Grocery store labels often list strange-sounding ingredients like BHT and BHA, sodium nitrate, sulfites, and sodium benzoate. These preservatives are added to food to keep it from spoiling—but some people might wonder how they work, or whether they're harmful.

The TED-Ed video above explains how microbes (like bacteria and fungi) and oxidation cause food items to go bad. It also gives a brief overview on the different types of preservatives, how they help prevent the chemical changes responsible for decomposition, and how they’ve been used historically. For now, TED-Ed says, the jury's still out on whether these additives are conclusively linked to major health risks. But if you're still concerned, a growing number of companies are getting rid of preservatives, or trying to find alternative ways to help foods stay fresh.

[h/t TED-Ed]

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