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Vitamin B1

Vitamins Biomarker

Sample Needed

Collection Type: Blood

Body System

Related System: Vitamins

Overview

Vitamin B1 (thiamine) is a water‑soluble vitamin converted intracellularly to thiamine pyrophosphate (TPP), an essential coenzyme for carbohydrate metabolism (pyruvate dehydrogenase, α‑ketoglutarate dehydrogenase) and the pentose phosphate pathway (transketolase). The laboratory test measures thiamine (often as whole‑blood TPP) or functional status via erythrocyte transketolase activity. Testing is used when deficiency is suspected examples include unexplained fatigue, weight loss, peripheral neuropathy, confusion/ataxia or signs of heart failure (wet beriberi) and suspected Wernicke encephalopathy. Levels vary with age, pregnancy/lactation (increased need), renal replacement therapy, and heavy alcohol use; assay type (plasma vs whole blood vs enzyme assay) also affects reference values.

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Test Preparation

No special preparation is required

Why Do I Need This Test

Profile: included in vitamin/nutritional deficiency panels (Vitamins profile) - Symptoms indicating testing: chronic fatigue, neuropathy, cognitive changes, unexplained cardiomyopathy, malnutrition, chronic vomiting, or signs of Wernicke encephalopathy - Diagnoses/monitoring: thiamine deficiency (beriberi, Wernicke–Korsakoff), monitoring repletion - Reasons for abnormal levels: poor intake, malabsorption, alcoholism, bariatric surgery, increased demand (pregnancy, hyperthyroidism), dialysis, certain medications - Biological meaning: low thiamine → impaired energy metabolism, lactic acidosis, neuronal and cardiac dysfunction - Behaviors/lifestyle: heavy alcohol use, very restrictive diets, chronic diarrhea/vomiting - Family history: rare inherited transporter or enzyme defects (eg, thiamine transporter mutations or thiamine‑responsive anemias) may prompt testing

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Understanding Test Results

Values below the lower limit (<18 μg/L or <70 nmol/L) are consistent with thiamine deficiency and may explain symptoms such as fatigue, anorexia, peripheral neuropathy (dry beriberi), or cardiomyopathy/edema (wet beriberi).
Severely low or symptomatic deficiency (clinical signs of Wernicke encephalopathy: confusion, ophthalmoplegia, ataxia) requires immediate treatment regardless of exact level.
Borderline/low‑normal results (approx.
18–30 μg/L or 70–120 nmol/L) may represent early deficiency or increased requirement and warrant clinical correlation and possible supplementation.
Normal values (18–48 μg/L or 70–180 nmol/L) usually exclude deficiency when measured by whole‑blood TPP, but a normal plasma level can miss intracellular deficiency; a functional test (erythrocyte transketolase activation coefficient >1.25) indicates biochemical deficiency even if concentrations appear normal.
Elevated values (>48 μg/L or >180 nmol/L) most commonly reflect recent supplementation; clinically significant toxicity is rare because excess is renally excreted.

Normal Range

18–48 μg/L OR 70–180 nmol/L

FAQs

Q: What is the vitamin B1 good for?

A: Vitamin B1 (thiamine) helps convert carbohydrates into energy and supports normal metabolism, appetite, digestion and healthy nerve function. It’s essential for proper heart and muscle function, nerve signaling and cognitive performance, and plays a role in preventing deficiency conditions such as beriberi and Wernicke–Korsakoff syndrome in at‑risk people. Adequate intake supports overall energy levels and nervous system health.

Q: Which food is rich in vitamin B1?

A: Pork, whole grains and fortified cereals are especially rich in vitamin B1 (thiamine). Other good sources include brown rice, oats, legumes (beans, lentils, peas), sunflower seeds and nuts. Vegetables like spinach and asparagus, eggs and some fish also provide thiamine. Eating a variety of these foods helps meet thiamine needs for energy metabolism and nervous-system health.

Q: What is the main deficiency of vitamin B1?

A: Vitamin B1 (thiamine) deficiency primarily causes beriberi dry beriberi presents with peripheral neuropathy, muscle weakness and wasting; wet beriberi causes cardiovascular dysfunction, tachycardia, high-output heart failure and edema. Severe deficiency, especially in alcohol misuse, can cause Wernicke–Korsakoff syndrome: acute confusion, ophthalmoplegia and memory loss. Other signs include anorexia, irritability and gastrointestinal upset.

Q: How much vitamin B1 should a diabetic take?

A: General daily thiamine (vitamin B1) for adults is about 1.1–1.2 mg. People with diabetes sometimes use higher, often benfotiamine (a more absorbable B1 form) at roughly 150–300 mg/day in studies to help diabetic neuropathy or deficiency. Individual needs vary—consult your healthcare provider before starting supplements, especially if you take other medications or have kidney disease.

Q: Who cannot take vitamin B1?

A: Most people can take vitamin B1 (thiamine). Avoid it only if you have a known allergy or hypersensitivity to thiamine or any ingredient in the product—rare anaphylactic reactions have occurred with IV formulations. Use with medical advice in infants/children, pregnant or breastfeeding women, people with severe kidney disease, or anyone on multiple medications.

Q: How to test for B1 deficiency?

A: To test for vitamin B1 (thiamine) deficiency, a clinician reviews symptoms and diet, then orders laboratory tests: whole-blood or plasma thiamine concentration and erythrocyte transketolase activity (and activation coefficient). Urinary thiamine excretion can help. In uncertain or urgent cases, a therapeutic thiamine trial may be given and response monitored. Diagnosis combines clinical findings, labs, and response to supplementation.