Benfotiamine is a synthetic, fat-soluble form of thiamine (vitamin B1) that raises blood and tissue thiamine levels more than ordinary thiamine. It has been studied mainly for diabetic neuropathy: two small placebo-controlled trials of 300–600 mg a day for 3–6 weeks found modest improvement in symptom scores, while a larger one-year trial of 300 mg a day found no effect on nerve function. Evidence is limited, effects if any are small, and it does not repair nerves. It is well tolerated and has no known serious interactions. Alpha-lipoic acid has somewhat better evidence for the same use.
What benfotiamine is
Benfotiamine (S-benzoylthiamine O-monophosphate) is a synthetic derivative of thiamine, vitamin B1. Unlike thiamine itself, it is fat-soluble, so it is absorbed more completely from the gut and produces substantially higher thiamine levels in blood and tissues. It was developed in Japan in the 1960s and is prescribed in some countries for thiamine deficiency and diabetic neuropathy; elsewhere it is sold as a supplement.
How it is supposed to work
Thiamine is a cofactor for the enzyme transketolase, which diverts glucose metabolites away from several of the pathways thought to damage nerves and blood vessels in diabetes — the formation of advanced glycation end-products, the polyol pathway and others (see blood sugar and nerve health). Laboratory and animal studies show benfotiamine activates transketolase and reduces markers of this damage. People with diabetes also tend to have lower thiamine levels than people without, because it is lost in urine.
Whether these mechanisms translate into fewer or milder complications in people is the question the trials address, and the answer so far is "not clearly".
Evidence by use
| Use | Rating | What the trials show |
|---|---|---|
| Symptoms of diabetic peripheral neuropathy | Limited | Two small placebo-controlled trials (about 40 and 165 people) of 300–600 mg a day for 3–6 weeks found modest improvements in symptom scores, mainly pain. A 24-month trial of 300 mg a day in 67 people found no improvement in nerve conduction, vibration perception or symptoms. |
| Diabetic kidney disease | Insufficient | A 12-week trial found no reduction in urinary albumin. |
| Alcohol-related neuropathy | Insufficient | One small trial with some improvement in symptoms. |
| Thiamine deficiency | Strong (for raising thiamine levels) | Reliably corrects deficiency; whether it is better than thiamine for outcomes is not established. |
| Cognitive decline | Insufficient | A small pilot trial in mild Alzheimer's; larger trial results awaited. |
Doses studied
150–600 mg a day, usually 300 mg a day in two divided doses, for neuropathy. Higher doses did not show clearly larger effects.
Safety
Benfotiamine is well tolerated. Reported side effects are rare and mild — stomach upset, skin rash. Thiamine has no upper intake limit because excess is excreted, and the same appears true of benfotiamine. There are no known significant drug interactions. Safety in pregnancy has not been studied.
Where it appears in supplements
Benfotiamine is a standard component of "nerve support" formulas, usually at 100–300 mg, alongside alpha-lipoic acid, B12 (as methylcobalamin), B6, acetyl-L-carnitine and sometimes turmeric. Two cautions: formulas that include high-dose vitamin B6 (over 100 mg a day) can themselves cause neuropathy with long use; and a formula that contains B12 should not be started before B12 deficiency has been tested for, because it will mask the diagnosis. See nerve supplement research.
Bottom line
Benfotiamine is safe, plausible and under-evidenced. If you have diabetic neuropathy and want to try a supplement for symptoms, alpha-lipoic acid at 600 mg a day has better trial support; benfotiamine at 300 mg is a reasonable addition or alternative for a few months with a symptom diary. Neither substitutes for glucose control, foot care or the medications that reliably reduce nerve pain — see diabetic neuropathy.
Frequently asked questions
Is benfotiamine the same as vitamin B1?
It is a derivative of vitamin B1 that is converted to thiamine in the body. Because it is fat-soluble it is absorbed several times more efficiently than thiamine hydrochloride and produces higher tissue levels, which is the rationale for using it rather than plain thiamine.
Does benfotiamine lower blood sugar?
No meaningful effect on glucose has been shown. Its proposed benefit is in blocking some of the damaging pathways that high glucose activates, not in lowering glucose itself.
Should I take it with alpha-lipoic acid?
The two are often combined in nerve formulas and one small trial tested the combination. There is no evidence the combination is better than alpha-lipoic acid alone, which has the stronger evidence.
References
- NIDDK. Diabetic Neuropathy (2023). https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-problems/nerve-damage-diabetic-neuropathies
- National Institute of Neurological Disorders and Stroke. Peripheral Neuropathy (2024). https://www.ninds.nih.gov/health-information/disorders/peripheral-neuropathy
- National Center for Complementary and Integrative Health (NCCIH). Diabetes and Dietary Supplements: What You Need To Know (2021). https://www.nccih.nih.gov/health/diabetes-and-dietary-supplements-what-you-need-to-know
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