Extra-Virgin Olive Oil Polyphenols Improve HDL

By Kimberly Lord Stewart

As dietary guidance moves out of the no-fat, low-fat era in to the healthy-fat era, extra-virgin olive oil still comes out as the top culinary oil for taste and a top oil for health. But a lingering question among many is, what oil should I buy?

As a food journalist, who has won awards on the topic, and former resident of southern Italy, I have covered this industry for decades. I’ve also uncovered some of the shady practices used by producers. Even so, I continue to be enamored by the health properties of this ancient oil. A recent study confirmed why you should encourage your patients to buy extra-virgin olive oil from a quality producer.

In a study supported by the American Heart Association, researchers compared a low polyphenolic extra-virgin olive oil with a high-quality polyphenolic oil for its ability to reduce HDL cholesterol. The study included 47 healthy European male volunteers. Participants ingested 25 mL/d of polyphenol-poor (2.7 mg/kg) or polyphenol-rich (366 mg/kg) raw olive oil in 3-week intervention periods, preceded by 2-week washout periods.

Here is what they found:

1. HDL cholesterol efflux capacity significantly improved after polyphenol-rich intervention versus the polyphenol-poor one (+3.05% and -2.34%, respectively; P=0.042).
2. Incorporation of olive oil polyphenol biological metabolites to HDL, as well as large HDL (HDL2) levels, was higher after the polyphenol-rich olive oil intervention, compared with the polyphenol-poor one.
3. Small HDL (HDL3) levels decreased, the HDL core became triglyceride-poor, and HDL fluidity increased after the polyphenol-rich intervention.

The study authors concluded that extra-virgin olive oil polyphenols promote the main HDL antiatherogenic function, its cholesterol efflux capacity. These polyphenols increased HDL size, promoted a greater HDL stability reflected as a triglyceride-poor core, and enhanced the HDL oxidative status, through an increase in the olive oil polyphenol metabolites content in the lipoprotein.

These results provide for the first time a first-level evidence of an enhanced HDL function by polyphenol-rich olive oil.

Fantastico, my Italian friends would say. However, how do you know which oils have the most polyphenols? Here is my best advice for recommending extra-virgin olive oil to your patients.

1. Region: In general, extra-olive oils from specific regions within oil producing countries or states will be of higher quality, which means the oil will have high polyphenols. For instance, an oil produced from a single estate in Spain, Italy, Greece or California, will have higher polyphenols than a brand that blends oils from multiple countries.

Why? Bulk oil is pooled from different regions, transportation and mass production practices degrade the quality of oil that is produced regionally.  Time is of the essence for quality, and small producers stake their reputation on harvesting the olives early and pressing their oil quickly. Look on the label for the estate, region or single country for the best quality oil.

2. Bottling Date: Extra-virgin olive oil is not a commodity fat, like corn or canola oil. It’s a freshly pressed oil that is bottled once a year. It only lasts for a year to 18 months. Many producers now put a date on the bottle, so look for it as a measure of freshness.

3. Taste: How will you know beyond the date that the oil is fresh? A fresh oil will leave a kick in the back of your throat. That kick is the p0lyphenols. If it’s bland, most likely the oil is poor quality. Rancid oil will also smell a bit like your kid’s play dough. There is no need to refrigerate, just use it up quickly and buy another bottle.

4. Dark Glass: Grocery store lights degrade the polyphenols in extra-virgin olive oil. So, look for dark green glass bottles or metal cans.

5. Extra-Virgin vs Pure Olive Oil: There is only one choice here. Extra-virgin olive oil contains all the heart healthy properties. If the producer lists the acidity level, look for low acidity. Extra-virgin olive oil is by law .08% free fatty acid acidity. Pure olive oil is made using a highly refined oil where all the taste and healthy qualities have literally been squeezed out. Producers will add a bit of extra-virgin olive oil to make it palatable.

6. Variety: Keep a few bottles in the kitchen for different uses. Small estate oils can be pricey and depending on their flavor profile can pack a punch. These oils are best used for salads, vegetables and dipping. Use single country or state oils for everyday cooking. If you want to see the world’s best oils, link here.

7. Price: Above all, if you see a blended oil on the store shelf that is dirt cheap, most likely it’s old, rancid or not pure. It cost the farmer at least a few dollars per liter to produce, so a fire sale oil is not worth your attention.

8. Ignore the color: The oils home soil, harvest season and weather determines the color. Cheap producers will sometimes add green color to fool unsuspecting shoppers. So admire the color in good oils and ignore the color as a measure of quality.

9. Cold pressed is somewhat obsolete: Producers used to press the oil between stones, while maintaining a constant temperature, hence the term cold pressed. Today, most mills (even small ones) use steel plates and a centrifuge to spin the oil from the water and residue.

10. Cooking with extra-virgin olive oil: The term smoke point comes up frequently when talking about extra-virgin olive oil. It refers to the temperature at which the oil begins to break down, resulting in poor taste and even some health concerns. It’s myth that you can’t cook with extra-virgin olive oil. However, it is expensive. Low free fatty acid oils, aka high quality oils, do not break down as quickly as poor quality oils. I have talked with a number of oil chemists who have tested the smoke point of extra-virgin olive oils and they found good quality oil have a smoke point of 410ºF or 210ºC, which is well above the ideal temperature for frying food at 356ºF or 180ºC.