[Soya supplements in the treatment of neuropathic pain]

Neuropathic pain is a typical symptom of a number of neurological diseases that is often difficult to treat. Drugs used include antidepressants, opiates, topical agents and antiepileptic drugs and, despite the fact that combination therapy regimens are becoming increasingly frequent, a considerable percentage of cases are pharmacoresistant. In this regard, other therapeutic approaches, such as diet, can play a fundamental role. In spite of the use of soya as treatment for certain situations, such as premenstrual or joint pain, and the fact that it has been shown to be effective in preventing the development of neuropathic pain in animal pain models, no studies have been conducted to examine its role as a possible analgesic in neuropathic pain.

Our study involved a series of nine patients (four males and five females) who were diagnosed with neuropathic pain due to varying aetiologies which was refractory to an average of 2.3 drugs; these subjects were treated with soya extracts and phytoestrogens. The mean dose was 300 mg every 12 hours and the follow-up lasted 62 days. Data concerning the intensity of the pain (according to a visual analogical scale), the number of days with pain and the side effects were collected and analysed. No improvement was observed in any of the variables under study, although there were no side effects either.

Soya supplements did not display any analgesic properties to combat neuropathic pain in our study. Nevertheless, given previous findings in other types of pain, the data obtained in animal models and the absence of side effects, we believe it is necessary to carry out further studies in this line.