Short answer: No trial has compared them for nerve symptoms. Oral alpha-lipoic acid eased burning, stabbing pain and numbness more than placebo over 5 weeks in SYDNEY 2,1 and a meta-analysis of 10 trials agreed.2 Benfotiamine, a form of vitamin B1, helped in two short trials,34 but a 12-month trial found no effect on nerve measures.5
| Alpha-lipoic acid (ALA) | Benfotiamine | |
|---|---|---|
| What it is | An antioxidant studied for diabetic nerve damage2 | A fat-soluble form of vitamin B1 (thiamine)3 |
| Short trials | SYDNEY 2, 181 people, 600 to 1,800 mg once a day for 5 weeks: symptom scores fell about 50% vs 32% on placebo1 | BEDIP, 40 people, 3 weeks: better neuropathy score and less pain; BENDIP, 165 people, 300 or 600 mg a day for 6 weeks: borderline benefit34 |
| Long trials | NATHAN 1, 460 people, 600 mg a day for 4 years: main outcome no different; some exam scores better6 | BOND, 57 people, 300 mg twice a day for 12 months: no effect on any nerve or symptom measure5 |
| Pooled evidence | 10 trials, 1,242 people: fewer symptoms, more with higher doses; nerve tests unchanged2 | No meta-analysis in the sources checked |
| Side effects | Nausea, vomiting and vertigo rose with dose; more serious adverse events than placebo over 4 years (38.1% vs 28.0%)16 | Well tolerated; no difference from placebo in adverse events45 |
In SYDNEY 2, 181 people with diabetic neuropathy took 600, 1,200 or 1,800 mg of ALA once a day, or placebo, for 5 weeks. Symptom scores (stabbing and burning pain, tingling, numbness) fell by about half with every dose, versus 32% on placebo. Nausea, vomiting and vertigo rose with dose, and the authors judged 600 mg the best balance.1
In NATHAN 1, 460 people took 600 mg a day or placebo for 4 years. The main combined nerve score did not differ, partly because it barely worsened on placebo, but some nerve exam scores were better with ALA. Serious adverse events were more common with ALA.6 A 2023 meta-analysis of 10 trials found ALA eased symptoms but did not improve nerve conduction or vibration sense.2
In the 3-week BEDIP pilot, 40 people taking 400 mg a day had better neuropathy scores and less pain than placebo.3 In the 6-week BENDIP trial, 165 people took 300 or 600 mg a day or placebo; the main symptom score improved in the per-protocol analysis but only narrowly missed significance in the full analysis, and the total symptom score did not change.4
The longest trial, BOND, gave 57 people with type 2 diabetes 300 mg twice a day or placebo for 12 months. Thiamine levels rose, but nerve fiber length, nerve tests, symptoms and quality of life did not differ. Several authors were employees of, or paid by, Wörwag Pharma.5 One 4-week lab study gave both together to 9 people with type 1 diabetes and found some damage markers returned to normal; it did not measure symptoms.7
ALA has more trials and more consistent short-term symptom relief; benfotiamine's short-term results are mixed and its 12-month trial was negative. Neither has been shown to repair nerves. This is general information, not personal advice. More detail: the Alpha-Lipoic Acid and Benfotiamine guides.