Thiamin (Vitamin B1)

 

What Is Thiamin (Vitamin B1)?

Thiamin, or vitamin B1, is one of the essential water-soluble B vitamins. B vitamins are vital for energy metabolism, while thiamin supports the nervous system, heart activity, and overall cellular function. Because the body does not produce thiamin or store much of it, individuals must regularly obtain it through food intake or dietary supplements.

As the first B vitamin discovered, thiamin was dubbed B1 due to its classification. Despite the small amount needed, thiamin is crucial for enabling the body to generate sufficient energy and maintain normal metabolism.

How Does the Body Use Thiamine?

When thiamin is ingested through food or supplements, it is primarily absorbed in the small intestine. At normal intake levels, thiamin uptake occurs mainly through active transport; however, very large doses may also be absorbed by passive diffusion, though not efficiently. Once absorbed, thiamin is converted into the active form thiamin diphosphate, also known as thiamin pyrophosphate. This active derivative functions as a coenzyme in many enzymatic reactions, particularly in:

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The anaerobic breakdown of carbohydrates to usable energy in the form of ATP

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The metabolism of amino acids and fatty acids

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The production of neurotransmitters

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Nerve transmission and coordination

Thiamin is stored only in small amounts by the body, mainly in the liver, and small amounts are also found in the heart, kidneys, and brain. Since the body has very little thiamin and its stores are quickly depleted by the absence of intake (within 7-18 days), deficiency symptoms may develop rapidly if thiamin is not taken consistently.

Thiamin is needed for various functions in the body, mainly energy production and the functioning of the nervous system. Some of its primary functions are

1. Energy Metabolism

Thiamin plays a role in changing carbohydrates into energy. It acts as a coenzyme for pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase, both of which lead the Krebs cycle of the main energy-generating mechanism of the body.

2. Nervous System Support

Thiamin helps in the conduction of nerve impulses. Deficiency may be responsible for nerve damage, numbness, and tingling, particularly affecting the lower extremities (peripheral neuropathy).

3. Heart and Muscle Functions

Thiamin is important for heart muscle function. Some symptoms of congestive heart failure in cases of thiamin deficiency include edema and shortness of breath.

4. Brain Health

Memory, cognitive health, and emotional well-being are paramount to thiamin. Severe deficiency results in Wernicke-Korsakoff syndrome, especially in those suffering from alcoholism.

5. Digestive System Health

Thiamin has a role in the production of hydrochloric acid (HCl) in stomach contents that helps with digestion and absorption of nutrients.

How Do We Check Thiamine Levels?

Since thiamine is found in very low concentrations in blood and varies with recent intake, measuring thiamine levels directly in blood may not provide accurate results. Therefore, healthcare practitioners use several functional tests to determine thiamine status.

1. Transketolase Activity in Red Blood Cells

This procedure assesses the activity of transketolase, the enzyme that requires thiamine. A significant increase of enzyme activity following the addition of thiamine to the test sample indicates a deficiency. 

Interpretation of enzyme activities:

0%–15% increase → Normal (thiamine adequate)

15%–25 % increase → Low thiamine status (mildly deficient)

>25% increase → Deficiency (thiamine is deficient)

2. Urinary Thiamine Excretion

Determining the quantity of thiamine that ends up in urine can also help evaluate the thiamine status. If thiamine excretion in the urine is low, it may correlate with inadequate intake or, indeed, a deficiency. 

<100 mcg/day → May suggest marginal deficiency

<40 mcg/day → Suggests severe deficiency                                               

Daily Requirement for Thiamin

The amount of thiamin you need depends on your age, gender, and life stage. Here are the Recommended Dietary Allowances (RDAs) for thiamin according to the National Institutes of Health (NIH):

Group	RDA (mg/day)
Infants (0–6 months)	0.2
Infants (7–12 months)	0.3
Children (1–3 years)	0.5
Children (4–8 years)	0.6
Males (9–13 years)	0.9
Males (14+ years)	1.2
Females (9–13 years)	0.9
Females (14–18 years)	1.0
Females (19+ years)	1.1
Pregnancy	1.4
Breastfeeding	1.4

   What Are the Best Sources of Thiamin?

