Vitamin B1 (Thiamine)

Written by Slawomir (“Swavak”) Gromadzki, MPH

We know that B vitamins work together and all are essential for maintaining our mental health, mood, normal metabolism, and energy levels, among other functions. One of the most important B vitamins is Vitamin B1, known also as Thiamine.

Unfortunately due to poor nutritional habits, high stress levels, regular use of alcohol and other factors deficiency of this vitamin is very common today and leads to tiredness, heart complications, low mood, irritability, confusion, muscle weakness, indigestion, appetite problems and nerve damage.

Thiamine helps us to maintain normal body weight and avoid tiredness by breaking down food to provide energy. On the other hand, deficiency of this vitamin may lead to lack of appetite, weight loss and underweight. It also helps support muscle function (including heart muscle), immune system, digestion, endocrine function (hormonal balance), and maintains a healthy nervous system, vision, memory, focus and mood.


Nutritional Yeast (2 tablespoons): 10mg (640% of recommended daily intake!)

Seaweed such as Spirulina (1 cup): 2.70mg (216% RDI)

Sunflower seeds (1 cup): 2mg (164% RDI)

Wheat germ breakfast cereal (toasted, plain) 1 cup 1.88mg (150% RDI)

Macadamia Nuts (1 cup): 1.6mg (130% RDI)

Black beans (1/3 cup dried, or about 1 cup cooked): 0.60mg (50% RDI)

Lentils, Navy beans & White beans (1/3 cup dried, or about 1 cup cooked): 0.50mg (44% RDI)

Green peas (cooked, boiled ½ cup) 0.20

Long-grain brown rice (cooked 1 cup) 0.19

Lentils (cooked, boiled ½ cup) 0.17

Pecans (1 ounce) 0.19

Orange (1 fruit) 0.11

Egg (cooked, hard-boiled) 1 large 0.03


– Deficiency of thiamine is caused by poor nutritional habits, eating refined foods (such as sugar, white flour products, white pasta, refined white rice, etc.).

– Chronic stress, nervousness, anxiety also contribute to B1 deficiency.

– Thiamine deficiency is one of the results of chronic alcoholism as alcohol interferes with absorption of thiamine. Most drugs and stimulants, including tobacco, alcohol, caffeinated and carbonated drinks, reduce the amount of thiamine in the body. Thiamin deficiency in alcoholics is known as Wernicke-Korsakoff syndrome.

– Huge deficiency of vitamin B1 can can be caused by Lasix (furosemide) – an anthranilic acid derivative that is used as a strong diuretic in adults and children to treat excessive fluid accumulation (edema) caused by congestive heart failure, liver failure, renal failure, and nephritic syndrome. Lasix and other diuretics make patients pee out most of thiamin leading to its deficiency. 

– Also heating foods that contain thiamine reduces its content. For example, pasteurization of milk reduces thiamine content by 20% (>).

– Pregnancy and breastfeeding increase the need for B vitamins (including B1) to support fetal growth and development.

– Elderly people require more thiamine as they have reduced ability to assimilate all the vitamins from food due to changes in the GI tract.

– People with diabetes, anaemia or liver disease, HIV/AIDS are deficient in thiamine.

– Low Magnesium intake from food and avoiding supplemental magnesium contributes to thiamine deficiency as magnesium is needed in the body to convert B1 to its biologically active form and is also required for certain thiamine-dependent enzymes. Overcoming thiamine (B1) deficiency might not possible if magnesium deficiency is not addressed.

– Too much supplemental Vitamin B6 can inhibit the biosynthesis of thiamine (vitamin B1).


Chronic thiamine deficiency leads to a condition known as beriberi. There are three main types of this disease: wet, dry, and acute.

– Wet type affects the cardiovascular system resulting in a fast heart rate, shortness of breath, and leg swelling.

– Dry beriberi affects the nervous system causing numbness of the hands and feet, mental confusion, pain, etc. Wernicke encephalopathy and Korsakoff syndrome are forms of dry beriberi.

– Acute beriberi, is found mostly in babies and results in lactic acidosis, loss of appetite, vomiting, changes in heart rate, and enlargement of the heart.

Risk factors include alcoholism, refined diet of mostly white rice, white flour products, as well as, taking high doses of diuretics,dialysis, and chronic diarrhoea, etc.

Treatment with thiamine supplementation usually resolve symptoms in a couple of weeks.


  • Nerve damage
  • Burning in the feet (particularly severe at night)
  • Nerve inflammation (neuritis)
  • Fatigue and low energy
  • Weight loss
  • Lack of appetite
  • Colitis
  • Digestive problems,
  • Diarrhoea
  • Poor memory
  • Confusion
  • Irritability
  • Mood changes,
  • Depression
  • Cardiovascular problems, such as an enlarged heart
  • Muscle weakness,
  • Muscle cramps & pains in legs


Immune system function

Vitamin B1 helps strengthen the immune system. Giving rats a Vitamin B1 blocker decreased  immune system function (>).

