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James Cain

Olive oil vs. canola oil

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I've often wondered about the physiological impact of including extra virgin olive oil vs. cold-pressed canola oil in one's diet, assuming both were high quality. It seems the research shows similar metabolic benefits, and for similar reasons--high MUFA and relatively low SFA and PUFA, high antioxidants and bioactive compounds, similar effects on lipids, glucose, inflammation, etc. Canola oil does have more linolenic acid, but also more linoleic acid, but otherwise I can't think of anything glaringly obvious on why one would choose one over the other. Sure, EVOO has a lot of epidemiology, but there seems to be a lot of interventional research suggesting similar effects.

 

Before I spend some time reading more in depth about this, has anyone looked into this before and have thoughts on one vs. the other? I can, and have been, choosing what are likely good sources of EVOO (much thanks to MR for making this easier), but concerns over adulteration and cost have led me to wonder every so often about canola oil as a viable alternative.

 

James

 

P.S., he archives seem to be  down so I can't search. I've heard talk of permanently disabling the email list to move to the forums--is this related? I have used Grep to search through the archive files on my computer but this doesn't seem to work as well as the archives.

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Yes, the forums will soon replace the email lists primarily because hardly anyone participates on the email anymore.  It used to be a hotbed of discussion, but now it is mostly the resting place of Al Pater's constant deluge of mostly irrelevant science postings.  The archives will remain fo as long as it is useful.  So much in science haschanged since 1995 when we started that much of the older material nested there is useless.  There are still quite a few gems to be mined there however and it is great from a histiorical perspective to see the progression of CR science through the past two decades.  Roy Walford thought we would have cracked the aging code by now.

 

Regading canola vs. olive, I use canola for cooking (except for Italian and Greek cooking) and olive for mostly uncooked (salads) and the two aforementioned couisines.  Also, I use very little of each.  A quart of canola will last roughly a year and twice that amount for olive.

 

My diet has changed over the CR years, but that is the subject of a different post which I do not have time to write about right now.

 

Happy New Year everyone, and let's stick to those resolutions this time. :)

 

Bob

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James, and all:

 

I've often wondered about the physiological impact of including extra virgin olive oil vs. cold-pressed canola oil in one's diet, assuming both were high quality. It seems the research shows similar metabolic benefits [... including] similar effects on lipids, glucose, inflammation, etc.

First, let me express my admiration for daring to raise in the health-conscious public the possibility that canola might be anything other than an inherently toxic GMO Frankenfood ;) .

 

I'd agree broadly with those particular metabolic benefits; however, there are some that AFAIK have only been shown in high-phenolic olive oil, such as reduced circulating oxidized LDL (as opposed to reduced ex vivo LDL oxidizability, with which it is too often confused) and elevated free levels of anti-oxLDL antibodies. See many of these studies. I'm not aware of similar findings for canola.

 

[The two oils have] high MUFA and relatively low SFA and PUFA, high antioxidants and bioactive compounds

I was surprised to read from you that even unrefined canola has "high antioxidants and bioactive compounds," as it's been my impression that they're rather low. I did some digging (eventually finding myself in an oddly-familiar rabbit hole ...), and the studies I found indicate that the levels of phenolics in unrefined canola oil vary very wildly -- far more so even than EVOO:

 

http://www.researchgate.net/publication/259537645_Micronutrient_content_of_cold-pressed_hot-pressed_solvent_extracted_and_RBD_canola_oil_implications_for_nutrition_and_quality

 Cold‐pressed Mighty Trio canola oil 2.9±0.7 ppm

Cold‐pressed Highwood Crossing canola oil 3.0±0.2 ppm [This is a brand whose flax oil I used to buy and whose quality and integrity I quite trust -MR]

 

http://www.sciencedirect.com/science/article/pii/S0308814609000351

 124 ± 0.16 ppm

 

http://onlinelibrary.wiley.com/doi/10.1111/j.1745-4522.2007.00107.x/full

13.1 ± 0.4 ppm

 

http://www.sciencedirect.com/science/article/pii/S0889157513000094

 591.7 ± 1.2 ppm phenolic acids (not total phenolic compounds) + 164.1±1.1 ppm flavonoids

 

http://link.springer.com/article/10.1007%2Fs00217-003-0721-4

 This tested unrefined oils of two "canola" varieties: "turnip rapeseed (Brassica rapa) and rapeseed (Brassica napus)". Most of the studies I looked at identified canola as B. napus, but per both the Canada and the Canadian Food Inspection Agency, both of these species are widely grown in Canada and around the world for canola/edible rapeseed oil. This study reported quite high levels for tested samples of both canola species: 730 and 1066 ppm, respectively.

