Categorizing oils like this seems counter-productive to studying the effect of consuming certain fatty acids, as oils from the same category have wildly different composition. Coconut and olive oils are both from fruits, but contain different fatty acids.
I believe the oils aren't divided this way for any taxonomic reason, but rather because we already have evidence of olive, avocado, coconut etc. oils having little-to-no impact on health, in contrast to other oils. The groups are basically "presumed innocent" oils and "presumed guilty" oils.
Or, to be more charitable, the groupings can also be looked at as "oils humans evolved eating" (olive oil, butter, coconut milk, etc) vs "oils we just started eating recently, because they can't be extracted without modern technology."
Humans did not evolve eating olive or coconut oil.
Seed oils do not require modern technology. Soybean, sesame, sunflower, etc. can be extracted with stone pressing and were extracted that way prior to any chemical extraction process. Where my family is from they’ve been eating sunflower and peanut oil for hundreds of years, milled and pressed with stone.
You are right that some cold-pressed seed oils have been used since antiquity, e.g. sesame oil.
Nevertheless, until modern extraction methods based on the use of high temperature and organic solvents have been introduced during the last two centuries such oils had remained expensive, so they were only a minor part of the food, unlike today, when if you look at the label of any kind of industrially-made food you will invariably see that some cheap oil has been added to it, e.g. soybean oil, canola oil or palm oil.
Even today, if you choose vegetable oils extracted by good methods, i.e. by cold pressing or with supercritical carbon dioxide, they are much more expensive than standard oils. For instance, the price range for cold-pressed sunflower oil overlaps with that of the cheaper kinds of extra-virgin olive oil and the prices are several times higher than for standard sunflower oil.
I have read all the 4 parts of this "Death by Vegetable Oil" series of posts.
Some of its conclusions are likely to be true, but the title is extremely misleading. A much more appropriate title would be "Death by the Cheaper Vegetable Oils".
All the data presented in these posts about the harmful effects of some vegetable oils are not applicable to vegetable oils in general, but only to those vegetable oils that have one or more of the following characteristics:
1. A high content of linoleic acid and also a too high daily intake. The optimum daily intake of linoleic acid is unknown, but it is believed to be around 10 g/day and not much over 20 g/day. In my opinion, based on the current data, an example of a daily fat intake optimized for the fatty acid profile and vitamin E content, for a sedentary human, would be 55 mL of extra-virgin olive oil + 15 mL of cold-pressed sunflower oil + a DHA+EPA omega-3 supplement. The rest of the food should have low fat content, like in grains, vegetables, fruits or lean meat. For a higher calorie intake, only the amount of extra-virgin olive oil should be increased.
2. Extraction with high temperature and/or organic solvents. One should always prefer extra-virgin oils, cold-pressed oils or oils extracted with supercritical carbon dioxide. All such oils are very sensitive to light, so they must be stored in darkness, preferably in dark glass bottles. Avoid those sold in clear plastic bottles.
3. Vegetable oils that have been heated during cooking. All vegetable oils should be mixed with the food only after cooking it and cooling it. They should not be used for frying.
4. Vegetable oils with artificial additives, e.g. with TBHQ. Avoid these.
>In my opinion, based on the current data, an example of a daily fat intake optimized for the fatty acid profile and vitamin E content, for a sedentary human, would be 55 mL of extra-virgin olive oil + 15 mL of cold-pressed sunflower oil + a DHA+EPA omega-3 supplement.
Can you provide link to this current data? I thought sunflower oil is not good for our health.
In the last 2 years, I started replacing all my cookware with a combination of cast iron, carbon steel, and stainless steel pans. So far, the only way to cook something in all of them without making the food stick is by using oil.
So I have a dilemma: What kind of oil to use with this type of cookware if I want to cook often?
Traditionally, lard was used for this purpose, not oils. This remains one of the best choices.
Good alternatives are butter or high-oleic sunflower oil or other high-oleic refined vegetable oils, which also have a low content of PUFA and of substances that are not triglycerides.
This is different from the case when the purpose of an oil is to be eaten without being heated, when cold-pressed non-refined oils are preferable, because they include various beneficial nutrients.
In any case, even if some kind of fat is used for frying, it is good to try to avoid eating most of it.
It is also possible to never use frying. In this case everything that is neither boiled nor steamed can be baked in an oven. This includes all kinds of meat (which must be cut into slices or small pieces before baking).
Home cooking is generally going to be better than particularly fast food because you are not reheating the same oils over and over.
Coconut oil is generally held as better. Cold pressed oils otherwise. Prepare to pay more for them. Be aware that food packaging labels have been known to lie about oil origin. Basically, fewer steps between growing the food and your mouth the better.
Preparing food at home is going to reduce a lot of the processing and reprocessing that happens to commercial packaged foods. I think that's going to be a net win.
Maybe get a feel for exactly how much oil is required and keep it to a minimum.
When I was using pans with a non-sticking coating, I used very little oil.
