Checking Your Oil: The Definitive Guide to Cooking with Fat
Caveman Doctor posted several weeks ago on the “internet” (whatever that is) about these so called “healthy” vegetable oils. Since then, he has received many emails asking which oils and fats are best to cook with. He also received many comments regarding grass-fed butter and if he is scared to eat this “dangerous” saturated fat. Caveman Doctor is only scared of grizzly bears (and making Cavelady mad) and is currently eating a big salmon filet with crispy skin that he cooked in a pan of butter. However, he still uses some other oils to cook with as well. This post covers how he chooses which oils to use. It is quite long for Caveman Doctor’s short attention span, but has been broken up into sections with quick reference and tables at the end. Also, as Caveman Doctor has been getting asked where to get these oils, he has added a CDR Approved Oils Link at Amazon to help guide you.
The Five Rules of Cooking with Fat
There are several benefits to cooking with healthy fats and oils and adding them to your food:
- They add flavor (macadamia oil is the best!).
- They help avoid burning of your food.
- They provide fat as an energy source.
- They provide healthy omega-3 fatty acids, like DHA.
- They provide cancer-fighting conjugated lineoleic acid (CLA).
- They help keep you full after you eat.
However, nothing comes without a cost, and just as there are many benefits, there are several potential harmful risks from improper usage of oils:
- High heat can damage the oil, loading it with free radicals.
- Oil can go rancid sitting on the shelf, which often loads it with free radicals.
- Some oil types contain a high amount of inflammatory omega-6 fatty acids.
- Vegetable oils, trans-fats, and other oils go through intense processing and refining and contain harmful chemicals.
There are several ways to enjoy the benefits of oils while avoiding the risks. These include considering the structural backbone of fats and oils (i.e. saturated, mono or polyunsaturated), the smoke point, and of course, how the oil is made.
Rule 1: Pick an oil with a high smoke point.
Oils are created out of glycerol and fatty acids, and when exposed to heat they break down into these two components. This point is called the smoke point, or the temperature at which the oil starts to burn and literally smoke. Once this occurs, the oil basically becomes rancid and free radicals and oxidation start forming within. At this smoke point, the glycerol in oil is converted to acrolein. Acrolein is a chemical that is found in cigarette smoke and is considered one of the most important cancer-causing agents from smoking1. Not only does it damage our DNA, but it renders our cells unable to fix the damage, which can lead to cancer. In lab studies, acrolein has been shown to cause lung and bladder cancer2. In fact, fumes from peanut oil3 and canola oil4, two common vegetable oils, have been shown to cause lung cancer when inhaled. Also, there has been in increase of prevalence of young Asian women diagnosed with lung cancer, though they have no history of smoking. Well, newer studies are pointing to the inhalation of fumes from cooking with vegetables oils in these patients5,6. Acrolein also activates EGFR7, a receptor that is frequently amplified in young Asian women with lung cancer and no history of smoking.
The effect of heating oils to their smoke point doesn’t stop with the release of harmful chemicals, as the fatty acids in the oil also become oxidized at this temperature, forming even more free radicals. This is a double whammy as some oils contain free radical-fighting antioxidants, which are rendered useless after damage from the high heat. This “cooks” away any free radical fighting value of the oil.
In review, heating oil above its smoke point releases toxic chemicals, damages the oil, and loads it with free radicals. Below is a list of average smoke points of common oils. Click on the icon to see the full picture.
Rule 2: Pick a stable oil with few, if any, polyunsaturated fatty acids.
One way to combat the damage that results from heating oil to a high temperature is to cook with more stable oils. Saturated fats are much more stable than unsaturated fats, which is why they are solid at room temperature (note: they are solid at room temperature of around 70º F, not necessarily at our body temperature of 98.6º F). Saturated fats, like all fats, have a long carbon backbone. The difference between saturated fats and unsaturated fats if the saturated fat is “saturated” with hydrogen atoms bound to the carbon backbone, while unsaturated fats have less hydrogen, leaving many unbound carbon atoms on its backbone (the carbon bonds are unsaturated). All of these hydrogen atoms attached to the backbone keep saturated fats intact, but also help protect it against oxidation and the binding of free radicals. A simple way to think about it is: free radicals attack the unbound carbons of an unsaturated fat. Saturated fats have no unbound carbons.
