Oil

Oils and health factors to consider

Oils are widely used in cooking, ranging from being simple condiments to being the key ingredient to cooking something a certain way.

However, oils present three major downsides, that vary in severity according to the type of oil, amount used, and cooking way:

Empty calories

Oils have a very poor nutrient profile, consisting mainly of some vitamin E and some essential fatty acids.
Similarly to sugar and white rice, they do not provide anything really useful, and while they do provide very little of a few things, they would be much better off replaced with other--more nutritious--foods.

This is especially true when considering that oils are very high in calories, and that it is easy to use lots of them without realizing because of the ways they are used. For example, when mixing oils in a sauce or to stir fry some vegetables and coating them, you can easily use more than you realize by dropping a little extra oil, and going from 1 tbsp to 2 tbsp can be as simple as inclining the bottle of oil a bit too much or not seeing the quantity of oil precisely due to reflection of light on the pan.
However small of an error this may seem, 1 extra tbsp of olive oil would already present an extra 119 kcal, which is a considerable amount--that is 119 kcal that would give you pretty much nothing, and make you less hungry for nutritious food (therefore, miss more nutrition and be more unlikely to get optimal levels of the nutrients you need), and/or add extra weight to you.

This is not always a concern, as using oil sparsely and in controlled quantities would have a pretty much negligible effect--still net negative to do, but the conveniency of using oil would likely outweigh the damage after a certain point.

It is important to note that oil ends up not being an 'empty calories'-related problem if it actually allows you to eat healthy foods you would otherwise be unwilling to eat. That is, the calories of the healthy food + the oil used to cook it would still be far better than eating some unhealthy food instead.
For example, it would be far better to eat some sautéed broccoli than to eat some white bread instead. Of course, eating steamed broccoli would be even better, but if by sautéing the broccoli you would eat considerably more of them or you would need to sauté the broccoli in order to tolerate eating them (making them more tasty and palatable), then eating sautéed broccoli is better than eating considerably less steamed broccoli or not eating broccoli at all.

High saturated fat content

High amounts of saturated fats lead to cardiovascular disease by increasing the amount of cholesterol the body produces.
Saturated fats raise LDL cholesterol [1], and LDL cholesterol causes cardiovascular disease (CVD). [2]

Saturated fat in oil is a problem because of the often-high quantity of it. However, oils are very different from each other when it comes to fat profile, and some oils are much better/worse than others.

There are three types of fat:

• Saturated fat
• Monounsaturated fat
• Polyunsaturated fat (which represent the essential fatty acids)

Polyunsaturated fat then can be categorized into another two types:

• Omega3
• Omega6

Both of these have requirements that need to be met daily.

When it comes to fat profile, there are essential fatty acids to take into consideration (omega3, omega6), and some oils are quite rich in those--which helps towards getting enough essential fatty acids throughout the day. EFAs (essential fatty acids) become a negative when frying or heating the oil to high temperature, because of instability and oxidization (more explained below). There are also monounsaturated fats, which are empty calories like saturated fats, are less stable then saturated fats at high temperature but more stable than polyunsaturated fats (EFAs), and do not represent the risk of saturated fat in regards to health.

Here below you can see the amount of saturated fats for most common oils per 1 tbsp.

Name	Saturated (grams / 1 tbsp)	Monounsaturated (grams / 1 tbsp)	Omega3 (grams / 1 tbsp) with % RDA	Omega6 (grams / 1 tbsp) with % RDA
Avocado oil	1.6	9.6	0.1 (7%)	1.7 (10%)
Canola oil	1.0	8.6	1.2 (78%)	2.5 (15%)
Coconut oil	11.2	0.9	0.0 (0%)	0.2 (1%)
Corn oil	1.8	3.8	0.2 (10%)	7.3 (43%)
Flaxseed oil	1.2	2.5	7.3 (454%)	1.9 (11%)
Grapeseed oil	1.3	2.2	0.0 (1%)	9.5 (56%)
Cocoa butter	8.1	4.5	0.0 (1%)	0.4 (2%)
Extra-virgin olive oil	1.9	9.8	0.1 (6%)	1.3 (8%)
Palm oil	6.7	5.0	0.0 (2%)	1.2 (7%)
Palm kernel oil	11.1	1.6	0.0 (0%)	0.2 (1%)
Peanut oil	2.3	6.2	0.0 (0%)	4.3 (25%)
Sesame oil	2.0	5.4	0.0 (3%)	5.6 (33%)
Soybean oil (unhydrogenated)	2.1	3.1	0.9 (58%)	6.9 (40%)
Sunflower oil	1.4	2.7	0.0 (0%)	9.0 (53%)
Sunflower oil, high oleic	1.3	11.4	0.0 (2%)	0.0 (0%)
Walnut oil	1.3	3.1	1.4 (89%)	7.2 (42%)

Trans fats with high heat

With high heat, unsaturated fats (which would be otherwise good) can be degraded by oxidization and some can become trans fats [3].