Boosts metabolism, helps maintain normal body weight & energy levels

Thiamine helps us to control body weight and feel energised by converting carbohydrates into glucose, which is the preferred source of energy our body uses to keep metabolism running smoothly.

In addition, Vitamin B1 also helps break down fats and proteins. That is why its deficiency leads to digestive problems and fatigue. Another reason why Thiamine helps us to feel better is the fact that it is also required for the production of red blood cells, which are used for an ongoing energy.

Eye Health & Vision

Foods with thiamine help prevent eye problems such as cataracts by working together with omega-3 and omega-6 fatty acids to improve eye health. Thiamine can also help prevent vision loss due to nerve swelling in the eyes (>). To improve vision and eye health you should also provide your body with proper amounts of vitamin A, zinc, magnesium, or vitamin D .

Prevents nerve damage

Together with Vitamin B12 Thiamine is also required for proper development and protection of the myelin sheaths (>), which wrap around nerves preventing their damage and death. For this reason supplements containing Vitamin B1 and B12 are often recommended for those who are on statins and other medications that are known to impose damaging effect on nerves.

People with Multiple sclerosis may be benefited by supplementing Thiamin, Vitamin B12, Magnesium, Alpha lipoic acid, Vitamin D3, K2, Selenium, and Zinc. Vitamin B1 and other mentioned above nutrients can also help in other neurodegenerative diseases such as Parkinson’s, Alzheimer’s, and Huntington’s disease (>).

Parkinson’s Disease

Administration of high-dose thiamine was effective in reversing motor and non-motor symptoms in Parkinson’s Disease! The clinical improvement was stable over time in all the patients (>).

Improves mood, memory & focus

Thiamine is a critical vitamin for maintaining and improving focus, mood and memory. It also increases our ability to fight chronic stress. That is why it is often called the “anti-stress” vitamin because it may improve the body’s ability to withstand stressful conditions (>).

Scientific research has linked deficiency of this vitamin to learning difficulties. One of the studies also demonstrated that Thiamine supplements speed up reaction times in those taking tests.

Promotes healthy heart

Thiamine is essential in our body for the production of neurotransmitter acetylcholine used to send messages between nerves and muscles. Since heart and other internal organs are basically muscles they all rely on these vital for their proper function signals. Medical research has shown that Vitamin B1 plays very important role in maintaining healthy heart (especially ventricular) function.

Supplementation with thiamine improves cardiac function in people with heart failure (>).

Diabetes & high blood glucose

Since thiamine helps us control body weight and improve metabolism by converting carbohydrates into glucose, it is very beneficial in preventing and treating type 2 diabetes.

According to studies, the proportion of people with type 1 or type 2 diabetes who are deficient in thiamine ranges from 20% to 80%. It was also found that increasing thiamine intake reduces symptoms associated with early-stage diabetes (>).


Alcohol consumption can damage the brain through various mechanisms, one of them involves reduced availability of Vitamin B1 to the brain (>). Thiamine deficiency is the cause of Wernicke–Korsakoff syndrome (WKS), an alcohol–linked neurological condition.

Muscle Weakness, Spasms & Soreness

Low intake of thiamine is linked to restless leg syndrome, fluid retention, soreness, weakness, apathy, tenderness,  and numbness or tingling in the limbs. Vitamin B1 is especially helpful in preventing these symptoms in people with diabetes or chronic high blood glucose levels which over time lead to neurological damage and thiamine (like vitamin B12) protects the outer coating of nerves called the myelin sheath (>).

Thiamine can also help reduce recovery time after intense exercise and helps reduce lactic acid, which causes soreness.



The safe upper intake of thiamine from supplements is set at 100mg per day for adults.

However, in some conditions much higher dosages of about 500mg per day are used to reduce symptoms.

There is no established upper limit of thiamine because it is water-soluble vitamin and our body removes any excess. According to the Mayo Clinic, studies have investigated the effects of up to 100 milligrams of thiamine, and this dose is considered safe.

Benfotiamine (a fat soluble vitamin B1) has also been tested at 100 milligrams ad is regarded as safe too, although since it is a fat soluble form a caution and consultations are required.


Regarding supplemental thiamine, some sources suggest that fat soluble form of this vitamin, known as benfotiamine, is much better absorbed than the regular water-soluble one as absorption of normal (water soluble) thiamin is limited by an active transport mechanism to only a few milligrams a day. There are fat soluble forms of vitamin B1 such as alliathiamin, benfotiamine or sulbutiamine which solve this problem effectively

In addition to higher bioavailability, benfotiamine also inhibits several pathways involved in glucose-induced vascular changes and supports healthy neuron function. Clinical studies showed that benfotiamine supports healthy neurological structures and glucose metabolism, limiting the formation of advanced glycation end products (AGEs).