Monounsaturated fats have a single unsaturated site (i.e. one site without a hydrogen bound to it and therefore a double bond with its neighbor). Polyunsaturated fats have many free and hence unguarded carbon atoms on their backbone, leaving weak points for free radical attack. This also leaves them less structurally sound and is partly why they are liquid at room temperature. Just as when oil reaches its smoke point and becomes vulnerable to oxidation, the extra unprotected areas in polyunsaturated fats are easy targets for oxidation and free radicals.
The structure of fats also affects their shelf life. Because polyunsaturated fats are less stable, they tend to break down into oxidized products not just in the pan, but also on the shelf. When exposed to light, oxygen, and even non-cooking temperatures they get oxidized.
The converse to this is coconut oil, primarily a saturated fat. It is solid at room temperature due to its stability, and its shelf life is very long, coming in at around 2 years. However, vegetable oils and polyunsaturated oils spoil after only several months and become rancid. Even olive oil, a monounsaturated non-vegetable oil, goes rancid after about 6 months.
There are 3 main benefits of the more structurally sound saturated and monounsaturated fats versus PUFAs:
- Less heat-induced degradation during cooking
- Less degradation during storage and longer shelf-life (and more economical)
- Less or no defenseless areas where free radicals can attack and bind
The issues of polyunsaturated oil and their propensity to get attacked by free radicals were discussed at length here and here. When these weak fats become damaged, degraded, and bound with free radicals, they can potentially lead to atherosclerosis, inflammatory joint disease, rheumatoid arthritis, damage to the GI tract, and most importantly, mutagenicity and genotoxicity, which can lead to birth defects and cancer8. Chronic ingestion of oxidized unsaturated lipids in oils increases atherosclerosis and cancer incidence in animals. When ingested, these oxidized lipids have also been shown to damage our liver cells as well as our lymphocytes (the cells that fight infection, and likely, cancer)9. Oxidized LDL collects on our artery walls and is attacked by macrophages to form atherosclerotic plaques. I repeat OXIDIZED LDL, not LDL. Studies have even shown that oxidized lipids are absorbed and directly sent into the bloodstream, where they can wreak havoc on our arteries and organs10.
Saturated fats!! Won’t my arteries clog?
Your knee-jerk reaction is likely a common one when we encounter the thought of eating more saturated fat and cholesterol: clogged arteries and heart attacks! However, the entire lipid hypothesis (the theory that fat clogs your arteries) was simply built on bad science. It barely made it through the research process several decades ago, was jammed into placed by the infamous McGovern Report, and would likely never have survived the current peer-review process. Beyond that, it has been disproven many times11-13 (note there are dozens of references, but I just listed my three favorite). Also, for those of you following a caveman/paleo lifestyle, you and your fellow modern cavemen have personally been disproving the lipid hypothesis.
Interestingly, it’s quite possible that, while fats alone may not be the main culprit behind atherosclerosis, oxidized unsaturated fats and their oxidized constituents may be a contributor through similar mechanisms that cause inflammation and cancer (as discussed above). In fact, palm oil, which contains almost 50% saturated fat, has been shown to reduce the risk of atherosclerosis, arterial thrombus, and blood pressure, and inhibit platelet aggregation and cholesterol biosynthesis14. However, it also contains a significant amount of polyunsaturated fats, and when oxidized by high heat and repetitive usage, it has been shown to result in an unhealthy plasma lipid proﬁle, as well as damage to the kidneys, lungs, liver, and heart15. Polyunsaturated fats from vegetable oils have also been shown to promote cancer over saturated fats or polyunsaturated fish fat sources16, even in a randomized-controlled trial17.
However, the potential for oxidation does not only happen on the shelf or when cooking at high heat. The warm and acidic environment of the stomach has also been shown to cause damage and oxidation to unstable fats after consumption18, as has cooking items in the microwave19. However, even in the microwave, higher percentages of saturated fat in the lipid results in less oxidation, while the opposite occurs with polyunsaturated fats.
In conclusion, the stability of oil, often meaning the oil with the least amount of polyunsaturated fats, will be the most stable and defend against oxidation and free radical formation in your stomach, on your shelf, and in the frying pan. Below is a picture of the structure of common fats and oils. They are organized from least to most polyunsaturated fat percentage.
Rule 3: Pick an oil or fat that is not artificially hydrogenated (avoid trans-fats).
