Sugar has a longer life cycle than crops like wheat, so it is more difficult for farmers to adapt quickly to market dynamics. Decisions taken to increase production during the last boom in sugar prices, back in 2010-2011, are therefore still affecting supply.
"There's lots of sugar on the market and there's been a surplus now for going on five years. Demand just can't keep up," Crandall told CNBC.
One factor at play is the weakness of the real, the currency of Brazil, the world's biggest sugar exporter. As the U.S. dollar has stayed strong, Brazilian farmers can take lower prices in the dollar-denominated sugar market.
"This is really being led by Brazil. With the weakening real, farmers are still incentivised to produce," Crandall said.