Now switching to cast-iron or carbon-steel I noticed that the best point to cook the food is to add some oil to the pan, wait for the oil to be heated properly, and only then start adding the food. Of course, I still add very little oil (maybe 1-2 tablespoons) but compared with non-sticking pans it is yet a visible thin film.
I am currently using extra-virgin olive oil but I am not sure it is good. Now I understand that instead of focusing on "extra-virgin" label I should focus on the process used to produce the oil.
On the other hand, sharing here a bit of anxiety I am no sure what to eat:
- On one hand I could try to eat more non-processed, non-cooked food like salads, vegetables ... But the risk there is being contaminated with various pesticides. So I am a bit concerned to switch to a diet mostly based on this as it means to increase a lot the quantity of such food
- On the other hand, cooking using what people consider healthy cookware means (so far for me) using some oil which I now get should be limited
- There is also the idea of red meat being bad, but also fish having mercury or radioactive elements. Probably not all of them but after reading this kind of information, I am a bit more aware of buying fish as I don't know exactly which one can be contaminated and from what area.
- The chickens seem also be not be healthy (don't remember where I read this and I somehow suspect it is false).
So I am really a bit puzzled about what to eat.
I don't think there is an easy answer.
Probably the correct answer is to grow my own food. But that is another style of life.
If you rinse vegetables well most pesticide residue will be removed. Also, some vegetables that are peeled remove that exposure route as well.
There are studies showing some kinds of organic products are worth buying because of the reasons you mention, but others are not.
I think the more you can buy food that you trust the better. This doesn't mean growing your own, it means learning more about where your food is coming from and the chain of producing and selling it. It may mean going to smaller shops, more trips, farmers markets etc. It may just mean reading about brands etc.
I think many people are wrestling with similar questions as you; you're not alone.
Using saturated or monounsaturated fats or oils are your best bets for sauteing. You can also braise things, in some kind of liquid.
Not the use of oil to avoid sticking is the problem, but eating it after that.
Besides choosing a kind of fat that is less sensitive to temperature, as described in another answer, when possible you should try to clean the fried food of the frying oil and to throw away most of the used oil.
Long story short, plants that live where it is cold need to use less stable oils with a lower melting points. These oils lead to our cells being more fragile, and also lead to more free radicals.
Particularly if the oil is repeatedly heated. As happens in restaurants. And even more so when deep frying fast food.
For any kind of nutrient, saying that it is good or bad, without saying at which daily intake that is true, is totally meaningless.
Any essential nutrient, whose absence from your food can kill you, can also become a poison over a certain daily intake. For certain essential nutrients, the difference between the optimum daily intake and the lethal daily intake may be quite small, e.g. for selenium.
In the case of linoleic acid, it is likely that 10 g/day is very healthy, but 50 g/day is very unhealthy. It is not known for sure where the threshold between healthy and unhealthy lays, but it might be between 20 g/day and 30 g/day.
Most of the cheapest vegetable oils contain between 60% and 80% of linoleic acid.
With all kinds of industrially-made food containing large amounts of cheap oils, it has become very easy to eat too much linoleic acid per day, without being aware, like also too much sugar.
Wait a moment. The stereotypical unstable oil is alpha-linolenic acid, which seems to be generally regarded as quite healthy. Certainly oxidized ALA is disgusting (keep those flax seeds in the freezer!), but I’ve never heard of omega-3 fatty acids leading to fragile cells.
ALA is very unstable as oils go. It’s an omega-3 fatty acid. It’s generally regarded as healthy. The claim that unstable oils are somehow bad for you because they are unstable in your body seems entirely unsupported.
Certainly flaxseed oil is a terrible cooking oil unless you are trying to make furniture [0], but that’s a very different claim.
[0] You can also use flaxseed oil to produce a beautiful but mostly useless seasoning on cast iron. But the inside of your body is not made of hot iron, and the reactions that occur on a skillet don’t seem particularly relevant to what happens if you eat the oil.
it's really not. It's a useful grouping because the methods of extraction differ along these lines. Vegetable oils generally require a chemical intensive process to acquire involving solvents and cleaners. These oils tend to have high levels of linoleic acid which is toxic to humans.
Vegetable oils do not require chemical extraction. But even so, what does that have to do with the oil? Oil extracted with solvent shouldn’t have any significant solvent left in it when consumed.
Linoleic acid is not “toxic” to humans. It’s an essential fatty acid. You need it to survive. Your body needs it to
make other fats. https://en.wikipedia.org/wiki/Linoleic_acid
seed oils do often require chemical extraction and the method of extraction does matter because it may have effects on the chemical structure of the oil in question. For example, to make canola oil, the seeds are ground at high temperatures to extract a very fragile oil. During this harsh process, the oil is oxidized and then needs to be washed with hexane (a known neurological toxin) and then bleached and deodorized so that the product does not smell rancid (which it is after the processing). Contrast this to cold pressing olives.
As for linoleic acid, it does store in adipose issue and cause oxidative stress and inflammation in humans. Below is one of several papers you can find on this.
