TheVeganAtheist wrote:
Could you please provide source for this, as I was under the impression that grapeseed oil was one of the healthier oils, especially for frying. Im not sure where I got that impression, as Ive been using it for a few years. Doing a quick search on google Ive found a few pages (not sure if they are reputable) that suggest that grapeseed oil is one of the most healthy.
The grapeseed oil fad is mostly riding on the coat tails of some of the known benefits of other grape compounds, and some clever marketer took advantage of that association. Grapes are healthy, right? Grapeseed oil must be too.
The problem is, grapeseed oil is just oil; it hardly contains any trace of those "good" substances from the grapes.
Health claims abound. I have not found any to be substantiated.\
Regarding use for frying, there are two elements to cooking oil.
You may be thinking about the smoke point:
http://en.wikipedia.org/wiki/Smoke_point
In cooking, the smoke point of an oil or fat is the temperature at which, under defined conditions, enough volatile compounds emerge from the oil that a bluish smoke becomes clearly visible. At this temperature, volatile compounds, such as water, free fatty acids, and short-chain degradation products of oxidation come up from the oil. The smoke point is not the temperature at which the oil is decomposed and where possibly toxicological relevant compounds are formed.
Grapeseed oil's smoke point is about 216°C, which is pretty respectable (better than virgin olive oil or coconut oil, but not as good as refined coconut oil).
Smoke point is mostly what chefs worry about. And in that sense, Grape seed oil is quite useful (particularly as it's flavorless). But while this may be relevant to a chef, allowing them to cook things at a higher temperature (thus faster, and maybe crispier), it's largely irrelevant to nutrition (just don't heat beyond the smoke point, and use a vent hood when frying at higher temperatures).
From a nutritional standpoint, you want a stable oil which will not become carcinogenic with exposure to heat and oxygen, and one with a good fatty acid profile.
Note the fatty acid composition of grapeseed oil:
http://en.wikipedia.org/wiki/Grapeseed_oil
It's one of the worst there is. Just based on the obvious numbers on the tin, we should be avoiding it for nutritional reasons because it will screw with your overall omega 3:6 ratio.
I haven't looked into every additional health claim surrounding grape seed oil in detail, but I don't think they are credible relative to other superior oils.
It would be wise to be dubious of these (in the same sense that wine health claims are dubious).
Grapes contain a lot of great substances- grape seed oil does not contain any of these in appreciable amounts.
Grapeseed oil does contain Phytosterols, which lower LDL cholesterol.
http://en.wikipedia.org/wiki/Phytosterol
And that's all well and good, but:
Phytosterol-enriched foods and dietary supplements have been marketed for decades. Despite well documented LDL cholesterol lowering effects, no scientifically proven evidence of any beneficial effect on cardiovascular disease (CVD) or overall mortality exists.[2]
So it probably doesn't matter, while the deleterious effects of the Omega-6 overdose and the carcinogens in the oil are more established ills that do seem more to correspond to heart disease, and overall mortality.
And grapeseed oil doesn't even contain very much Phytosterols. I'm having trouble finding a single site with number on this, but from what I've found:
Grapeseed oil:
__24 mg/tablespoon
Olive oil:
________22mg/tablespoon.
Canola oil:
______92mg/tablespoon.
(please correct me if you can find good number on this)
Is that worth the difference in nutrition?
No. First off, it's not worth it because it's not proven it does anything at all. But even more so, because it's not substantially more concentrated in grape seed oil than in other oils- and
Canola oil is even better.
For a frying oil, though, out of the three, olive oil is the most viable choice due to stability differences (at a molecular level, not smoke point).
If you want olive oil with a higher smoke point, you can find in more processed forms (but I don't recommend those).
Is frying with grapeseed or canola oil going to kill you? No, probably not. There is unfortunately not a lot of solid research on oil oxidation, or on the effects of oxidized oils on the body. Still, I recommend avoiding high heat on polyunsaturated fats particularly, because we do know they are less stable, and that the compounds produced are bad for us.
Note in the wikipedia article on grapeseed oil:
Grapeseed oil has sometimes been found to contain dangerous levels of polycyclic aromatic hydrocarbons because of direct contact with combustion gases during the drying process.[8]
PAHs are some of the nasty carcinogens I was talking about that form from unstable polyunsaturated fatty acids when they're exposed to heat- in this case, quite high heat from processing. It is the inherent instability of the oil that lends itself to this happening so easily.
There are some people who claim that even olive oil (monounsaturated) is bad to cook with, and recommend cooking exclusively with saturated oils (like coconut) because saturated fats are the most heat stable. I won't go that far, and I think that's a little counterproductive given the apparent health differences between monounsaturated fats and saturated fats.
Here's an article arguing against that, which incidentally has a great list of facts about what happens to oils under heat, and the relative stability.
http://scienceornot.net/2012/09/15/is-i ... olive-oil/
- Vegetable oils oxidise as they age and are exposed to air and light. This process is accelerated when they are heated (here, here).
- Some of the oxidation products are toxic (here, here, here and here), but (here) we have good natural defences against such substances.
- The ease of oxidation of an oil is influenced by its degree of unsaturation. Polyunsaturated oils oxidise more easily than saturated oils (here).
- Corn oil and sunflower oil contain high proportions of polyunsaturated oils; they oxidise easily. Coconut oil is high in saturated oils; it doesn’t oxidise easily.
- Olive oil contains a high proportion of monounsaturated oil. It oxidises less easily than polyunsaturated oils (here, here).
- Virgin and extra-virgin olive oils also contain antioxidants which help resist oxidation as the oil is heated (here, here and here). Several studies have shown that virgin olive oil produces fewer oxidation products than polyunsaturated oils when heated (here, here)
- If an oil is heated beyond its smoke point, it gives off toxic smoke. The smoke point of olive oil is around 200°C. Some refined oils, such as palm, peanut, safflower and soybean oils can have smoke points around 230°C to 260°C, but unrefined oils can have smoke points in the low hundreds.
- I could find no studies showing evidence of damage to the health of humans resulting from oxidation products of cooking oils.
(Check the article itself for linked references)
How harmful are the oxidation products of polyunsaturated oils?
I don't know.
But there's no good nutritional reason to fry with them, particularly when we're talking about an oil with a gross excess of Omega-6 fats and no apparent health benefits when sized up among its more healthy peers.
TheVeganAtheist wrote:
Also, you mentioned that coconut oil is an option, yet I just finished watching a Dr. Michael Gregor video in which he states that coconut oil is one of the worst for frying.
I'd love to see the video.
Can you find a link?
I don't generally recommend coconut oil, because it's a saturated fat, but the evidence seems to indicate that it is more heat stable because of that (in its refined form, at least).
Although, I also don't generally recommend frying anyway.