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The True Shelf Life of Cooking Oils

Cooking oil manufacturer “best-by” dates are put to the test by comparing the development of rancidity between almond oil, avocado oil, hazelnut oil, macadamia oil, grape seed oil, rice bran oil, toasted sesame oil, and walnut oil. Find out which oil starts going rancid within just a few weeks in my video pick for the day, above.

The best way to keep and consume walnut oil is, of course, within the walnut itself. In my Care2 video What Should Women Eat to Live Longest? I noted that the Harvard Nurses Health Study found that eating just two handfuls of nuts per week may extend a woman’s lifespan as much as four hours of weekly jogging.

Which kinds of walnuts are best, though? Black walnuts or English—also known as common—walnuts? I would have guessed black just based on their rich flavor and color, but I would have been wrong. In a study I profile in my 2-min. video Black Versus English Walnuts, when subjects were given a salami and cheese sandwich on white bread smeared with 2 spoonfuls of butter and then a big handful of either black or English walnuts, something very different happened.

When we whack our arteries with that kind of load of saturated animal fat, within hours our blood vessels become inflamed and stiff. Eating English—but not black—walnuts with the salami sandwich appeared to diminish the damage, which perhaps relates to the finding that English walnuts have nearly 10 times the antioxidant capacity of black walnuts.

The anti-inflammatory power of certain nuts is really quite astonishing. See my 2-min. video Fighting Inflammation in a Nutshell and my Care2 post Dietary Treatment for Crohn’s Disease for other anti-inflammatory foods.

I explore why meat and dairy tend to be so inflammatory in my three part video series The Leaky Gut Theory of Why Animal Products Cause Inflammation, The Exogenous Endotoxin Theory, and Dead Meat Bacteria Endotoxemia. I also give an abbreviated summary of it in my full-length “live” presentation Uprooting the Leading Causes of Death.

If you haven’t yet, you can subscribe to my videos for free by clicking here.

In health,
Michael Greger, M.D.

Image credit: @kevinv033 / Flickr

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Read more: Diet & Nutrition, Eating for Health, Food, Health, Heart & Vascular Disease, Uncategorized, Videos, , , ,

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Dr. Michael Greger

A founding member of the American College of Lifestyle Medicine, Michael Greger, M.D., is a physician, author, and internationally recognized speaker on nutrition, food safety, and public health issues. Currently Dr. Greger serves as the Director of Public Health and Animal Agriculture at The Humane Society of the United States. Hundreds of his nutrition videos are freely available at


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4:23AM PST on Mar 9, 2013

Thank you :)

1:55PM PDT on Aug 22, 2012

i do keep all my oils in the fridge, using many of these for homemade skin care as well as culinary (except olive oil, which i use quickly enough)
good to know about English versus Black walnuts though...but which ones am i consuming?
Here in france they don't discern the type....

11:55AM PDT on Aug 22, 2012

I use extra virgin olive oil...but i am delighted to know that it is correct to keep it in the dark, cold refrigerator. It does take a short time to unsolidify.

11:27PM PDT on Aug 19, 2012


2:53PM PDT on Aug 19, 2012

I would like to know about Olive oil, canola oil, and vegetable oil. Are these supposed to be kept in the fridge also? And how long before they go rancid? Most ordianry people don't use the oils in the video.

5:22AM PDT on Aug 19, 2012

This would be considerably more helpful if it were oils we used every day!

2:23AM PDT on Aug 19, 2012

Thanks for sharing.

11:45PM PDT on Aug 18, 2012

Yes,making your salad dressing with cold pressed organic flaxseed oil will give you a good ratio of omega3- omega 6 levels to keep your cells in good form.

11:07PM PDT on Aug 18, 2012

Never heard of most of these, period. I'll stick to extra virgin olive oil, thank you.

10:58PM PDT on Aug 18, 2012

I think, that all info about oils is important, thanks for this also.

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