A high linoleic acid diet increases oxidative stress in vivo and affects nitric oxide metabolism in humans
That study also shows that a diet high in chemically-extracted high-oleic sunflower oil did not have increased urine metabolites compared to control. So that study actually works against the hypothesis that seed oils or chemically extracted oils are inherently bad.
And here’s another study that directly tests the hypothesis that linoleic acid consumption causes damage via oxidative stress and concludes “our results provide no indication of increased oxidative stress or genetic damage as a result of increased dietary intake of linoleic acid. Therefore, we see no scientific basis to reconsider the public health policy to stimulate the intake of polyunsaturated fatty acids aimed at the reduction of coronary heart diseases.”
I agree that there is not consensus in the scientific/medical community about this. You can find MDs who will advise avoiding linoleic acid as a top health prioty (i.e Paul Saladino) and other scientists who do not agree there is sufficient evidence to indict seed oils (i.e Andrew Huberman). Likewise, you can find all sorts of studies.
To address your point about the study I linked -- I think you're mistaken. The LA group did have a significant increase in 8-iso-PGF2alpha urine metabolites, and decrease in nitric oxide metabolites. From the study:
> Urinary excretion of 8-iso-PGF2alpha was significantly increased after the LA diet (170 vs 241 ng/mmol creatinine, P=0.04), whereas the urinary concentration of nitric oxide metabolites decreased (4.2 vs 2.6 mg/mmol creatinine, P=0.03).
also
> In conclusion, the high-LA diet increased oxidative stress and affected endothelial function in a way which may in the long-term predispose to endothelial dysfunction.
The oleic acid group, the group that didn’t see an increase of metabolites, was given high-oleic sunflower oil. I brought that up because it’s a chemically extracted seed oil, and one of the most common seed oils. “Seed oil” is not a significant distinction of fatty acid composition. Seed oils have varying linoleic acid composition (sesame oil for example is quite balanced, high-oleic sunflower is close to olive oil ratios).
The study you linked showed an increase in oxidation metabolites for the LA group. But as far as I understand, those metabolites don’t demonstrate damage to anything or an impact on mortality. That’s why I linked to a study that measures oxidative DNA damage via 8-oxo-dG in blood, which found no impact from increased linoleic acid consumption. So the theory that linoleic acid is dangerous because of damage via oxidative stress isn’t clearly supported by current literature.
Not really. Here’s a study that measured hexane in various oil brands and didn’t find any problem. “The hexane residue was detected in thirty-six out of forty examined samples, ranged from lower than LOD to 42.6 µg/kg. However, in all of them hexane content were below the MRL of 1 mg/kg which set by the European Union.”
I just checked my "vegetable oil", and it is further labled as 100% soybean. I can't imagine why would waste the more expensive olive oil by using it as an additive for cheap vegetable oil.
it doesn’t really matter though because they all share the same common characteristics that make them unhealthy…eg high polyunsaturated fat content that easily degrades in high heat.
Do you fry in >400 degree oil? There are many foods that are fried in olive oil for example in Spanish food. It seems fine since most frying is done well below the smoke point.
"Monitoring of Quality and Stability Characteristics and Fatty Acid Compositions of Refined Olive and Seed Oils during Repeated Pan- and Deep-Frying Using GC, FT-NIRS, and Chemometrics"
There are several types of olive oils. Extra virgin (with lowest smoking point) is mostly used raw in salads and dressings, etc. Pure or refined(with highest smoking point) mostly used for cooking.
That’s why people started using the term “seed oil”. Olive oil is not a seed oil while sunflower and rapeseed oil is. Olives also aren't a vegetable though.
From what I understand, Canola is a more specific product. Like how Flaxseed oil and Linseed oil come from the same plant. Wikipedia mentions Canola as "a version" rather than "also known as"
Canola was bred from rapeseed cultivars of B. napus and B. rapa at the University of Manitoba, Canada, by Keith Downey and Baldur R. Stefansson in the early 1970s,[9][10] having then a different nutritional profile than present-day oil in addition to much less erucic acid.[11] Canola was originally a trademark name of the Rapeseed Association of Canada, and the name was a condensation of "Can" from Canada and "OLA " meaning "Oil, low acid",[12][13] but is now a generic term for edible varieties of rapeseed oil in North America and Australasia.[14] The change in name serves to distinguish it from natural rapeseed oil, which has much higher erucic acid content.[15]
It’s not really a gotcha. Seed oil isn’t a perfect term but if the oil comes from some seed that requires an extensive chemical process to extract, refine, and deodorize it’s a being referenced as a “seed oil” here.
Coconut oil is not that. Neither is olive oil or avocado oil.
Aren’t they nuts? Every time a story about oil comes up on HN I’m so confused. Everyone has different terms and expectations. Is there a one pager somewhere where we can all agree on some common ground?
The science is too shoddy to draw any conclusions. It’s hard to take seriously studies that don’t consider olive oil a “vegetable oil”.