title: Dietary soy supplement on fibromyalgia symptoms: a randomized, double-blind, placebo-controlled, early phase trial.
abstract: Most patients with fibromyalgia use complementary and alternative medicine (CAM). Properly designed controlled trials are necessary to assess the effectiveness of these practices. This study was a randomized, double-blind, placebo-controlled, early phase trial. Fifty patients seen at a fibromyalgia outpatient treatment program were randomly assigned to a daily soy or placebo (casein) shake. Outcome measures were scores of the Fibromyalgia Impact Questionnaire (FIQ) and the Center for Epidemiologic Studies Depression Scale (CES-D) at baseline and after 6 weeks of intervention. Analysis was with standard statistics based on the null hypothesis, and separation test for early phase CAM comparative trials. Twenty-eight patients completed the study. Use of standard statistics with intent-to-treat analysis showed that total FIQ scores decreased by 14% in the soy group (P = .02) and by 18% in the placebo group (P < .001). The difference in change in scores between the groups was not significant (P = .16). With the same analysis, CES-D scores decreased in the soy group by 16% (P = .004) and in the placebo group by 15% (P = .05). The change in scores was similar in the groups (P = .83). Results of statistical analysis using the separation test and intent-to-treat analysis revealed no benefit of soy compared with placebo. Shakes that contain soy and shakes that contain casein, when combined with a multidisciplinary fibromyalgia treatment program, provide a decrease in fibromyalgia symptoms. Separation between the effects of soy and casein (control) shakes did not favor the intervention. Therefore, large-sample studies using soy for patients with fibromyalgia are probably not indicated.
authors.affiliation: Division of General Internal Medicine, Mayo Clinic, Rochester, MN, USA.
authors.forename: Dietlind L
authors.initials: DL
authors.lastname: Wahner-Roedler
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Thompson
authors.forename: Connie A
authors.initials: CA
authors.lastname: Luedtke
authors.forename: Susan M
authors.initials: SM
authors.lastname: King
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Cha
authors.forename: Peter L
authors.initials: PL
authors.lastname: Elkin
authors.forename: Barbara K
authors.initials: BK
authors.lastname: Bruce
authors.forename: Cynthia O
authors.initials: CO
authors.lastname: Townsend
authors.forename: Jody R
authors.initials: JR
authors.lastname: Bergeson
authors.forename: Andrea L
authors.initials: AL
authors.lastname: Eickhoff
authors.forename: Laura L
authors.initials: LL
authors.lastname: Loehrer
authors.forename: Amit
authors.initials: A
authors.lastname: Sood
authors.forename: Brent A
authors.initials: BA
authors.lastname: Bauer