Dr Costantini, an Italian neurologist, and his team in 2013 developed a protocol for a therapy with high doses of thiamine for Parkinson’s disease (PD), the so called HDT or B1 therapy [Costantini, 2013].

According to this protocol, high doses of thiamine (B1) are given to Persons with Parkinson’s (PwP). Oral doses could be as high as even 4,000 times the RDA[1].

Published case study reports and an open label study with a long follow-up conducted by the same team suggested that thiamine given at high doses was able to cause a significant clinical improvement not only in motor signs but also in non-motor signs in PwP [Costantini, 2015]. An improvement was noted in all stages of the disease and was sustained for as long as the therapy was continued. It was de facto associated with a slow down of disease progression, suggesting a potential disease-modifying effect. Thiamine given at such high doses was reported to be well tolerated and safe (Costantini, 2018).

The background and rationale for the use of thiamine at high doses in PD as well as summaries of the relevant studies, are described in the section on “The Scientific Evidence”, together with notes on the applicability and implications of the placebo effect.

Dr Costantini emphasized that HDT (B1) therapy was not a replacement for traditional treatment (e.g. levodopa) but rather an adjunct therapy, i.e. a therapy given in addition to primary treatment [Costantini, 2018]. PwP on levodopa and other medicines would therefore continue taking the prescribed medicines, at the same doses, and would add thiamine (B1) at high doses. One of the B1 therapy beneficial effects described by Dr Costantini was also the lack of development of levodopa typical side effects, such as dyskinesia (Costantini, HDT website).

[1] RDA: Recommended Dietary Allowance

Selected references
Costantini, MI Pala, L. Compagnoni, M. Colangeli, High-dose thiamine as initial treatment for Parkinson's disease, BMJ Case Rep 2013 Aug 28.

A. Costantini, MI Pala, E. Grossi, S. Mondonico, L. Ercoli Cardelli, C. Jenner, S. Proietti, M. Colangeli, Roberto Fancellu, Long-Term Treatment with High-Dose Thiamine in Parkinson Disease: An Open-Label Pilot Study, J Altern Complement Med. 2015 Dec;21(12):740-7

Costantini and R. Fancellu, Effects of Overdose of High-Dose Thiamine Treatment, Gerontology & Geriatrics Studies, December 06, 2018

Dr Costantini’s website on High-dose Thiamine (HDT) Therapy for Parkinson’s Disease, Accessed 28.02.2023

Text author: Sergio Pièche
Page updated - 24/04/23