"Urinary tract infection? You're not drinking enough cranberry juice!" At least that would be my mother's analysis. Urinary tract infections, or UTIs, affect eight million people in the United States each year. Research has shown that cranberry juice is effective in preventing recurrent UTIs in certain populations. Should we all go out and stock up on cranberry supplements? Not so fast! A new study on commercially available cranberry supplements will make you think twice.
You might be wondering how cranberries can help prevent UTIs in the first place. Initially, doctors thought the acidity of cranberry juice acted as an antibacterial in the bladder. However, newer research revealed that cranberries contain a potent component called "proanthocyanidins." Proanthocyanidins are condensed tannin molecules (yes, tannins, as in that robust red wine you had with dinner last night). Proanthocyanidins inhibit bacteria's adhesion ability, making it harder for the bacteria to stick around and cause an infection.
As I mentioned above, UTIs are extremely common, affecting eight million people in the United States each year. Treating these infections is also costly: $2.14 billion in 2000 in the US alone. Many UTIs are treated with antibiotics, but antibiotic resistance is on the rise. If something as safe and natural as cranberries can prevent UTIs in the first place, they present a great alternative. However, the FDA does not require the same rigorous testing for herbal supplements, such as cranberry supplements, as it does for pharmaceuticals. A group of researchers from the Weill Cornell Medical College in New York set out to test seven commercially available cranberry supplements to see how they measure up.
The Cornell researchers tested various metrics for each of the seven supplements. First, they measured the levels of proanthocyanidins. They found a wide range of proanthocyanidin levels in the seven supplements. In prior trials, a proanthocyanidin level of 36mg was associated with reductions in recurrent UTIs. The supplements in this study has proanthocyanidin levels ranging from 0.56mg to 175mg. Six of the seven supplements had proanthocyanidin levels less than 36mg.
Cranberries likely prevent UTIs through their ability to prevent bacteria from adhering, or their "antiadhesion activity." The researchers tested the antiadhesion activity of the whole supplements. Four of the supplements had no antiadhesion activity at all. The target range for antiadhesion activity is 0.47-7.5 mg/mL. The remaining three supplements were all within this range.
Unfortunately, this study highlights the fact that the quality and anti-UTI activity of cranberry supplements available in the market are highly variable. One supplement had great proanthocyanidin levels, but the rest had very low levels. Four of the seven whole supplements had no antiadhesion activity whatsoever. The study does not list the names of the tested supplements, so I am sad to report that we can't all just buy the one supplement that passed with flying colors. Perhaps in the future, new regulations will change the way herbal supplements are labeled, providing consumers with information on key metrics, like proanthocyanidin levels for cranberry supplements. In the meantime, we want to hear from you! Do you take any health supplements? Do you trust their quality? Would you still try cranberry supplements to prevent UTIs, despite the variability in quality?