Vitamin B1 Deficiency

Vitamin B1, also known as thiamine, is a water-soluble B-complex vitamin that can be naturally found in certain foods, added to fortified products, and taken as a dietary supplement.

Discovery of Vitamin B1 Deficiency

Vitamin B1 deficiency was first identified in the late 1890s by two Dutch physicians. Their experiments showed that feeding birds exclusively white rice led to polyneuritis, a condition similar to beriberi in humans. Birds fed whole rice did not develop this issue, leading to the understanding that the outer layer of rice contained essential nutrients—specifically, thiamine.

Today, vitamin B1 deficiency is rare in healthy adults living in developed countries, but it can occur in individuals with certain medical conditions such as Crohn's disease, anorexia, kidney dialysis, use of loop diuretics like furosemide, gastric bypass surgery, or HIV infection.

Risk Factors for Thiamine Deficiency

• Poor nutrition, especially diets high in processed foods like white rice and refined grains.
• Malabsorption due to gastric bypass surgery or gastrointestinal disorders.
• Excessive loss of thiamine from chronic diarrhea, use of diuretics, or severe vomiting during pregnancy.
• Increased nutritional demands during pregnancy, breastfeeding, or refeeding syndrome.
• Consumption of foods rich in thiaminase (raw shellfish, raw freshwater fish, white rice).
• Chronic alcohol consumption, which impairs absorption and storage of thiamine.

Symptoms of Vitamin B1 Deficiency

Vitamin B1 deficiency can be subtle or easily overlooked. Common symptoms include:

• Muscle weakness—particularly in the upper arms and legs.
• Blurred vision—linked to optic nerve inflammation or damage.
• Reduced reflexes—notably in the knees, ankles, and arms.
• Nausea and vomiting—especially in infants consuming thiamine-deficient formulas.
• Shortness of breath—due to fluid retention from heart failure.
• Slow heart rate—causing fatigue, dizziness, or fainting.
• Delirium—confusion and mental disturbances, potentially leading to brain damage.
• Fatigue—ranging from mild exhaustion to extreme tiredness.
• Tingling sensations—resulting from peripheral nerve damage.
• Irritability—an early emotional symptom of deficiency.
• Loss of appetite—due to impaired function of the brain's hunger regulation center.

Severe Vitamin B1 Deficiency

Severe deficiency can lead to life-threatening conditions, especially with long-term poor dietary intake. These include:

Beriberi

This disease comes in two forms:

• Wet beriberi—affects the heart and circulatory system, causing fluid buildup and poor blood flow.
• Dry beriberi—affects the nerves and muscles, leading to nerve degeneration and muscle wasting.

A rare genetic form of beriberi also exists, where the body is unable to absorb thiamine effectively. Risk groups include those with diabetes, older adults, and individuals with compromised immune systems.

Wernicke–Korsakoff Syndrome

This condition is a neurological disorder caused by brain damage from severe thiamine deficiency. It includes:

• Wernicke’s encephalopathy—affects the hypothalamus and thalamus, leading to confusion, coordination problems, and eye movement abnormalities.
• Korsakoff syndrome—characterized by severe memory loss and cognitive impairments.

Congestive Heart Failure

Low thiamine levels are common among heart failure patients, especially the elderly or those on high-dose diuretics. Supplementing with vitamin B1 can improve heart function and reduce symptoms.

The Importance of Vitamin B1

Thiamine is essential for glucose metabolism and energy production from carbohydrates. It also supports proper function of the heart, muscles, and nervous system.

Dietary Sources of Vitamin B1

Thiamine is found in a wide range of foods. However, it is sensitive to heat and water, so cooking and food processing can reduce its levels. Key dietary sources include:

Whole Grains

• Brown rice – 0.4 mg per cup (30% of daily value)
• Whole wheat bread – 21% of daily value per 2 slices
• Oats – 15% per cup
• Quinoa – 17% per cup
• Cornmeal – 20% per cooked cup

Legumes

• Lentils – 28% per cup
• White beans – 0.4 mg per cup (36%)
• Black beans – 35% per cup
• Black-eyed peas – 29% per cup

Seafood

• Tuna – 39% per 170g
• Salmon – 28% per 100g
• Catfish – 27% per 141g
• Trout – 33% per 85g
• Mussels – 0.3 mg per 100g (25%)
• Clams – 24% per 20 small pieces

Nuts and Seeds

• Flaxseeds – 0.5 mg per 28g (39%)
• Sunflower seeds – 35% per 28g
• Pistachios – 21% per 28g
• Macadamia – 28% per 28g

Soy Products

• Firm tofu – 0.4 mg per cup (33%)
• Edamame – 39% per cooked cup
• Tempeh – 11% per cup
• Soy milk – 62% per 473 ml

Vegetables

• Green peas – 0.4 mg per cup (35%)
• Asparagus – 0.3 mg per cup (24%)
• Acorn squash – 0.3 mg per cup (29%)

Other Sources

Wheat germ, eggs, beef, and fortified foods like bread, pasta, cereals, and flour also contribute to thiamine intake.

Recommended Daily Intake of Vitamin B1