Thiamine: the vitamin without which the body loses energy

Vitamin B1 is rarely discussed loudly. It does not have the popularity of vitamin D, it is not marketed as a beauty symbol like collagen, and it has not become a wellness trend in the way magnesium has. Yet thiamine - vitamin B1 - belongs to that quiet group of nutrients without which the body quickly begins to lose stability. It is needed to turn food into energy and to support the normal function of the nervous system, heart, muscles and brain. Deficiency can look very different from one person to another: from fatigue and weakness to serious neurological and cardiovascular problems.

The important thing about thiamine is that the body cannot store it for long. Reserves are limited, and the need for it rises during illness, stress, fever, intense physical activity, pregnancy, breastfeeding and diets high in fast carbohydrates. Vitamin B1 is therefore not an exotic supplement, but a basic element of metabolic safety. This is especially true for people with monotonous diets, heavy alcohol use, absorption problems, chronic illness or critical medical conditions.

Why vitamin B1 matters so much

Thiamine participates in carbohydrate metabolism and helps cells obtain energy from food. Tissues with high energy demands are especially sensitive to a lack of it: the brain, nervous system, heart and muscles. When thiamine is insufficient, the body seems to lose its ability to use fuel efficiently. A person may experience weakness, irritability, rapid fatigue, tingling or numbness in the hands and feet, poor coordination, memory problems, palpitations or swelling.

Severe deficiency can lead to a disease known as beriberi. It is classically described in two main forms. Dry beriberi mainly affects the nervous system and may appear as peripheral neuropathy, weakness, sensory changes and reduced reflexes. Wet beriberi affects the cardiovascular system and can lead to swelling, heart failure and dangerous circulatory problems.

Another well-known form of severe deficiency is Wernicke encephalopathy and Wernicke-Korsakoff syndrome. They are most often associated with alcoholism, but the underlying issue is broader: inadequate intake or absorption of thiamine. This condition can include confusion, poor coordination, eye movement problems and severe memory impairment, and it requires urgent medical attention.

Why deficiency can develop faster than it seems

In developed countries, severe thiamine deficiency is considered relatively uncommon because many foods are fortified with B vitamins. But uncommon does not mean impossible. Deficiency can occur with heavy alcohol use, eating disorders, long-term poor nutrition, after bariatric surgery, with chronic vomiting, severe gastrointestinal disease, in older adults, during long-term use of certain medications and in critically ill patients.

A separate factor is a diet built mainly on refined carbohydrates: white rice, white flour, sweets, fast food and ultra-processed products. Historically, beriberi often appeared in populations whose diets depended heavily on polished rice, because processing removed the outer layers of the grain that contain thiamine. The World Health Organization has noted that deficiency can develop within several months of inadequate intake, especially when the diet is monotonous and low in nutrients.

The paradox of modern eating is that a person can receive enough calories while getting too few micronutrients. A diet can be energy-rich and still poor in vitamins. That is why fatigue, weakness and irritability are not always explained only by stress. Sometimes the body truly lacks basic substances required for normal function.

Thiamine, infection and critical illness

In recent years, interest in thiamine has grown not only as a vitamin connected with classical beriberi, but also as an important factor in severe illness. Among patients in intensive care units, thiamine deficiency is more common than in healthy people. This is not surprising: critical illness sharply increases the body’s needs, disrupts metabolism and is often accompanied by inflammation, poor nutrition, medication burden and organ dysfunction.

Thiamine is studied especially closely in sepsis and septic shock. Sepsis is a severe, potentially fatal response to infection in which the blood vessels, organs, metabolism and immune system are affected. Thiamine is of interest here because it participates in energy metabolism and may influence lactate levels, mitochondrial function and the metabolic resilience of cells.

Medical literature has discussed protocols in which thiamine is used together with vitamin C and hydrocortisone in patients with sepsis. Early observational studies looked promising, but larger clinical trials have produced mixed results and have not confirmed a clear reduction in mortality or meaningful improvement in major outcomes for all patients. This approach therefore cannot be viewed as a universal proven treatment for sepsis. Even so, thiamine remains an important and safe component of medical support for patients with suspected deficiency, especially in intensive care settings.

Immunity: not a miracle cure, but part of resilience

Sometimes thiamine is described too dramatically, almost as a “super-antibiotic” or a remedy for severe infections. That is inaccurate and dangerous. Thiamine does not replace antibiotics, antiviral medications, vaccination, oxygen support, intensive care or any other treatment when those are medically needed.

But it does have another, more honest role. Thiamine helps cells produce energy, and the immune system cannot function normally without energy. Research suggests that vitamin B1 may take part in regulating innate immune responses, inflammatory signals and the work of immune cells. The scientific interest in these mechanisms is real, but it does not mean that taking thiamine can independently prevent or cure a serious infection.

The better way to say it is this: normal thiamine status is part of the body’s overall physiological resilience. Deficiency may weaken systems that help a person cope with stress, illness and recovery. Correcting deficiency matters, but it is not a magical shield against infection.

Who should pay particular attention to vitamin B1

Most people with a varied diet do not need to worry about thiamine deficiency every day. But some groups are at higher risk. These include people who regularly consume large amounts of alcohol; those with monotonous diets; patients after stomach or intestinal surgery; people with chronic vomiting or malabsorption; older adults; patients with heart failure; people with diabetes; those taking diuretics long term; and patients who have had severe infections or are critically ill.

It is especially important not to self-diagnose when symptoms are significant: confusion, problems walking, severe weakness, numbness, swelling, shortness of breath, sudden memory decline or heart-related symptoms. This is not the time for experimenting with supplements. A medical evaluation is necessary because similar symptoms can have many causes, and severe thiamine deficiency requires treatment under medical supervision.

Where thiamine is found

Thiamine can be obtained from ordinary food. Good sources include whole grains, legumes, pork, nuts, seeds, fortified cereals and breads, some fish, peas, beans and lentils. The more refined and processed a food is, the fewer B vitamins it usually contains unless they have been added back through fortification.

The practical conclusion is simple: a diet that includes whole grains, legumes, protein foods, nuts and seeds is usually more reliable than one built on white flour, sweets, sugary drinks and fast food. Thiamine is a good example of why the quality of calories matters. The body needs not only energy and fullness, but also the substances that allow it to use that energy.

Supplements: when they make sense

Thiamine is available as a supplement and is often included in B-complex vitamins. For a healthy person without risk factors, high doses are usually unnecessary. Water-soluble vitamins do not accumulate in the same way as fat-soluble vitamins, but that does not mean any dose should be taken carelessly. Supplements should answer a real need: correcting an insufficiency, supporting the diet, meeting increased requirements or following a medical recommendation.

In medical practice, thiamine is often prescribed for people at risk of deficiency, especially in alcohol dependence, nutritional disorders, after bariatric surgery and in hospital settings. In critical care it may be given intravenously, but that is not a wellness decision; it is part of medical treatment determined by a physician.

Why thiamine is worth remembering

Thiamine does not promise endless energy, does not replace sleep, does not cure infections on its own and should not become another fashionable myth. Its strength lies elsewhere: it is one of the fundamental substances that supports the body’s ability to function normally. Without it, cells are less able to produce energy, the nervous system becomes vulnerable, the heart works under greater strain and recovery from illness may become more difficult.

In a world where we often look for complicated solutions, thiamine reminds us of something simple: health depends not only on advanced medical technology, but also on basic biochemistry. Adequate nutrition, a varied diet, attention to high-risk groups and timely correction of deficiency can sometimes matter more than the next loud wellness idea. Vitamin B1 may not look glamorous, but it is often these quiet elements that determine how resiliently the body works.