You can find thiamin in many foods. Food manufacturers also add it to other products through fortification (like breakfast cereals). Here's a list of great food sources of thiamin:

Animal-Based Sources

Pork (lean cuts)

Liver

Fish (like trout and tuna)

Eggs

Plant-Based Sources

Whole grains (brown rice, oatmeal, whole wheat bread)

Legumes (black beans, lentils, peas)

Nuts and seeds (sunflower seeds stand out)

Fortified cereals and bread

Potatoes and sweet potatoes

Asparagus

Spinach

Fortified and Enriched Foods

Enriched white rice

Fortified breakfast cereals

Enriched pasta and flour products

Cooking tip: Thiamin dissolves in water and breaks down with heat, so cooking for a long time or boiling can lower the thiamin in foods. To keep more of the vitamin, try steaming or quick sautéing.

Who's More Likely to Lack Thiamin?

Some groups face a higher chance of not getting enough thiamin. This can happen because they need more, eat less, or can't absorb it well.

1. Those Who Drink Too Much

Heavy drinking makes it hard to take in and keep thiamin. It also makes you pee more. These folks might get Wernicke-Korsakoff syndrome, a bad brain problem.

2. Older Folks

As we age, our guts change. Some meds and eating less can lead to low thiamin in older people.

3. People With Gut Issues

Things like Crohn's, celiac, or weight loss surgery can stop the body from soaking up thiamin.

4. Women Having or Feeding Babies

They need more nutrients, including thiamin.

5. Carb Lovers

You need thiamin to use carbs. So, if you eat lots of sugar or starch, you'll need more thiamin.

6. People Taking Water Pills

Thiazide and loop diuretics, which doctors prescribe to treat high blood pressure and fluid buildup, can make you lose more thiamin when you pee.

Signs of Not Getting Enough Thiamin

You might not notice a slight lack of thiamin, but if you don't treat it, it can lead to serious health issues:

1. Beriberi

This illness comes in two main types:

Dry beriberi: This affects your nerves. You might feel weak muscles, have trouble walking, lose your reflexes, and get a feeling in your hands and feet.

Wet beriberi: This impacts your heart and blood vessels. It can cause heart failure, make you swell up (edema), and leave you short of breath.

2. Wernicke's Brain Problem

This needs immediate medical help. You might feel confused, have trouble moving, and your eyes might move. People who drink too much alcohol often get this.

3. Korsakoff's Mind Trouble

This long-term brain issue can make you forget things, see things that aren't there, and have trouble thinking. It often happens after Wernicke's brain problem if you don't treat it.

Is It Possible to Overdo Thiamin?

Thiamin belongs to the water-soluble vitamin group, which means your body gets rid of extra amounts through urine. Scientists haven't set an upper limit for thiamin intake because it's unlikely to cause harm even in large doses.

Doctors sometimes prescribe high doses of thiamin supplements (way more than you'd get from food) to treat certain brain or metabolic problems. They keep a close eye on patients during this treatment.

Thiamin Supplements

Thiamin is available in 3 different types of supplements:

Thiamin hydrochloride—the cheapest and most common

Thiamin mononitrate

Benfotiamine—thought to be better absorbed as it is a fat-soluble derivative of thiamin. Believed to be particularly useful in diabetic neuropathy

TPP (thiamin pyrophosphate)—the coenzyme and sometimes a form used in clinical settings.

Supplements are appropriate for some individuals who benefit from thiamin supplementation, such as those with known deficiencies, chronic conditions, or strict dietary restrictions.

Summary: Why Thiamin is Important Daily

While we only need it in small amounts, thiamin is something we need to get daily. Since we do not store much thiamin in our bodies, receiving inadequate amounts of thiamin over just a few weeks can lead to devastating health impacts. Eating a variety of whole foods, especially whole grains, legumes, lean meats, and vegetables, will support you in maintaining healthy levels of thiamin.

Calls to Action

Now you understand how important thiamin is for your energy, brain, and overall health. Take a closer look at your daily diet. Are you eating enough foods that contain thiamin? If not, consider incorporating more whole grains (for example, oatmeal or quinoa), beans, and lean meats into your meals, or ask your health professional to discuss whether or not a thiamin supplement could be beneficial. 

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