A study concluded that, “Benfotiamine (fat soluble B1) suppresses oxidative stress-induced NF-κB activation and prevents the bacterial endotoxin-induced inflammation indicating that vitamin B1 supplementation could be beneficial in the treatment of inflammatory diseases” (>).

Studies on congestive heart failure patients who received water soluble thiamin produced no effect while fat soluble thiamine gave huge benefit.

According to Verywell Health and University of Michigan Health benfotiamine can help in the following health problems: Diabetes & Diabetic neuropathy, Thyroid & Hashimoto’s disease, Back pain, Anxiety, Depression, Sciatica, & Fibromyalgia, (>, >).


In his 2018 article titled, “Learn more about Benfotiamine, Peripheral Neuropathy”, Sunil T. Pai MD wrote:

“Studies have shown that benfotiamine improves neuropathy scores significantly, increases nerve conduction velocity, and reduces HbA1c and pain. On the Russian market, it is one of the most studied drugs for neuropathic pain. In addition, it lowers inflammation and may be useful for ameliorating the analgesic effect of mu-opioid agonists on neuropathic pain. In a randomized, placebo-controlled, double-blind pilot study and phase III clinical study, investigators demonstrated a pronounced effect on the decrease in pain in conjunction with the previously described benefits. Benfotiamine may also be beneficial in preventing diabetic nephropathy and retinopathy. Therapeutic benefits can be seen as early as 3 weeks, with the most significant improvements occurring in patients taking the highest-dose of benfotiamine, that is, 600 mg/day at 6 weeks. The recommended dose of benfotiamine is 150–300 mg twice daily specifically for diabetic peripheral neuropathy”. (SOURCE >, >)

According to 2001 study results, “Unlike treatment with water-soluble thiamine nitrate timely administration of liposoluble (fat soluble) benfotiamine was effective in the prevention of functional damage and of AGE and cmL formation in nerves of diabetic rats.” (>)


– Benfotiamine reduces polyneuropathy symptoms >

– Benfotiamine reduces polyneuropathy symptoms >

– Benfotiamine aids the post-ischemic healing of diabetic animals >

– Benfotiamine, a form of thiamine, attenuates nicotine and uric acid-induced vascular endothelial dysfunction in the rat >

– Benfotiamine has antioxidant activity and may protect DNA >

– Thiamine may be an essential supplement for preventing complications of diabetes type 1 and type 2 >

Benfotiamine and alpha-lipoic acid normalises complication-causing pathways in type 1 diabetes >

– Benfotiamine inhibits oxidative stress with type 2 diabetes >


Benfotiamine seems to be available in US market and on Amazon (>), but unfortunately it is not allowed to be sold as a nutritional supplement in EU countries, including UK. Here is an official statement explaining the reason for that:

“Benfotiamine Benfotiamine is absorbed much better than water soluble thiamine salts. Maximum plasma levels of thiamine are about 5-fold higher after benfotiamine intake and the bioavailability is about 3.6 times as high as that of thiamine hydrochloride and better than that of other lipophilic thiamine derivatives. The increase in relative bioavailability is most significant in muscle (5-fold greater incorporation) and brain (25-fold increase), but thiamine from benfotiamine is also 10-40% better incorporated in other organs, such as liver and kidney… For benfotiamine several human clinical studies at dose levels from 40 up to 400 mg/day for several (3-12) weeks do not report adverse effects, except for one study conducting an open trial at a dose level of 40 mg benfotiamine (dosed together with 90 mg pyridoxine hydrochloride and 250 μg cyanocobalamin for 12 weeks) and reporting nausea, dizziness, stomach ache and weight gain at the twelfth week of the study in 8.4% of the patients… the Panel concludes that the submitted data are insufficient to demonstrate the safety of the proposed use of benfotiamine.” (SOURCE >)


– Vitamin B1 helps increase absorption of B2.

– Very high levels of B1 may interfere with absorption of B2.

Magnesium is required to convert B1 to its biologically active form and is also required for certain thiamine-dependent enzymes. Overcoming thiamine (B1) deficiency might not occur if magnesium deficiency is not addressed.

– Vitamin B6 can inhibit the biosynthesis of thiamine (B1).


Talk to your healthcare provider before taking thiamine or benfotiamine as potential interactions with some medications are possible.



Any information or product suggested on this website is not intended to diagnose, treat, cure or prevent any medical condition. Never disregard medical advice or delay in seeking it because of something you have read on this website. Consult your primary healthcare physician before using any supplements or making any changes to your regime.