Vitamin B1

Vitamin B1, also known as thiamine, is a water-soluble vitamin that plays a crucial role in numerous physiological functions. As an essential nutrient, it must be obtained through our diet, as our bodies cannot synthesise it. 


The journey to discovering vitamin B1 began in the late 19th century when scientists observed that polished rice seemed to be associated with the development of beriberi, a disease characterised by symptoms such as weakness, nerve damage, and heart failure. In 1912, Polish biochemist Casimir Funk isolated a substance from rice bran, which he believed could prevent beriberi, and coined the term “vitamine” (derived from “vital amine”) to describe it.

Further research led by Dutch physician Christiaan Eijkman, who had been investigating the relationship between beriberi and polished rice, helped to confirm Funk’s findings. It wasn’t until 1935 that thiamine, or vitamin B1, was chemically isolated and synthesised by Robert R. Williams, an American chemist. Both Eijkman and Williams played crucial roles in elucidating the importance of vitamin B1 in human health.

Vitamin B1 is an organic compound with a molecular formula of C12H17N4OS. It consists of a pyrimidine ring connected to a thiazole ring, making it a heterocyclic aromatic compound. Thiamine is highly soluble in water, which is why it’s classified as a water-soluble vitamin. Due to its water solubility, it’s not stored in large amounts in the body and must be regularly replenished through dietary intake.

Functions Of Vitamin B1

Vitamin B1 is a critical component in various cellular processes. Its primary functions include:

  • Energy metabolism: Thiamine is a vital cofactor for several enzymes involved in carbohydrate metabolism. It is necessary for the conversion of glucose into energy, which is essential for cellular functions and overall health.
  • Nervous system function: Vitamin B1 plays a role in the synthesis of neurotransmitters and the maintenance of myelin, the protective sheath surrounding nerve fibres. This helps support proper nerve function and communication between nerve cells.
  • Heart health: Thiamine is involved in maintaining the normal functioning of the heart muscle and the nervous system that regulates the heartbeat. It also helps the body maintain a proper balance of electrolytes, which is essential for heart function.

Good Sources Of Vitamin B1

  • Whole grains: Whole grain products such as brown rice, whole wheat bread, whole wheat pasta, barley, and quinoa are rich sources of thiamine.
  • Fortified cereals: Many breakfast cereals are fortified with vitamin B1, making them a convenient and easy way to boost your thiamine intake.
  • Legumes: Beans, lentils, and peas are good plant-based sources of vitamin B1. Some examples include black beans, navy beans, pinto beans, chickpeas, and green peas.
  • Nuts and seeds: Sunflower seeds, flaxseeds, chia seeds, and nuts such as almonds, pistachios, and Brazil nuts contain thiamine.
  • Lean meats: Pork is an excellent source of vitamin B1, while other lean meats like chicken and turkey also contain moderate amounts of thiamine.
  • Fish: Certain types of fish, such as trout and salmon, are good sources of vitamin B1.
  • Dairy products: Milk, yogurt, and cheese provide small amounts of thiamine.
  • Vegetables: Some vegetables, such as asparagus, Brussels sprouts, and spinach, contain small amounts of vitamin B1.
  • Yeast: Nutritional yeast and Brewer’s yeast are rich sources of thiamine and are often used as supplements or flavour enhancers in vegetarian and vegan diets.
  • Thiamine-fortified products: Some food products, such as bread and flour, are fortified with thiamine to help prevent deficiencies.

How Much Vitamin B1 Do We Need?

The Recommended Dietary Allowance (RDA) for vitamin B1 (thiamine) varies depending on your age, sex, and life stage. The National Institutes of Health (NIH) provides the following recommended daily intakes for vitamin B1 (thiamine):

  • Infants 0-6 months*: 0.2 mg/day (milligram)
  • Infants 7-12 months*: 0.3 mg/day
  • Children 1-3 years: 0.5 mg/day
  • Children 4-8 years: 0.6 mg/day
  • Children 9-13 years: 0.9 mg/day
  • Teens 14-18 years (males): 1.2 mg/day
  • Teens 14-18 years (females) 1.0 mg/day
  • Adults 19 years and older (males): 1.2 mg/day
  • Adults 19 years and older (females) 1.1 mg/day
  • Pregnant women: 1.4 mg/day
  • Breastfeeding women: 1.4 mg/day

* Adequate Intake (AI)

What Are The Signs Of Vitamin B1 Deficiency?

Some of the signs and symptoms of vitamin B1 deficiency include:

  • Fatigue and weakness: A lack of vitamin B1 can lead to feelings of fatigue, weakness, and general malaise, as it is crucial for energy production in the body.
  • Loss of appetite and weight loss: Vitamin B1 deficiency can cause a loss of appetite and unintended weight loss due to impaired carbohydrate metabolism.
  • Muscle pain and weakness: A lack of vitamin B1 can result in muscle pain, weakness, and wasting as it plays a role in maintaining healthy muscle function.
  • Nerve dysfunction: Vitamin B1 deficiency can affect the nervous system, leading to symptoms like numbness, tingling, and burning sensations in the hands and feet.
  • Rapid heartbeat and shortness of breath: Vitamin B1 deficiency can impact cardiovascular function, leading to symptoms such as rapid heartbeat, shortness of breath, and chest pain.
  • Swelling in the lower limbs: Severe cases of vitamin B1 deficiency can cause fluid retention and swelling in the lower limbs, particularly in the legs and feet.

What Happens If I Take Too Much Vitamin B1?

Vitamin B1, or thiamine, is a water-soluble vitamin, which means that any excess intake is typically excreted through urine rather than stored in the body. As a result, the risk of toxicity from consuming too much vitamin B1 is relatively low. In fact, vitamin B1 toxicity is extremely rare and is generally not a cause for concern when consuming thiamine from food sources.

However, excessive intake of vitamin B1 through supplements, particularly in very high doses, can lead to some side effects, although they are generally mild and reversible. Some potential side effects of excessive vitamin B1 intake include:

  • Mild gastrointestinal symptoms: High doses of thiamine may cause mild gastrointestinal symptoms in some individuals, such as nausea, stomach discomfort, or diarrhoea.
  • Headaches: In rare cases, consuming excessive amounts of vitamin B1 can lead to headaches or migraines.
  • Allergic reactions: Although uncommon, some people may experience an allergic reaction to vitamin B1 supplements, which can cause symptoms like itching, hives, or skin rashes.

It’s important to note that these side effects are typically associated with very high doses of vitamin B1, which are usually obtained from supplements rather than food sources. Consuming a balanced diet rich in a variety of foods that provide vitamin B1 is the best way to meet your nutritional needs without risking adverse effects. If you are considering taking vitamin B1 supplements or have concerns about your thiamine intake, consult a healthcare professional or registered dietitian for personalised advice.