Olive oil
Carried in 9.2% of Amazon's products. Most often listed in mackerel fillets in olive oil (100% of products in that category list it).
Looking for just olive oil? 100% olive oil products, no processing→Olive oil · health claims, ranked by evidence
Olive oil — particularly extra virgin — has one of the strongest evidence bases of any single ingredient on this site, mostly through Mediterranean-diet research. PREDIMED (Spain, ~7,000 participants) is the landmark RCT. Important distinctions: extra virgin > refined > 'pomace' for polyphenol content; standard cooking does not destroy most of the benefits.
PREDIMED (NEJM 2013, re-published 2018) randomised participants to a Med-diet supplemented with extra-virgin olive oil, the same diet with mixed nuts, or a control low-fat diet. After ~5 years, the EVOO group had ~30% fewer major cardiovascular events than control. Follow-up cohort and meta-analyses support the directional finding. EVOO specifically; refined olive oil has less polyphenol content.
Multiple controlled trials report extra-virgin olive oil consumption modestly lowers circulating CRP and IL-6, particularly when high-polyphenol varieties are used. Effect is most consistent against high-saturated-fat or ultra-processed control diets — i.e. the comparison matters.
PREDIMED-PLUS and observational follow-ups suggest associations between Mediterranean-diet adherence (with olive oil as a centrepiece) and slower cognitive decline. Causal evidence specifically attributable to OLIVE OIL (rather than the whole diet) is harder to isolate. Plausible, suggestive, not yet definitive.
Weight outcomes in Mediterranean-diet trials are usually neutral to slightly favourable when olive oil REPLACES other fats. It's calorie-dense (~120 kcal/tablespoon), so total intake matters. Substitution > addition.
Reverse claim worth addressing. Despite popular concern, refined olive oil has a smoke point around 200–220°C and even extra virgin is around 180–200°C — well above typical pan-frying. Studies measuring oxidation by-products in domestic cooking find olive oil at least as stable as many seed oils. The 'never cook with olive oil' claim is more rhetoric than data.
Mediterranean-diet adherence associates with lower cancer mortality in observational research, but isolating an olive-oil-specific cancer-prevention effect is not supported by current human RCT evidence.
- Extra virgin > refined > pomace for polyphenol content. Storage matters: light + heat oxidise the polyphenols over months. Dark glass bottles, cool cupboards.
- Olive oil is calorie-dense (~120 kcal/tablespoon); benefits are clearest when it REPLACES less favourable fats (butter, lard, ultra-processed seed oils), not when added on top.
- Most 'olive oil' on UK shelves is genuine; high-end fraud (passing refined as extra virgin) does happen — check IOC certification and country of origin.
- Allergy is very rare. Topical use can occasionally cause contact dermatitis.
This is editorial summary, not medical advice. Mediterranean diet evidence is among the strongest in nutrition science, but the effect is from the WHOLE PATTERN — olive oil is a centrepiece, not a magic bullet.Last hand-reviewed: 2026-04-30