 

http://link.springer.com/article/10.1007/s00217-001-0479-5

 Of "three cold-pressed low erucic acid rapeseed oils [ie, canola] and three virgin olive oils ... The rapeseed oils ...  hydrophilic phenol content was low, only 3–4 ppm. Olive oils contained ... 40–100 times more hydrophilic phenols compared to the rapeseed oils."

 

I don't know what to make of this: from having looked at the EVOO literature, I'd be surprised if methodological differences explained it. If indeed <150 ppm is more typical, I would actually characterize that as a relatively low level of phenolics compared to premium EVOO: certainly even some fresh, good-quality EVOO of some varieties (Arbequina, Chemlali, Chétoui) have levels this low, but as many of these studies show, it's pretty clear that the benefits of EVOO phenolics continue dose-responsively at least as far as 350 ppm (thereafter, it's not clear if there is a plateau or if benefits continue to improve: the graded dose-response studies haven't been done).

 

Moreover, I actually haven't seen any studies showing that there are any benefits to the endogenous phenolics in olive oil: the oil has a quite distinctive profile of phenolic compounds (vinylsyringol and, in smaller amounts, sinapine and sinapic acid), and I don't think we can automatically assume that they deliver the same kind of benefits as the even more-distinctive phenolic compounds that dominate EVOO (secoiridoids). We don't even, AFAIK, really know anything about their pharmacokinetics, let alone their metabolic effects as part of the oil or the dose-response dynamics.

 

The levels of α-tocopherol reported for these unrefined canola oil (100-200 mg/kg) seem fairly similar to those reported for EVOO (100–300 mg/kg), but the  γ-tocopherol levels (≥200 ppm, and as high as 529 ppm in the Koski et al report) are substantially higher.  I get plenty of α-tocopherol myself, though I'd prefer to be getting more γ-tocopherol: my intake is rather low because I don't consume any seed oils.

 

Canola oil does have more linolenic acid, but also more linoleic acid

Canola has a twice as much linoleic as high-oleic EVOO (tho' it's "only" an extra ≈1.3 mg in absolute terms per tablespoon), and tho' Arbequina, Chemlali, Chétoui oils often have lots): this may be less of an issue for you on your (at last check) low- to very-low-fat regimen, and maybe you have a higher target for LA, but at 35% fat I have no room for canola: I'm looking for 12 g, and that's what I get, but I do so using very low-linoleic fat sources (high-oleic EVOO; hazelnuts, which are lower than either; some avocado here and there; a bit of flax — q.v.).

 

I get my linolenic omega-3 with 1.5 tsp flax oil, which provides 3.6 g ALA, 1.0 g LA, and 2.0 mg γ-tocopherol; to get that much ALA, I would need 9 tsp of canola oil, and would be getting 7.5 g LA (yes, and 11 g γ-tocopherol; I don't consider that to be a fair tradeoff). And don't get me started on walnuts ;) .

 

Sure, EVOO has a lot of epidemiology, but there seems to be a lot of interventional research suggesting similar effects.

By "interventional research," I expect you mostly mean the short-term metabolic stuff -- vide supra. The olive oil epidemiology is very powerful, particularly when restricted to Mediterranean countries where the dose is actually adequate to test the hypothesis; moreover, I suspect that it underestimates the actual effect size of a diet enriched with ultra-premium EVOO (high-oleic, high-phenolic, super-fresh), since the epidemiology is (almost?) entirely derived from self-report and will reflect what's on the general market (a substantial amount adulterated, refined, authentic but low-quality, or just old/subtly rancid product, bought in clear bottles, (still almost universal in Europe) and then taken home and left in the light and heat beside the stove), rather than The Good Stuff. (Of course, per contra, there is also the matter of EVOO in these countries being a general marker of adherence to a traditional Med diet).

 

And, of course, there is PREDIMED, which is real interventional research and goes a long way toward validating the value of EVOO but still underrepresents the potential benefit IMO (it was secondary prevention and most people in both arms were receiving strong drug therapy to correct the very metabolic disorders that UP EVOO would help to correct).

 

Before I spend some time reading more in depth about this, has anyone looked into this before and have thoughts on one vs. the other? I can, and have been, choosing what are likely good sources of EVOO (much thanks to MR for making this easier), but concerns over adulteration and cost have led me to wonder every so often about canola oil as a viable alternative.

 

Well, as you say, if you follow my sourcing suggestions you should have no worries about adulteration. I would certainly strongly endorse canola to be the single go-to oil for the general population, but I personally think that if someone is willing to go to the trouble of getting their omega-3 elsewhere, premium EVOO wins hands-down.

 

[P.S., he archives seem to be  down so I can't search. I've heard talk of permanently disabling the email list to move to the forums--is this related? I have used Grep to search through the archive files on my computer but this doesn't seem to work as well as the archives.

