B1 is a vitamin your body needs to turn food into energy and keep your nerves working

Thiamine, also called B1, is a water-soluble vitamin that helps your cells convert the carbohydrates, fats, and proteins you eat into usable energy. It also supports nerve function and helps your brain and heart work properly. Your body cannot store B1, so you need to get it regularly from food or supplements.

B1 is one of eight B vitamins that work together in your body. While each one has its own job, they often work as a team—which is why you often see them grouped together in multivitamins or B-complex supplements.

Key Takeaways

  • B1 helps convert food into energy and is essential for nerve and brain function.
  • Your body does not store B1, so you need a steady supply from food or supplements.
  • Common food sources include whole grains, pork, legumes, seeds, and fortified cereals.
  • Deficiency is rare in developed countries but can occur with heavy alcohol use, certain medications, or specific medical conditions.
  • Most people get enough B1 from a balanced diet without needing supplements.

How B1 works in your body

B1 acts as a coenzyme—a helper molecule that allows enzymes to do their job. Specifically, it helps enzymes break down glucose (sugar) so your cells can use it for energy. This process happens in every cell, which is why B1 is important for overall energy levels.

B1 also plays a direct role in nerve signaling. It helps produce neurotransmitters, which are chemical messengers your brain uses to communicate with the rest of your body. This is why B1 deficiency can cause tingling, numbness, or weakness in your hands and feet.

Additionally, B1 supports heart muscle function and helps regulate blood sugar. Some research suggests it may also play a role in reducing inflammation, though more study is needed in this area.

Food sources of B1

You can get B1 from both animal and plant sources. Pork is one of the richest sources, along with organ meats like liver. Fish, poultry, and eggs also contain B1.

Plant-based sources include whole grains, brown rice, legumes (beans and lentils), nuts, seeds, and asparagus. Many breakfast cereals and breads are fortified with B1, which means the vitamin has been added during manufacturing. If you eat whole grains and lean proteins regularly, you are likely getting enough B1 from food alone.

Keep in mind that B1 is water-soluble, so it can leach into cooking water. Steaming or microwaving vegetables preserves more B1 than boiling them.

Who is at risk for B1 deficiency

B1 deficiency is uncommon in developed countries where food is abundant and fortified. However, certain groups face higher risk. People with heavy alcohol use are vulnerable because alcohol interferes with B1 absorption and storage in the liver. Individuals with diabetes may lose more B1 through urine.

Some medical conditions increase the risk: dialysis patients, people with inflammatory bowel disease, and those who have had weight-loss surgery may not absorb B1 well. Certain medications, including some diuretics and anti-seizure drugs, can lower B1 levels.

Older adults sometimes have lower B1 intake straightforward because they eat less food overall. If you fall into any of these categories, talking with your doctor about whether you need extra B1 is worth considering.

Signs of B1 deficiency

Early signs of B1 deficiency include fatigue, weakness, and difficulty concentrating. You might notice tingling or numbness in your hands and feet, or feel irritable or anxious.

Severe B1 deficiency can lead to a condition called beriberi, which causes nerve damage, heart problems, and muscle weakness. Another serious condition, Wernicke-Korsakoff syndrome, can develop in people with severe alcohol use disorder and involves confusion, memory loss, and coordination problems. These severe forms are rare in developed countries but can occur when deficiency goes unaddressed for a long time.

If you experience persistent fatigue, nerve symptoms, or confusion, seeing a doctor is important—not because these symptoms always mean B1 deficiency, but because they can signal other health issues that need attention.

B1 supplements and daily needs

The recommended daily amount of B1 is 1.1 mg for adult women and 1.2 mg for adult men. Pregnant and breastfeeding women need slightly more. These amounts are straightforward to meet through a balanced diet.

B1 supplements are available as standalone pills or as part of B-complex or multivitamin formulas. They come in various strengths, from small amounts (5–10 mg) to much higher doses (100 mg or more). Because B1 is water-soluble, excess amounts are excreted in urine rather than stored, so taking more than you need does not cause harm—it straightforward leaves your body.

Most people do not need supplements if they eat a varied diet with whole grains, proteins, and vegetables. However, if you have a condition that affects absorption or take medications that deplete B1, your doctor might recommend a supplement.

B1 and energy, mood, and brain function

Because B1 is central to energy production, some people wonder whether taking extra B1 will boost energy or mood. The evidence is clear: if you already have adequate B1 from food, taking more does not increase energy or improve mood. Supplements help only if you have a deficiency.

That said, B1 is genuinely important for brain function and nerve health. If you are deficient, correcting that deficiency can improve concentration, mood, and energy. This is why people with certain conditions—like diabetes or heavy alcohol use—may benefit from paying attention to their B1 intake.

Some older research suggested B1 might help with stress or anxiety, but modern studies have not confirmed this. B1 is one piece of the larger picture of nutrition and mental health, not a standalone treatment.

Frequently Asked Questions

Can I get too much B1?

No. Because B1 is water-soluble, your body excretes excess amounts in urine. There is no known toxicity from high B1 intake, even from supplements. However, taking more than you need is straightforward wasteful.

Does B1 help with energy if I am not deficient?

No. B1 helps your body convert food into energy, but only if you are deficient does supplementing improve energy levels. If you already have adequate B1, more will not boost your energy.

What happens if I cook vegetables in water—do I lose all the B1?

Some B1 leaches into the cooking water, but you do not lose all of it. Steaming, microwaving, or stir-frying preserves more B1 than boiling. If you boil vegetables, you can use the cooking water in soups or broths to recover some of the lost vitamins.

Do I need a B1 supplement if I eat a balanced diet?

Probably not. Most people who eat whole grains, lean proteins, and vegetables get enough B1 from food. Supplements are most useful for people with absorption issues, certain medical conditions, or heavy alcohol use.

Is B1 the same as thiamine?

Yes. Thiamine is the scientific name for B1. You will see both terms used on food labels, supplements, and in medical literature—they refer to the same vitamin.