When scientific studies first provided evidence that cranberries are a powerful agent in fighting urinary tract infections (UTI), the supplement industry was fast to react by putting cranberry pills and extracts on the market. But are they as effective as drinking cranberry juice or eating the sauce?

Recent analysis by Worcester Polytechnic Institute offers answers. The researchers tested proanthocyanidins (PAC), a group of flavonoids found in cranberries and thought to be what gives the juice its infection-fighting properties, offering hope that these could translate into an effective extract.

However, the report concluded that cranberry juice itself is far better at preventing biofilm formation-the precursor of infection-than PACs alone. The virulent form of E. coli bacteria that is the cause of most UTIs is covered with small, hair-like projections, known as fimbriae, which act like hooks and latch onto cells that line the urinary tract.

When enough bacteria adhere to the cells, they form a biofilm that leads to infection. Cranberry juice prevented the bacteria from forming this biofilm, while PACs alone were not as effective.