“Beriberi” may sound cute, but the consequences of this condition can be fatal. Advanced thiamine deficiency causes heart and nerve damage and increases the risk of various diseases. Read on to learn what signals deficiency early on and what you can do to prevent it.
What is Thiamine Deficiency?
Roles of Vitamin B1
Thiamine, also known as vitamin B1, helps you break down food and deliver energy to each cell in your body. In the form of thiamine pyrophosphate (TPP), or thiamine diphosphate (TDP), vitamin B1 supports the enzymes that [1, 2, 3, 4]:
- Produce energy in your mitochondria
- Maintain nervous system health and brain function
- Boost immunity
- Combat inflammation
Thiamine deficiency can result from reduced intake, enhanced loss, or impaired metabolism of this essential nutrient.
The term “beriberi” was coined to describe malnourished people with severe thiamine deficiency and distinct symptoms of heart and nerve damage. In developed countries, it’s mostly limited to people with alcoholism and other health disorders, which we’ll discuss later in this post [5, 6].
However, blood thiamine has notable limitations as a diagnostic tool. Please see the “Diagnosis” section for more details.
People at Risk
Some vulnerable groups have increased demand for thiamine and are at a higher risk of deficiency; they include:
- Athletes and active people 
- Alcohol abusers [10, 11]
- Pregnant and nursing women 
- Diabetics 
- Cancer patients 
- Preventing people from eating enough food
- Blocking thiamine absorption in the gut
- Increasing the body’s demand for thiamine
- Inhibiting thiamine storage due to liver damage
- Preventing the brain and other organs from using thiamine
A lack of this vitamin can severely damage the nerves, and experts recommend extensive thiamine treatment for all people with a history of alcohol abuse .
2) Poor Nutrition & Eating Disorders
Unfortunately, thiamine deficiency is a serious issue for malnourished people in “third world” countries. It’s particularly common in poor Asian regions where polished rice and other processed grains are staples of the diet, and people cannot afford vitamin-rich foods [17, 18].
Bran contains most of the thiamine in rice; thus, milling and the removal of rice bran deplete vitamin B1, making people prone to deficiency if they don’t or can’t eat meat and legumes .
Breastfed infants from deficient mothers face similar dangers, often with severe impact on their development. Babies may also suffer from beriberi if they are fed inadequate milk-replacement formulas [19, 20, 21].
People with eating disorders such as anorexia lack an array of essential nutrients because they do not eat enough food. They may experience life-threatening nerve damage due to thiamine deficiency [22, 23].
3) Digestive Disorders
Prolonged diarrhea and vomiting may cause excess vitamin B1 loss. Patients who experience confusion and vision impairment need immediate medical care and the supply of thiamine, fluid, and electrolytes [26, 27].
For the same reason, severe vomiting during pregnancy (hyperemesis gravidarum) may cause thiamine deficiency if left untreated .
4) Gut Surgery
Any surgery performed on the stomach or intestines can reduce thiamine absorption and make you prone to deficiency.
Thiamine deficiency is also a possible side effect of bariatric (weight loss) surgeries, which change the size or structure of the stomach and small intestine. Experts suggest checking thiamine status before the surgery and supplementing in people at risk of deficiency [32, 33, 34, 35].
According to a study of 400 patients, higher BMI (body mass index) increases the risk of thiamine deficiency. This may be due to a diet high in refined sugar and fats and low in whole grains [35, 36].
6) Parenteral Nutrition
People who are unable to eat and digest food depend on a steady supply of parenteral (injected) nutrients. Despite decades of experience and advances in parenteral nutrition, some patients still get thiamine deficiency due to low vitamin B1 content in the formulations [38, 39, 40].
People who take diuretics (“water pills”) long-term produce larger amounts of urine, which flushes more thiamine from the body and raises the risk of deficiency.
In one clinical trial, high doses of furosemide (80 mg/day) caused severe thiamine deficiency in 98% of patients (24/25). Besides increasing urination, this drug may also directly inhibit thiamine uptake into the cells that need it [44, 45].
Vitamin B1 supports several enzymes involved in glucose metabolism. The function of these enzymes is often impaired in people with diabetes .
