A pilot study on the impact of a low fructose diet and allopurinol on clinic blood pressure among overweight and prehypertensive subjects: a randomized placebo controlled trial.

Fructose and sodium intake have been associated with hypertension and metabolic syndrome. Although various mechanisms are involved, fructose causes hypertension partly through rising intracellular and serum uric acid. To date, there are no studies in adults that have evaluated the impact of low fructose diets and allopurinol on prehypertensive and overweight subjects. The objective of this study was to compare the effect of low fructose diet and allopurinol or placebo on blood pressure (BP) and metabolic syndrome components The study was a controlled clinical trial and consisted of two phases; in the first phase of intervention (4 weeks), patients were randomized to either low fructose diet (34 patients) or control diet (38 patients). In the second phase of intervention (weeks 4-8), the same groups continued with the same diet prescriptions but were further randomized to receive placebo or allopurinol (300 mg/d). Clinic and 24-hour ambulatory BP, anthropometric measures, and laboratory data were determined at baseline, weeks 4 and 8. Seventy-two patients were included in the trial. At the end of the dietary phase, both diet groups significantly reduced their BP, but there were no between-group differences. Compared to placebo, at the end of follow-up, subjects in the allopurinol group had a lower clinic systolic blood pressure and this was significant within- and between-group comparisons. The percentage of dippers was higher in the allopurinol group, and weight was reduced significantly despite the absence of caloric restriction Allopurinol was associated with a significant reduction in clinic BP, an increase in the percentage of dippers, and significant weight loss. Larger studies with longer follow-up are needed to confirm our findings.