# Vitamin B1 (Thiamine): Energy Metabolism and Nerve Function

B Vitamins | By Longevity Futures Research Team | Updated November 2025

Vitamin B1, also known as thiamine, is the first of the B vitamins to be discovered and remains essential for converting food into cellular energy. This water-soluble nutrient plays a critical role in glucose metabolism, nerve function, and muscle contraction—making it foundational for both physical and mental performance.

Unlike fat-soluble vitamins, thiamine cannot be stored in significant amounts in your body. This means consistent daily intake is necessary to maintain optimal levels and support the hundreds of enzymatic reactions that depend on this vital nutrient.

The Energy Connection: Thiamine is essential for converting carbohydrates into ATP—your body's energy currency. Without adequate thiamine, glucose metabolism becomes impaired, leading to fatigue, weakness, and eventually serious neurological symptoms. Your brain, which relies heavily on glucose, is particularly vulnerable to thiamine deficiency.
1.2 mg
RDA for Men
1.1 mg
RDA for Women
14-18
Days to Deplete Stores
30%
Lost in Cooking

## How Thiamine Powers Your Body

Thiamine functions primarily as a coenzyme in its active form, thiamine pyrophosphate (TPP). This coenzyme is essential for several critical metabolic pathways:

- Pyruvate dehydrogenase complex: Converts pyruvate to acetyl-CoA, linking glycolysis to the citric acid cycle
- Alpha-ketoglutarate dehydrogenase: A key enzyme in the citric acid cycle for ATP production
- Branched-chain ketoacid dehydrogenase: Metabolizes branched-chain amino acids (leucine, isoleucine, valine)
- Transketolase: Essential for the pentose phosphate pathway, which produces NADPH and ribose-5-phosphate

Research Insight: Studies show that thiamine requirements increase with carbohydrate intake. Athletes and individuals consuming high-carbohydrate diets may need 2-3 times the standard RDA to maintain optimal energy metabolism. Thiamine status directly correlates with exercise performance and recovery.

## Nervous System and Brain Health

The nervous system has extraordinarily high thiamine requirements. Your brain uses approximately 20% of your body's total energy, and most of that comes from glucose metabolism—which requires thiamine at multiple steps.

Thiamine supports neurological health through:

- Neurotransmitter synthesis: Required for producing acetylcholine, GABA, and glutamate
- Myelin maintenance: Supports the protective sheath around nerve fibers
- Nerve signal transmission: Essential for proper action potential conduction
- Brain energy supply: Ensures adequate ATP production in neurons
- Antioxidant function: Helps protect neural tissue from oxidative stress

Cognitive Benefits: Research in the Journal of Alzheimer's Disease suggests that higher thiamine intake is associated with better cognitive function in older adults. Thiamine deficiency has been linked to memory impairment, confusion, and in severe cases, Wernicke-Korsakoff syndrome—a serious neurological condition often seen in chronic alcoholism.

## Cardiovascular Support

Your heart is one of the most metabolically active organs, beating approximately 100,000 times per day. This constant work requires enormous amounts of ATP, making thiamine essential for cardiac function:

- Heart muscle energy: Ensures adequate ATP for continuous cardiac contraction
- Blood vessel health: Supports endothelial function and vascular tone
- Heart failure connection: Deficiency is common in heart failure patients and may worsen outcomes
- Diuretic interaction: Loop diuretics increase thiamine excretion, potentially causing deficiency

Clinical Finding: A study in the American Journal of Medicine found that thiamine supplementation improved left ventricular ejection fraction in heart failure patients who were thiamine deficient. This highlights the importance of assessing thiamine status in cardiovascular disease.

## Best Food Sources of Thiamine

#### Pork

0.9 mg per 3 oz serving. One of the richest natural sources—a single serving provides most of the daily requirement.

#### Fortified Cereals

0.5-1.5 mg per serving. Many breakfast cereals are fortified to 100% of daily value.

#### Black Beans

0.4 mg per cup cooked. Excellent plant-based source with additional fiber and protein.

#### Sunflower Seeds

0.5 mg per 1/4 cup. Nutrient-dense snack with healthy fats and minerals.

#### Trout

0.4 mg per 3 oz serving. Provides thiamine along with omega-3 fatty acids.

#### Brown Rice

0.2 mg per cup cooked. Whole grain option; white rice has thiamine removed during processing.

## Who is at Risk for Deficiency?

While severe thiamine deficiency (beriberi) is rare in developed countries, subclinical deficiency is more common than recognized:

- Heavy alcohol users: Alcohol impairs thiamine absorption and increases excretion
- Older adults: Reduced absorption and often inadequate dietary intake
- Diabetes patients: May have increased urinary thiamine losses
- Bariatric surgery patients: Reduced absorption capacity post-surgery
- People on diuretics: Increased urinary excretion of thiamine
- Those with GI disorders: Crohn's, celiac disease, or chronic diarrhea
- Athletes: Higher requirements due to increased energy metabolism

## Signs of Thiamine Deficiency

Early signs of thiamine deficiency can be subtle and easily overlooked:

- Fatigue and weakness: Impaired energy production affects all tissues
- Loss of appetite: Often one of the first symptoms
- Irritability: The brain quickly responds to energy deficits
- Tingling in extremities: Peripheral nerve involvement
- Poor concentration: Cognitive effects of reduced brain energy
- Muscle weakness: Especially in the legs

Advanced Deficiency: Severe thiamine deficiency can lead to beriberi (affecting the cardiovascular and nervous systems) or Wernicke-Korsakoff syndrome (a serious brain disorder). These conditions require immediate medical attention and high-dose thiamine therapy.

## Thiamine and Longevity

Optimal thiamine status supports healthy aging through multiple mechanisms:

- Mitochondrial function: Supports efficient energy production as mitochondrial function naturally declines with age
- Neuroprotection: Helps maintain cognitive function and nerve health
- Glucose metabolism: Supports healthy blood sugar regulation
- Cardiovascular health: Essential for maintaining heart function
- Antioxidant activity: The pentose phosphate pathway produces NADPH for regenerating antioxidants

## Supplementation Considerations

Thiamine supplements come in several forms:

- Thiamine HCl: Standard form, water-soluble, well-absorbed
- Benfotiamine: Fat-soluble form with potentially better bioavailability and tissue penetration
- Thiamine mononitrate: Stable form commonly used in fortification
- Sulbutiamine: Synthetic derivative that crosses the blood-brain barrier more effectively

Thiamine is water-soluble with no known toxicity at high doses—excess is simply excreted in urine. This makes it a safe supplement for those who may benefit from higher intakes.

## Recommended Thiamine Supplement

### Thorne B-Complex #12

A comprehensive B-complex with active B12 and folate. Contains all eight B vitamins including optimal thiamine for energy metabolism and nerve function. Uses bioactive forms for maximum absorption. NSF-certified for sport and third-party tested for purity.

$42.87
View on Amazon

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