ZOE Science & Nutrition - Recap: How to get the most out of olive oil | Elizabeth Berger & Tim Spector

Episode Date: July 8, 2025

Today we’re talking about olive oil. Touted as one of the hottest health foods right now, olive oil has been linked to a range of benefits - from reducing inflammation and boosting heart health to even increasing longevity. But is it truly liquid gold, or just another fad? I’m joined by olive oil grower Elizabeth Berger and Professor Tim Spector to explore the science behind this ancient elixir and share practical tips for getting the most out of your drizzle. 🥑 Make smarter food choices. Become a member a zoe.com - 10% off with code PODCAST 🌱 Try our new plant based wholefood supplement - Daily30+ *Naturally high in copper which contributes to normal energy yielding metabolism and the normal function of the immune system 📚 Books from our ZOE Scientists: The Food For Life Cookbook by Prof. Tim Spector Food For Life by Prof. Tim Spector Every Body Should Know This by Dr Federica Amati Free resources from ZOE: Live Healthier: Top 10 Tips From ZOE Science & Nutrition  Gut Guide - for a healthier microbiome in weeks Have feedback or a topic you'd like us to cover? Let us know here Listen to the full episode here

Hello and welcome to Zoë Recap, where each week we find the best bits from one of our podcast episodes to help you improve your health. Today we're talking about olive oil. Touted as one of the hottest health foods right now, extra virgin olive oil has been linked to a range of benefits, from reducing inflammation and boosting heart health, to even increasing longevity. But is it truly liquid gold or just another fad? I'm joined by Elizabeth Berger and Professor Tim Spector

to explore the science behind this ancient elixir and share practical tips for getting the most out of your drizzle. In the 1960s, it was noted that Mediterranean countries had much less heart disease than Northern European countries. People thought it was something in the diet. They thought it was just about the wine or the lifestyle. They couldn't really know what it was, but it was the vegetables.

It turns out that it's been a slow bit of detective work to work out that the amounts of fats consumed in Mediterranean countries is actually quite high, which went against the sort of theories of 20 years ago that fats were bad for you. But it turns out the main source of fats in the Mediterranean is olive oil. So huge amounts of fats are consumed in the form of olive oil. So that started people thinking, well, maybe there's something in olive oil that's actually healthy despite the fact that you can get up to 12% of it is saturated fat, which we're all told in the US and the UK is really bad for you.

So you have these Mediterranean countries drinking a lot of saturated fat in their olive oil and they have much lower rates of heart disease. So people started then looking at olive oil itself, which it wasn't studied much because it was very low levels in the US and the UK where a lot of this epidemiology was being done. And so gradually more and more studies have shown that people who drink olive oil regularly compared to those in the same country that drink lesmantes, have significantly lower rates of heart disease, stroke, and increasingly evidence that cancer is less.

Now, this was all observational. There are at least 30 studies of observational cohorts showing this, and there are hundreds of smaller studies now showing that if you give say you know the normal diet type study of 20-30 people, give control groups you can see changes in their bloods and their blood fats and inflammation going down. There haven't been any large-scale long-term studies until 2018 when they did something called the PrediMed study. It was randomized but not blinded because they were delivering large amounts of olive

oil to 7,000 Spaniards, large amounts of mixed nuts to another group, another group that were just giving the standard Mediterranean meals and they followed them up for six years. And this was about the best study that had been done and clearly showed that the olive oil group had these really significant reductions in heart disease and strokes and breast cancer. So Tim, I just want to be clear, like the drug intervention in this study over six years was literally just got sent bottles of olive oil and the people who got sent bottles of olive oil actually had lower levels of strokes and

things like this. And heart disease, yes. It sounds crazy, right? And breast cancer and some signs that were getting less brain dysfunction leading to dementia. And it was an amazing study because it was a huge logistic exercise to keep people stocked up with this. And they were giving them the equivalent of about four tablespoons a day, which actually

is not far off some levels you'd have in bits of grease, for example, which would be seen as quite normal, but 100 times more than you'd get in the UK or the US, where we're only really drinking one bottle of olive oil a year, as opposed to one every two days in many Mediterranean countries. So this, I think, was a fairly pivotal study, but there have been other ones since in the US showing it's not just a Spanish thing, because they were sponsored by the olive oil industry, and Spain does have a slight interest in promoting it.

