Beer sales in the U.S. have been declining, and some have pointed to the legalization of cannabis as a possible explanation. But Anheuser-Busch InBev CEO Carlos Brito said that the company still doesn't have any data to prove that.

AB InBev is world's largest beer company, but its North America beer volume dropped by 3 percent during the first nine months of 2018.

"We still don't have enough data points because there's noise to prove that beer — alcoholic beverages — suffers," Brito said Wednesday on CNBC's "Squawk Box."

Marijuana laws have been relaxed in more than two dozen states, but the drug remains illegal federally. That means that states that have legalized cannabis can see a jump in tourism as enthusiasts travel to partake legally. For example, Colorado began selling marijuana to the public in 2014. The state's tourism board said that 15 percent of the 82 million people who visited Colorado in 2016 participated in marijuana-related activities.

The tourism driven by cannabis is good for the states, but it makes it difficult for the AB InBev to collect data. A large number of tourists makes it difficult for the company to analyze any correlation between alcohol and cannabis sales, Brito said.

Meanwhile, the alcoholic beverage company is getting into cannabis itself. Anheuser-Busch announced last month that it was partnering with Canadian cannabis producer Tilray. The $100 million joint venture will focus on beverages infused with CBD, a non-psychoactive marijuana compound.