Setting your best before date: stability testing explained
Your best before date is a promise that the product still meets its label, including every nutrient amount, until that date. Stability testing is how you back it up.
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What has to stay true
- Nutrient amounts must stay within accepted tolerances of the declared values until the best before date.
- The product must stay safe and of acceptable quality: appearance, smell, taste, moisture and microbiology.
- Some vitamins, such as C, A, D, B12 and folic acid, degrade over time, especially in heat, light and humidity.
Real-time and accelerated testing
- Real-time: store samples in the final packaging under normal conditions and test at intervals (for example 0, 6, 12, 18 and 24 months). This is the strongest evidence.
- Accelerated: store samples hotter and more humid (often around 40°C and 75% relative humidity) to predict shelf life faster. It's a guide, so confirm it with real-time data.
Overages
Manufacturers often add extra of unstable vitamins at the start, called an overage, so the declared amount is still met at the end of shelf life. Keep overages sensible, and check they don't take the product over safe upper levels.
Packaging matters
The same formula can last longer in a foil pouch or an amber glass jar with a desiccant than in a clear tub. Test in the packaging you'll actually sell in.
Writing the date
Most supplements carry “Best before end” with a month and year. See best before, use by and expiry dates for the formats.
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ProofMyLabel is an automated pre-check, not regulatory sign-off or legal advice. The food business operator remains responsible for the packaging.