Olive oil consumption is linked with longer life – and less risk from heart disease, cancer and Alzheimer’s. But how much do you need to live longer?
A new study has provided a little more evidence that olive oil, is, in the words of one distinguished researcher, “virtually a magic substance”. The research, questioned 90,000 health workers about their consumption of olive oil over a 28 year period. It found that those who consumed olive oil – even in small amounts – reduced their risk of dying over the following 28 years by an impressive 19%.
Of course, it’s not as simple as that, and the study reminded me a little of the often cited statistical link between eating ice-cream and an increased risk of drowning. In this famous case, it’s not hard to see that the same weather that increases ice-cream sales might prompt more hazardous swimming, and it also seems likely that people who consume more olive oil might be doing other things that make them live longer.
But the research, published in the Journal of the American College of Cardiology and including notable figures from Harvard University’s T.H. Chan School of Nutrition and Public Health such as Walter Willett and Frank Hu, presents an intriguing association rather than a slam-dunk cause and effect. It’s about the beneficial effect of a type of diet, indeed a kind of lifestyle – the sort that includes olive oil – on the risk of disease.
The observational study was on a huge scale, with questionnaires about diet put every four years to the 60,000 women from the Nurses’ Health Study and the 32,000 men from the Health Professionals’ Follow-up Study. It also carefully measured other factors putting them at risk of disease.
During the almost 30 years of the study, around 37,000 people died (they’d been an average of 56 years old at the beginning of it). The researchers, led by Marta Guash-Ferré, compared the incidence of disease among those who had the lowest intake of olive oil – rarely or never – with those who consumed the highest amount – more than 7 grams a day or about half a tablespoon.
Olive oil consumption is linked with a lower risk of disease – but it could also be a marker for a healthier lifestyle.
They found that compared to those with the lowest intake, participants with the greatest consumption had a 17% reduction in their risk of death from cancer, an 18% lower risk of dying from respiratory disease, 19% lower risk of mortality from cardiovascular disease, and a 29% reduction in the risk of death from neurodegenerative diseases such as Alzheimer’s, Parkinson’s, and multiple sclerosis.
Naturally, the benefit of consuming olive oil comes partly from what it’s replacing, what you’re NOT eating – for example, saturated fats such as butter, and other processed fats such as margarine and mayonnaise. Dr Guash-Ferré and her colleagues estimated that replacing 10g a day of these fatty foods with the largely monounsaturated fat of olive oil was associated with a lower risk of death from various causes of somewhere between 8 and 34%.
Replacing just 10g of a fat such as butter with the same amount of olive oil each day was linked with a lower risk of death as high as 34%.
There are a couple of aspects to the study about which the critical might raise an eyebrow. Firstly, the difference in consumption of olive oil between the lowest and highest category is a mere half tablespoon a day (barely enough to make a salad dressing), and less than a quarter of that – half a teaspoon or around 1.5g – was enough to register a 12% reduction in the risk of death.
In an editorial accompanying the article, Dr Susanna Larsson of the Karolinska Institute in Stockholm summed it up like this: “it’s a bit hard to believe that such a small amount could have an independent effect on mortality risk”. Olive oil is virtually a magic substance, but perhaps not that magical.
Apart from this generally low consumption of olive oil, modeling by the researchers suggested that vegetable oils were about as effective in reducing the risk of mortality. That reinforces the idea that at least part of the reason for olive oil’s benefit to health lies in replacing more harmful processed or saturated fats with either monounsaturated or unprocessed polyunsaturated fats.
Olive oil has properties lacking in most vegetable oils however: it is largely made up of monounsaturated fat (as is avocado oil) and contains protective antioxidant polyphenols (see article, Oxidation is Killing Us. Antioxidants in Foods Can Neutralize the Free Radicals Causing Aging and Disease). Monounsaturated fat has been shown to be more friendly to the heart than other fats, it’s less inflammatory than the omega 6 fats in polyunsaturated vegetables oils, and it is less susceptible to oxidation than they are.
However, perhaps the most significant factor is the sort of lifestyle that goes with even remarkably modest amounts of olive oil. The study found that people consuming more olive oil had a better diet in general, were more physically active, and less likely to smoke. Any one of these factors could eclipse olive oil consumption alone in giving you a longer health span, and indeed a longer life.
It’s also worth bearing in mind that virtually all the participants in the study were white, they were generally of normal weight and ate between 4.8 and 7.2 servings of fruit and vegetables a day. They were also all in the health biz!
One other intriguing finding about this population emerged: their average intake of olive oil increased significantly in the 28 years of the study between 1990 and 2019, from 1.6g a day (around half a teaspoon) to 4 grams a day. It means that whatever benefit they were getting from the olive oil, it was increasing at the same time as was their risk of these diseases of aging.
However, compare that with the intake of the Spanish population that took part in a well-known study called PREDIMED that suggested significant benefits from olive oil. They were consuming between 20 and 22g a day of extra virgin olive oil (replete with polyphenols), and 16 to 18g a day of refined or mixed olive oil (enough to displace a lot of saturated fat). That sort of intake suggests not only an opportunity for the properties of olive oil to act in the body, but also the true Mediterranean diet, and perhaps also the Mediterranean lifestyle of healthy aging.
The average intake of olive oil for people in the study grew to 4g a day in 2019. Even this tiny amount was linked with significant reductions in the risk of disease.
