Also known as: Thiamine, Thiamin, Benfotiamine, Thiamine HCl, TTFD
VitaminsStrong evidence
A water-soluble vitamin central to turning carbohydrate into usable energy. Requirements rise with carbohydrate intake, which makes it quietly relevant to anyone eating a lot to support heavy training.
Typical dose
1.0–100.0 mg per day
With food; any time of day
What it is
Thiamine was the first B vitamin identified, which is why it carries the number one. It is water-soluble, poorly stored by the body, and needs replacing regularly through the diet.
Good sources include pork, wholegrains, legumes, nuts and seeds. In the UK, white and brown flour is fortified with thiamine by law, which means bread contributes a meaningful share of most people's intake without anyone thinking about it.
Supplemental forms differ in how well they are absorbed. Thiamine hydrochloride and mononitrate are the standard water-soluble forms. Benfotiamine is fat-soluble and reaches considerably higher blood levels, which is why it commands a premium and appears in more expensive formulas.
How it works
Thiamine is converted to thiamine pyrophosphate, which acts as a cofactor for several enzymes that sit at critical junctions in energy metabolism, including the step that feeds carbohydrate into the citric acid cycle.
This is why thiamine requirements scale with carbohydrate intake rather than being fixed. The more carbohydrate you process, the more thiamine those enzymes get through.
It also supports the pentose phosphate pathway, which generates the reducing power used in fat synthesis and antioxidant defence, and has a role in nerve signal conduction that is separate from its metabolic function.
What the evidence shows
Thiamine's essentiality is beyond question, and the consequences of running short are well characterised and appear relatively quickly given how little the body stores.
For supplementation in people with adequate intake, there is little evidence of benefit to energy, performance or anything else. This is a nutrient where correcting a shortfall matters and topping up sufficiency does not.
Groups more likely to fall short include heavy drinkers, since alcohol impairs both absorption and storage, people eating very high carbohydrate diets without matching micronutrient intake, and anyone on a long-term restricted diet. For most people eating varied food, a B1 supplement is solving a problem they do not have.
Dosing
Reference intakes are around 1 mg daily for adults, which ordinary food covers comfortably in most cases.
Supplements typically supply 25-100 mg, far above requirement. Because thiamine is water-soluble and excess is excreted, this is not harmful, but it is also not doing anything useful once needs are met.
Benfotiamine is used at lower doses, typically 150-300 mg, and achieves much higher blood levels than the standard forms. If there is a genuine reason to raise thiamine status, that is the more effective route. Take with food.
At a glance
Common forms
Thiamine HCl, Thiamine mononitrate, Benfotiamine, TTFD (sulbutiamine family), Within B-complex
Half-life / duration
Poorly stored; body reserves last only a few weeks without intake
Timing
With food; any time of day
Competition status
Permitted — not on the WADA Prohibited List
Category
Vitamins
Safety and side effects
Thiamine has an excellent safety record. It is water-soluble and excess is cleared in urine, so no tolerable upper intake level has been set for oral intake.
Adverse effects at supplemental doses are rare and mild. Very high doses may cause digestive upset in some people.
Speak to your doctor before use if you take regular medication, since some medicines affect thiamine status.
Who should avoid it
Speak to your doctor before use if you take regular medication or are under medical care. Generally very well tolerated otherwise, with no significant interactions established at ordinary supplemental doses.
This entry is provided for information only. Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle. Consult a qualified healthcare professional before use if you are pregnant, breastfeeding, taking medication or under medical supervision.
