Purpose: Hyperuricemia is a recognized risk factor for cardiovascular diseases. Soy foods contain a moderate amount of purine and may predispose to raised serum uric acid (UA). However, no study has examined the long-term effect of soy intake on UA levels. We examined whether consumption of soy foods and isoflavone extracts for 6 months altered serum UA.
Methods: The analysis included two randomized controlled trials (soy protein trial and whole soy trial) among total 450 postmenopausal women with either prehypertension or prediabetes. We conducted a pooled analysis by combining participants from both the soy flour and soy protein groups (combined soy foods group), participants from both the isoflavone and daidzein groups (combined isoflavone group) and participants from both milk placebo groups. Fasting venous samples were obtained at baseline and the end of the trial for serum UA analysis.
Results: In the pooled data, 417 subjects completed the study according to protocol. The baseline serum UA levels were comparable among the three combined groups. There was a lower decrease in UA levels among women in the combined soy foods group compared with women in the other two groups (p = 0.028 and 0.026). The net decrease and % decrease in UA were 14.5 μmol/L (95 % CI 1.93-25.6, p = 0.023) or 4.9 % (95 % CI 1.3-8.5 %, p = 0.023) between the combined soy foods group and placebo group.
Conclusions: Among Chinese postmenopausal women with either prehypertension or prediabetes, soy intake did not increase urate levels.