Choosing the right cooking oil makes a big difference. While there are several oils and fats that are great for your diet, each needs to be treated in a different way to maximize nutrition and minimize toxicity.
Every fat and oil has its own smoking point, which is the absolute highest temperature to which they should be heated. All cooking fats and oils can be dangerous once they’ve been heated up past their smoke point—it doesn’t matter if the oil is super refined canola oil, freshly-pressed olive oil, or organic coconut oil.
Smoke points are determined by the number of free fatty acids (FFAs) in the fats and oils: the lower the FFA content, the lower the smoke point. Refined vegetable oils have a low FFA content, and that’s why they’re listed as being good for high heat cooking. (Now, we’re certainly not recommending cooking with vegetable oils; their high PUFA (polyunsaturated fatty acid) content makes them highly susceptible to oxidation at any temperature.) Unrefined oils generally have a higher FFA content and so they need to be treated more carefully.
The other factor to consider when picking a cooking oil is its percentage of saturated fatty acids. Saturated fats are more stable than unsaturated fats and less likely to oxidize, no matter the temperature. Unsaturated fats have a range of stability: monounsaturated fats are more stable than polyunsaturated fats. You can see the stability of the fat when you look at it at room temperature. Fats that are solid or semi-solid at room temperature (think coconut oil, animal fats, butter, and ghee) are more saturated than those that are liquid (vegetable, nut, and olive oils).
So, what oils should you use for cooking? Here are our favorites, plus some tips and suggestions for using them in the kitchen:
COOKING OILS IN THE KITCHEN:
Coconut oil is safe for cooking at medium to medium-high temperatures. We use coconut oil to enrich vegetables that we want to keep dairy-free, in our vegetable meatballs, and as a spread on Yucan Crunch crackers. Coconut oil is also a fabulous body product—it’s great for the hair and skin!
Ghee is safe for cooking at medium to medium-high temperatures. We use unflavored ghee in soups and stews and spread infused ghee on Yucan Crunch.
Rendered animal fats like tallow (beef fat), lard (pork fat), and schmaltz (chicken fat) are all safe at medium to medium-high temperatures. We use them in meat sauces, soups, and especially meatballs!
Butter is best used only at low temperatures. We add it to soups and vegetables that we’re cooking low and slow, or as a finisher to add an extra dose of richness.
Extra-virgin olive oil is a special case. As most of you know, high-quality, fresh, extra-virgin olive oils certainly have a lot going for them: they’re monounsaturated and therefore less reactive than polyunsaturated fats, they have a very low FFA content, and they contain a high level of beneficial polyphenol antioxidants. However, this standard is inconsistent across brands and even olive varieties. Some of the freshest oils, like olio nuovos, contain particulate matter that can burn quickly and bring down the smoke point (just like the milk solids in butter). The science is also out on how much heating changes the nutritional profile of the oil. Even from a taste perspective, heating olive oils too much can change and mute the flavor of the oil.
NERD OUT ON COOKING OILS
What is a fat?
All fats are made up of lipid compounds called triglycerides. Each triglyceride compound is composed of three fatty acid molecules connected to a glycerol molecule (a short 3-carbon chain that acts as a frame for the triglyceride). The fatty acid molecules are have two parts, shaped like a tadpole: an oxygen-hydrogen “head” and a long “tail” made from a chain of carbon atoms, each with one or two hydrogen atoms attached. Each fatty acid tail can be anywhere from 4 to 34 carbons long. The “head” of the fatty acid molecule attaches to the glycerol molecule to form the -glyceride. If there’s one fatty acid attached to the gylcerol, the compound is called a monoglyceride; if there’s two fatty acids, it’s a diglyceride; and three makes a triglyceride, which is what we’re primarily concerned with here.
It is important to pay attention to the structure of the hydrocarbon tail in the fatty acid, as it will determine if it is saturated or unsaturated. Saturated fatty acids have the simplest hydrocarbon structure. In those fatty acids, every carbon in the tail has two hydrogens projecting from it. The term “saturated” refers to the carbons; each is holding onto the maximum number of hydrogens possible. Saturated fatty acids can pack together tightly, resulting in a solid fat at room temperature.
