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B19.0
Thiamine Research
Probably helpsHigh safety
30 peer-reviewed studies
What the evidence says
Probably helps
Thiamine helped in about half (5/10) of the studies that measured an effect — promising, but not unanimous.
Most evidence is from high-quality meta-analyses and randomised trials published 2005–2026 with a typical study size of 165 participants.
Based on 30 studies · 8 meta-analyses · 9 RCTs · 14,516 total participants
Confidence
High
What the studies found
5helped2unclear3didn't help· 20 more without graded effect data
By outcome
Therapeutic & clinical
Mixed evidence22 studies
Beriberi & Wernicke-Korsakoff
Mostly mechanism / observational4 studies
Heart & blood pressure
Too few graded studies2 studies
Cognitive function
Too few graded studies2 studies
Women's healthMay help reduce menstrual discomfort and PMS symptoms · 1-3 cycles · Provides essential nutrients for healthy pregnancy · Ongoing
Too few graded studies2 studies
Safety profile
Too few graded studies2 studies
Glucose & metabolic
Too few graded studies1 study
Energy & fatigueImproved energy from carbohydrate metabolism · 2-4 weeks
Too few graded studies1 study
Anxiety & stress
Too few graded studies1 study
By the numbers
Pulled from 23 studies with measurable effects
Likely real effects
50%
across studies
People studied
15k
typical study: 165 people
Strongest designs
17
8 pooled, 9 randomised
Showed benefit
50%
5/10 studies
How long studies ran
1–4 weeks
1
1–3 months
2
3+ months
2
Populations Studied
Heart failure patients2
Patients who underwent bariatric surgery1
Women with dysmenorrhoea1
Episodic ataxia patients1
Active research area
23 studies in the last 5 years · Latest meta-analysis: 2023
200520152026
1Systematic ReviewCited 16×n=3,254 · very large study2025
There is some evidence to support the use of nutritional interventions for improving psychological symptoms of PMS.
Robinson J et al. · Nutrition reviews (2025)
There is some evidence to support the use of nutritional interventions for improving psychological symptoms of PMS.
However, more research using consistent protocols, procedures to minimize risk of bias, intention-to-treat analysis, and clearer reporting is required to provide conclusive nutritional recommendations for improving PMS-related psychological outcomes.
3Vitamin B1 deficiency prevalenceMeta-AnalysisCited 21×n=1,494 · large study2022
Bahardoust M et al. · Obesity surgery (2022)
Large benefit
← WorseNo effectBetter →
Twenty-seven percent of patients who underwent bariatric surgeries experience vitamin B1 deficiency.
A total of 11 studies examining 1494 patients were included in this meta-analysis.
Thiamine supplements should be prescribed for the patients for the rest of their lives, and also standard post-surgery follow-ups are necessary in terms of monitoring dietary factors.
4Dysmenorrhoea symptomsMeta-AnalysisCited 69×n=3,101 · very large study2016
There is no high quality evidence to support the effectiveness of any dietary supplement for dysmenorrhoea, and evidence of safety is lacking.
Pattanittum P et al. · The Cochrane database of systematic reviews (2016)
Supplements versus other supplementsThere was no evidence of a difference in effectiveness between ginger and zinc sulphate (MD 0.02 points, 95% CI -0.58 to 0.62; one RCT, 101 women).
Vitamin B1 may be more effective than fish oil (MD -1.59 points, 95% CI -2.25 to -0.93; one RCT, 120 women).
There is no high quality evidence to support the effectiveness of any dietary supplement for dysmenorrhoea, and evidence of safety is lacking.
7Thiamine status markersMeta-AnalysisCited 20×2023
Diabetes is associated with lower levels of various thiamine markers, suggesting that individuals with diabetes may have higher thiamine requirements than those without diabetes, but well-designed studies are required to confirm these findings.
