Adverse events associated with dietary supplements: an observational study - Palmer, M E; Haller, C; McKinney, P E; Klein-Schwartz, W; Tschirgi, A; Smolinske, S C; Woolf, A; Sprague, B M; Ko, R; Everson, G; Nelson, L S; Dodd-Butera, T; Bartlett, W D; Landzberg, B R (Lancet, 2003)