How healthy is olive oil and what is it good for?

Olive oil is one of the most studied dietary fats in the world. The oil contains a rich combination of monounsaturated fatty acids, phytosterols, squalene and phenolic compounds (polyphenols). Those polyphenols have antioxidant, anti-inflammatory, anti-allergic and anti-mutagenic properties, meaning they can slow down harmful processes in the body. A review of 39 plant-based oils ranks olive oil as one of the most nutritionally rich choices, while noting that you should not always rely exclusively on a single type of oil (PMID 37687222).

The strongest evidence for olive oil concerns heart and cardiovascular health. Better adherence to the Mediterranean diet, of which extra virgin olive oil is a key element, is associated with a clinically meaningful reduction in coronary heart disease, ischaemic stroke and total cardiovascular disease. This is supported by 4 randomised trials and 32 independent observational cohorts (PMID 30817261, 38336153). Olive oil is also explicitly recommended as a heart-healthy alternative to saturated fats in the prevention of atherosclerosis (PMID 34924350). Virgin olive oil additionally lowers total cholesterol and LDL cholesterol ('bad' cholesterol), although the evidence for this is of moderate to very low certainty (PMID 39053603).

A large American cohort study with more than 221,000 participants and up to 33 years of follow-up shows that every additional 5 grams of olive oil per day is associated with an 8% lower total mortality (HR 0.92 per 5 g/day). People who replace 10 grams of butter per day with a vegetable oil such as olive oil have an estimated 17% lower risk of total mortality and a 17% lower risk of dying from cancer. Higher butter consumption was associated with 15% higher mortality (PMID 40048719). These are associations, not proven causal relationships, but the direction is consistent and the effect is large enough to take seriously.

For cancer, the picture is more nuanced. The polyphenols in olive oil have anti-mutagenic properties, and an umbrella review (an overview of multiple meta-analyses) shows that olive oil consumption may lower the risk of breast, digestive and other cancers. The evidence is of low to very low certainty, however, meaning that future research could substantially change this picture. Caution in interpreting this finding is therefore warranted (PMID 39053603, 40048719, 29495598).

There are also promising but early indications that extra virgin olive oil can favourably influence the composition of the gut microbiome and gut immunity. Through the so-called gut-brain axis, this could contribute to better cognitive and metabolic health. This is, however, a relatively new area of research without quantitative outcomes, and the evidence is still limited (PMID 33576418). For blood sugar regulation the evidence is even weaker and of very low certainty; no firm conclusions can be drawn there yet (PMID 39053603).