when it comes to cooking an enriched egg? Well, I guess it depends on the exact feed. In this case, the more you know about the farm, the better you can judge. If you get plenty of omega-3s from good supplements, as I suggested last week, choosing high omega-3 eggs aren’t a necessity. Nonetheless, it’s still useful to know what kind of feed your food is getting.
One last note on reducing oxidation… Anti-oxidants like mixed tocopherols (Vitamin E) appear to reduce oxidation of omega-3s, and companies are increasingly incorporating Vitamin E in omega-3 rich (or enriched) products. Other synthetic additives apparently do the same, but I’d have less faith in their relative safety.
My bottom line? Know your eggs. Eat your herbs. As for cooking itself? Let’s just say that I’m not about to give up grilled salmon, but I’m going to make sure I don’t cook it any more than I have to. And I’ll also be sure to have a nice big salad on the side.
Thanks for your comments, and look for more on best cooking practices later this week. In the meantime, keep your questions coming!
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