Buy tomato ketchup which has been most recently packaged & try to finish it soon as an important nutrient lycopene in ketchup deteriorates over time.

The same applies to any other tomato product like canned tomato juice. Lycopene, the most important nutrient in tomato, has been shown to have anti-aging and cancer protecting properties (especially prostate cancer). Buy smaller bottles of ketchup if it sits in your refrigerator for months.