Salt is a magical substance. An essential nutrient, it was once even used as currency. So what’s behind the push to get food makers to reduce sodium — one of salt’s components — in Americans’ diets?

In partnership with the Gastropod podcast, we look at the science and history of salt, and explain how and why the government is trying to lower sodium intake. For more, check out the Gastropod episode of Salt Wars here and FDA’s proposed guidelines here.