Core Tip: Olive oil is just a relatively good edible oil, but it does not have significantly higher nutritional value than other vegetable oils; replacing animal fats in recipes with it is beneficial for cardiovascular health; frying with olive oil does not significantly produce harmful substances, but its antioxidant components will be destroyed, thereby losing the "possible" "nutritional advantage" of cold-pressed olive oil.
Rumor: Olive oil is considered the most suitable oil for human nutrition among all fats discovered so far. Olive oil undergoes no chemical treatment during production, all its natural nutrients are preserved very well, it contains no cholesterol, and its digestibility is around 94%. Olive oil is extremely suitable for the development of infants and young children, as the ratio of its essential fatty acids is similar to that of breast milk. Whether in old age or during the growth and development period, olive oil is the best edible oil for humans.
Truth: Olive oil is just a relatively good edible oil, but it does not have significantly higher nutritional value than other vegetable oils. The composition of olive oil does not meet the nutritional needs of infants, and its fat composition is far from that of breast milk. It is not only unsuitable for infant development but can even be considered a "substandard food" for them. When used for frying, the antioxidant components in olive oil are easily destroyed, thus losing the "possible" "nutritional advantage" of cold-pressed olive oil.
What is so "special" about olive oil?
Olive oil is a vegetable oil, originally consumed in the Mediterranean region. Later, it spread worldwide for its "possible" health benefits and was gradually marketed as a "premium edible oil." From a chemical composition perspective, its "special features" are three points:
(1) High oleic acid content, which can reach over 70%. Oleic acid is a monounsaturated fatty acid. Some experimental results show that replacing saturated fats in the diet (such as animal fats, butter, etc.) with unsaturated fats can help reduce the risk of coronary heart disease. The US FDA approved in 2004 the following claim for olive oil: "Limited and not conclusive scientific evidence suggests that because of the monounsaturated fat in olive oil, consuming about 2 tablespoons (23 grams) of olive oil daily may reduce the risk of coronary heart disease. To achieve this possible benefit, olive oil should replace a similar amount of saturated fat and not increase the total daily caloric intake."
Using olive oil instead of animal fats at room temperature can maximize the nutritional value of the expensive olive oil.
However, monounsaturated fatty acids are not unique to olive oil. For example, oil from double-low rapeseed (also called "canola oil") also contains a high content of oleic acid. In fact, the FDA has also approved canola oil to make the same claim. Corn oil has similar approval, although the recognition of the scientific evidence is a bit weaker. The various "high-oleic vegetable oils" currently in development or already on the market are even better in this regard. In product marketing, the qualifier "limited and not conclusive scientific evidence" from the FDA-approved claim and the condition for reducing the risk of coronary heart disease—"olive oil needs to be used to replace a similar amount of saturated fat and not increase the total daily caloric intake"—are ignored and are interpreted as "eating more can do this and that."
(2) Vegetable oils also contain some vitamin E and other polyphenolic compounds. If it is cold-pressed olive oil, the content of these components is relatively high. They are generally considered to have antioxidant effects.
(3) Primary cold-pressed olive oil contains many other impurities, giving it a flavor different from other vegetable oils.
Apart from these three points which are indeed special about olive oil, the other claims in the rumors are by no means its advantages. For example, the claim that olive oil "contains no cholesterol." This is true, but it is not an advantage of olive oil, because no vegetable oil contains cholesterol. Touting this as an advantage of olive oil is like saying "I am exceptionally talented because I have two hands" or "This girl is naturally beautiful because she has one nose and two eyes." Another claim, "digestibility is around 94%," is an even more baffling "advantage." First, digestibility is not typically used to measure the quality of an oil. Second, without comparing it to other vegetable oils, there is no basis for saying whether it is high or low. Third, a high "digestibility" for an oil is not necessarily what people want. Many weight-loss drugs work by inhibiting lipase to reduce fat absorption. If an oil is naturally "less digestible," wouldn't it become a safe and effective weight-loss food?
In fact, olive oil is a "substandard food" for babies.
If other advertising slogans are just misleading, then "olive oil is extremely suitable for the development of infants and young children, and the ratio of its basic fatty acids is similar to that of breast milk" is a harmful deception.