They're the biggest producer in the world. But in the US, cohort studies comparing olive oil drinkers against non-olive oil have found virtually the same results. So I think we're now very confident that drinking extra amounts of olive oil and particularly extra virgin olive oil has these major benefits. It seems to be that that is quite important, that the quality is important and the few studies that have looked and compared extra virgin against virgin or basic industrial level olive oil have shown clear differences. So I think it's, it suggests it's the extra ingredients in the extra virgin

olive oil rather than necessarily just the fats themselves. So perhaps a combination of both. I'd really like to just spend a minute on this sort of thing about the composition of the extra virgin olive oil over time. We've had a lot of questions around that. And I heard Tim mentioned that there'll be lots of American and British listeners who might have like a bottle of extra virgin olive oil that might be sitting, you know, in the shelf for two years.

How stable is this extra virgin olive oil? How does it change in the following months and years? Yeah. So the process is, is that the olive oil is produced and then it then typically naturally decants. So it takes a little bit of time where the sediment falls to the bottom. You then have a choice as a producer whether you filter or you don't filter. In terms of super high quality, you would wish for a light filtration of your oil. And there's a reason for that because an unfiltered oil, and I'm sure that this is one of those myths that's out there

that an unfiltered olive oil is really great because you see it in those lovely clear bottles and it's got that lovely cloudy look to it. It must be real. It must be the real deal. It's actually not. That's actually not great for a couple of reasons. One, you shouldn't have your olive oil in clear glass because it will change its quality. So you're looking for dark glass as the very, very best format for extra virgin olive oil. But the other thing is that that sediment that is in suspension in the olive oil will actually start to oxidize the oil with time. So anything that needs to be shipped, we have to think about these things. You know, if something's being shipped globally, it does need to be stable.

And so a light filtration won't change the quality at all. It will actually enhance the quality because it'll give it a little bit of stability in terms of shipping. So to confirm, if you see a bottle of olive oil that sort of says it's unfiltered and has some sediment in, which I've definitely seen and always thought that looks pretty cool and very authentic. Actually, that's like a complete no-no. Don't buy that because basically that sediment will have been continuing to react with the olive oil and I'm going to lose the health properties we're talking about. Exactly right.

Yeah. That's even if it's really bright green as well. Totally. Which is another marketing thing, isn't it? Well, that's to do with the cultivar. And when I say cultivar, I mean the variety. So when you start to dig deep, you've got over $3,000 cultivars in the world. In Italy alone, there are over 600. So they are different varieties, and they will give a slightly different flavor of oil.

And we're going to taste that, and we're going to see what that difference might be. But I think as well, heading a little bit back to the polyphenol point, there are certain olive cultivars that have a naturally higher polyphenol level. Each area has got its own, and even within the variety, you know, when it's low lying or high on a hill you get very different. Exactly. Provenance makes a real difference.

And I think the other thing to consider is whether something's a blend or whether it's a monocultivar. You know, having a pure monocultivar, what you get from that in an olive oil is just definition. So you will be able to taste its different points. Whereas a blend, as with wine, it doesn't diminish the quality at all of the olive oil, but the blend should be greater than the sum of its parts. So the end result should be better than if those particular oils had been made

as monocultivars. So if we imagine that we've now learned to reject the bottles that have all that really nice stuff at the bottom. Not clear glass because that's going to damage the olive oil over time? It will oxidize, yeah. It's much more likely to oxidize because it'll get the light rays that will just damage it and change it. And so does that mean, back to the question I asked at the beginning about tin versus bottle? Yeah, so I mean in terms of the bottle, the very best is dark glass and you shouldn't keep it next to your stove. So all of the things that I used to do when I was just putting my olive oil in the cart, lovely clear bottle, looked really authentic, sort of Italian sounding perhaps, nice and

unfiltered and then keeping it next to the stove, all of those things are wrong. So really what you want to do is you want to keep it where the temperature is constant. So away from the stove, away from a window where the temperature will fluctuate quite a lot. So if you can keep it, you know, you could always keep it in a cupboard, perhaps where you keep your salt and pepper and that sort of thing. And is a tin better than a dark glass therefore because no light comes through? So what happens with a tin is that it's a very good container. There's no question about that. But the trouble is that as it depletes, as the oil depletes in the tin, that space is filled with oxygen, which is oxidizing the rest of the oil. There are ways around this.

