The packaging is part of the formula.

Light and oxygen break down cold-pressed olive polyphenols, vitamin C and gingerols. Glass and plastic let one or both of them in. Here is what the research says that costs — and what a sealed aluminium stickpack removes.

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01Oxygen

One oil. Three packs. Forty days.

In 2026 researchers put a single extra virgin olive oil into three different containers, left them at 25 °C under 500 lux for twelve hours a day, and poured 75 mL from each every day for forty days — a kitchen counter, in other words. Only the packaging differed.

Total polyphenols lost Vitamin E lost

Clear PET
Total polyphenols 26% Vitamin E 44%
also broke the legal peroxide limit within 30 days
Bag-in-box
Total polyphenols 11% Vitamin E 1%
Chrome-plated tin
Total polyphenols 12% Vitamin E 5%

Sordini et al., Foods, 2026

100%

of the vitamin C in a model juice was gone in 20 days of contact with air. With the oxygen removed, 65% was still there.

Van Bree et al., Czech Journal of Food Sciences, 2009
55%

of an olive oil's oxidative stability lost in clear glass over ten months — against 36% in a sealed metal can.

Martín-Tornero et al., Molecules, 2022
1000×

the gap in oxygen ingress between clear PET film and high-barrier packaging. Foil laminate is the reference the others are measured against.

Murray, TAPPI PLACE, 2005 Zhang et al., Food and Bioprocess Technology, 2016

02Time

Then you open it.

89%

of an olive oil's vitamin E is gone within eight months of the bottle being opened — even stored in the dark.

Mousavi et al., Foods, 2021

Even in dark amber glass at room temperature, the same study found oils lost around half their polyphenols — over 70% for the richest ones. A bottle you open sixty times is running that clock sixty times. A stickpack is opened once, and finished.

03Light

Two years in the light.

Researchers stored one Umbrian extra virgin olive oil in light and in dark for twenty-four months. Light accelerated its oxidation, and by the end the two phenols the oil is prized for had largely gone.

Oleacein lost 75%
Oleocanthal lost 60%

Both figures describe the oil in that study. No loss figure is claimed for GLO Shot.

Blasi et al., Foods, 2025

14×

more acrolein formed in clear glass than in amber after five weeks on a windowsill. Foil-wrapped bottles showed no deterioration at all.

Kishimoto, Food Science and Technology Research, 2019
40%

of an oil’s vitamin E left after a year under light — against 71% at the same temperature in the dark.

Caipo et al., Foods, 2021

For reference: to be called “light-resistant,” a container must transmit no more than 10% of light across 290–450 nm. Glass of any colour transmits some. Aluminium foil transmits none.

United States Pharmacopeia, General Chapter ⟨660⟩ Containers — Glass

04Heat

Which is also why it's never heated.

76%

of hydroxytyrosol destroyed by 150 minutes at ordinary sauté temperature. Oleocanthal: 71%.

Attya et al., Molecules, 2010
21.7%

of 6-gingerol lost to a single hour of dry heat at 60 °C — well below any pasteurisation temperature.

Kamal et al., Journal of Analytical Science and Technology, 2015
79%

of 6-gingerol gone from stored ginger over eight months at 15 °C. At 5 °C, as little as 19%.

Ghasemzadeh et al., BMC Complementary and Alternative Medicine, 2016

Two barriers, or one, or none.

How each container is built: whether it blocks light, whether it blocks oxygen, whether headspace grows as it is used, and how many times it is opened.
Container	Blocks light	Blocks oxygen	Headspace grows as you use it	Times opened
Clear plastic bottle	No	Partly	Yes	Many
Clear glass bottle	No	Yes	Yes	Many
Dark amber glass bottle	Mostly	Yes	Yes	Many
Metal tin	Yes	Yes	Yes	Many
GLO Shot aluminium stickpack	Opaque	Sealed	No — zero headspace	Once

Foil is opaque at the gauges used in food packaging; no light-transmission percentage is claimed for it. Figures on this page describe published research on the containers named, not measurements of GLO Shot.