This is sort of related, but not in the way you suggest:  we've had a lot of problems with hosting reliability with the Archives and the Listserv itself over the years (including several recent Archive down-periods and people getting automatically unsubscribed for dumb reasons), and once again this time they were down for purely technological reasons outside of our control (and are now back up again). This is, however, just one more of many arguments in favor of migrating from the List to the Forums.

Edited by Michael R

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Michael, much thanks for taking the time to provide such a detailed response! I'm kind of embarrassed as I was looking for a quick reply to give me some ideas to follow up on and maybe a point in the right research direction, and you supplied an exquisitely detailed response (as usual). Knowing well how much time and mental effort this can take, I very much appreciate the legwork (and brain work) you put in here.

 

My thoughts in red:

 

James, and all:
 

First, let me express my admiration for daring to raise in the health-conscious public the possibility that canola might be anything other than an inherently toxic GMO Frankenfood ;) .
 
I'd agree broadly with those particular metabolic benefits; however, there are some that AFAIK have only been shown in high-phenolic olive oil, such as reduced circulating oxidized LDL (as opposed to reduced ex vivo LDL oxidizability, with which it is too often confused) and elevated free levels of anti-oxLDL antibodies. See many of these studies. I'm not aware of similar findings for canola.
 

JC: I'm aware of research showing olive oil with its phenolic compounds removed is mostly neutral or worthless. The fatty acid composition does have some metabolic effect, but it seems that the bioactive compounds are the major contributor in this regard.

I was surprised to read from you that even unrefined canola has "high antioxidants and bioactive compounds," as it's been my impression that they're rather low. I did some digging (eventually finding myself in an oddly-familiar rabbit hole ...), and the studies I found indicate that the levels of phenolics in unrefined canola oil vary very wildly -- far more so even than EVOO:
 
http://www.researchgate.net/publication/259537645_Micronutrient_content_of_cold-pressed_hot-pressed_solvent_extracted_and_RBD_canola_oil_implications_for_nutrition_and_quality
 Cold‐pressed Mighty Trio canola oil 2.9±0.7 ppm
Cold‐pressed Highwood Crossing canola oil 3.0±0.2 ppm [This is a brand whose flax oil I used to buy and whose quality and integrity I quite trust -MR]

http://www.sciencedirect.com/science/article/pii/S0308814609000351
 124 ± 0.16 ppm
 
http://onlinelibrary.wiley.com/doi/10.1111/j.1745-4522.2007.00107.x/full
13.1 ± 0.4 ppm

http://www.sciencedirect.com/science/article/pii/S0889157513000094
 591.7 ± 1.2 ppm phenolic acids (not total phenolic compounds) + 164.1±1.1 ppm flavonoids

http://link.springer.com/article/10.1007%2Fs00217-003-0721-4
 This tested unrefined oils of two "canola" varieties: "turnip rapeseed (Brassica rapa) and rapeseed (Brassica napus)". Most of the studies I looked at identified canola as B. napus, but per both the Canada and the Canadian Food Inspection Agency, both of these species are widely grown in Canada and around the world for canola/edible rapeseed oil. This study reported quite high levels for tested samples of both canola species: 730 and 1066 ppm, respectively.
 
http://link.springer.com/article/10.1007/s00217-001-0479-5
 Of "three cold-pressed low erucic acid rapeseed oils [ie, canola] and three virgin olive oils ... The rapeseed oils ...  hydrophilic phenol content was low, only 3–4 ppm. Olive oils contained ... 40–100 times more hydrophilic phenols compared to the rapeseed oils."
 
I don't know what to make of this: from having looked at the EVOO literature, I'd be surprised if methodological differences explained it. If indeed low level of phenolics compared to premium EVOO: certainly even some fresh, good-quality EVOO of some varieties (Arbequina, Chemlali, Chétoui) have levels this low, but as many of these studies show, it's pretty clear that the benefits of EVOO phenolics continue dose-responsively at least as far as 350 ppm (thereafter, it's not clear if there is a plateau or if benefits continue to improve: the graded dose-response studies haven't been done).
 

JC: Great resources. I read over a few studies some time back but didn't give it a serious effort since I didn't plan on including it in my diet. It seems there's a lot more going on here. This reminds me of the EVOO research showing varying levels of bioactives depending on the source and processing of the oil. I'd say that well-sourced EVOO would be better compared to well-sourced canola oil (if even possible to find). I wouldn't buy a random bottle of canola at the grocery store just as i wouldn't buy a random bottle of EVOO.

