Four participants withdrew from the trial (reasons not given), so the calculated statistical power of 80% was not met. The researchers found no signif- icant differences between groups in any outcome measures except serum vitamin K concentration, which was higher (0.56 ng/mL versus 0.33 ng/mL) in the chitosan group. No serious adverse effects were reported for either group. A poststudy analysis of the chitosan preparation used showed that the capsules contained only 42% of the labeled amount of chitosan.