The Mediterranean diet has become a darling of medical researchers. It’s known for its veggies and grains, limited amounts of meat, and a good helping of olive oil.
“The health benefits of olive oil are 99% related to the presence of the phenolic compounds, not the oil itself,” explains Nasir Malik, a researcher at the U.S. Department of Agriculture. 
Polyphenols decrease heart disease risk factors by lowering blood pressure and cholesterol, reducing blood clotting and improving the health of artery linings. They also reduce cancer risk by lowering inflammation and cellular proliferation. They even reduce microbial activity and infections.
Sounds great, right? But here’s the catch…
When tested, polyphenols were surprisingly low in most commercially available olive oils.
It turns out that 69% of the “extra-virgin” olive oil imported into the U.S. has been shown to be substandard, according to a study out of UC Davis.
Often, the oil is just too old. It’s shipped from place to place before it’s imported and usually isn’t stored well. By the time it arrives in the U.S., Many of the heart-health compounds have degraded and fizzled out.
Here’s what to look for:
- Harvest date on the label: The bottle should have a “harvest date” instead of a “sell by” label. The olives should be harvested within the past year.
- The container: Buy olive oil in a container that protects it from the light (dark glass or tin).
- The taste & smell: If the oil stings the back of your throat a little that tells you the beneficial polyphenols really are there. High-quality olive oil is pungent and often described as “grassy” or “peppery.”
The brands that failed to meet the extra virgin olive oil standards, according to this study: Bertolli, Carapelli, Colavita, Star, Pompeian. 
The real deal: California Olive Ranch, Cobram Estate, Lucini. (Kirkland Organic, Lucero (Ascolano), McEvoy Ranch Organic are also noted by Eat Grown Local.)