Any dietary or drug treatment with high doses of micronutrients may override the body's own control mechanisms. Therefore, micronutrient therapies may be associated with potential side effects and toxicities. High-dosed micronutrients should not be used without medical supervision.
Wernicke-Korsakoff syndrome is a brain disorder caused by vitamin B1 (thiamin) deficiency. The syndrome is actually two disorders: Wernicke's disease involves damage to nerves in the central and peripheral nervous systems and is generally caused by malnutrition stemming from habitual alcohol abuse. Korsakoff syndrome is characterized by memory impairment and nerve damage.
High doses of thiamin have shown to improve muscle coordination and confusion, but only rarely improved memory loss (6).
Thiamine has become the only vitamin supplement to be regularly administered via the veins (‘parenteral’) to treat extreme alcoholism and Wernicke-Korsakoff syndrome in hospital emergency departments.
Because lack of vitamin B1 (thiamine) can cause dementia in Wernicke-Korsakoff syndrome (see above), it has been proposed that thiamin might help reduce severity of Alzheimer's disease.
A recent review of randomized controlled trials in patients with dementia of Alzheimer's type found no evidence that thiamin was a useful treatment for the symptoms of the disease (7).
More research is needed before thiamin could be proposed as an effective treatment for Alzheimer's disease.
Congestive heart failure (CHF), a condition in which the heart cannot pump enough blood to the body's other organs, is a common disease, especially in the elderly. As in the general population, older CHF patients were found to be at higher risk of vitamin B1 (thiamin) deficiency than younger ones (8). Diuretics used in the treatment of CHF, notably furosemide, have been found to increase thiamin excretion, potentially leading to marginal thiamin deficiency (9). Therefore, it may be reasonable to provide such patients with thiamine supplementation during heart failure exacerbations (22).
Presently, the role of thiamin supplementation in maintaining cardiac function in CHF patients remains controversial. Conclusions from studies published to date (10, 11) are limited due to small sample sizes of the studies, lack of randomized controlled study design, and a need for more precise assays of thiamin nutritional status.
As vitamin B1 (thiamin) deficiency has been observed in some cancer patients with rapidly growing tumors, thiamin supplementation is common in such patients to prevent deficiency.
Some experts have theorized that too much thiamin may actually fuel the growth of cancer cells (12), as rapidly dividing cancer cells have a high requirement for thiamin, due to an increased level of nucleic acids (13).
However, there is no evidence available from studies in humans to support this theory. Cancer patients who are considering thiamin supplementation should discuss it with the managing clinician.
Authored by Dr Peter Engel in 2010, reviewed and revised by Angelika Friedel on 29.06.17