First, cholesterol is crucial for the composition of cell membranes. Adults need to limit their cholesterol intake not because cholesterol is useless, but because the daily intake for adults usually exceeds the requirement and reaches a harmful level. However, infants are different; they are growing vigorously and have a greater demand for cholesterol. In breast milk, the cholesterol content ranges from 115-150mg/L. Current standards for formula milk do not require it, and it is usually significantly lower than in breast milk. In 1996, a study by Japanese scholars was published in the "American Journal of Clinical Nutrition," comparing the effects of breast milk, regular formula milk, and cholesterol-fortified formula milk on the red blood cell membranes of infants. The cholesterol contents of the three milks were 117mg/L, 42mg/L, and 82mg/L, respectively. The results showed that infants fed the cholesterol-fortified formula were closer to breastfed infants in terms of plasma cholesterol content and red blood cell membrane composition than those fed regular formula. On one hand, it is emphasized that it contains no cholesterol at all, and on the other hand, it is said to be extremely suitable for infant development. Isn't this a contradiction?
Second, the fat composition of breast milk is greatly influenced by factors such as population, diet, and lactation period. According to analysis results of breast milk from around the world, saturated fat generally accounts for about 40% of total fat, which includes many short-chain fats. In addition, breast milk also contains some long-chain omega-3 polyunsaturated fatty acids. It can be said that the fat composition of breast milk is quite unique. How can olive oil, which is mainly oleic acid, have a "ratio of basic fatty acids similar to that of breast milk"?
Olive oil for frying?
Because the misleading advertisement that "olive oil is the most suitable for human nutrition" has deeply ingrained itself in people's minds, many people use olive oil as a regular cooking oil, for example, for stir-frying. However, using olive oil for stir-frying is not its best use.
When used for stir-frying, olive oil doesn't have much advantage over other common vegetable oils.
If "can" means that the food fried is not harmful to health, then of course there is nothing wrong with stir-frying with olive oil. The reason olive oil is "not suitable" for stir-frying is as follows:
First, "good olive oil" should be cold-pressed and unrefined, containing more other components, with a smoke point of 190~200°C. Compared to other unrefined vegetable oils, this smoke point is relatively high. This is also the basis for many advertisements claiming that "olive oil has a high smoke point and is less prone to smoking." The temperature for general stir-frying is "seven or eight parts hot," which is over 200°C. Smoking produces some harmful substances, although the amount may not be enough to significantly harm health, but it is after all not a good thing. In fact, not just olive oil, all kinds of unrefined oils are not suitable for stir-frying. Refined vegetable oils have higher smoke points, for example, peanut oil and soybean oil have smoke points above 230°C, and canola oil has a smoke point above 220°C.
Second, if the "unique value" of olive oil exists, it mainly comes from its polyphenolic compounds. (The value of high oleic acid is not unique, as high-oleic acid rapeseed oil or soybean oil contains more oleic acid than olive oil). The "health benefits" of these polyphenolic compounds come from their antioxidant properties, and the mechanism of antioxidant action is to sacrifice themselves to protect the target when faced with oxidative stress. Heating is a severe oxidative test, so these polyphenolic compounds "heroically sacrifice" themselves. Olive oil after high-temperature heating is just on par with other "ordinary" vegetable oils.
"Mid-to-low-grade olive oil" that has been refined is similar to other refined vegetable oils, with a high smoke point, and most of the antioxidant substances and flavor components have been removed. Without the advantages of "premium olive oil," there is no loss, and it is no different from other vegetable oils when used for frying.
Using "premium olive oil" for stir-frying is like using Maotai for cooking wine, using top-grade Longjing to boil tea eggs, using LV to package cabbage, or driving a Ferrari to deliver food. It doesn't harm society or affect health. Of course, there is nothing wrong with it as long as you like it. Although you spend a high price without getting "substantial benefits," the psychological satisfaction is after all a无可厚非 happiness.
Conclusion
Olive oil is just a relatively good edible oil, but it does not have significantly higher nutritional value than other vegetable oils. It contains more oleic acid and no cholesterol, just like other vegetable oils. Replacing animal fats in recipes with it is beneficial for cardiovascular health. Cold-pressed, unrefined olive oil contains relatively more polyphenolic compounds and other antioxidants, which are considered to have certain health benefits. However, the composition of olive oil does not meet the nutritional needs of infants, and its fat composition is far from that of breast milk. It is not only unsuitable for infant development but can even be considered a "substandard food" for them. Frying with olive oil does not significantly produce harmful components, but its antioxidant components will be destroyed, thereby losing the "possible" "nutritional advantage" of cold-pressed olive oil.