What is the function of vitamin B1 during exercise?

December 4, 2025 •

3 min read

While often overshadowed by other nutrients, thiamine, or vitamin B1, plays a foundational role in energy metabolism, with deficiencies being associated with fatigue and impaired performance. It is an essential water-soluble vitamin that is vital for converting food into the energy your body needs to power through a workout.

Quick Summary

Vitamin B1, also known as thiamine, functions as a critical coenzyme in energy metabolism, converting carbohydrates into usable fuel for muscles and the nervous system during exercise. It helps reduce fatigue, supports muscle contraction, and is vital for athletic performance, with increased needs correlating with higher activity levels.

Key Points

Energy Metabolism Catalyst: Vitamin B1, or thiamine, acts as a crucial coenzyme for breaking down carbohydrates into usable energy (ATP) for muscles during exercise.
Supports Muscle Contraction: It aids in nerve signal transmission and electrolyte flow in and out of muscle cells, which is vital for proper and efficient muscle contraction.
Fatigue Reduction: By promoting efficient carbohydrate metabolism, thiamine helps reduce the accumulation of lactate, a byproduct linked to fatigue during intense exercise.
Increased Athlete Needs: Due to higher metabolic demands, athletes may have an increased requirement for thiamine, and inadequate intake can negatively impact performance and recovery.
Supports Nervous System: Thiamine helps maintain the proper functioning of the nervous system, which is essential for coordination and overall physical performance.
Dietary Intake is Crucial: Since the body stores only small amounts of thiamine, it must be regularly replenished through dietary sources like whole grains, pork, legumes, and fortified foods.

The Core Role of Vitamin B1 in Exercise

Vitamin B1, or thiamine, is essential for metabolic processes that generate energy. As a coenzyme, thiamine is particularly crucial for converting carbohydrates into glucose, the body's main fuel during exercise. Without enough thiamine, the body struggles to produce adenosine triphosphate (ATP), the cellular energy currency, leading to poorer performance and fatigue.

Thiamine's Function in Carbohydrate Metabolism

Exercise increases the demand for energy, requiring a quick breakdown of carbohydrates. Thiamine's active form, thiamine pyrophosphate (TPP), is a key cofactor for enzymes in this process, including:

Pyruvate Dehydrogenase (PDH): This enzyme links glycolysis (glucose breakdown) to the Krebs cycle, the main ATP production site. PDH converts pyruvate to acetyl-CoA, which enters the Krebs cycle. Insufficient TPP hinders this step, slowing energy production.
$\alpha$-Ketoglutarate Dehydrogenase: Another enzyme in the Krebs cycle that requires TPP and is vital for ATP synthesis. A deficiency further limits energy supply to muscles.

How Thiamine Supports Muscle and Nerve Function

Thiamine also maintains nervous system health and aids muscle contractions, crucial for athletic performance, coordination, strength, and endurance. It helps regulate electrolytes in nerve and muscle cells for efficient signal transmission. Low levels can cause nerve damage, muscle weakness, and poor coordination, negatively affecting physical activity.

Thiamine Deficiency and Its Impact on Exercise

While severe thiamine deficiency is uncommon in developed countries, low intake can still affect athletes. Since the body stores limited thiamine, regular dietary intake is needed. Athletes have higher metabolic demands, potentially increasing their thiamine needs. Chronic low intake can compromise muscle repair and maintenance, affecting performance and increasing fatigue.

Research indicates thiamine supplementation can benefit athletes by reducing fatigue and improving endurance. This suggests even minor deficiencies can impact how someone feels and performs.

The Link Between Thiamine, Lactate, and Fatigue

Lactate, a byproduct of intense exercise, is linked to muscle fatigue. Thiamine helps reduce lactate concentration. As a cofactor for PDH, it helps process pyruvate into acetyl-CoA for the aerobic Krebs cycle instead of being converted to lactate. This efficient fuel use can delay fatigue and improve endurance.

Dietary Sources and Intake Recommendations

Athletes should prioritize dietary sources of thiamine, found in various foods, although cooking can reduce content. Fortified foods and supplements also contain thiamine.

Comparison Table: Thiamine Sources


Food Source	Type	Natural / Fortified	Benefit for Athletes
Pork	Meat	Natural	A naturally rich source, particularly good for muscle function.
Fortified Cereals	Grain	Fortified	Easy and consistent source of thiamine, suitable for breakfast before a workout.
Whole Grains	Grain	Natural	Contains natural thiamine along with other B vitamins and fiber for sustained energy.
Legumes (Beans, Lentils)	Plant	Natural	Excellent plant-based source, also rich in carbohydrates for fuel.
Sunflower Seeds	Seed	Natural	Provides a concentrated source of thiamine and healthy fats.
Salmon & Tuna	Fish	Natural	Good source of thiamine and other B vitamins for energy metabolism.
Nutritional Yeast	Yeast	Can be fortified	Extremely high source of B vitamins, often used as a dietary supplement.

The Potential Role of Supplementation

Supplementation may be considered for some athletes, particularly those with high training volumes or dietary restrictions. A 28-day study showed vitamin B-complex supplementation improved endurance and reduced fatigue in healthy individuals. However, for those with adequate diets, supplements may not offer extra benefits. Athletes should consult a healthcare professional before starting supplements to ensure they meet their needs.

Conclusion

Vitamin B1 is a fundamental part of energy metabolism and directly affects exercise performance. As a coenzyme for key metabolic pathways, it converts carbohydrates into usable energy, supports muscle contraction, and helps manage fatigue. A balanced diet with whole grains, meats, and legumes provides adequate intake, but athletes with high energy needs may need careful planning or supplementation. Consistent vitamin B1 is vital for optimal energy and athletic potential.

Frequently Asked Questions

Thiamine deficiency impairs the body's ability to convert carbohydrates into energy, leading to decreased ATP production. This can result in increased fatigue, muscle weakness, and compromised nerve function, all of which negatively impact athletic performance.

No, thiamine is a water-soluble vitamin and is not stored in large amounts in the body. The body holds a limited reserve, mainly in the skeletal muscles, liver, and heart, which can be depleted in as little as 2-3 weeks without regular intake.

Good dietary sources of thiamine include pork, whole grains, fortified breakfast cereals, legumes like black beans and lentils, nuts, sunflower seeds, and fish such as salmon and tuna.

For individuals with insufficient thiamine intake, supplementation can help correct deficiencies and improve performance by reducing fatigue and enhancing energy metabolism. However, for those with adequate dietary intake, supplementation may not provide significant additional benefits.

By fueling the energy production processes, vitamin B1 indirectly supports muscle recovery. Proper energy production ensures that muscle cells have the fuel needed to repair tissue, metabolize amino acids, and manage inflammatory responses post-exercise.

Yes, exercise can increase the body's metabolic demand and nutrient turnover, which may increase the need for thiamine. This is particularly true for endurance and high-intensity training.

Yes, thiamine, as a cofactor for the pyruvate dehydrogenase complex, promotes the efficient conversion of pyruvate into acetyl-CoA for the Krebs cycle. This process can help reduce the amount of pyruvate available for conversion into lactate, thus potentially mitigating lactate buildup and associated fatigue.