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Which Cooking Oil Is Best? A Cardiologist Clears the Confusion
We have been taking up one important topic at a time and discussing health. Today I am going to talk about a very important and very controversial subject: which cooking oil to use. There is a lot of confusion about oil, because we have too much information and too little clarity.
If you look on Instagram, wellness influencers, food start-ups and doctors are all in divided camps. Certain words keep coming up: cold-pressed, refined, omega-6, seed oils. If you take this you will get cancer; if you take that you will live longer; this is why you are dying. There is a lot of information about oils with no clarity at all. Even for doctors and scientists, the science is not clear enough to give a black-and-white answer: use this and do not look at anything else. Because of that, everyone is confused. So today I will give you clarity: what oils actually are, why, and how to use them. By the end, which oil to use will be completely clear to you.
What makes an oil healthy or harmful
Whether an oil is healthy or harmful depends mainly on the fatty acid composition inside it. There are four types:
- Saturated fatty acids
- Monounsaturated fatty acids
- Polyunsaturated fatty acids
- Trans fatty acids
Among these, the one we definitely must not use is trans fatty acids. They are very, very dangerous. That is why vanaspati, or dalda, which people used in my childhood, is not used by anyone now, because it is very high in trans fatty acids. Leave it completely.
Of the remaining three, saturated fats increase both LDL and HDL, the good cholesterol and the bad cholesterol, so overall cholesterol rises. Saturated fatty acids should be used in limited amounts.
Monounsaturated fatty acids, such as olive oil or groundnut oil, are somewhat protective and good for the heart, but taken in large amounts they are not good.
Polyunsaturated fatty acids are in sunflower, corn and seed oils. The sunflower advertisements say “high PUFA content”; PUFA is polyunsaturated fatty acid. It is okay, but it has two kinds again: omega-6 and omega-3. Too much omega-6 is not so good for us; along with omega-6 there should be balancing omega-3 fatty acids. Sunflower oil has a lot of omega-6.
What we need to understand is that we can say which fat is higher in which oil, but saturated and unsaturated fatty acids are present in all of them. No oil is completely one type. For example, ghee has a lot of saturated fatty acids, and coconut oil also has a lot of saturated fatty acids.
Smoke point
Another important concept is the smoke point. People talk about high smoke point and low smoke point. The temperature at which an oil breaks down and toxic compounds form is called the smoke point. Some oils have a high smoke point, which means they are useful for deep frying. I will say more about this again.
Omega-6 to omega-3 ratio
To elaborate a little on the omega-6 to omega-3 ratio: ideally it should be less than 4:1, that is, for four parts of omega-6 there should be at least one part of omega-3. But sunflower oil has far too much omega-6.
Cold-pressed oils
Cold-pressed oils are now in a big trend. Everyone is saying cold-pressed oils. What are they and what is their advantage? If we extract oil at less than 50 degrees centigrade without using chemicals, it is called cold-pressed oil. Two or three words matter here: cold, and no chemicals.
When we press cold, the antioxidants are retained: vitamin E, polyphenols and plant sterols all stay. If oil is extracted at very high heat, these are lost. But what we must understand is that if we take that oil and deep fry with it, they are lost again. That means cold-pressed oil should not be used for very high heat.
In refined oil, a chemical called hexane is added and the solution is extracted, so refined oils contain hexane. How much hexane, and whether it is dangerous, is a separate discussion, but cold-pressed oils do not have hexane.
Cold-pressed oils also have low smoke points, so they can be used for salads and sautéing, and for curries too, but they are not suitable for frying. Another thing: cold-pressed oils have a short shelf life, so they must be stored carefully. I will tell you how.
Yield and price
There is a lot of discussion about yield too. If we take one kilogram of groundnuts and make cold-pressed oil, only 350 to 400 ml comes out. So to get one litre of cold-pressed oil, we need two and a half to three kilograms of groundnuts. If groundnuts cost 100 to 200 rupees, the raw cost itself becomes 300 to 360 rupees. Cold-pressed oils are costly.
Why refined oils got a bad name
Why so much fuss about refined oils? The main thing is that nutrients are lost. Why? Three processes are done: bleaching, deodorisation and chemical neutralisation. In that process, solvents like hexane are added. So in refined oils, nutrients are lost, and some of these solvents remain as contamination. Another thing is the doubt whether some trans fatty acids may form during high-heat processing.
The commonly used refined oils, sunflower, corn and soybean, are all high in omega-6 fatty acids. There is some information that too much omega-6 can increase inflammation and autoimmune disease, so refined oils got a bad reputation. Also, because refined oils are used in packaged foods, which are not good for health, this bad association made the perception worse.
