Vitamin B1 (Thiamine)
Vitamin B1, also known as thiamine, is a B-vitamin that plays a vital role in the growth and function of various cells, including brain cells. It is key in neurological function, with deficiency causing neuronal death, mitochondrial dysfunction, energy shortage, and chronic oxidative stress in the brain1. For this reason, thiamine deficiency has been used to model some neurodegenerative diseases in animal studies.
In an animal model of MS comparing a regular to thiamin-deficient diet, the latter increased the severity of neurological dysfunction as demonstrated by walking and other movement disabilities. The mechanism appeared to be activation of autoimmune cell reaction and increase in inflammation regulatory activity in the spinal cord2.
In an open (uncontrolled) clinical study, RRMS patients suffering from associated fatigue were given high-dose thiamine therapy orally or intravenously. Doses were 10-23 mg/day depending on weight; for reference, the daily recommended dose for adults is 0.9-1.0/day. Although blood thiamine and thiamine metabolite levels were normal at the beginning of the study, treatment led to a significant improvement in fatigue. The absence of thiamine deficiency despite the presence of symptoms suggests that these patients may have a related metabolic dysfunction. Reversal of symptoms by high-dose thiamine indicates that such abnormalities could be overcome with the proper treatment3.
The recommended daily intake of thiamine during pregnancy is 1.4 mg per day for all ages, with women carrying more than one fetus possibly needing a higher dose. While the safe upper limit for most people is considered to be 100 mg/day4, doses of 300 mg/day have been used long-term without adverse effects in adults with increased needs5.
Only small amounts of thiamin are stored in the body, so a daily intake of thiamin-rich foods is needed. These include fortified/enriched grain products such as breakfast cereals and breads, pork, fish, legumes (beans, lentils, peas), sunflower seeds, and yogurt6.
References
1.Mrowicka M, Mrowicki J, Dragan G, Majsterek I. The importance of thiamine (vitamin B1) in humans. Biosci Rep. Oct 31 2023;43(10)doi:10.1042/BSR20230374
2.Ji Z, Fan Z, Zhang Y, et al. Thiamine deficiency promotes T cell infiltration in experimental autoimmune encephalomyelitis: the involvement of CCL2. J Immunol. Sep 1 2014;193(5):2157-67. doi:10.4049/jimmunol.1302702
3.Costantini A, Nappo A, Pala MI, Zappone A. High dose thiamine improves fatigue in multiple sclerosis. BMJ Case Rep. Jul 16 2013;2013doi:10.1136/bcr-2013-009144
4.Safe upper intake levels for vitamins and minerals (Ministry of Family and Consumer Affairs) (2006).
5.Bager P, Hvas CL, Rud CL, Dahlerup JF. Long-term maintenance treatment with 300 mg thiamine for fatigue in patients with inflammatory bowel disease: results from an open-label extension of the TARIF study. Scand J Gastroenterol. Jan 2022;57(1):37-43. doi:10.1080/00365521.2021.1983640
6.Health HCSoP. Thiamin – Vitamin B1. The Nutrition Source Accessed 18 Feb 2022. https://www.hsph.harvard.edu/nutritionsource/vitamin-b1/