Thiamine: What Does Vitamin B1 Do?

What Exactly is Thiamine?

Thiamine is the official name for vitamin B1. It was the first of the eight B-vitamins to be discovered, and because of its important role in supporting nerve cells, the nervous system, and energy metabolism, thiamine is considered a vital nutrient. It’s often referred to as the "nerve vitamin" or "energy vitamin" for this reason.

Our bodies can’t produce vitamin B1 on their own, so we need to get it through food. And since we can’t store this water-soluble vitamin either, it’s important to include thiamine-rich foods in your daily diet.

Fun fact: The discovery was made in the early 20th century by Polish biochemist Casimir Funk, who found that removing the outer layers of rice grains led to nutrient deficiencies and Beriberi (a disease that occurs in people lacking thiamine).

Why is Vitamin B1 So Important?

Vitamin B1 is essential for our bodies as it helps break down proteins and carbohydrates so they can be used for energy. Along with proteins and the trace element manganese, thiamine helps form enzymes in the liver that convert carbohydrates into glucose (sugar), which fuels our energy metabolism.

But that’s not all it does. While most cells in the body can use fats and proteins for energy, nerve and brain cells rely solely on glucose—and therefore on vitamin B1—to perform their functions. Thiamine helps convert glucose into energy, ensuring the flow of information between nerves and throughout the nervous system.

And what else is vitamin B1 good for? The brain also uses glucose to produce serotonin, the so-called "happy hormone." So, maintaining enough vitamin B1 can help support your focus, energy levels, and mental well-being.

What’s the Recommended Daily Intake of Thiamine?

The German Nutrition Society (DGE), along with the nutrition societies of Switzerland, Austria, and the European Food Safety Authority (EFSA), regularly updates reference values for nutrient intake. The recommended daily intake of vitamin B1 depends on age and lifestyle. Here’s a breakdown in milligrams per day:

• Infants: 0.2 to 0.3
• Children (up to 13 years old): 0.6 to 0.9
• Adolescents and teens (up to 19 years old): 1.0 to 1.4
• Women: 1.0
• Men (up to 65 years): 1.2 to 1.3
• Men (65+ years): 1.1

Pregnant and breastfeeding women are recommended to consume slightly more, around 1.2 to 1.3 mg daily.

Which Foods Contain Vitamin B1?

Thiamine is found primarily in plant-based foods, but it’s also present in beef, pork, fish, milk, and eggs. To ensure you’re getting enough vitamin B1, try incorporating the following foods into your diet:

• Whole wheat and rye
• Oats
• Unpolished rice
• Flours made from oats, wheat, maize, barley, and rye
• Legumes like peas and beans
• Potatoes
• Asparagus
• Cauliflower and kale
• Fennel
• Lamb’s lettuce
• Carrots
• Tomatoes
• Peanuts, walnuts, Brazil nuts, and almonds
• Sunflower and cashew seeds
• Lean beef and pork
• Offal
• Fish and shellfish
• Eggs
• Dairy products

Thiamine is a delicate vitamin and can be lost through heating, washing, or cooking food in water. Storing foods in open air also reduces thiamine content. To retain as much of the vitamin as possible, try to eat these foods raw or prepare them gently.

In addition to a varied, balanced diet, supplements can help ensure you meet your daily thiamine requirements.

How Can I Recognise a Thiamine Deficiency?

Signs of a thiamine deficiency include:

• Fatigue and sluggishness
• Difficulty concentrating
• Forgetfulness and confusion
• Loss of appetite
• Muscle cramps
• Increased susceptibility to infections due to a weakened immune system

If these symptoms occur frequently, it’s a good idea to discuss them with your doctor.

Overdosing on vitamin B1 is rare with a balanced diet. In the event of an excess, your body will simply excrete it in your urine.