Trans fats are the most unhealthy fats, posing a multitude of risks: increasing cancer risk, causing brain damage, and particularly raising LDL cholesterol and lowering HDL cholesterol, which significantly increases cardiovascular disease risk. [4] [5] [6] [7]

When considering which oil should be used and in which way, trans fats should be the main priority of avoidance, as saturated fats would definitely be the lesser evil between the two.

Stability of different types of fat differs when it comes to their likelihood to degrade into trans fats:

• Saturated fat is the most stable (and therefore the one least likely to degrade into trans fats)
• Monounsaturated fat is less stable than saturated fat but still quite stable, and does not present the CVD risk of saturated fat
• Polyunsaturated fats (EFAs) are the least stable and most susceptible to oxidization, and even though they represent the healthiest fats in normal conditions, they are the ones most likely to become trans fats when exposed to high heat

Best oils for high temperatures (baking/frying)

Using the table above and the information we know about which types of fat present the most risk when exposed to high temperature, we can determine which oils are best (or least bad) for different scenarios.

Sautéing/stir frying

When it comes to high temperatures, as explained above, we know that:

• Saturated fat is the most stable to not degrade into trans fats, but pose CVD risk
• Monounsaturated fat is less stable than saturated fats but still stable overall, without the CVD risk
• Polyunsaturated fat (EFAs) are unstable and the ones most likely to become trans fats (trans fats -> worse than saturated fat)

Sautéing/stir frying is usually (and better) done quickly and with not-very-high temperatures (so as to avoid as many trans fats as possible, while still being able to fry things).

Therefore, when it comes sautéing/stir frying, we can conclude that monounsaturated fat is preferable to unsaturated fat, which is preferable to polyunsaturated fats (monounsaturated > saturated > polyunsaturated). This is because:
1- the temperature is not (and should not) be high enough for the monounsaturated fat, which is quite stable, to degrade into trans fats
2- saturated fat is stable and would remain the same (similar to the monounsaturated fat), but pose CVD risk, thus being less preferable than monounsaturated
3- polyunsaturated fats (EFAs) are unstable, and would pose a risk of becoming trans fats (which are significantly worse than saturated fat in healthfulness), thus being less preferable than saturated fat

By sorting the table by putting a positive value for monosaturated fat (unlikely to turn into trans fats and no CVD risk), a somewhat positive value for saturated fat (very unlikely to turn into trans fats but CVD risk), and a negative value for polyunsaturated fats (vulnerable to turn into trans fats, which pose the highest risk by far), we can see which oils are best for sautéing, and which ones are the worst.

The equation used to arrive at the 'Final value of safety for sautéing' = (saturated fat / 2) + (monounsaturated fat) + (- polyunsaturated fats)

Name	Final value of safety for sautéing	Saturated (grams / 1 tbsp)	Monounsaturated (grams / 1 tbsp)	Polyunsaturated fats (grams / 1 tbsp)
Avocado oil	8.6	1.6	9.6	1.8
Canola oil	5.4	1.0	8.6	3.7
Coconut oil	6.3	11.2	0.9	0.2
Corn oil	-2.8	1.8	3.8	7.5
Flaxseed oil	-6.1	1.2	2.5	9.2
Grapeseed oil	-6.65	1.3	2.2	9.5
Cocoa butter	8.15	8.1	4.5	0.4
Extra-virgin olive oil	9.35	1.9	9.8	1.4
Palm oil	7.15	6.7	5.0	1.2
Palm kernel oil	6.95	11.1	1.6	0.2
Peanut oil	3.05	2.3	6.2	4.3
Sesame oil	0.8	2.0	5.4	5.6
Soybean oil (unhydrogenated)	-3.65	2.1	3.1	7.8
Sunflower oil	-5.6	1.4	2.7	9.0
Sunflower oil, high oleic	12.05	1.3	11.4	0.0
Walnut oil	-4.85	1.3	3.1	8.6

On top of these values, it should be taken into consideration that extra-virgin olive oil is known to have protective antioxidative polyphenols (that prevent it further from oxidizing and turning into trans fats)--this together with the high level of monounsaturated fat (and low polyunsaturated fat), makes it not surprising that studies show olive oils to be resistant to frying conditions. [8]

Extra-virgin olive oil and high oleic sunflower oil are the clear winners, followed by avocado oil, cocoa butter, palm oils (which should although be avoided for their problematic impact on the environment), coconut oil, and canola oil.