Unsaturated fatty acids are slightly more complicated. In these fatty acids, the hydrocarbon tail has one or more “kinks” in it. Each “kink” results from the presence of a double-bond between two of the carbons in the chain. Each of these double-bonded carbons can each hold on to only one hydrogen. (In other words, they are “unsaturated” with hydrogen.) Monounsaturated fatty acids have one kink in their hydrocarbon tail; polyunsaturated fatty acids have at least two kinks. Because of these kinks, unsaturated fatty acids cannot pack together very tightly, resulting in liquid oil at room temperature. It is general practice to refer to fats that are solid at room temperature as fats and those that are liquid at room temperature as oils. For the sake of brevity, we’ll call everything a fat going forward.
Cooking fats all contain different ratios of saturated and unsaturated fatty acids. We generally categorize cooking fats based on whichever fatty acid is in the highest proportion. For example, fats that have a higher proportion of saturated fatty acids are generally referred to as “saturated fats,” even if they do contain some mono- and polyunsaturated fatty acids.
What is oxidization?
Oxidization (or oxidation) is a chemical reaction in which an atom or ion within a molecule loses an electron, giving the entire molecule an increased positive charge. The molecule is now called the “oxidized agent.” The free-floating electron attaches itself to the next nearest molecule, giving it an increased negative charge. This is called the “oxidizing agent.” Oxygen molecules often function as this oxidizing agent. Oxidization happens at a molecular level, but you can see it happening all the time. For example, apple slices turn brown because of oxidization. It’s a natural process, and it is important to remember that oxidization isn’t necessarily bad.
Oxidization becomes a problem when it leads to the formation of large amounts of free radicals in our food and in our bodies. Free radical formation occurs when the oxidizing agent’s new electron cannot pair with another electron. The electron will “dangle” off of the molecule and attempt to grab more electrons off of other surrounding molecules. This process sets off a chain reaction of electrons being grabbed from surrounding molecules, which now all become charged.
Free radicals occur naturally in our bodies, but a build-up of these highly reactive atoms and molecules can lead to unwanted cell damage and cell death, which in turn promotes cancer, other diseases, and inflammation.
What does oxidization have to do with cooking fats?
Different types of fats are more or less prone to oxidization. The more saturated the fat, the more stable the structure of the fat is at any temperature, and the less likely it will be for the fatty acids in the oil to oxidize. The less saturated the fat, the less stable it is, and the more likely it will be for its fatty acids to oxidize. As we discussed above, you can see the stability of the fat when you look at it at room temperature. Fats that are solid or semi-solid at room temperature (think coconut oil, animal fats, butter, and ghee) are more saturated than those that are liquid (vegetable, nut, and olive oils).
The kinks in the hydrocarbon tails of unsaturated fats also make the fats less stable. At each kink, the bond between the hydrogen and carbon is highly reactive and itching to ditch an electron. The more kinks there are in a hydrocarbon tail, the more opportunity there is for reactivity. This means that monounsaturated fats (with only one kink) are less susceptible to oxidization than polyunsaturated fats. Fat oxidization happens slowly at room temperature (after repeated oxidization, the fat becomes rancid), or more rapidly when the oils are heated since heat is a catalyst for chemical reactions.
But this doesn’t mean that you can’t heat fats at all. In order to cook safely with fats, you need to pay attention to two things: the type of oil you’re using and the temperature to which you’re heating it. As you’ve probably figured out, it is much safer to heat saturated fats than unsaturated fats. (There are many other reasons to avoid most unsaturated fats, which we’ll go into below.) The only fat we use in the kitchen that isn’t primarily saturated is olive oil, and we use it in very particular way. Each fat has its own threshold of safety, and that threshold is linked to its smoke point.
What is a smoke point, and what does it have to do with oxidization?
A fat’s smoke point is the temperature at which the fat begins to give off carcinogenic, smelly, blue smoke. Once a fat reaches its smoke point, its nutritive values begin to degrade and it begins to oxidize rapidly. It’s easy to tell once a fat has reached its smoking point—you’ll see the smoke! The more polyunsaturated fatty acids in the fat, the greater chance of oxidization once the fat reaches this point.
Smoke points are determined by the number of free fatty acids (FFAs) in the fat: the lower the FFA content, the lower the smoke point. Unrefined oils generally have a relatively high FFA content and therefore a lower smoke point. Refined, polyunsaturated vegetable oils (or PUFAs) have a low FFA content, and that’s why they’re listed as being good for high heat cooking. But just because the packaging says they’re safe to use, it doesn’t mean PUFAs should be in your kitchen.