In order to turn a vegetable or plant-based food into oil requires several intricate processes described here. Making trans-fats goes one step further to artificially solidify them, as we already discussed here. Ever wonder why natural peanut butter is mostly liquid that rises to the top of the jar, while your common peanut butters are solid? That’s hydrogenation for you. Imagine what it does in your body…
The question remains: are trans-fats that bad? Well, besides decreasing the ability of our cell walls to adequately let nutrients in and out, disrupting the function of the infamous insulin receptor20, and possibly leading to cardiovascular disease and heart attacks21 there must be some positives to trans-fats– wait, ok there are NONE!
In conclusion: AVOID ALL TRANS-FATS.
Rule 4: Aim for more omega-3 and less omega-6 fatty acids:
We have been eating foods with about a 1:1 to 4:1 ratio of omega-6 to omega-3 fatty acids for millions of years. With the advent of grains, grain feeds for our animals, and vegetable oils, this ration has ballooned to over 15:1, or even more. As increased omega-6 consumption can lead to inflammation, circulatory issues, and even cancer, aim to eat fat sources or oils with the highest amounts of omega-3s and the fewest omega-6s, as we discussed here.
Linoleic acid, our prime source of omega-6, is found in vegetable oils, seeds, and grains. Avoid these foods and fat sources that are made from them. While it is difficult to reach a 1:1 ratio in cooking oils, I generally aim for those with the least amount of omega-6 as my animal fats generally have high amounts of omega-3, like grass-fed beef. Remember, eat animals that are fed the foods they are meant to eat , as grain-fed beef are loaded with omega-6s and have few omega-3s. Also keep in mind that farmed salmon has few omega-3s, while wild-salmon is packed with them.
As you can see from the chart above, sources like linoleic sunflower oil give you 65.7 g omega-6 per 100g serving with no omega-3! Consuming enough omega-3s to balance this would take over a week. Luckily we don’t eat vegetable oils as we know of their many health issues…
Rule 5: Never Use Vegetable or Refined Oils:
Throw them out, donate them to labs studying cancer, use them to start camp fires or for biodiesel. Do not consume! Stick for the unrefined, ideally organic, pressed oils. Even the healthy listed above can often be refined, so make sure to read the label correctly.
What are the best oils to use?
Reviewing all of the above rules, several oils consistently have high-smoke points, few polyunsaturated fats, low omega-6 amounts, and are not processed vegetable oils. The winners are (in no particular order):
- Macadamia nut oil
- Avocado oil
- Grass-fed butter
- Ghee (clarified grass-fed butter)
- Palm oil
- Coconut oil
- Olive oil (avoid high heat cooking due to smoke point)
Of course, animal fats are also great to cook with as they are structurally sound and taste delicious. Also, don’t throw out your olive oil due to its low smoke point; just don’t fry foods with it. I still use it for marinades and garnishes for vegetables and sometimes even after I microwave them – I often microwave vegetables when pressed for time, but one trick I do is to microwave the vegetable first, THEN add oil so it is not heated.
Fats and oils are a delicious way to cook your food and supplement your diet with fat. However, caution must be taken to ensure we are not introducing potentially harmful substances into our bodies. This list can help you minimize these risks by using the most healthy and stable fats and oils.
As a final note, one thing you may have noticed in this post was the underlying theme that cooking your food, especially in unstable oils, can introduce damaging elements into the body. While eating all food raw is not always possible for most of us, (and some foods like certain meats are not safe to eat raw) it may be worthwhile to try to increase the amounts of raw foods you eat daily. One good method is to eat vegetables in vinegar or other acidic marinades, with or without added oil. This will help soften up the vegetables and give them some extra flavor without damaging the oils or the vegetables themselves, and saves time.
Finally, as you notice from the list, the more manipulation and processing required in making the oil, the worse it is for you. Once again, good old Mother Nature provided us with all the healthy sources we need. Follow Her path to good health and enjoy the benefits.
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19. Yoshida H: Influence of fatty acids of different unsaturation in the oxidation of purified vegetable oils during microwave irradiation. Journal of the Science of Food and Agriculture 62:41-47, 1993, http://dx.doi.org/10.1002/jsfa.2740620106
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*Nutritional Data compiled mostly from the USDA National Nutrient Database. Missing data was averaged from several documents I have in the cave. These are estimates to give you a general idea, so I apologize if any are not 100% accurate!
© Caveman Doctor 2012. All Rights Reserved.