When olive oil is stored for a long time with air or light, its natural healthy compounds break down into different chemicals, some of which are less beneficial.
Scientific Claim
Exposure to oxygen and light during prolonged storage degrades secoiridoids—including oleuropein and ligstroside aglycones, oleacin, and oleocanthal—in extra virgin olive oil, leading to the formation of oxidative byproducts such as carboxylic acid derivatives and hydrolytic products like elenolic acid, decarboxymethyl elenolic acid, tyrosol, and 3-hydroxytyrosol.
Original Statement
“oxidative/hydrolytic degradation processes occurring on the important bioactive components of EVOO known as secoiridoids, i.e., oleuropein and ligstroside aglycones, oleacin, and oleocanthal... isomeric oxidative byproducts resulting from the transformation of a carbonylic group of the original secoiridoids into a carboxylic group and compounds resulting from hydrolysis of the ester linkage of secoiridoids, i.e., elenolic and decarboxymethyl elenolic acids and tyrosol and 3-hydroxytyrosol”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design cannot support claim
Appropriate Language Strength
association
Can only show association/correlation
Assessment Explanation
Based on abstract only - full methodology not available to verify. The claim describes observed chemical changes without implying causation or health impact, which aligns with the in vitro observational design.
Evidence from Studies
Supporting (1)
The study found that when olive oil is stored in clear bottles or exposed to air and light, its healthy compounds break down into other chemicals—exactly what the claim says. Dark bottles and metal cans help keep those good compounds intact.