(Reuters) - Coca-Cola Co (>> The Coca-Cola Co) on Wednesday reported higher-than-expected quarterly earnings and revenue as it raised prices and boosted sales volumes in North America, where it has struggled to grow as consumers ditch soda for healthier options.

Coke has called 2015 a transition year as it tries to cut costs and boost sales of its mainstay carbonated soft drinks.

Global sales volumes of its sodas rose 1 percent in the second quarter, helped by growing demand for Coke Zero, Sprite and Fanta.

Sales volumes of still beverages were up 5 percent, with increases in ready-to-drink tea and packaged water offsetting declines in juice and juice drinks.

For the second straight quarter, sales rose in North America, which accounts for nearly half of the total. Prices there increased 4 percent in the quarter, while volume was up 2 percent.

Coke effectively raised prices by switching to smaller-sized packaging, and it boosted ad spending for its brands.

Expanded distribution of energy drink maker Monster Beverage Corp's products (>> Monster Beverage Corp) in North America contributed to the increase. The company bought a stake in Monster last year as a way to diversify into faster-growing beverage categories.

Coke's net revenue fell 3 percent to $12.16 billion, but it would have increased 4 percent without the impact of the strong dollar, acquisitions and divestitures. Analysts on average were expecting $12.06 billion, according to Thomson Reuters I/B/E/S.

Net income attributable to shareholders rose nearly 20 percent to $3.11 billion, or 71 cents per share.

The company said it would buy back shares worth up to $2.0 billion to $2.5 billion this year. Earlier, it had earmarked $2 billion to $3 billion.

"We looked at where we were for the first half of the year, and we looked at cash, particularly because of the currency getting worse in the back half and just tightened the range," Chief Financial Officer Kathy Waller said on a conference call.

Cowen and Co analyst Vivien Azer said in a note that the tighter range seemed "consistent with the share repurchase revision that we saw last October, where the company narrowed their outlook for buybacks."

Coke's shares were up 0.7 percent at $41.46 in morning trading. At Tuesday's close, they had fallen 2.5 percent this year.

(Reporting by Anjali Athavaley in New York; Editing by Lisa Von Ahn)

By Anjali Athavaley and Yashaswini Swamynathan

Stocks treated in this article : The Coca-Cola Co, Monster Beverage Corp