New Delhi, July 19 -- the fuel that once cost him 800 naira per liter had climbed past 1,400 naira, driven by the closure of the Strait of Hormuz, and the math of running a vehicle no longer worked. Without income, his family's food supply thinned. By the time his 18-month-old daughter Farisa was taken back to a hospital in Kware Sokoto, in northwestern Nigeria, she was being treated for malnutrition for the second time in less than a year.

"Times are tough, and the food is not consistent," his wife, Maryam, told Arab News.

Their story is one of tens of thousands unfolding thousands of kilometers from the waters where Iran's conflict has redrawn the economics of global oil supply. The Hormuz closure, in force since February, has sent fu...