The 19-market Thomson Reuters Core Commodity Index was at its lowest in a week.
SUGAR
July raw sugar settled down 0.19 cent, or 1.6pc, at 11.62 cents per lb after earlier touching a one-week high of 11.95 cents.
In the previous session, prices had fallen to a 7-1/2-month low of 11.36 cents before reversing course to close higher.
The market continues to be pressured by plentiful supplies and large global stockpiles, dealers said.
Lower oil prices were also a bearish influence. Oil futures tumbled more than 2pc as an unexpected build in US crude stockpiles compounded investor worries that a prolonged trade fight between Washington and Beijing could dent global demand.
Lower oil prices can encourage cane mills in top-producer Brazil to produce more sugar rather than ethanol biofuel.
August white sugar settled down $3.50, or 1.1pc, at $322.80 per tonne.
Chinese white sugar futures, meanwhile, had their biggest daily dip in nine months after a Brazilian trade association said it expects exports to China to recover this year.
Brazil will no longer seek a panel at the World Trade Organization to investigate China's sugar trade policies, the Brazilian government said on Tuesday.
COFFEE
July arabica coffee settled down 1.15 cents, or 1.2pc, at 91.75 cents per lb after hitting a three-week high of 93.85 cents.
The market erased some of the previous session's gains, when the contract climbed over 3pc on a short-covering rally on the backs of early concerns about cold weather in Brazil.
"I'm not saying that we won't have a frost (in Brazil) ... but there's no legitimate frost scare in May," said Shawn Hackett, president of Hackett Financial Advisors.
Rabobank forecast a 5.4 million 60-kg bag global coffee surplus in 2018-19 but a 1.8 million bag surplus for 2019-20 in a quarterly report issued on Wednesday.
"Lower prices should result in lower 2019-20 washed arabica crops, whereas for robustas, availability is now higher due to excellent weather," the bank said.
July robusta coffee settled down $3, or 0.2pc, at $1,361 per tonne.
COCOA
July New York cocoa settled down $33, or 1.4pc, at $2,413 per tonne, after trading within the previous session's range.
The contract hit a six-week peak on Tuesday at $2,353 per tonne.
London July cocoa settled down 10 pounds, or 0.6pc, at 1,761 pounds per tonne.