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Dr. Sears' Blog

Breaking down the latest research on Anti-Inflammatory Nutrition
Written By: Dr. Barry Sears, Ph. D | Creator of the Zone Diet

Written by Dr. Barry Sears
on February 22, 2016

Olive oil can be considered the first nutrition supplement since its first use more than 6,000 years ago. We now know the reason: the polyphenols.

The Good – Olives Contain Unique Anti-Inflammatory Properties

Olives are a fruit, not a seed. As a result, it contains unique types of polyphenols not found in other fruits and vegetables. Tyrosol, hydroxytryrosol, oleocanthal and oleuropein each provide unique anti-inflammatory properties. This is why olive oil was so prized in the ancient world and remains an integral component of the Mediterranean diet. That’s the good.

The Bad – The Impact of Pesticides

Polyphenols are the reason that olive oil has health benefits for humans, but they have even greater health benefits to the olive fruit itself. It is polyphenols that protect plants from microbial attack. Once you start using pesticides to increase production, the plants generally decrease the product of polyphenols since it requires a lot of energy to produce them. This effect is more profound in fruits than vegetables.

However, not all conventionally grown fruits and vegetables have high levels of chemical residues. It really depends on how they are farmed. The following table outlines these varying levels of chemical residues in conventional fruits and vegetables.

Most Commonly Contaminated Moderate Commonly Contamination Least Commonly Contaminated
  • Apples
  • Celery
  • Strawberries
  • Peaches
  • Spinach
  • Nectarines
  • Grapes-Foreign
  • Sweet Bell Peppers
  • Potatoes
  • Blueberries
  • Lettuce
  • Kale/Collard Greens
  • Green Beans
  • Summer Squash
  • Peppers
  • Cucumbers
  • Raspberries
  • Grapes - Domestic
  • Plums
  • Oranges
  • Cauliflower
  • Tangerines
  • Bananas
  • Winter Squash
  • Cranberries
  • Onions
  • Sweet Corn
  • Pineapples
  • Avocado
  • Asparagus
  • Sweet Peas
  • Eggplant
  • Cantaloupe
  • Kiwi
  • Cabbage
  • Sweet Potato
  • Grapefruit
  • Mushrooms
What about olives?

Although many olive growers don’t use herbicides or pesticides, you never really know those who do. Finding certified organic extra-virgin olive oil is always your best bet for maximum polyphenol content. More importantly, the taste of organic olive oil is always significantly better than conventional olive oils.

The Really Ugly – Your Olive Oil May Be Faking It

Since olive oil is valuable, it is likely to be adulterated by adding other inferior substances. This was a problem in even ancient Roman times where containers were stamped with official seals to make it difficult to adulterate the oil.

Today, the problem is far more widespread with nearly 70% of extra-virgin oil olive being sold in the U.S. having been adulterated.

Harvesting Perfect Olives

What's a consumer to do in a world of pesticides and adulterated olive oil?

It has to taste great (which it does) and be rich in polyphenols (that we analyze in every lot, because like Fox Mulder of the X-Files says: “we trust no one”).

I searched out the few organic cooperatives in Italy making high quality extra-virgin olive oil.  Then, we harvested in late fall, followed by processing over the winter. Then the various processed lots were tested for polyphenol content. Those lots that met our polyphenol requirements were bottled and brought to the U.S. under the Zone brand. We purchased the entire year’s production that met our quality standards. It wasn’t much, but those olives made about 190 cases worth of Dr. Sears’ Zone Extra Virgin Olive Oil. And we have it all.

Branding is crucial. With my Zone Extra-Virgin Olive Oil, you can have the ideal anti-inflammatory condiment for every meal – at least while it lasts. As of today, we have less than 100 cases of Dr. Sears’ Zone Extra Virgin Olive Oil remaining in stock. Order yours today.New call-to-action


  1. Faller ALK and Fialho E. “Polyphenol content and anti-oxidant capacity in organic and conventional plant foods.” J Food Composition and Analysis 23: 561-568 (2010).
  2. Muller T. Extra Virginity: The Sublime and Scandalous World of Olive Oil. W.W. Norton. New York, NY (2013).
  3. Blechman N. “Extra virgin suicide: The adulteration of Italian Olive Oil.

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