Ziegler D et al. · Metabolism: clinical and experimental (2023)
Huge benefit
← WorseNo effectBetter →
Compared to controls, individuals with diabetes showed lower concentrations of thiamine (pooled estimate SMD [95 % CI]: -0.97 [-1.89, -0.06]), thiamine monophosphate (-1.16 [-1.82, -0.50]), and total thiamine compounds (-1.01 [-1.48, -0.54]).
Diabetes is associated with lower levels of various thiamine markers, suggesting that individuals with diabetes may have higher thiamine requirements than those without diabetes, but well-designed studies are required to confirm these findings.
8Neuropathy symptom improvementMeta-AnalysisCited 49×n=46 · small study2021
PN is associated with lowered plasma vitamin B12 and elevated methylmalonic acid and homocysteine.
Stein J et al. · European journal of neurology (2021)
Huge harm
← WorseNo effectBetter →
Borderline
B12 treatment (vs. the comparators) showed a non-significant association with symptom improvement (1.36 (0.66-2.79), n = 4, I2 = 28.9%).
Treatment with B1 was associated with a significant improvement in symptoms (5.34 [1.87-15.19], n = 3, I2 = 64.6%, p = 0.059).
Analysis of seven trials combined showed a non-significant higher odds ratio for improvement under treatment with the B-vitamins (2.58 [0.98-6.79], I2 = 80.0%, p < 0.001).
The findings of this systematic review suggest that supplementation of B Complex vitamins, especially folic acid, may have a positive effect on delaying and preventing the risk of cognitive decline.
Gil Martínez V et al. · Nutrients (2022)
The findings of this systematic review suggest that supplementation of B Complex vitamins, especially folic acid, may have a positive effect on delaying and preventing the risk of cognitive decline.
Ascorbic acid and a high dose of vitamin E, when given separately, also showed positive effects on cognitive performance, but there is not sufficient evidence to support their use.
The results of vitamin D supplementation trials are not conclusive in assessing the potential benefits that vitamin D might have on cognition.
The final outcomes of ongoing trials of vitamin supplementation are awaited with interest.
Jovic TH et al. · Nutrients (2020)
Vitamins A to E highlighted potentially beneficial roles in the fight against COVID-19 via antioxidant effects, immunomodulation, enhancing natural barriers, and local paracrine signaling.
Level 1 and 2 evidence supports the use of thiamine, vitamin C, and vitamin D in COVID-like respiratory diseases, ARDS, and sepsis.
Although there are currently no published clinical trials due to the novelty of SARS-CoV-2 infection, there is pathophysiologic rationale for exploring the use of vitamins in this global pandemic, supported by early anecdotal reports from international groups.
We performed a GRADE evaluation of the quality of evidence for interventions.
Latthe PM et al. · BMJ clinical evidence (2011)
Systematic review examining Thiamine efficacy
Further research warranted to confirm findings
13Prevalence of peripheral neuropathy in chronic alcohol abusersMeta-AnalysisCited 109×2019
There is presently sparse data to support a particular management strategy in alcohol-related peripheral neuropathy, but the limited data available appears to support the use of vitamin supplementation, particularly of B-vitamin regimens inclusive of thiamine.
Julian T et al. · Journal of neurology (2019)
No clear effect
← WorseNo effectBetter →
The prevalence of peripheral neuropathy amongst chronic alcohol abusers is 46.3% (CI 35.7- 57.3%) when confirmed via nerve conduction studies.
Alcohol-related peripheral neuropathy generally presents as a progressive, predominantly sensory axonal length-dependent neuropathy.
The most important risk factor for alcohol-related peripheral neuropathy is the total lifetime dose of ethanol, although other risk factors have been identified including genetic, male gender, and type of alcohol consumed.
Better prospective studies using contemporary phenotype-based audiovestibular assessment are needed.
Chen JJ et al. · International journal of molecular sciences (2026)
Vestibular involvement was also reported, but the evidence was smaller and less phenotypically specific, consisting mainly of syndromic reports, broad peripheral/central classifications, and historical nystagmographic findings.
Direct treatment evidence was very limited; improvement after thiamine replacement was reported in alcohol-related Wernicke-spectrum presentations, but no established disease-specific therapy was identified.
