Most people have heard of vitamin D deficiency and vitamin B12 deficiency, but vitamin B1 (thiamine) is rarely mentioned – even though it is just as crucial for the body's energy metabolism and nervous system. Thiamine is involved in how the body converts carbohydrates into energy, and a prolonged deficiency can significantly affect muscles, heart, and the nervous system. In this post, we review what vitamin B1 does, who is at particular risk, which symptoms you should be aware of, and how to find out if your body is lacking it.
What is vitamin B1, and why does the body need it?
Vitamin B1, also called thiamine, is a water-soluble vitamin that the body cannot produce or store in large quantities itself. This means that we are dependent on a continuous supply through our diet – from sources such as whole grains, pork, legumes, nuts, and green vegetables. Thiamine plays a central role in the conversion of carbohydrates into energy and is also important for the proper functioning of nerve cells and muscles – including the heart muscle. Because the body's stores typically only last for a few weeks, a deficiency can arise relatively quickly if intake is insufficient over a period, or if the body's needs increase significantly, for example, due to illness or heavy alcohol consumption.
Who is at particular risk of vitamin B1 deficiency?
Most healthy people with a varied diet meet their vitamin B1 requirements without problems. However, there are a number of groups where the risk of deficiency is significantly higher:
- Individuals with high alcohol consumption, as alcohol inhibits both the absorption and utilization of thiamine in the body
- Individuals who have undergone weight loss surgery (bariatric surgery), where nutrient absorption is reduced
- Pregnant women with severe nausea and vomiting (hyperemesis gravidarum)
- Elderly people, whose diet is often more monotonous, and whose intestinal absorption is reduced
- Individuals with chronic gastrointestinal diseases that affect nutrient absorption
- Individuals undergoing dialysis treatment, where thiamine is excreted from the body to a greater extent
If you belong to one of these groups and are also experiencing symptoms as described below, there is good reason to have your levels checked.
Symptoms of vitamin B1 deficiency
The symptoms of mild to moderate B1 deficiency are often diffuse and can easily be mistaken for other conditions such as stress, poor sleep, or vitamin D deficiency. The most common signs include:
- Fatigue and low energy, even after sufficient sleep
- Irritability and difficulty concentrating
- Tingling or numbness in hands and feet (often an early sign of nerve involvement)
- Muscle weakness, especially in the legs
- Decreased appetite and unintentional weight loss
- Rapid pulse or shortness of breath during normal physical activity
- Memory and concentration problems with more pronounced deficiency
If you notice several of these symptoms simultaneously – especially if you also belong to one of the risk groups above – it may be a sign that your body's thiamine stores are low and that it is worth investigating further.
What diseases can vitamin B1 deficiency lead to?
Untreated and severe B1 deficiency can develop into actual medical conditions. The two most well-known are:
- Beriberi – a condition that exists in two forms: "wet beriberi," which affects the heart and circulatory system and, in severe cases, can lead to heart failure, and "dry beriberi," which primarily affects the nervous system and causes muscle weakness, reduced sensation, and difficulty walking.
- Wernicke-Korsakoff syndrome – a serious neurological condition mainly seen in severe and prolonged deficiency, typically associated with heavy alcohol consumption, and which can cause confusion, balance problems, eye movement disorders, and permanent memory impairment.
These conditions are rare in Denmark and typically only occur with severe, prolonged deficiency in individuals belonging to one of the risk groups mentioned above. Even without reaching these extremes, a mild, persistent deficiency can significantly affect your quality of life, energy levels, and mood over time.
How to find out if you are lacking vitamin B1
The only sure way to confirm a deficiency is through a blood test that measures your thiamine level. Since the symptoms of B1 deficiency can easily be confused with other vitamin deficiencies or hormonal imbalances, we always recommend a broader vitamin and mineral analysis rather than testing in isolation for a single substance. This way, you get a comprehensive picture of where your body actually needs support, instead of guessing based on symptoms alone.
At Valida Health, you can book a Vitamin & Mineral Health Check, where we examine the most important vitamins and minerals, including B vitamins, vitamin D, and iron, in a single private blood test. You will receive results quickly and a clear explanation of what your numbers mean, as well as concrete advice on the next steps.
How to treat vitamin B1 deficiency
Treatment depends on the extent of the deficiency. For a mild deficiency, it is often sufficient to adjust the diet and possibly supplement with a dietary supplement for a period. For a more pronounced deficiency, higher doses may be necessary under professional medical guidance, and in rare, severe cases, thiamine is administered directly into the bloodstream in a hospital. Regardless of the extent, it is important that the treatment is based on a concrete measurement of your levels – not guesswork – so that you neither undertreat nor unnecessarily take high doses of a dietary supplement.
Frequently asked questions about vitamin B1 deficiency
Can you take too much vitamin B1?
Since thiamine is water-soluble, excess is typically excreted via urine, and the risk of overdose is low with common dietary supplements. However, high doses should always be taken in consultation with healthcare professionals, especially if you are being treated for a diagnosed deficiency.
How quickly can a deficiency be corrected?
For mild deficiency, many experience an improvement in energy levels and concentration within a few weeks after dietary adjustment or supplementation. For more pronounced deficiency, it may take longer, and it is important to follow up with a new blood test to ensure that the level has normalized.
Can vitamin B1 deficiency be confused with other conditions?
Yes. The symptoms largely overlap with, among others, vitamin B12 deficiency, iron deficiency, and hormonal imbalances, which is precisely why we recommend a comprehensive analysis rather than guessing based on symptoms alone.
Have your vitamin and mineral levels checked at Valida Health
If you experience persistent fatigue, numbness in your hands and feet, or several of the symptoms above, you don't have to guess. At Valida Health, we help you get a clear picture of your vitamin and mineral status through a thorough blood test, so you can act on informed grounds rather than assumptions.
Book an appointment at Valida Health today and find out if your body is lacking vitamin B1 or other important nutrients.
