Is sunflower oil better for you than olive oil?

Cooking oil is a slippery subject. With seemingly endless varieties, ranging from dependable vegetable oil to trendy avocado oil, it’s hard to know where to turn in the oil aisle. Add to this the doubts over the health benefits of some oils when they are heated, such as extra virgin olive oil, and you may be tempted to stick to lard.

In fact, the ideal choice may be one of the most common oils used for cooking in Australia. In its “virgin” form, it contains healthy organic compounds called polyphenols, which are powerful antioxidants. And while these are removed to create oil for cooking, the refined version many of us use still has health benefits.

With seemingly endless varieties of cooking oils, it’s hard to know where to turn in the oil aisle. But sunflower oil can have its benefits.Credit: iStock

What is sunflower oil?

Sunflower oil is an unsaturated fat that is mainly sold in two forms, refined and virgin. Both are sources of vitamins E and K. Vitamin E helps maintain the immune system, healthy skin and eyes, while vitamin K helps blood to clot properly.

In addition to polyphenols, the virgin version contains lecithin, a nutrient similar to the B vitamins, and carotenoids, which have anti-inflammatory properties. The more the oil is refined, however, the more these compounds are removed. One study found that heavily refined sunflower oil lost almost all of its carotenoid content.

Many of the extra nutritional benefits of virgin sunflower oil are also lost when it is heated beyond a point known as the “smoke point”. This is where the fats and compounds in the oil change and start to break down. For this reason, in order to gain the maximum nutritional punch from virgin sunflower oil, it is best used as drizzle and in dressings.

All types of sunflower oil contain omega-6, a type of polyunsaturated fatty acid (PUFA) that the body cannot make itself. It plays an important role in brain function and helps stimulate skin and hair growth, maintain bone health, regulate metabolism and maintain the reproductive system.

Sunflower oil also contains low levels of omega-3, which is important for the heart, blood vessels, lungs, immune system and endocrine system (the network of hormone-producing glands).

Potential health benefits of sunflower oil

1. Heart health benefits

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Research shows it can play a role in lowering levels of LDL (bad) cholesterol, and raising levels of HDL (good) cholesterol, thereby reducing risks of high blood pressure and cardiovascular disease. According to a 2019 paper, the high levels of omega-6 (also known as linoleic acid) in sunflower oil can reduce the risks of cardiovascular disease.

Replacing saturated fats with sunflower oil will also benefit heart health, as Tracy Parker, a senior dietitian at the British Heart Foundation, says: “The current advice is that it is better for our hearts to replace saturated fats with unsaturated ones.”

Professor Sarah Berry, chief scientist at health science company Zoe, says: “There’s some evidence that omega-3 might help reduce high blood pressure.”

2. Brain health benefits

Sunflower oil contains 41g of vitamin E per 100g and several studies draw links between vitamin E deficiency and cognitive impairment. Some evidence even suggests vitamin E may slow the progression of Alzheimer’s disease, with a 2022 study concluding a diet high in vitamin E might be helpful in preventing future cognitive decline. Another analysis published in BMJ Open suggests omega-3 can lower the risk of “mood dysfunction”.

3. Anti-inflammatory properties

Vitamin E is also an antioxidant, and sunflower oil contains twice as much as olive oil. Antioxidants help to prevent inflammation.

4. Gut health properties

Virgin sunflower oil may also provide gut health benefits, as Dr Emily Leeming, author of Genius Gut, explains: “Depending on the quality of the oil, it can supply our gut microbiome with polyphenols, which are a group of antioxidants that feed our gut microbiome in a similar way to fibre, which then helps gut bacteria to produce these special molecules that influence our health.”

In order to gain the maximum nutritional punch from virgin sunflower oil, it is best used as drizzle and in dressings.Credit: iStock

Potential health risks of sunflower oil

1. Oxidation and aldehydes

Heat sets off chemical reactions in oils that change the compounds in them and degrade them. This is known as oxidation. When cooking oils reach their smoke point, they can also emit fumes that contain toxic substances called aldehydes, which have been linked to cancer and other diseases. Polyunsaturated cooking oils such as sunflower and rapeseed have high smoke points, which make them more stable to cook with, but they have been shown to emit high levels of these compounds.

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However, normal home cooking is unlikely to create significant levels of oxidation or aldehydes. Berry explains: “This is only a concern if cooking oil is used repeatedly at very high temperatures. That’s why chip shops and fast-food restaurants have to regularly change their oil.

“But at home, we don’t cook like that, so there’s no need to worry. Sunflower oil does produce toxic aldehydes when heated, but again, this is more of a concern for high-temperature cooking and oil that is reused. Randomised controlled trials have studied the effects of heating oils and show no harmful effects on human health when heated in the way we would typically use oils in the home.”

2. High omega-6 content concerns

While the benefits of omega-6 have been well studied, there is debate that too much can increase inflammation. However, most experts agree that these fears are unfounded.

Berry says: “There’s a lot of misinformation surrounding seed oils and nonsense around the potential harms due to their omega-6 content. But it’s all based on the cherry-picked evidence. Studies show that there’s no clear link between consuming linoleic acid [omega-6] and inflammation. In fact, the evidence clearly shows a benefit. Unfortunately, there are lots of people on social media who can’t interpret evidence, making wild unsubstantiated claims about the ‘harms’ of omega 6 and seed oils such as sunflower oil.”

3. Potential impact on cholesterol levels

While studies have shown that a diet rich in high-quality sunflower oil can lower LDL cholesterol, it is also a high-calorie food, and over-consumption can lead to excess body weight and the associated health risks.

Comparing sunflower oil with other cooking oils

Organic virgin sunflower oil that is not heated has numerous beneficial compounds, and refined sunflower oil used in cooking also maintains some health benefits. Neither virgin nor refined sunflower oil contain the artery-clogging saturated fat of tropical oils such as palm oil, coconut oil and shea butter.

However, Berry says: “The queen of cooking oils is extra virgin olive oil, which contains high levels of antioxidant polyphenols. However, some of the beneficial compounds, called polyphenols, in extra virgin olive oil are sensitive to heat, which means it loses some of its benefits when cooking at a higher temperature.” It’s fine for frying, sautéing, roasting and baking but, like sunflower oil, not deep frying or for reuse.

The best oil for frying is regular olive oil, as it’s less likely to degrade than sunflower, rapeseed and extra virgin olive oil. It doesn’t contain the same level of beneficial compounds as extra virgin olive oil, but it’s still a source of heart-healthy monounsaturated fats.

Is sunflower oil a healthy choice overall?

Berry concludes: “Sunflower oil is versatile, cost-effective and widely available. These days, there’s a lot of hype about new, relatively expensive types of oil, like coconut oil and avocado oil, but sunflower oil performs well as a healthy oil with broad applications for many different cooking needs. It’s also important to remember that we typically use a small amount of oil when cooking, so cooking oil’s impact on your overall health, whether positive or negative, is likely to be small.”

The Telegraph, London

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