San Diego, CA—A prescription medical food was shown to improve the level of neuropathic symptoms and health-related quality of life in a placebo-controlled trial of patients with diabetic peripheral neuropathy.
The prescription food contains L-methylfolate, methylcobalamin, and pyridoxal 5’-phosphate (LMF-MC-PLP), and is known commercially as Metanx. The immediately bioavailable forms of folate, vitamin B12, and vitamin B6 in LMF-MC-PLP may promote nitric oxide synthesis and improve vascular function and nerve conduction, said coinvestigator Tina K. Thethi, MD, Assistant Professor of Medicine, Department of Endocrinology, Tulane University, New Orleans, who presented the study at the 2011 Scientific Sessions of the American Diabetes Association.
“The activated form bypasses several steps needed for activation to the biologically activated form, because about 50% of the population has a polymorphism…and cannot convert folate to its active form. You need the active form of folate to help the vitamin B12,” she said.
Use of metformin in patients with type 2 diabetes has been associated with vitamin B12 deficiency; “also, in people with neuropathy, regardless of whether or not they use metformin, data show vitamin B12 deficiency and an increase in homocysteine,” Dr Thethi said.
In the trial, 214 patients aged 25 to 80 years with diabetic peripheral neuropathy were randomized to LMF-MC-PLP or placebo for 24 weeks. The change in the vibration perception threshold was not different between the LMF-MC-PLP and placebo groups, but the mean score on the Neuropathy Total Symptom Score-6 instrument improved at a significantly greater rate at 16 weeks and 24 weeks in patients assigned to LMF-MC-PLP. Also, significant improvement in the mental component subscale of the Short Form-36 Health Survey was observed with LMF-MC-PLP after 24 weeks.
Although the improvement in the Neuropathy Disability Score was significantly greater in patients randomized to LMF-MC-PLP compared with placebo at 16 weeks, this difference was no longer significant at 24 weeks.
Patients assigned to LMF-MC-PLP showed lower levels of homocysteine, methylmalonic acid, and the inflammatory marker S-adenosylmethionine, and levels of vitamin B12 increased.
“Interestingly, people taking metformin had a lesser response than those not taking metformin, so perhaps those taking metformin have a higher grade of vitamin B12 deficiency, and perhaps might have needed a longer period of LMF-MC-PLP to bring their levels up to have a more significant response,” Dr Thethi said.