 

Moreover, I actually haven't seen any studies showing that there are any benefits to the endogenous phenolics in olive oil: the oil has a quite distinctive profile of phenolic compounds (vinylsyringol and, in smaller amounts, sinapine and sinapic acid), and I don't think we can automatically assume that they deliver the same kind of benefits as the even more-distinctive phenolic compounds that dominate EVOO (secoiridoids). We don't even, AFAIK, really know anything about their pharmacokinetics, let alone their metabolic effects as part of the oil or the dose-response dynamics.
 
The levels of α-tocopherol reported for these unrefined canola oil (100-200 mg/kg) seem fairly similar to those reported for EVOO (100–300 mg/kg), but the  γ-tocopherol levels (≥200 ppm, and as high as 529 ppm in the Koski et al report) are substantially higher.  I get plenty of α-tocopherol myself, though I'd prefer to be getting more γ-tocopherol: my intake is rather low because I don't consume any seed oils.

 

JC: Agreed. I hadn't checked the isoforms and this is good to know.
 
Canola has a twice as much linoleic as high-oleic EVOO (tho' it's "only" an extra ≈1.3 mg in absolute terms per tablespoon), and tho' Arbequina, Chemlali, Chétoui oils often have lots): this may be less of an issue for you on your (at last check) low- to very-low-fat regimen, and maybe you have a higher target for LA, but at 35% fat I have no room for canola: I'm looking for 12 g, and that's what I get, but I do so using very low-linoleic fat sources (high-oleic EVOO; hazelnuts, which are lower than either; some avocado here and there; a bit of flax — q.v.).

 

JC: I do eat a vegan diet, and I enjoy eating a fairly low-fat diet (at times very-low-fat) both for the types and amounts of carbs I can eat, but if I'm more active or stressed I find the level of hunger very annoying. Low-fat as I prefer usually means a lot more volume, and this sometimes doesn't agree with my digestive comfort. I otherwise have a great response to low-fat diets with regards to energy, mood, and general well-being. I've been experimenting with various dietary changes including changing the forms and/or amounts of dietary fats to balance the downsides mentioned above, and I do enjoy olive oil. My curiosity spurred me question EVOO alternatives mostly out of a thought experiment (as I can source and afford good EVOO).
 
I get my linolenic omega-3 with 1.5 tsp flax oil, which provides 3.6 g ALA, 1.0 g LA, and 2.0 mg γ-tocopherol; to get that much ALA, I would need 9 tsp of canola oil, and would be getting 7.5 g LA (yes, and 11 g γ-tocopherol; I don't consider that to be a fair tradeoff). And don't get me started on walnuts ;) .

 

JC: I include 10-20 g/d ground flaxseed for ALA. I've considered switching to flax oil out of concerns over lignans/phytoestrogens, especially given your thoughts on the potential for long-term soy consumption to increase dementia (especially since I'm ApoE 4/4), but I otherwise have no negative response to this much ground flaxseed. One of my major concerns with a proper low-fat diet is getting adequate vitamin E, which I would usually get from EVOO and almonds.
 
By "interventional research," I expect you mostly mean the short-term metabolic stuff -- vide supra. The olive oil epidemiology is very powerful, particularly when restricted to Mediterranean countries where the dose is actually adequate to test the hypothesis; moreover, I suspect that it underestimates the actual effect size of a diet enriched with ultra-premium EVOO (high-oleic, high-phenolic, super-fresh), since the epidemiology is (almost?) entirely derived from self-report and will reflect what's on the general market (a substantial amount adulterated, refined, authentic but low-quality, or just old/subtly rancid product, bought in clear bottles, (still almost universal in Europe) and then taken home and left in the light and heat beside the stove), rather than The Good Stuff. (Of course, per contra, there is also the matter of EVOO in these countries being a general marker of adherence to a traditional Med diet).
 
And, of course, there is PREDIMED, which is real interventional research and goes a long way toward validating the value of EVOO but still underrepresents the potential benefit IMO (it was secondary prevention and most people in both arms were receiving strong drug therapy to correct the very metabolic disorders that UP EVOO would help to correct).
 
 
Well, as you say, if you follow my sourcing suggestions you should have no worries about adulteration. I would certainly strongly endorse canola to be the single go-to oil for the general population, but I personally think that if someone is willing to go to the trouble of getting their omega-3 elsewhere, premium EVOO wins hands-down.

 

JC: Agreed, and I'm glad I now have more info to reinforce my own conclusions.

This is sort of related, but not in the way you suggest:  we've had a lot of problems with hosting reliability with the Archives and the Listserv itself over the years (including several recent Archive down-periods and people getting automatically unsubscribed for dumb reasons), and once again this time they were down for purely technological reasons outside of our control (and are now back up again). This is, however, just one more of many arguments in favor of migrating from the List to the Forums.

 

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