Olive oil and the heart: a daily dose can cut your heart disease risk
Just four teaspoons of olive oil a day can reduce heart disease risk in six weeks, according to research.
Just four teaspoons of olive oil a day can reduce heart disease risk in six weeks, according to research.
We all know the virtues of the Mediterranean diet, but whose spirits don’t sink at the thought of a healthy tomato or chickpea salad as winter approaches?
You may be happy to hear, then, that scientists have managed to prove conclusively that having a small daily portion of olive oil can improve heart health on its own, without a single chickpea or aubergine.
Metabolic health researcher Dr Bill Mullen from Glasgow University discovered that just 20ml (4 tsp) a day of raw – uncooked – olive oil can reduce biomarkers for heart disease within six weeks.
“In 25 years of nutritional research, I have never seen results as statistically significant and as clear,” he says. “You can tell someone to eat an apple a day all you like, but you can’t prove the effect of that apple.
“Now we can say for certain that olive oil has a measurable effect.”
His study took volunteers from Glasgow, an area with a traditionally low intake of olive oil and a high incidence of heart disease. They were given as a drink either a daily 20ml of standard olive oil or extra virgin olive oil (they didn’t know which), then their urine was measured.
Samples were taken in 2013, but it was only recently that Dr Mullen was able to use a new kind of test involving “multi-peptide biomarkers” to search for certain protein fragments in the urine linked to poor heart health – a kind of fingerprint for heart disease.
A reading above zero meant you had heart disease (+1 was the worst); a reading of -1 meant very healthy, with no heart disease present. Both kinds of oil produced a positive change in the readings from week three, and it was still improving at week six when it reached 0.3.
Not unless you want to. “It’s really easy to get 20ml a day,” says Dr Mullen. “You can use it in salad dressings and drizzle it on all kinds of things. As a wee starter, I have a little bowl of olive oil with some balsamic vinegar and dip my bread into it. It’s so simple. Or just eat olives – four or five may give you 4.4ml of oil.
“Instead of using butter, I pierce my warm toast with a fork and drizzle olive oil over so that it soaks in.”
And even if you don’t consume it every day, it will still be advantageous to your health if, in the long term, you have more days of olive oil intake than not.
Other oils, like rapeseed and sunflower, don’t appear to have the same effect on heart health, though Dr Mullen tested those on different volunteers in a separate study, so the comparison is not exact.
Scientists aren’t sure if it’s one nutrient, or the fact that you tend to use it in place of less healthy fats. “It’s really difficult to know, which is why we need more research,” says Dr Mullen, who conducted his latest research using funding from Italian olive oil producers Filippo Berio, though he has been working on oils for 12 years using a variety of funding.
Olive oil is what’s called a monounsaturated oil, the kind also found in nuts and avocados. It contains predominantly monounsaturated fatty acids such as oleic acid, which have an anti-inflammatory effect. It also contains a little saturated fat (14%) and polyunsaturated fat (11%).
Some studies have found that olive oil lowers levels of “bad” LDL cholesterol that builds up as plaque deposits in your blood vessel walls and narrows them.
“Olive oil in your diet can also increase HDL, which is protective against heart disease,” says Priya Tew of Dietitian UK.
It also contains vitamin E (1 tbsp or 14g has 1.9mg, which is around half your recommended daily amount, according to the NHS), which is a powerful antioxidant and good for heart and eye health, plus vitamin K (1 tbsp or 14g has 8mcg, around 10% of your RDA), which plays a role in blood clotting and bone health.
Extra virgin olive oil – the purest kind that’s pressed from ripe olives without heat – also has high levels of polyphenols, antioxidants that protect cells from damage and reduce your risk of many chronic diseases.
It doesn’t seem so, based on this study. Both groups enjoyed the same benefits to heart health. And there were fewer dropouts in the standard olive oil group, probably because of its milder taste. However, most studies do show that extra virgin oil has greater health benefits as it is less refined and therefore retains powerful plant chemicals.
“In all the big population studies, extra virgin olive oils always come out better over 20 or 30 years, probably because they contain polyphenolic compounds that act as antioxidants in the body,” says Dr Mullen.
Generally, the more expensive the olive oil, the less processed it is, and hence the higher concentration of polyphenols it has. In a study at the University of Granada, researchers showed that frying vegetables gently in extra virgin olive oil increased their antioxidant capacity and was healthier than cooking them in water.
However, if you’re frying something at high heat – such as steak – it’s best not to use extra virgin oil. Heat destroys the polyphenols, so you’re wasting your money, and it has a lower smoke point than normal olive oil, so it could release harmful compounds, according to Professor Martin Grootveld at De Montfort University, Leicester.
Anything that’s good for your heart is also good for your brain, as it keeps blood vessels healthy and preserves blood flow – including to your head, which reduces the risk of cognitive decline. This may be why studies have consistently found low rates of dementia in cultures that consume a lot of olive oil.
In fact, a US population study, published in 2022, analysed the diet of 90,000 people over 28 years and found that those with the highest olive oil intake – more than half a tablespoon a day (7.8ml) – had a 29% lower risk of dying from neurogenerative diseases like dementia. They had a 19% lower risk of dying from cardiovascular disease, 18% less chance of dying from respiratory disease and a 17% lower risk of dying from cancer. Even one teaspoon of olive oil a day was associated with a 12% reduced risk of death from all causes.
“Once the plaque is there in your arteries, it’s there – you can’t move it,” says Dr Mullen. “You can control it with drugs, but you can’t cure it. That’s why the whole basis of our study was to pick up biomarkers of heart disease before it got to a bad state in 20 years.
“However, if you change your diet, you could stop it getting worse.”
(Hero image: Getty Images)
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