Coca-Cola Co. has aligned its sales practices in US schools and introduced guidelines to counter growing criticism. Coke's contracts with public school districts has come under increased scrutiny as obesity studies have shown figures are on the rise. Complaints about excessive commercialism in schools have also pulled Coke under the microscope.

The guidelines include banning the sale of carbonated drinks in elementary schools during the school day, with juices, milk-based products, sports drinks and waters being offered instead; no carbonated drinks to be offered in cafeterias in middle schools and high schools; and schools to receive consistent payments over the length of the contract and not one-time, upfront payments. Coke has also proposed placing timers on vending machines to control when carbonated drinks may be sold.

Speaking to The Wall Street Journal, a Coke spokesperson said: "This represents total system alignment." All of Coke's US bottlers have agreed to follow the practices in schools. The guidelines apply to all current and future deals with K-12 schools in the US.

Coca-Cola has contracts with at least 6,000 of the more than 14,000 public school districts.