Coca-Cola Co. reported flat beverage sales for the second quarter but the company said it was encouraged by the performance of no-calorie and low-calorie sodas in foreign markets and by sales of drinks prepared for immediate consumption.

The beverage giant's total drink sales were effectively unchanged, compared to a year ago, but the company said the performance of its new Coca-Cola Zero Sugar is providing a lift.

Now sold in more than 25 markets, the drink is set to hit the U.S. in August, Coke said Wednesday. Sales of no-calorie and low-calorie drinks rose in the "mid single digits," with Coca-Cola Zero Sugar in the "double digits," the company said.

That's good news for an industry that's grappling with American consumers' drift away from sodas branded as "diet" drinks toward more natural sounding products.

Altogether, core revenue rose 3% for the period, compared to a year earlier. Net revenue fell 16% to $9.7 billion, though that was because the company is transforming bottling operations into franchises and experiencing a slight hit due to unfavorable currency rates.

"Our performance gives us confidence that we will achieve our full-year financial objectives even in the face of challenging conditions, and also demonstrates further success in evolving our portfolio to meet changing consumer tastes and preferences," Coke CEO James Quincey said in a statement.

Sparkling soft drink sales were even, tea and coffee sales rose 2%, sales of water and sports drinks increased 1% and sales of juice, dairy and plant-based beverages was up 3%.

Net income fell 60% to $1.37 billion, amounting to earnings of 32 cents per share. Revenue of $9.71 billion outpaced S&P Global Market Intelligence expectations of $9.62 billion.

Coke shares rose 0.6% in pre-market trading to $45.50.