But what we need to understand is that not all refined oils are bad, because refining also improves shelf life. You can take rice bran oil or groundnut oil; used in moderation they are fine. And for high-heat cooking these are necessary. So refined oil is better used for high-heat cooking.
What happens above the smoke point
If an oil goes above its smoke point, vitamin E, polyphenols and sterols are all lost; the nutrients go. Along with that, some toxic compounds form, aldehydes such as acrolein. Free radicals increase, taste and smell change, and smoke increases, so smoke inhalation increases for people at home.
- Low smoke point oils: virgin olive oil, flaxseed oil and unrefined sunflower oil have low smoke points of only about 100 to 160 degrees.
- High smoke point oils, suitable for frying: groundnut oil, rice bran oil, refined sunflower oil and avocado oil. These can be used for frying.
The economics again
As we said, if someone sells you “cold-pressed oil” for 180 to 200 rupees, under 200 rupees, it definitely means some other oil has been mixed in, because only with two and a half to three kilograms of groundnuts do we get one litre. With refined oil the cost of production is a little lower, because with solvent extraction one kilogram of groundnuts gives up to 550 ml, while cold pressing gives 400 ml. So even if refined oil comes at 200 to 250 rupees, or even around 300 rupees, that is okay. If it comes very cheap, then we need to think.
What the scientific studies show
- A 2021 study in BMC Medicine showed that olive oil and canola oil reduce cardiometabolic mortality.
- A study published in Harvard reviews shows that vegetable oils or seed oils high in polyunsaturated fatty acids have lower heart disease risk when compared with saturated fat. But they compared polyunsaturated with saturated fat, not polyunsaturated with monounsaturated, and not omega-6 with omega-3.
- An umbrella review published in 2024 shows that monounsaturated fats, olive oil or groundnut oil, reduce LDL to some extent and also reduce inflammation.
- Another published study suggests olive oil may reduce breast and other cancers and digestive diseases to some extent.
Frequently asked questions
How much cooking oil should we use?
This is more important than which oil we use. Roughly 500 to 750 ml per person per month. So if there are four people at home, use two to three kilograms. If we use more than that, we must understand that we are using too much oil.
Can we mix different oils?
Blending is healthy, because then the polyunsaturated and monounsaturated fatty acids and the omega-3 to omega-6 ratios combine. Mix them so that there are monounsaturated fats along with polyunsaturated fats: groundnut oil, rice bran oil and sesame oil (our gingelly oil) can be mixed.
Which oil is best for heart patients?
Olive oil is best, canola oil can be taken, or rice bran oil or groundnut oil. But oils very high in saturated fatty acids, such as ghee and coconut oil, may not be so good for people who already have heart disease.
Can we fry again in oil that was already used?
Reusing is not good. When oil is reused, free radicals are generated, and oxygen free radicals can cause many diseases. Aldehydes and acrylamide can form, and trans fatty acids can increase. That increases inflammation, heart disease and cancer risk. So once we fry in oil, we should not reuse it repeatedly. Similarly, if we buy bajjis from a roadside bajji cart and the oil is being reused, we must notice that it is dangerous for us.
Is coconut oil healthy?
There is a lot of discussion on this. Coconut oil is about 90% saturated. Because of it, LDL rises and HDL rises. Within the rising LDL, people talk about small dense LDL and so on; we will discuss that separately. Coconut oil can be used, but in small amounts, and people with heart disease are better off not using much. For example, in Kerala they use coconut oil for everything, and heart disease in Kerala is not low; it is high. So the idea that coconut oil reduces heart disease is not correct. Because it is high in saturated fatty acids, it may raise risk somewhat or keep it the same, but it will not reduce heart disease.
What about ghee?
We have spoken about ghee in a previous video; you can watch that. Taking a little occasionally is fine, but if we use a lot of ghee it has a lot of saturated fat, so problems are more likely. Do not use too much ghee.
Can olive oil be used in Indian cooking?
Extra virgin olive oil can be used for salads, sautéing and low-heat cooking. When I make salads occasionally, I use extra virgin olive oil. But it is not suitable for deep frying or high-heat Indian cooking. Light olive oil or pomace olive oil can be used for higher heat; its smoke point is a little higher.
Can we avoid oil completely?
Avoiding it completely is not good, because the fat-soluble vitamins A, D, E and K are not absorbed without fat. Some fat is needed, but limited. I have said the worst possible food is high-fat, high-carbohydrate food. You do not need to take low-fat, low-carbohydrate food; if we take both moderately, it is better both ways.
