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

Summary

Podcast Summary: Recap: How to Get the Most Out of Olive Oil | Elizabeth Berger & Tim Spector

Podcast Information

• Title: ZOE Science & Nutrition
• Host: Jonathan Wolf
• Episode: Recap: How to Get the Most Out of Olive Oil
• Release Date: July 8, 2025

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Introduction: The Olive Oil Debate

In this episode of ZOE Science & Nutrition, host Jonathan Wolf delves into the enduring question: Is olive oil truly the "liquid gold" hailed for its myriad health benefits, or just another dietary fad? To unpack this, Wolf is joined by nutritionist Elizabeth Berger and Professor Tim Spector, a renowned epidemiologist, who together explore the science behind olive oil's health claims and offer practical advice on maximizing its benefits.

The Mediterranean Connection and Health Benefits

Professor Tim Spector begins by tracing the origins of olive oil's reputation. He explains, "In the 1960s, it was noted that Mediterranean countries had much less heart disease than Northern European countries... but it turns out the main source of fats in the Mediterranean is olive oil" ([00:41]). Contrary to the prevailing belief that high fat intake is detrimental, the Mediterranean diet's emphasis on olive oil correlates with significantly lower rates of heart disease, stroke, and even certain cancers.

Spector highlights the Predimed study, a pivotal randomized trial conducted in Spain, where participants were provided with large quantities of olive oil, mixed nuts, or standard Mediterranean meals over six years. "The olive oil group had these really significant reductions in heart disease and strokes and breast cancer" ([03:17]), Spector notes, underscoring the robust evidence supporting olive oil's cardiovascular and anti-cancer properties.

Quality Matters: Extra Virgin vs. Other Olive Oils

Elizabeth Berger seeks clarification on the nuances of olive oil quality. She summarizes the findings, saying, "the quality is important... the extra ingredients and the extra virgin olive oil rather than necessarily just the fats themselves" ([05:15]). Professor Spector and the Expert Guest elaborate that extra virgin olive oil (EVOO) contains higher levels of polyphenols and other beneficial compounds compared to regular or industrial-grade olive oils.

The Expert Guest emphasizes, "there are over 3,000 olive cultivars in the world... certain olive cultivars that have a naturally higher polyphenol level" ([07:58]). This diversity in olive varieties contributes to differences in flavor and health benefits, with monocultivar oils offering distinct profiles compared to blended oils, which aim to enhance overall quality.

Storage and Shelf Life: Preserving Quality and Benefits

A significant portion of the discussion focuses on the proper storage of EVOO to maintain its health benefits. Berger raises concerns about olive oil longevity, asking, "How stable is this Extra virgin olive oil... How does it change in the following months and years?" ([05:44]). The Expert Guest responds by explaining the importance of light and temperature in preserving olive oil: "You shouldn’t have your olive oil in clear glass because it will change its quality... you want dark glass as the very, very best format for extra virgin olive oil" ([06:56]).

The conversation further delves into the degradation process:

• Oxidation: Unfiltered oils with sediment are more prone to oxidation, leading to rancidity. Berger is advised against purchasing unfiltered oils despite their "authentic" appearance, as sediment can degrade the oil's quality ([07:21]).
• Polyphenol Depletion: Spector notes that "polyphenols go down by about a half every six months" ([11:25]). These compounds not only provide health benefits but also protect the oil from oxidation.
• Shelf Life: The Expert Guest states, "after 18 months, it's really lost the majority of its health benefit" ([13:38]). Berger probes further, confirming that oils older than 18 months significantly lose their health-promoting properties and may not taste as fresh ([13:30]).

Practical Tips for Consumers

To ensure maximum benefits from olive oil, the guests offer several practical recommendations:

• Check the Harvest Date: Always verify the harvest date on the label to ensure freshness. Berger is cautioned, "a bottle of oil that was over 18 months from the harvest date" ([14:06]).
• Preferred Containers: Store EVOO in dark glass or specialized containers like bag-in-box to minimize light exposure and oxidation. The Expert Guest advises against keeping olive oil near heat sources like stoves, suggesting cupboard storage instead ([09:00]).
• Quantity Purchased: To avoid prolonged storage times, consumers should purchase quantities they can use within a reasonable timeframe, typically within a year of harvest ([10:15]).

Conclusion: Embracing Quality and Freshness

The episode wraps up with a consensus that not all olive oils are created equal. Extra virgin olive oil, rich in polyphenols and minimally processed, stands out as the healthiest option when stored correctly and consumed fresh. Berger encapsulates the takeaway: "If it's not within 18 months, you're really not getting the [health benefits]... and it doesn't taste very nice" ([14:42]).

By understanding the science behind olive oil's benefits and implementing proper storage practices, listeners can make informed choices to enhance their health through this time-honored elixir.