In a study of 94 patients, blood thiamine was 76% lower in type 1 and 75% lower in type 2 diabetic people, compared with healthy volunteers. Both diabetic groups also lost more thiamine in their urine .
According to a study of 60 patients, kidney damage may cause thiamine loss in diabetics .
Mutations in the following genes can impair thiamine transport into cells and increase the risk of deficiency :
An error can also occur due to mutations in one or more enzymes that transform thiamine into its active forms, such as thiamine pyrophosphokinase 1 (TPK1) .
The following conditions can increase the risk of thiamine deficiency:
- Kidney failure [49, 50]
- High thyroid hormones [51, 52]
- Cancer and chemotherapy [53, 54]
- HIV/AIDs [55, 56, 57]
Magnesium enables the conversion of thiamine into its active form, thiamine pyrophosphate (TPP), and they work together to produce energy. Magnesium deficiency may thus mimic thiamine deficiency and lessen the effects of supplementation [58, 59, 60].
Therefore, if you suspect you are deficient in thiamine, make sure you get enough magnesium in your diet as well.
Signs & Symptoms
1) General Symptoms
- Reduced appetite and weight loss
- Muscle cramps
- Tongue and mouth inflammation
- Leg numbness
- Tingling and burning sensations
- Visual impairments
- Loss of memory
That said, beriberi is rare in the US and other developed countries. It occurs after months of severe deficiency, mostly due to alcohol abuse or health disorders described above .
Dry beriberi is a form with dominant nerve damage and neurological symptoms described above. It can sometimes resemble Guillain-Barré syndrome with ascending paralysis (progressing from the legs up), numbness, and low blood pressure [65, 14].
- Increased heart rate
- Fast breathing
- Dilated heart muscle
- Swollen hands and feet
Some symptoms, especially the burning and tingling sensations in the feet and legs, can appear in both wet and dry beriberi .
3) Digestive Symptoms
In rare cases, thiamine deficiency can manifest with digestive symptoms such as nausea, vomiting, and stomach pain. Scientists coined the term “gastrointestinal beriberi” to describe such cases, which are more common among infants [68, 21].
4) Lactic Acidosis
The lack of thiamine shifts your cells to anaerobic metabolism (energy production without oxygen), which results in lactate accumulation. Over a long period of time, this process can lead to a dangerous metabolic disorder called lactic acidosis [71, 72].
Toxic amounts of lactate contribute to a range of beriberi symptoms, such as nerve damage and heart failure .
5) Brain Damage
The brain is particularly sensitive to the lack of vitamin B1. Deficiency causes oxidative stress, inflammation, lactic acidosis, and nerve damage. If energy production remains compromised and thiamine stays low, brain cells will die [75, 76].
- Uncontrolled eye movements
- Eye muscle weakness
- Double vision
- Lack of coordination
If left untreated, Wernicke’s encephalopathy can progress into psychosis with memory loss, known as Korsakoff syndrome. Once the disease progresses this far, brain injuries are permanent and often end in death [78, 79].
Wernicke-Korsakoff syndrome, also called wet brain, is a transitional state between Wernicke’s encephalopathy and Korsakoff syndrome, with mixed features of both .
These conditions are most common in alcoholics, and they greatly contribute to alcohol-induced brain damage and delirium. However, Wernicke-Korsakoff syndrome can also develop in other cases of thiamine deficiency .
Conditions Linked to Thiamine Deficiency
Mild thiamine deficiency won’t harm the organs instantly, but in the long run, it may increase the risk of various health disorders.
In diabetes, toxic glucose levels damage the blood vessels. Thiamine deficiency intensifies the problem by causing inflammation and oxidative stress .
- Nephropathy (kidney damage)
- Retinopathy (eye damage)
- Neuropathy (nerve damage)
2) Heart Disease
A meta-analysis of 9 clinical trials found that thiamine deficiency is 2.5 times more common among patients with heart failure. They often lack this vitamin due to diuretic use, malnutrition, and alcoholism [88, 64].
