Constant fatigue, low energy and brain fog aren’t always caused by stress.
Sometimes, these symptoms may be linked to low levels of Vitamin B1, also known as Thiamine.
Vitamin B1 plays a critical role in converting food into energy and supporting the nervous system. Without enough, your body’s energy production, nerve function and heart health can be compromised.
Because Vitamin B1 isn’t stored in large amounts in the body, a steady daily intake is essential. Modern diets especially those high in refined carbohydrates like white rice, noodles, bread, pastries and other highly processed foods have made thiamine deficiency more common than many people realize. So, why is Vitamin B1 so important and how can you ensure you’re getting enough?
Understanding Vitamin B1 (Thiamine)
Vitamin B1 is a water soluble vitamin, meaning it dissolves easily in water and the body cannot store much of it. Any excess is excreted through urine, so regular daily intake is crucial.
Thiamine plays a central role in:
Converting carbohydrates into energy
Supporting nerve function
Helping muscles (including the heart) work properly
Supporting digestion and metabolism
Your brain relies heavily on B1 to function well. Without it, concentration drops, memory suffers and mood may feel off. Since thiamine is involved in thousands of metabolic reactions, a deficiency can appear quickly and affect multiple organs at once.
Why Vitamin B1 Matters

1. Energy Production
   Vitamin B1 helps your cells turn food especially carbohydrates into usable energy. When levels are low, fatigue sets in quickly, even after light activity.
2. Nerve Health
   Thiamine helps maintain healthy nerve signals. Deficiency often causes tingling in the hands and feet, numbness, irritability or nerve pain.
3. Healthy Heart Function
   Your heart relies on thiamine to pump efficiently. Long-term deficiency can weaken the heart muscle, causing breathlessness or rapid heartbeat.
4. Brain Function & Mental Clarity
   Thiamine supports memory, focus, and emotional balance. Low levels can cause confusion, forgetfulness, and mood swings.
5. Digestion & Metabolism
   It helps enzymes break down nutrients efficiently. Deficiency may make digestion feel difficult or tiring, often accompanied by reduced appetite.
   Sources of Vitamin B1
   Getting enough thiamine from food is easy with a varied diet.
   Animal Sources:
   Lean pork
   Fish (especially tuna and trout)
   Eggs
   Organ meats
   Dairy (in moderation)
   Plant Sources:
   Whole grains (brown rice, oats, whole wheat bread)
   Beans and lentils
   Peanuts and other nuts
   Sunflower seeds
   Soybeans
   Bananas
   Fortified cereals
   Fresh vegetables like cabbage and spinach
   Tip: Since Vitamin B1 is water soluble, cooking in excess water can reduce its content. Also, highly refined foods like white rice and white flour contain much lower levels.
   How Much Vitamin B1 Do You Need?
   Daily needs vary slightly:
   Adult men: ~1.2 mg/day
   Adult women: ~1.1 mg/day
   Pregnant & breastfeeding women: 1.4–1.5 mg/day
   Your requirement increases if you:
   Consume alcohol frequently
   Eat a high-sugar or highly processed diet
   Have digestive issues that affect absorption
   Signs of Vitamin B1 Deficiency
   Because B1 is required daily, deficiency symptoms can appear quickly. Common signs include:
   Persistent fatigue or weakness
   Tingling or numbness in hands and feet
   Rapid or irregular heartbeat
   Poor appetite
   Irritability or mood changes
   Muscle cramps
   Brain fog or difficulty concentrating
   Shortness of breath
   Sensitivity to light
   Severe deficiency can lead to:
   Beriberi – affecting nerves (dry beriberi) or heart function (wet beriberi)
   Wernicke-Korsakoff syndrome – primarily in chronic alcohol users, causing memory, balance, and coordination issues
   Early detection is critical, as long-term deficiency can permanently affect the brain and nervous system.
   Who Is Most at Risk?
   You may be more prone to low B1 if you:
   Consume diets high in white rice or processed foods
   Drink alcohol frequently
   Have a high carbohydrate intake
   Have certain thyroid disorders that affect metabolism
   Experience chronic stress
   Are pregnant or breastfeeding
   Have digestive issues that reduce absorption
   Can You Take Too Much Vitamin B1?
   Because B1 is water-soluble, the body flushes out excess amounts, and toxicity is extremely rare.
   However, supplements should only be taken under medical guidance, especially when combined with other B-complex vitamins. Food sources remain the safest and most effective way to meet daily needs.
   Summary
   Vitamin B1 (Thiamine) is a powerful but often overlooked nutrient responsible for:
   Energy production
   Nerve and heart health
   Digestion and metabolism
   Mental clarity
   Since the body cannot store it in large amounts, daily intake is essential. Eating a balanced diet rich in whole grains, lean proteins, beans, nuts, and vegetables ensures your needs are met.
   When Vitamin B1 levels are adequate, your energy improves, your mind becomes sharper, and your body functions more efficiently from the inside out.
   References (APA 7th Edition)
   Healthline. (2024). Vitamin B1 (Thiamine): Benefits, sources and deficiency symptoms. Retrieved January 13, 2026, from https://www.healthline.com/nutrition/thiamine
   National Institutes of Health, Office of Dietary Supplements. (2024). Thiamin fact sheet for health professionals. U.S. Department of Health and Human Services. https://ods.od.nih.gov/factsheets/Thiamin-HealthProfessional/
   World Health Organization. (2023). Micronutrient deficiencies: Thiamine. https://www.who.int
   WebMD. (2024). Thiamine (Vitamin B1): Uses, benefits, and risks. https://www.webmd.com/vitamins/ai/ingredientmono-964/thiamine-vitamin-b1
   Gropper, S. S., & Smith, J. L. (2021). Advanced nutrition and human metabolism (8th ed.). Cengage Learning.
   Whitney, E., & Rolfes, S. R. (2020). Understanding nutrition (16th ed.). Cengage Learning.
   Mayo Clinic. (2024). Thiamine (Vitamin B1): Benefits and risks. https://www.mayoclinic.org