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Notable Quotes with Timestamps:

• Professor Tim Spector: "In the 1960s, it was noted that Mediterranean countries had much less heart disease than Northern European countries... but it turns out the main source of fats in the Mediterranean is olive oil." ([00:41])
• Elizabeth Berger: "If it's been sitting there for five years, I probably really lost quite a lot of health benefits." ([13:30])
• Expert Guest: "You shouldn't have your olive oil in clear glass because it will change its quality... you want dark glass as the very, very best format for extra virgin olive oil." ([06:56])
• Professor Tim Spector: "They go down by about a half every six months or so." ([11:25])
• Elizabeth Berger: "Imagine that. We have now learned also it's in dark glass, it's been lightly filtered... How fast do these amazing chemicals decaying, you know, how many months or years does this olive oil remain good? Does it remain good forever?" ([10:40])

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By integrating scientific research with practical advice, this episode equips listeners with the knowledge to select, store, and utilize olive oil effectively, ensuring they reap its full spectrum of health benefits.

Transcript

[Zoe]

Hello and welcome to Zoe 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.

[Professor Tim Spector]

In the 1960s, it was noted that Mediterranean countries had much less heart disease than Northern European countries. And people thought it was something in the diet. They thought it was just a. It was about the wine or the lifestyle or they couldn't really know what it was, but it was the vegetables. And 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, 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, you know, 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, you know, 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 Les Mints, 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 2030 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 it was. 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.

[Elizabeth Berger]

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.

[Professor Tim Spector]

Yes.

[Elizabeth Berger]

And sounds crazy, right?

[Professor Tim Spector]

And breast cancer and some signs they were getting, you know, less brain dysfunction leading to dementia. So it, and it was an amazing study because it was 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 Greece, for example, which would be seen as quite normal, but 100 times more than you'd get in the UK or the US where, you know, 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 that 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, the 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, 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 and the extra virgin olive oil rather than necessarily just the fats themselves. So perhaps a combination of both.

[Elizabeth Berger]

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, because we had a lot of questions around that and I heard Tim mention that 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 on the shelf for two years. How stable is this Extra virgin olive oil. How does it change in the following months and years?

[Expert Guest]

Yeah, so the process 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 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, you know, an unfiltered olive oil is really great because you see it in those lovely clear bottles and it's got that lovely clamorous. Must be real, 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 quality because it'll give it a little bit of stability in terms of shipping.

[Elizabeth Berger]

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 like very authentic. Authentic, actually, that's like a complete. No, no, like, don't buy that because basically that sediment will have been continuing to react with the olive oil and I'm going to lose sort of the health properties we're talking about.

[Expert Guest]

Exactly right. Yeah.

[Professor Tim Spector]

That's. Even if it's really bright, which is another marketing thing, isn't it?

[Expert Guest]

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 olive cultivars in the world. In Italy alone, there are over 600. So they are different varieties and they will give a slightly different flavour 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.

[Professor Tim Spector]

Each area has got its own. And even within the variety, depending on its low lying or high on a hill, you get very different.

[Expert Guest]

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.

[Elizabeth Berger]

So if we imagine that we've now learned to reject the bottles that have all that really nice stuff at the bottom, we not clear glass because that's going to damage the olive oil over time.

[Expert Guest]

It will oxidise. Yeah, it's much more likely to oxidise because it'll get the light rays that will just damage it and change it.

[Elizabeth Berger]

And so does that mean back to the question I asked at the beginning about tin versus bottle?

[Expert Guest]

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.

[Elizabeth Berger]

And is a tin better than a dark glass, therefore? Cause no light comes through.

[Expert Guest]

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.

[Elizabeth Berger]

Imagine that. We have now learned also it's in dark glass, it's been lightly filtered. But, you know, I'm in America, right. Presumably it takes a long time for this to eventually arrive, you know, in my grocery store. How fast do these amazing chemicals decaying, you know, how many months or years does this olive oil remain good? Does it remain good forever?

[Expert Guest]

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 season 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 that.

[Professor Tim Spector]

They go down by about a half every six months or so.

[Expert Guest]

Is that if you think about the way that the Mediterraneans consume olive oil, they would be consuming that within a year. Because of course then there's the next.

[Professor Tim Spector]

Harshest on the two problems here. One is the, the amount of polyphenols you might lose with time, and the other is whether you're oxidising the fats and it's slowly going rancid.

[Expert Guest]

Exactly.

[Professor Tim Spector]

Just sort of tease those apart.

[Expert Guest]

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.

[Professor Tim Spector]

You, but they're also protecting the oil.

[Expert Guest]

They're protecting the oil and that's the fundamental thing. So as they go down, the oil is getting less protected and it's 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, you know, 20, 30 pounds on a really, or for that matter, on a really, really good bottle of olive oil. And it's a year old. You know, it would be a shame to do that. You know, 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, rancidity. And you can definitely smell it. As I said before, the light filtration can avoid anything like that.

[Elizabeth Berger]

If someone's thinking about this, as 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.

[Expert Guest]

Oh, five years? Yeah. You wouldn't want to consume it for five years.

[Elizabeth Berger]

Help me to understand. Has all the health benefits disappeared at 12 months from an extra virgin olive oil?

[Expert Guest]

Is this really something that 18 months is what 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 anything.

[Elizabeth Berger]

And if I went into a grocery store and. And just picked an extra version 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.

[Expert Guest]

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. And I turned it around and it was over 18 months from the harvest date.

[Elizabeth Berger]

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 got to accept you're not really getting the. You're going to tell me that doesn't taste very nice, but also that the health benefits are really not totally different.

[Expert Guest]

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 moisturiser, you know, it would have a shelf life and so you would need to know when it had been bottled.

[Zoe]

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