Food Babies

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All About Oil

Posted by Hilary on April 16, 2010

I got a couple of questions from my mom today, so I set off to do some research. Topic one: what’s a healthy oil, especially for high-heat cooking?

Oil is categorized in a number of different ways, so I’ll try to address some major points.

First, it is important to consider the type of fat each oil is composed of. We want to have the least amount of saturated fat, which raises total blood cholesterol and LDL (“bad”) cholesterol. We also want the least amount of trans fat, which raises LDL cholesterol and lowers HDL (“good”) cholesterol. What we do want is monounsaturated fat, which lowers total and LDL cholesterol and raises HDL cholesterol, and polyunsaturated fat, which also lower total and LDL cholesterol.

Next, consider that oil is either pressed or chemically extracted. Oils that come from soft fruits or nuts (e.g. olive, walnut, avocado) only require pressing. You’ll notice that these are often labeled as “cold pressed”. Some oilseeds are harder and cannot be cold-pressed (e.g. soy, canola). These are pretreated via a non-toxic process (like steaming) before pressing. Other oils are extracted with toxic chemical solvents, including hexane (scary chemical of the week!), and undergo very high heat processing.

Moving on, unrefined oils are filtered minimally, removing only large particles. They may look cloudy or have sediment that settles. Unrefined oils are thought to have greater nutritional value than refined oils. Refined oils are filtered and strained to a greater degree, often using additional heat. This type of processing is reported to reduce both nutritional value and flavor. The only pros of refined oils are a longer shelf life and a higher smoke point (for high-heat cooking).

For high heat cooking, the most important thing to know about an oil is its smoke point. You absolutely do not want to cook an oil hotter than that point, as the oil can destabilize and become not only gross tasting, but carcinogenic.

I typically keep 3 oils on hand, extra virgin olive oil (smoke point 406 F, but 320 F for unrefined), expeller pressed canola oil (smoke point: 225 F unrefined, 400 F refined), and sesame oil (smoke point 350 F unrefined, 410 refined). However, after the topic of coconut oil was brought up to me, I wanted to check out some alternatives.

Several oils are now being touted by various groups as “the healthiest oil”:

1. Coconut oil (Smoke point: 350 F)

This one proves to be pretty controversial. There are strong naturopath advocates, and websites chock full of glowing testimonials. Commenters on various websites are claiming that is cures everything from Alzheimer’s to Autism (uh, really folks?)! Coconut oil truly does contain lauric acid, which is a disease-fighting fatty acid found in breastmilk. Researchers on this side claim that coconut oil stimulates the thyroid (and is thus a good natural treatment for hypothyroid), which leads to lowered cholesterol. There are also claims of weight loss effects, anti-cancer effects, and antimicrobial effects.

But, here’s what the detractors say: One fact that is not contested is that coconut oil is very high in saturated fat (one source said 92% s. fat). In fact, coconut oil is one of the few plant-based sources of saturated fat. This is a hard stumbling block to get over. Click here for a 2003 SPC document summarizing research on coconut oil; pp. 12-14 specifically address links to cholesterol and heart disease.

From the linked document: “Overall, there is strong evidence to show that the main types of saturated fatty acid found in coconut (and in most foods rich in saturates) are effective at raising blood cholesterol levels and so increase the risk of developing heart disease. The individual effects of different fatty acids needs further research.” The research cited suggests that coconut oil raises all cholesterol, good and bad. But rahr!, proponents shoot back saying old (biased) research was done on hydrogenated coconut oil, and they are using organic unrefined, pressed oil. I have no answer on this one people. Try at your own will.

2. Macadamia nut oil (Smoke point: 389 F)

This is popular in Australian cooking. Proponents say macadamia nut oil is one of the highest in monounsaturated fat (even better than olive oil). The ratio of omega-3 to omega 6 in MNO is 1:8, which is purportedly great! MNO contains palmetolaic acid, which is thought to lower cholesterol.

3. Avocado oil (Smoke point: 520 F refined)

As with macadamia nut oil, avocado oil also has one of the highest concentrations on monounsaturated fat (again, higher than my beloved olive oil). Also, the omega-3 to omega-6 ratio is favorable. Avocado oil contains beta-sitosterol compounds, which help prevent LDL absorption. Vitamin E rounds out the list of benefits.

4. Rice brain oil (Smoke point: 490 F)

This one is popular is Asian cooking and perhaps the secret to great tempura. It contains vitamin E, antioxidants (Tocopherols, Tocotrienols, Gamma Oryzanol, Phytosterols, Polyphenols and Squalene), and micronutrients (can someone define “micronutrient”? Is it just a tiny nutrient?). Animal studies have shown that TRF (a concentrated fraction of vitamin E) extracted from rice brain oil and fed to rats lowered total cholesterol (2005, in Food and Chemical Toxicology). Similar studies found that TRF stimulates liver enzymes that clear toxic substances from the liver, thus having a positive effect on liver tumors. Critics say it contains too much omega-6 linoleic acid  (the omega-3: omega-6 ration is about 1:35) and not enough monounsaturated fat.

My personal choice for up to high-heat cooking: Organic refined canola oil,  maybe. I could still be persuaded. I’m very finicky. I’d like to try some of these others, especially avocado oil for high heat, but there’s no way I’m finding that in Idaho :/

P.S. Feel free to offer information here. I can tell there’s a wealth of information I’m not completely tapping and I may revisit the issue in the future.

Edited to add…

5. Safflower oil (Smoke point: 225 F unrefined; 450 F refined)

Safflower oil is good in that along with many of these other oils, it contains a higher percentage of monounsaturated fat (about 76%). However, it seems that the monounsaturated fat is pretty much all omega-6 linoeic. From the research I’ve done so far it seems that we really want omega-3 linolenic acid to be in there too.  However, if you really want something high in linoleic acid, safflower oil contains the most linoleic acid of any known seed. A plus for safflower oil is that it also has vitamin E.

6. My current canola oil (Smoke point: 425 F refined)

After I posted this I went and looked more carefully at my canola oil. What I was mainly worried about after reading was the possibility of genetically modified ingredients (common in canola) and of course the smoke point. After I examined the bottle I decided I was pretty happy with my my current high-heat oil.

Plus, canola oil is low in saturated fat and contains both omega-6 and omega-3, with a great ratio of 2:1!  Canola oil is made from rapeseeds (they had to change the name on this one), which are often sprayed with pesticides, so my only beef with my current bottle of oil is that it is not organic. But hey, that’s easily rectified in the future.

This is Spectrum expeller-pressed refined canola oil for medium to high heat:

Click here for a link for cooking oil smoke points.

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One Response to “All About Oil”

  1. Ray said

    A heathlier affordable high heat (450 degree) oil is safflower oil. I have used it in everything from baking to deep frying, and it is wonderful. Much more affordable than some of the exotic, hard to find oils you may encounter in Idaho.

    I hope you can find it.

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