Overall, current human clinical evidence supports heightened clinical awareness but not disease-specific screening algorithms or targeted therapeutic recommendations.
15Substance use risks and nutritional complicationsSystematic Review2026
Mitigation requires a lifelong, multidisciplinary framework involving preoperative risk stratification, validated screening (e.g., AUDIT-C), and targeted nutritional supplementation to safeguard the long-term metabolic and psychological benefits of MBS.
Campuzano-Donoso M et al. · Nutrients (2026)
Procedures like Roux-en-Y gastric bypass (RYGB) radically alter ethanol metabolism, eliminating first-pass metabolism and accelerating gastric emptying, while simultaneously recalibrating reward pathways, creating a "reward gap" that facilitates addiction transfer.
These physiological shifts exacerbate critical micronutrient deficiencies (thiamine, B12, iron), increase the risk of post-bariatric hypoglycemia, and correlate with higher rates of liver cirrhosis and suicide.
Furthermore, substance use is a primary driver of suboptimal weight loss trajectories and weight regain.
16Anemia and micronutrient deficiencySystematic Review2026
The following review highlights the current state of knowledge and the relevance of these micronutrient deficiencies in the broader context of nutritional anemia.
Datta Mitra A et al. · Nutrients (2026)
Increasing numbers of persons, mainly in low- and middle-income nations, are faced with malnutrition and malabsorption syndromes, giving rise to various micronutrient deficiencies that can lead to anemias refractory to treatment with iron, folate or vitamin B12.
Though relatively uncommon, such underlying nutrient deficiencies may be difficult to recognize as they can coexist with more common causes and there may be few or no specific clinical characteristics pinpointing a particular micronutrient.
The main examples of these micronutrients contributing to a small but important burden of anemia are other B-group vitamins, pyridoxine and thiamine, ascorbic acid, the fat-soluble vitamins, A and E and other trace elements such as copper, zinc and selenium.
This systematic-review examined the effects of Thiamine.
Pereira AG et al. · Medical principles and practice : international journal of the Kuwait University, Health Science Centre (2025)
Overall, 100-300 mg daily doses are enough to improve symptoms.
In this review, we aim to (1) provide a clinical update about how to identify and treat the Beriberi and (2) describe the historical perspective, pathophysiological mechanisms, and other relevant aspects which may have applications in clinical management of Beriberi. </p>.
1850% or greater reduction in seizure frequencyMeta-AnalysisCited 28×n=331 · medium study2005
In view of methodological deficiencies and limited number of individual studies, we have found no reliable evidence to support the routine use of vitamins in patients with epilepsy.
Ranganathan LN et al. · The Cochrane database of systematic reviews (2005)
No clear effect
← WorseNo effectBetter →
Two studies (75 participants) found no effect for the outcome 50% or greater reduction in seizure frequency (OR 0.96; 95% CI 0.32 to 2.29).
One study (226 participants) found a significantly higher bone mineral content (BMC) among patients with epilepsy taking AEDs with vitamin D supplementation compared to controls who were not given supplementation (OR 3.6; 95% CI 2.48 to 4.72; p < 0.00001).
One small study (24 participants) found a significant decrease in seizure frequency in those treated with vitamin E compared to placebo (p = 0.00005; Peto OR 26.73; 95% CI 5.46 to 130.92).
20Roland Morris score improvementRCTn=122 · medium study2024
Regarding pain, however, although there was a numerical improvement, it did not reach statistical significance.
Monfort J et al. · Nutrients (2024)
Noticeable benefit
← WorseNo effectBetter →
Likely real
Both groups showed pain improvement, but the VAS reduction (control: 24.58 vs. experimental: 31.35) was not statistically significant.
The Roland Morris score decreased significantly in the experimental group (estimate: -1.70, 95% CI -3.29 to -0.10; p = 0.038), and these patients were 5 times more likely to progress to a better CGI category (OR = 0.20, 95% CI 0.07 to 0.57; p = 0.003).
No significant differences were observed in EQ-5D-5L scores or analgesic consumption.