What are B1 deficiency symptoms? 9 signs you might need more thiamine

Thiamine, or vitamin B1, is a crucial vitamin that helps our bodies process carbohydrates, proteins and fats to provide energy. Thiamine is also essential for normal nerve and heart function.

Many people in the United States consume a refined Western diet that is high in sugar, highly processed carbohydrates, caffeine and sometimes alcohol. As a result, it’s possible to become deficient in thiamine.

B1 deficiency symptoms may be vague, and can mimic symptoms of other conditions, such as diabetes and congestive heart failure. So how do you know if you’re experiencing B1 deficiency symptoms and how can you boost your intake of thiamine?

Let’s find out.

Benefits of thiamine for the body

If you’ve never heard of it, thiamine is one of eight B vitamins that aid in the production of energy. It is essential because your body cannot make it on its own. Thiamine is needed to make adenosine triphosphate (ATP), which all the cells in your body use to store energy.

Thiamine may also provide these health benefits:

• Reduce the risk of heart failure
• Support a healthy nervous system  
• Prevent cataracts
• Manage diabetes  
• Improve memory and concentration
• Strengthen your immune system

How much thiamine do you need every day?

Thiamine requirements are measured in milligrams (mg) and are dependent on your age, sex and whether you’re pregnant or breastfeeding. The recommended dietary allowance (RDA) for thiamine varies. For most adults, 1-2 mg of thiamine per day is commonly recommended:

• For men 14 years and older, 1.2 mg is the recommended amount of thiamine.
• For women over 18 years old, 1.1 mg is the recommended amount thiamine.

You can aim to meet the RDA, however, there are no side effects to consuming more. Thiamine, like all B vitamins, is water-soluble. Therefore, your body flushes out any excess in your urine.

Food sources rich in thiamine

The best way to ensure you don’t start to experience a B1 deficiency is through eating a well-balanced diet. Some foods rich in thiamine include:

• Black beans
• Corn
• Fish (salmon)
• Fortified breakfast cereal
• Lentils
• Liver
• Nuts and seeds, such as sunflower seeds or macadamia nuts
• Pork
• Seafood (mussels)
• Whole grain bread and pasta

9 B1 deficiency symptoms

Signs of B1 deficiency can often be easy to overlook and sometimes may mimic symptoms of other conditions. Some of the most common thiamine deficiency symptoms include:

1. Blurred vision
2. Confusion
3. Delirium
4. Fatigue
5. Irritability
6. Loss of appetite
7. Nausea and vomiting
8. Short-term memory issues
9. Tingling and burning sensations in arms and legs

Very low thiamine levels may lead to beriberi, a condition that can affect both your cardiovascular system and the central nervous system.

If you are experiencing any of these symptoms, it is important to tell your primary care provider. B1 deficiency is typically diagnosed using a physical exam. Your primary care provider will look for symptoms and any issues such as behavioral or mobility changes. Your provider may also conduct laboratory testing to confirm, specifically a blood test to measure the activity of enzymes that require thiamine.

Who is at risk for a B1 deficiency?

The chances of developing a B1 deficiency are relatively low in countries where people have regular access to thiamine-rich foods. However, some people may be at a higher risk due to specific risk factors.

Some of the most common risk factors include:

• Advanced age
• Alcohol use disorder
• Anorexia nervosa, poor diet or malnutrition
• Chronically elevated blood sugar levels
• Conditions that increase your need for thiamine, such as hyperthyroidism 
• Conditions that prevent your body from absorbing thiamine, such as irritable bowel syndrome (IBS), ulcerative colitis, and Crohn’s disease 
• Congenital beriberi, a condition where you are born without the ability to absorb thiamine
• Drinking more than 16 ounces of coffee or tea daily
• Dialysis for chronic kidney disease
• Liver disease
• Obesity
• Prior gastric bypass surgery  or removal of the jejunum (the middle part of your small intestine)
• Chronically elevated blood sugar levels
• Taking certain medications, such as furosemide or other diuretics, including fluoroquinolone or metformin

Pregnant and breastfeeding mothers may also have a higher risk of thiamine deficiency due to an increased need for the nutrient. 

7 ways to prevent B1 deficiency

The main way to prevent (and treat) thiamine deficiency is to get more of it into your system, either by eating more thiamine-rich foods or by taking supplements. These dietary changes, along with supplementation, can help you safely and effectively increase your thiamine levels. Some practical ways to get started include:

1. Add thiamine-rich foods into your diet.
2. Choose fortified cereals and bread.
3. Avoid refined flours and choose whole grains instead.
4. If dietary changes aren’t enough, your provider may recommend a vitamin B1 supplement.
5. Limit alcohol consumption and excessive caffeine intake.
6. Limit added sugars such as ice cream, candy, cakes and pies. Since thiamine is required for glucose metabolism, a high consumption of sugar could deplete this nutrient.
7. Add vitamin C-rich foods to your diet, such as citrus fruits, strawberries, tomatoes, red and green bell peppers, broccoli, kale, spinach and Brussels sprouts. Vitamin C will lower the pH in your gut, which enhances the absorption of thiamine.

There isn’t a one-size-fits-all approach to tackling a thiamine deficiency, which is why it’s crucial to work with a healthcare expert.

Have questions about B1 deficiency symptoms? Connect with a registered dietitian to learn more.