As you probably know, PUFAs are the most common cooking fats around—you know them as soybean (or “vegetable”) oil, canola oil, corn oil, sunflower oil, and safflower oil. Refined versions of these oils contain a high amount of a fatty acid called omega-6 linoleic acid (or LA). Our bodies need this fatty acid, but only in very small amounts (think: 0.1% of our total calories per day). Because of the USDA’s push to get Americans to use “heart healthy” oils (this is a myth best debunked another day), most people get between 4 and 10% of their daily calories from these oils. It’s way too much LA.
Because of its structure, this particular fatty acid is highly prone to oxidization. The results can be devastating. When high-LA oils oxidize, they create several noxious compounds. Some of these, 9- and 12-hydroxy-octadecadienoc acid (9- and 13-HODE for short) and 9- and 13-oxo-octadecadienoic acid (9- and 13-oxoODE for short) are associated with cardiovascular disease and chronic pain. The biggest culprits, though, are the OXLAMs (or oxidized LA metabolites). They have been shown to be elevated in patients with Alzheimer’s disease and non-alcoholic fatty liver disease—so much so that they’re actually used as predictive tools for scientists to identify patients at high risk for the disease.
Oxidized LA fatty acids are also found in oxidized LDL cholesterol, which, when found in large amounts in the body, is a major culprit in atherosclerosis and resulting heart disease. Finally, a high amount of LA fatty acids in proportion to healthier unsaturated fats (omega-3s) creates a pro-inflammatory environment and could potentially interfere with neurological functions.
If you need any more convincing to ditch those industrial vegetable fats, keep in mind that they’re simply not good sources of nutritive value. They may be calorie-rich, but they’re nutrient-poor. Plus there aren’t any well-designed studies that prove that the unsaturated fats are actually better for your heart. (We think they’re worse!)
So, which fats should I use?
Whew, that was a lot of information. What does it mean for you and your kitchen? The good news is that there are many good choices when it comes to cooking fats. We’ll start with the fats that should get frequent use in your kitchen: the saturated fats.
First up: long-chain saturated fats. As you’ll recall from our discussion of fat structure above, each molecule of fat consists of an oxygen-hydrogen head and a hydrocarbon tail. Long-chain saturated fats have, well, a long tail. The most common of these fats are called myristic, palmitic, and stearic. They’re primarily found in dairy products and the meat of ruminant animals (beef, lamb, and pork). There’s a smaller amount in coconut and egg yolks.
Long-chain saturated fats are also the primary storage form for energy in humans and form the core structure of 75-80% of our fat cells. These fats help to incorporate calcium into our bodies, protect the liver from toxins like alcohol and acetaminophen (from Tylenol), deliver fat-soluble vitamins (A, D, K, E) to the bloodstream, support a healthy immune function, and regulate the availability of helpful polyunsaturated fatty acids like omega-3s. (We’ll learn more about these in a minute.)
Despite old studies that claim saturated fats are bad for heart health, more recent studies show that they’re actually highly beneficial. In fact, this recent research shows that saturated fats can actually help increase HDL cholesterol (the “good” kind); reduce the formation of lipoprotein(a), an inflammatory substance that is considered a risk factor for atherosclerotic diseases like coronary heart disease and stroke; and help to make LDL cholesterol larger, more buoyant, and less likely to cause problems.
Medium-chain saturated fats should also be in frequent use. You’ll most commonly find these fats in coconut oil, but they’re the primary fat in breast milk as well. The fatty acids that make up these fats have a shorter tail than the long-chain saturated fats, which gives them slightly different properties. These fats don’t require bile acids for digestion, which means they a great source of easily available energy. They’re also high in lauric acid, which has antibacterial, antiviral, and antioxidant properties, and promote the development of ketone bodies, which can be used by the brain as fuel.
Coconut oil in particular is a great cooking fat because it has a super-high proportion of saturated to unsaturated fatty acids. This makes it much less vulnerable to oxidative damage than other cooking fats. Some recent studies have also shown that coconut oil may be beneficial for weight loss, especially when eaten in concert with chile peppers. This combination promotes heat in the body by a process called thermogenesis, which aids in burning excess body fat.
Unsaturated fats appear in three different guises: as monounsaturated fatty acids, polyunsaturated fatty acids, and trans fatty acids. Despite the dangers we mentioned above regarding industrial polyunsaturated fats, each of these types of unsaturated fats (including certain natural trans fats) plays an important part in any diet.
