Signs and Symptoms of Thiamine Deficiency

Signs and Symptoms of Thiamine Deficiency-min

Although vitamin B1 deficiency is uncommon, age, HIV/AIDS infection, bariatric surgery, and other factors may increase the risk for deficiency. Learn about the signs and symptoms of thiamine deficiency.

Vitamin B1, otherwise known as thiamine is one of the many vitamins you need. Thiamine falls in the group of essential vitamins, as the body does not produce it and it has to be sourced from the foods you eat. Meat, grains, seeds, and nuts are some of the foods high in thiamine. While many people living in the developed countries are less likely to suffer from thiamin deficiency, bariatric surgery, HIV/AIDS infection, age, alcohol dependence, and many other factors may predispose a person to thiamine deficiency. Yet, many people rarely can tell that they are deficient in thiamine since the signs and symptoms are more subtle. Learn about the signs and symptoms of vitamin B1.

Loss of appetite

Appetite is regulated by the brain’s region known as the hypothalamus. However, when you are deficient in vitamin B1, this region of the brain is affected, and so is the satiety center. Such a person feels full or satiated most of the time, resulting in the loss of appetite. Studies in rodents actually prove that thiamine deficiency could cause a loss in appetite. In one study with rats eating thiamine-deficient foods, a 60-75% reduction in food intake was recorded. However, after supplementing with thiamine, the rats increased their food intake to the baseline. Many other studies prove the same.


Fatigue can be linked to many health conditions, which is why people often overlook it and rarely think it can be a sign of thiamine deficiency. Yet, it is a major symptom of thiamine deficiency. The level of fatigue varies from person to person, and this depends on how severe the thiamine deficiency is and how much it has taken roots. In some people, it may only be mild with a slight decrease in energy. In others, the fatigue might be intense and is characterized by extreme exhaustion. The reason why thiamine deficient people may be fatigued from time to time is that the deficiency means that the cells are deprived of energy since thiamine is critical in the conversion of food to energy.

Reduced reflexes

Reduced reflexes are a common sign of undiagnosed vitamin B1 deficiency in children, but it also affects adults. It starts when the motor nerves are affected and this progresses fast. If it goes unattended for a long time, the ankle and knees soon lose their reflexes. Reduced reflexes become noticeable when a person loses coordination and starts having difficulty walking, even staggering.


Many children with beriberi, a nutritional deficiency food that results from vitamin B1 deficiency, often have the problem of irritability. In fact, it is one of the earliest signs of thiamine deficiency and is noticeable only a few days or weeks following the vitamin B1 deficiency. A person who is irritable easily feels frustrated and anxious. Although a range of psychological, physical, and mental factors can cause irritability, thiamine deficiency is also a major cause of irritability, especially the type that affects mood.

Peripheral nerve damage and paresthesia

If you often experience ‘in and needle’ pain in your legs, tingling, and prickling sensation in the limbs, chances are high that you are deficient in vitamin B1. This condition is known as paresthesia and has thiamine deficiency as one of its major causes. For the limbs and legs to move with ease, thiamine is needed to convert food to energy, setting the peripheral nerves in motion. However, in the case of thiamine deficiency, the role of vitamin B1 is missing, and the peripheral nerves can hardly function. That explains why you will feel the prickles, tingles, and the ‘pin and needle pain’ in the limbs. In fact, these symptoms can be felt with the first few days or weeks of vitamin B1 deficiency.

Blurred vision

Blurry vision is a problem of the sigh that’s closely linked to thiamine deficiency. In many cases, blurry vision occurs when thiamine deficiency gets severe. It starts with the infection of the optic nerve, which then swells. In more severe cases, optic neuropathy results. This makes a person have blurred vision. In time, a person might even lose his sight completely, especially if the situation is left unattended. However, the situation can be improved when the thiamine deficiency is diagnosed in time and followed by thiamine supplementation. Documented cases of thiamine deficiency have shown that the patients’ vision improved after they took vitamin B1 supplements.


Whenever there is blurry vision, you often will find confusion; the two are closely linked. Thus, confusion is another sign of thiamine deficiency. That’s when you will find a thiamine deficient man calling Mary, the wife, as Nancy. The explanation for this is the effect thiamine deficiency has on the nerves and transmission of impulses. Studies have actually shown that confusion is problem linked with thiamine deficiency. As with the case of blurry vision, supplementing with thiamine leads to improvement, and the confusion reduces with time.

Muscle weakness

Muscle weakness is a problem that’s common today and even before, and sometimes it can be hard to tell its main cause. From time to time, any person can experience muscle weakness, especially short-term. However, when muscle weakness persists without any apparent cause or explanation, thiamine deficiency may just be the cause. In fact, many documented cases have linked muscle weakness with thiamine deficiency. Fortunately, these patients with muscle weakness significantly improved and felt better once they were supplemented with thiamine.

Nausea and vomiting

This is rather uncommon, but some thiamine-deficient people have experienced nausea and vomiting from time to time. While most symptoms of thiamine deficiency can be explained, explaining vomiting and nausea has been hard. However, documented cases show that some thiamine deficient people have had nausea and vomiting as common symptoms, and have greatly improved after they supplemented with thiamine.


Thiamine or vitamin B1 is one of the eight essential vitamins. Your body does not produce it on its own and must source it from foods such as nuts, seeds, meat, and grains. While thiamine deficiency is uncommon, some factors can cause it. Unfortunately, the symptoms are often subtle, which is why a person may fail to recognize the deficiency. This article has shared some critical symptoms of thiamine deficiency.

Elena Ognivtseva

Nutritionist, Cornell University, MS I believe that nutrition science is a wonderful helper both for the preventive improvement of health and adjunctive therapy in treatment. My goal is to help people improve their health and well-being without torturing themselves with unnecessary dietary restrictions. I am a supporter of a healthy lifestyle – I play sports, cycle, and swim in the lake all year round. With my work, I have been featured in Vice, Country Living, Harrods magazine, Daily Telegraph, Grazia, Women's Health, and other media outlets.