Vitamin B1, also known as thiamin, is a life-essential nutrient that is essential for the normal function of our cells. Thiamin is particularly important for the brain: A deficiency of this vitamin is a known cause of the Wernicke-Korsakoff syndrome, a neurological disorder characterized by brain damage and psychosis. Since people cannot produce thiamin themselves, it must be taken through food. Foods rich in thiamin are yogurt, lentils, pork, and green peas.
Thiamin and Parkinson’s disease
Although still poorly understood, thiamin and dopamine may be closely linked: Thiamin deficiency reduced dopamine concentration in the brain of animals 1. Similarly, the administration of thiamin increases dopamine release. People with Parkinson’s disease treated with levodopa have higher thiamin levels in the brain than those with untreated Parkinson’s 2. High concentrations of thiamin derivatives were found in the substantia nigra, the brain area affected in Parkinson 3.
Clincial Studies on Thiamin / Vitamin B1 in Parkinson’s disease
In a first study, researchers recruited 5 patients aged 65-82 years old with Parkinson’s disease (disease duration: 3–16 years), who were treated with Levo/Carbidopa 4. They received intramuscular doses of 100–200 mg thiamin daily. Within less than two weeks, the participants improved: they had no tremor and could walk normally. Three of them stopped Levo/Carbidopa therapy without worsening their movements.
Antonio Constantini, M.D. from the “Villa Immacolata” clinic in Viterbo, Italy, conducted several clinical studies with high thiamin doses to treat Parkinson. In a study from 2013, 3 patients—aged between 74 and 79 years and with a disease duration of more than 3 years—received twice weekly 100 mg thiamin intramuscularly over 3–4 months. Symptoms such as mask face, bradykinesia, rigidity, and fatigue improved after 15 days of therapy. The patients moved faster, smiled more, and felt less tired.
Some years later, Constantini and his team treated 10 patients (8 men aged around 74.5 years, with a disease duration of 5.2 years) with 100 mg thiamin twice weekly 5. All participants had normal thiamin levels in the blood before therapy. After one month, they improved clinically with higher thiamin or levodopa dosages. Motor coordination was significantly better after two months, and some patients with mild symptoms recovered completely. No side effects were reported during the study time.
Advantages of Long-term Thiamin / Vitamin B1 Therapy in Parkinson
Constantini also investigated the long-term effects of thiamin therapy. They recruited 50 patients (33 men aged 70.4 years, with a disease duration of 7 years), seven of whom did not take Parkinson medication. The participants received 100 mg of thiamin intramuscularly twice a week for up to 2.5 years. After three months, motor and non-motor symptoms improved and remained stable. The seven untreated patients did not need to start Levodopa therapy, and no side effects occurred during those years.
Vitamin B1 Deficiency in Brain Function
Constantini also found that thiamin therapy improved cognitive problems in three patients with dementia, although hallucinations and other psychiatric symptoms persisted. In 2020, researchers from Umea University in Sweden analyzed thiamin levels in the blood of people with Parkinson’s with or without mild cognitive problems 6. They found lower thiamin levels in men compared to women. Men with Parkinson’s and cognitive problems had lower thiamin levels than those without cognitive impairments.
Vitamin B1 in Parkinson: Intramuscular, Oral or Sublingual?
In the clinical studies mentioned above, thiamin was administered intramuscularly. This allows direct entry into the blood and therefore a faster onset of action.
Oral vitamin B1 supplements must first pass through the digestive system, which reduces their availability and effectiveness, especially in older adults with absorption problems 7. Despite these limitations, oral supplements are preferred for thiamin intake as they are convenient and safe. An adequate dosage is necessary to compensate for variability in absorption.
Sublingual tablets are an alternative method that has recently gained attention. Similar to intramuscular injection, sublingual tablets allow direct entry into the blood through the capillaries under the tongue, bypassing the digestive system. Earlier comparative studies with vitamin B12 have shown that intramuscular and sublingual administration are more effective in increasing blood thiamin levels than oral administration 8.
Among the three methods, sublingual tablets are more convenient and non-invasive, improving patient compliance. This can be particularly beneficial for people with Parkinson’s who have swallowing difficulties.
How Thiamin/ Vitamin B1 Neurologically Works in Parkinson
Thiamin helps certain proteins that provide energy for the proper function of cells. Given that thiamin deficiency causes the death of brain cells, scientists think that high thiamin doses could help surviving neurons in Parkinson’s function, potentially increasing dopamine production and release, or activating other thiamin-dependent proteins.
Final Thoughts on Thiamin / Vitamin B1 in Parkinson
Increasing evidence suggests that certain nutrients can reduce the risk and progression of Parkinson. Studies show that high thiamin doses significantly improve Parkinson’s motor symptoms. Thiamin may also protect against cognitive decline, especially in men. Remember to consult with your doctor before starting vitamin B1 supplementation.
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References
- Sjöquist B, Johnson HA, Neri A, Lindén S. The influence of thiamine deficiency and ethanol on rat brain catecholamines. Drug Alcohol Depend. 1988;22(3):187-193. doi:10.1016/0376-8716(88)90017-8
- Jiménez-Jiménez FJ, Molina JA, Hernánz A, et al. Cerebrospinal fluid levels of thiamine in patients with Parkinson’s disease. Neurosci Lett. 1999;271(1):33-36. doi:10.1016/s0304-3940(99)00515-7
- Baker H, Frank O, Chen T, Feingold S, DeAngelis B, Baker E. Vitamin content of some normal human brain segments. J Neurosci Res. 1984;11(4):419-435. doi:10.1002/jnr.490110409
- Luong KV, Nguyễn LT. The beneficial role of thiamine in Parkinson disease. CNS Neurosci Ther. 2013;19(7):461-468. doi:10.1111/cns.12078
- Costantini A, Fancellu R. An open-label pilot study with high-dose thiamine in Parkinson’s disease. Neural Regen Res. 2016;11(3):406-407. doi:10.4103/1673-5374.179047
- Håglin L, Domellöf M, Bäckman L, Forsgren L. Low plasma thiamine and phosphate in male patients with Parkinson’s disease is associated with mild cognitive impairment. Clin Nutr ESPEN. 2020;37:93-99. doi:10.1016/j.clnesp.2020.03.012.
- Sanz-Cuesta T, Escortell-Mayor E, Cura-Gonzalez I, et al. Oral versus intramuscular administration of vitamin B12 for vitamin B12 deficiency in primary care: a pragmatic, randomised, non-inferiority clinical trial (OB12). BMJ Open. 2020;10(8):e033687. Published 2020 Aug 20. doi:10.1136/bmjopen-2019-033687
- Abdelwahab OA, Abdelaziz A, Diab S, et al. Efficacy of different routes of vitamin B12 supplementation for the treatment of patients with vitamin B12 deficiency: A systematic review and network meta-analysis. Ir J Med Sci. 2024;193(3):1621-1639. doi:10.1007/s11845-023-03602-4