How we rank high-polyphenol olive oils, why we never normalize across lab methods, and how often we update.
Our master ranking orders oils by their raw polyphenol value in mg/kg, exactly as the laboratory reported it. We do not apply conversion factors between lab methods. Some comparison sites multiply NMR results by a fixed factor to estimate an “HPLC-equivalent” — we deliberately don't, because readers can't verify a hidden conversion, and a published raw number with its method beside it is checkable against the lab report.
Polyphenol values measured by different methods are not directly comparable. qNMR (quantitative Nuclear Magnetic Resonance) quantifies individual phenols like oleocanthal and oleacein; HPLC-DAD separates and sums individual compounds; Folin-Ciocalteu measures total reducing capacity and typically reads higher than either. That is why every value on this site carries its method label — treat cross-method comparisons as approximate.
Every oil we track with credible lab evidence is ranked — there is no fixed inclusion cutoff. “High-polyphenol” has no legal definition; specialist labs and curators commonly treat roughly 500–600 mg/kg as the informal bar, and we focus our coverage on oils in and above that range. The full comparison table lists every oil we track with its raw value and lab method, so you can apply whatever bar you prefer.
Separately from the master ranking, we compute a clearly-labeled editorial score that weighs polyphenol level (40%), buyer-service signals such as review scores (15%), freshness chemistry — acidity and peroxide value (15%), transparency — published lab method, visible report, residue screening (15%), harvest timing (10%), and filtration — filtered oils keep their polyphenols longer on the shelf (5%). The highest raw value is not always the best buy; this score says so explicitly instead of quietly re-ordering the master list. The two rankings are never blended.
Every entry carries an evidence tier: strongest proof (a linked certificate of analysis or a named, independent laboratory), good proof (producer batch data without an independent lab), or use with caution (retailer or tracker figures only). Entries with weak evidence are additionally kept out of search indexing until their evidence improves.
Polyphenol values change with every harvest. Our commitment: ranked entries are re-verified at least quarterly, and within 60 days of a new harvest lab report becoming available. Every entry shows a “last checked” date, and every material change is recorded in the public changelog.
We follow EU Regulation 432/2012: olive oil polyphenols contribute to the protection of blood lipids from oxidative stress, applicable when an oil provides at least 5 mg of hydroxytyrosol and its derivatives per 20 g consumed daily. We do not publish disease-treatment claims, and where EFSA has declined to establish cause and effect, we say so.