Monounsaturated fats (like oleic acid) should be eaten more abundantly than polyunsaturated fats. Found in olives, avocados, eggs, poultry fat, almonds, macadamia nuts, and lard, they’re a tasty, relatively stable choice. While cooked eggs, poultry fat, and lard are safe when cooked at low- to medium-temperatures, we believe that vegetable-based monounsaturated fats shouldn’t be heated at all. (See below for more information on olive oil.)
When prepared properly, monounsaturated fats help to reduced LDL cholesterol and increase HDL. They also help prevent oxidation and inflammation in the body, lower blood pressure, and help to prevent the formation of blood clots. The only caveat to eating monounsaturated fats from nuts is that they contain fairly significant amounts of linoleic acid (LA, see above), which is inflammatory in high amounts. When eaten with plenty of omega-3s, the excess LA isn’t a problem.
Speaking of omega-3s, they are some of the most important polyunsaturated fats for us to eat. There are 3 primary types of omega-3 fatty acids: ALA, which is the primary (shortest-chain) version of omega-3 and is found in walnuts and flax seeds; and EPA and DHA, which are longer-chain versions of omega-3 and are both found in seafood. ALA isn’t particularly helpful on its own, but it is a precursor to both EPA and DHA, and these two omega-3s are crucial in protecting our bodies against inflammation. The best way to get these long-chain omega-3s is to eat whole seafood; fish oil contains omega-3s as well, but is prone to rancidity and oxidization.
Omega-6 fatty acids are the second form of polyunsaturated fats found in our diets. They are also crucial to our bodies’ function, but most Americans already eat them in abundance (see above regarding industrial PUFAs). Like omega-3s, there are longer and shorter chain omega-6 fatty acids. The shortest chain, linoleic acid, is the primary fat in the industrial vegetable oils we discussed above. The most common long-form of omega-6 is called ARA, which is present in most animal foods. We need it to mediate cell signaling in the body and to help form lipoxins, which trigger the release of anti-inflammatory compounds that are synthesized from EPA and DHA. ARA is also abundant in our brains and is said to help to relax blood vessels.
The key with polyunsaturated fats is to have a proper balance between omega-3s and omega-6s. Too much omega-6 with too little omega-3 can lead to inflammation, but you can’t eliminate omega-6 altogether. As you may have interpreted above, both omega-6s and omega-3s are dependant on each other to combat inflammation. Most studies agree that a ratio of around 1:1 omega-6 to omega-3 leads to the best results.
In addition to the above-mentioned fats, omnivorous diets that include grass-fed meat will inevitably include some trans fat—but it’s far from the industrially produced trans fat that has been systematically outlawed in fast-food restaurants and processed foods. Instead, we’re talking about natural trans fats called CLAs. Any good grass-fed beef will include small amounts of this type of fat, which is totally normal and surprisingly beneficial. CLAs have been shown to be inversely associated with heart disease, to improve gluose tolerance and insulin sensitivity, to help block the growth and spread of tumors by reducing inflammation, and to potentially help reduce body fat. Of course, you wouldn’t go out and buy a jar of CLA fatty acids—they come right along inside grass fed beef.
The following charts provide a quick breakdown of the make-up and the smoke points of different cooking fats. You’ll notice that while there is a wide range in smoke points of both the good and poor choices, almost all of the oils listed as “good choices” all have a very high saturated fat content relative to the other fatty acids. This saturated fatty acid content is key. So when choosing cooking fats, it’s important to pay attention to both the fatty acid content first and the smoking point second. The less polyunsaturated fatty acids, the better! (Note: each temperature is approximate; every brand of oil will vary a little bit.)
|Oil Type||% Saturated||% Monounsaturated||% Polyunsaturated||Smoke Point|
|Virgin Coconut Oil||86||6||2||350|
|Extra-Virgin Olive Oil*||14||73||11||250-350|
*You’ll notice that we’ve included one oil on the good list that is mostly unsaturated fats—extra virgin olive oil. There are a couple of reasons why. First, despite its monounsaturated fat content, olive oil is still relatively low in polyunsaturated fat. Second, while this oil is prone to oxidation when it is heated (or if the oil itself is old), it is full of vitamins, minerals, and antioxidants when used raw. We keep our olive oil use away from the heat so we can enjoy all of its benefits without the dangers that come from its oxidization.
|Oil Type||% Saturated||% Monounsaturated||% Polyunsaturated||Smoke Point|
|Refined Safflower Oil||8||76||13||510|
|Refined Sesame Oil||14||40||46||450|
|Refined Sunflower Oil||10||45||40||440|
|Unrefined Seed Oils||8-10||45-76||13-40||225|