Connecticut Attorney General Richard Blumenthal has said his office is investigating claims by Coca-Cola and Nestle that their new drink can burn calories, saying it may amount to “voodoo nutrition.”

Blumenthal’s investigation focuses on Enviga, a green-tea drink that contains caffeine, calcium and a green tea extract known as epigallocatechin gallate, or EGCG. Coke says EGCG speeds up metabolism and increases energy use, especially when combined with caffeine.