In some of these patients, thiamine deficiency may further impair heart function and worsen their symptoms. A review of clinical and animal trials confirmed the role of thiamine deficiency in the development of heart disease [89, 90].
3) Mental Disorders
Vitamin B1 enables the production of neurotransmitters such as glutamate, acetylcholine, and serotonin. Flawed or reduced neurotransmitters can impact mental health and raise the risk of depression .
Oxidative stress and mitochondrial dysfunction induced by thiamine deficiency can harm the hippocampus, the brain’s hub for memory and emotions .
In over 1,500 elderly Chinese people, those with the lowest levels of thiamine had three times higher rates of depression, compared with those with the highest levels .
Thiamine (50 mg/day for 2 months) boosted mental clarity and energy in 120 healthy women. Further studies should evaluate the therapeutic effects of thiamine supplementation on mental health .
So far, we’ve discussed a few ways that thiamine deficiency can cause brain damage. These mechanisms might also play a role in autism spectrum disorders (ASD) .
However, the available clinical data is limited and far from conclusive. Autism is a complex developmental disorder, and we still don’t know much about causes and contributing factors.
Well-designed clinical studies should cast more light on the potential connection between autism and thiamine deficiency. There are no confirmed benefits of thiamine supplementation for autistic children.
According to some observational data, thiamine deficiency may be linked with dementia. However, there’s still no clinical evidence to support these preliminary observations.
In preliminary trials, supplementation with thiamine or benfotiamine has produced promising results for this condition. However, these trials included only a handful of patients and had other design flaws. A more recent review concluded there’s not enough data to evaluate the efficacy of thiamine supplementation for Alzheimer’s disease [105, 106, 107, 108].
Diagnosis & Tests
Thiamine Blood Test
When interpreting lab results, consult with your doctor and pay attention to:
- Units (nmol/L vs. ng/mL)
- Vitamin forms (free thiamine vs. thiamine diphosphate)
- Samples (blood vs. red blood cells)
Limitations and Other Tests
Blood (serum) thiamine levels represent only a small portion of the total thiamine in your body and are not a reliable indicator of your overall thiamine status.
Thiamine Deficiency Treatment and Prevention
People at risk of thiamine deficiency – such as alcohol abusers, pregnant women, and diabetics – should speak to their doctor about dietary changes, supplements, and monitoring their thiamine levels.
A doctor will initiate prompt treatment with intravenous or intramuscular thiamine (50-200 mg) in suspected thiamine deficiency. Doses can be even higher in suspected Wernicke-Korsakoff syndrome. if the symptoms resolve, the maintenance therapy follows with lower doses, oral or injected [61, 8].
Thiamine has a good safety profile, and doctors are encouraged to start the treatment as soon as they suspect a deficiency, instead of waiting for a definite diagnosis. Milder symptoms usually resolve promptly without permanent consequences .
If you notice the symptoms of nerve damage and suspect thiamine deficiency, seek medical attention immediately. The following natural approaches are meant to ensure adequate thiamine intake and prevent deficiency, not to treat a condition.
- Whole grains
- Sunflower seeds
An average adult needs 1.1–1.2 mg of thiamine daily, while the requirements during pregnancy and breastfeeding are slightly higher at 1.4 mg .
- Whole grains
- Leafy greens (spinach, Swiss chard)
- Nuts (almonds and cashews)
Most healthy people get enough thiamine (vitamin B1). In developed countries, thiamine deficiency is rare and mostly occurs in people who abuse alcohol. Obesity, digestive disorders, diabetes, and heart failure may also increase the risk.
Initial symptoms include confusion, vomiting, nausea, and muscle cramps. Severe deficiency causes leg numbness, tingling, lack of coordination (dry beriberi) and heart failure (wet beriberi). It can eventually lead to permanent brain damage and raise the risk of dementia, diabetes, and heart disease if left untreated.
To increase thiamine intake, eat a variety of whole grains, seeds, and legumes. Avoid drinking tea or coffee with meals, increase your dietary magnesium, and avoid drinking alcohol.
Your doctor will perform a physical exam, run several blood tests, and initiate medical treatment if they suspect deficiency.