Olive Oil Polyphenols Explained | Why Be Cautious About The Numbers

Polyphenols are at the heart of what makes extra virgin olive oil (EVOO) so special. They’re natural antioxidants that give olive oil its distinctive peppery and bitter taste and are linked to many of its health benefits, from anti-inflammatory effects to cardiovascular protection.

 

Many brands advertise themselves as 'high polyphenol' oil, citing numbers as high as 1,500 mg/L. But, here’s something few consumers realise: polyphenol content is extremely difficult to measure. In fact, depending on the test used, the same oil can appear to have double or even triple the amount of polyphenols.

 

If you want to separate fact from marketing fiction, then it's worth understanding why these figures vary so much, what different tests actually mean, and how to interpret polyphenol numbers when you see them on a bottle.

 

Why Polyphenol Counts Vary

 

1. There are many different tests

Polyphenol levels can be measured in as little as 5 minutes with a handheld device in a mill, or over several hours in a laboratory. Unsurprisingly, the quick methods usually give much higher readings — they’re great for mills that want to show off results to visitors, but they don’t always reflect the full picture (CDR FoodLab).

 

2. The strictest tests gives the lowest numbers

The most rigorous method is called the Folin-Ciocalteu colorimetric assay. It’s the standard used in much of academic research — but it also consistently reports lower figures than other tests, sometimes by almost 200% (Santas et al., 2008).

 

3. Even the same method has many variations

An academic review found over 50 variations of the Folin-Ciocalteu method alone. Results depend on details like:

• which chemicals are added,
• how long the reaction is left to develop,
• whether heat is applied, and
• which detection system is used.

This makes it nearly impossible to directly compare results from one lab to another.

 

4. Calibration curves change the outcome

Polyphenol results are usually expressed relative to a “standard” compound. Some labs use caffeic acid, others gallic acid, syringic acid, tyrosol, or oleuropein. The choice matters — the same oil could give very different numbers depending on the calibration (Jerman Klen & Mozetič Vodopivec, 2012).

 

What Our Tests Show

 

When our oil was tested by our regional state-run laboratory, the result was 389 mg/kg (as caffeic acid equivalent). To put that in context, an academic study testing high-priced EVOOs using the same method found the highest figure was only 180 mg/kg (as gallic acid equivalent). Our oil, even by this strict measure, came in 116% higher than that top-tier sample.

 

If we recalculated our result using the International Olive Council’s preferred test (which tends to give higher results), our oil would measure around 746 mg/kg. Looking ahead, with the new olive varieties we’ve planted, and using favourable test methods, we could soon be producing oils that score close to 1000 mg/kg.

 

So What Should Consumers Believe?

 

In certifying the health benefits of our oil we've been guided two main values. Firstly, we believe transparency about our results is a strength. We stick with the most rigorous state-run laboratory tests. That means our numbers may not look as high as some brands — but they are reliable, verifiable, and honest. For discerning consumers, this is a major selling point.

 

Secondly, we don't play the numbers game. Many private labs or mill machines will happily produce higher figures. Some brands lean on these methods to claim spectacularly high polyphenol counts. While tempting, we prefer to highlight that our conservative lab figures already demonstrate exceptional quality.

 

Polyphenols Are Only Part of the Story

 

While polyphenols get a lot of attention, they’re not the only marker of a great olive oil. Other key measures — like free acidity and oleic/linoleic acid ratios — are more straightforward to test and compare. On these measures, our oil scores right at the top of the range, confirming both its freshness and health benefits - more on this in a later blog post on how to decode olive oil test results!

 

Key Takeaways

 

Polyphenol numbers are fascinating but complicated. Don’t be misled by marketing claims of extreme figures — what really matters is (1) the method used to test,(2) whether results are consistent and transparent, and (3) how polyphenols combine with other markers of quality.