Answer: If you want to get extra virgin olive oil (EVOO) as a supplement in capsules, you can — although it will not be as pleasurable as consuming it as a food and it's likely not as healthful as using EVOO to replace saturated fats, such as in butter, in your diet. Studies showing benefits with olive oil (see "What It Does" section of our Extra Virgin Olive Oil Review) have involved its use as a food, not a supplement.
A 20 ml serving of EVOO (the amount in 4 teaspoons) is about 18 grams of oil, of which about 13 grams is oleic acid. However, oleic acid (an omega-9 fatty acid) in itself as a supplement has no special health benefit. Just as important is the polyphenol content in EVOO — as the polyphenols may contribute to the cardiovascular benefits of olive oil. ConsumerLab.com's tests of extra virgin olive oils found the concentration of polyphenols to vary by as much as 72% from product-to-product and, on average, 4 teaspoons of EVOO provides about 5 mg of total polyphenols.
A large softgel holds about one gram (1,000 mg) of oil, so you would need to take 18 softgels of EVOO to get the equivalent amount of oleic acid in 4 teaspoons of EVOO. That's a lot of capsules to swallow! It's also 162 Calories. Enjoying that olive oil sprinkled over warm focaccia, or over a salad or pasta, would seem more appetizing and, if you're substituting it for butter, may also reduce your risk of cardiovascular disease.