Clear plastic bottles let in light and air, which makes the healthy parts of olive oil break down faster—so they’re not good for keeping olive oil fresh long-term.

Storing olive oil in dark glass or a metal can helps keep its healthy compounds intact better than clear plastic bottles—metal cans produce the fewest bad breakdown products.

When olive oil sits too long, its natural compounds break down into simpler molecules like tyrosol and 3-hydroxytyrosol, which are also found in other foods.

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.