There is now a technology of bag-in-box and the bag actually closes in around the oil. That's very clever because then it's reducing the contact with oxygen, which is really important. But if you do like to have a tin and if you're buying your oil in quantities, the best thing that you can do is to decant it into dark glass and then put a proper top on it. Imagine that we have now learned also it's in dark glass. Yes. It's been lightly filtered. But you know, I'm in America, right? Presumably takes a long time for this to eventually arrive, you know, in my grocery store. How fast are these amazing chemicals decaying? You know, how many months or years does this olive oil remain good?

Does it remain good forever? Yeah, so it goes on a journey. So you've got very, very high polyphenols just after the point of harvest. So really, the main point is to be able to get access to that oil as soon as you can. And so, you know, finding a way of getting new seasonal olive oil into your life before Christmas is a great thing. That's when it's really going to have the greatest benefits for you. And you need to think about distribution, as you've quite rightly said,

because of course, if you're buying olive oil from a supermarket, it will have been stuck in the distribution chain for an amount of time. There's no question that you would have new season olive oil in the US before perhaps March or April time. And the polyphenols have taken a journey during that time. So they will have gone down in there. They go down by about a half every six months or so, is that? If you think about the way that the Mediterranean's consume olive oil, they would be consuming

that within a year because of course then there's the next harvest. On the two problems here, one is the amount of polyphenols you might lose with time. Yes. And the other is whether you're oxidizing the fats and it's slowly going rancid. Exactly. Could you just sort of tease those apart? Yeah, absolutely. So the polyphenols take this journey where they're very high at the start, just after they've been harvested, and then they taper off.

And they're protecting not only you, but they're also protecting the oil. They're protecting the oil, and that's the fundamental thing. So as they go down, the oil is getting less protected and it softens. So that pepperiness that you get right at the beginning of the season, many people have actually never tasted because of course, you know, if you're buying your olive oil in a supermarket already, it's been around for probably six months before you take it off the shelf. If you look at the back label of any bottle of extra virgin olive oil, it will tell you the harvest date. And it's really, really worth checking because there's no way that you want to be spending 20, 30 pounds on a

really, or dollars for that matter, on a really, really good bottle of olive oil. And it's a year old. It would be a shame to do that. You really want to be trying to get it when it's as young as possible. So there are a number of faults that you can get in the production process. Perhaps there was some imperfect fruit that went into the press. Perhaps something happened along the way of the production. Perhaps it's been oxidized prematurely. Exactly right. Exactly right.

It's a fault for acidity and you can definitely smell it. As I said before, the light filtration can avoid anything like that. If someone's thinking about this, it's like, I'm not as sophisticated about the taste as you, price probably plays into my thinking here as well, because it's expensive. I'm taking away from this that if it's been sitting there for five years, I probably really lost quite a lot of health benefits. Five years, yeah, you wouldn't want to consume it for five years.

Help me to understand, has all the health benefits disappeared at 12 months from an extraversion olive oil? Is this really something that- 18 months is what you're looking at. So after 18 months, then it's really lost the majority of its health benefit. It's still an oil that you're looking at. So after 18 months, then, you know, it's really lost the majority of its health benefit. It's still an oil that you could cook with. You know, you could roast your potatoes with it and that sort of thing. There wouldn't be, you know, there wouldn't be any issue.

And if I went into a grocery store and just picked an extra version of olive oil off the shelf, am I guaranteed that that will be within the, that it will have been harvested within the last 18 months? Or could that already be? It should have been, but that's why you need to check the label because, you know, distribution is a complex sort of a thing, you know, and it could well be that something could be on the shelf. I've actually seen it a number of times.

I recall most recently in New York seeing a bottle of oil that was $50 on the shelf. I turned it around and it was over 18 months from the harvest date. Oh wow. So this is like a very, very premium bottle. And you're saying that if it's not within 18 months, you're really, you've got to accept you're not really getting the, you're going to tell me that it doesn't taste very nice, but also that the health benefits are really not. Totally different.

You know, that works with, with many, many things. You know, shelf life is an important factor. You know, it's something that would happen, let's say with face moisturizer. You know, it would have a shelf life. And so you would need to know when it had been bottled. Thank you for listening to today's recap episode. I want to take 30 seconds to talk about something that's not talked about enough.

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