How to store cold-pressed oil
Storage of cold-pressed oils must be careful. Store them in dark glass bottles, keep them away from heat, and light should not fall on them. Do not buy a lot of cold-pressed oil at once, like 5 litres. Buy fresh in smaller bottles and the nutrient value stays higher. Some people I know buy 5 or 10 kilograms of cold-pressed oil at a time; that way they become ordinary oil, the nutrients are lost, and they also spoil. So even if you bring cold-pressed oil, use it within two to three months. Buy small amounts and use them over time.
Why are some oils yellow and others clear?
Natural pigments add colour. Refined oils are heavily bleached to remove colour, so they look light, almost white and transparent, and people present that as a sign of health. It is not a sign of health. Cold-pressed oils keep some natural colour, which changes depending on the seed.
Conclusions
We learned many things about oil today. The important thing is that when we talk about oil, we must look at the whole picture; looking too closely does not help.
- No single oil is a villain. Do not believe that one oil alone will ruin or fix your health. Even if you take sunflower oil or refined oil, do not think it will kill you. Chronic heart disease and chronic inflammatory diseases depend on overall diet, exercise, genetics, sleep and stress, not on oil alone. So do not overthink about oil. Total lifestyle is very important.
- Use less oil. Using less oil is more important than using a different oil. In Indian cooking we use a lot of oil: bajjis, samosas, pakodis, garelu, puris, chakralu, chips, boondi, vadiyalu, mixture; there are many snacks we fry in oil. Reduce them. Even our curries have mostly become fries; we hardly eat anything that is not fried. Reducing the quantity of oil is more important than using a different type of oil. Quantity is more important than quality. Take a spoon; do not pour.
- Do not be afraid of words. Do not simply fear internet villains like refined oil, seed oil and omega-6. Watch this video again if needed. Refining just means removing impurities and increasing shelf life; there is no need to see “refined” as a big ghost. But solvents like hexane used during refining are a problem if used too much, and we should also think about whether adulteration happens.
- Seed oils such as mustard oil, sesame oil and groundnut oil have been used in our kitchens for hundreds of years, and nothing very dangerous has happened because of them, so they can be used. We need omega-6 for the body too, but it should be in balance with omega-3.
- Reading studies on oil is difficult and complex, because in clinical studies people do not take oil alone; there are many confounding factors, along with lifestyle, genetics, medication and cultural diets. So it is very hard to say that eating this oil makes you live longer or shorter. Do not believe such claims.
Finally, do not think there is some magical oil that will work wonders. Use a small quantity, do not reuse it, eat more whole foods, reduce fries, and rotate oils: cold-pressed oils for low-heat cooking and refined oils for frying. Avoid fear-based marketing and ultra-purity obsession.
Also, if we take two or three oils and mix them monthly, we get good benefits, because we get monounsaturated, polyunsaturated and omega-3 fatty acids together. A simple regimen: take some groundnut oil, some sesame oil and some refined oil, and if you use these three without crossing about 3 litres a month, you can get good benefit.
So do not think some big ghost has come with oils. Whatever oil you use, using a little less is good. Saying scientifically which one is definitely best is hard, so in general it is enough to remember the broad guidelines: avoid trans fatty acids, avoid repeated reheating, maintain the oil quantity, and rotate oils.
In his words: the key point
Avoid trans fats, avoid repeated reheating, keep the quantity low (about 500–750 ml per person per month), and rotate oils.
Frequently asked questions
How much cooking oil should a family use per month?
Dr. Mukharjee advises about 500 to 750 ml per person per month, so two to three kilograms for a family of four.
Is cold-pressed oil better than refined oil?
Cold-pressed oil keeps antioxidants and has no hexane, but has a low smoke point and short shelf life, so use it for low-heat cooking. Refined oils such as rice bran or groundnut can be used in moderation for high-heat cooking.
Which oil is best for heart patients?
Olive oil is best; canola, rice bran or groundnut oil can be taken. Ghee and coconut oil, being high in saturated fat, may not be so good for people with heart disease.
Can I reuse frying oil?
No. Reused oil generates free radicals, aldehydes, acrylamide and trans fats, increasing inflammation, heart disease and cancer risk.
— Dr. M. S. S. Mukharjee
Senior Interventional Cardiologist
Pulse Heart Super Speciality Hospital, Miyapur, Hyderabad
This article is for educational purposes only and isn't a substitute for individualised medical advice. Talk to your own doctor before starting, stopping or changing any medicine.