Funding ran out_difficulties with study product (delays in authorization).

Neuropathic pain is one form of chronic pain lacking effective pharmacotherapy. Interest in the role of complementary and alternative medicine is growing and diet is at the forefront of the search for alternative treatments for pain. Soy protein is one of the most promising dietary ingredients tested for its pain-relieving properties. Results from animal studies show that soy-enriched diets reduce pain due to nerve injury. The purpose of this study is to determine the effects of soy protein supplementation on facial pain.

Neuropathic pain is a complex disorder with mixed results in response to pain medication due to a high degree of variability between patients. To address this issue, we are implementing a unique methodology using a series of N-of-1 or single subject randomized, double blind, controlled studies. With this, we will explore the role of soy protein supplementation in neuropathic pain patients. Each patient will be exposed in 3-week intervals to soy protein and a control, milk protein, in three paired treatment periods for a total of 18 weeks. This method allows for the measurement of treatment efficacy in individual distinct patients and has the potential for immediate and continued medical benefit using a simple and readily available dietary ingredient.

Inclusion Criteria:

• Male or female, age ≥ 18 years old
• Chronic neuropathic pain with tactile allodynia > 6 months
• Suboptimal pain pharmacotherapy (i.e. additional pain control felt by patient and physician to be necessary)
• Pain intensity score ≥ 5 on 11-point numerical rating scale (NRS) during 1-week screening period prior to randomization
• Stable medication use (if any) over 4 weeks before starting the trial. Current medication use will be maintained and no additional pharmacotherapy may be introduced during the trial.
• Up to date mammogram and gynecological evaluations.

Exclusion Criteria:

• History of significant heart, gastro-intestinal, liver or kidney disease
• History of alcohol/narcotic abuse or current excessive alcohol consumption
• History or diagnosis of cancer
• History of breast tumors, predisposition to breast cancer or a family member with breast cancer
• History of hormonal or gynaecological disease
• Current use of hormonal replacement therapy (HRT), except thyroid HRT
• Pregnant or breastfeeding women
• Use of any anticoagulant or blood thinner except acetylsalicyclic acid
• Malabsorption of any kind
• Diagnosed lactase deficiency;
• Known allergy to any of the dietary products
• Known allergy to acetaminophen
• Daily consumption of soy protein in quantities exceeding 10 g/day
• Strict vegetarians (i.e. no animal derived dietary sources)
• Antibiotic use within the last 3 months
• Any previous psychiatric diagnosis before pain onset
• Body mass index > 35