Vitamin B complex deficiency: Signs and symptoms to look out for

Vitamin B Complex, a group of eight essential nutrients, plays a critical role in maintaining our overall health. These nutrients are indispensable for a variety of bodily functions, from converting food into energy to producing red blood cells. Unfortunately, a deficiency in these vitamins can lead to numerous health problems. 

This comprehensive blog post aims to shed light on the signs and symptoms of Vitamin B Complex deficiency, helping you understand its potential impact on your health. We’ll discuss the causes, at-risk groups, symptoms associated with each B vitamin deficiency, and preventive measures.

What is vitamin B complex deficiency?

Vitamin B complex deficiency refers to a shortage of one or more vitamins in the B complex group within the body. The vitamin B complex is composed of eight vitamins, each playing a significant role in various body functions [1].

These include B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B7 (biotin), B9 (folic acid), and B12 (cobalamin). Each of these vitamins has a unique function, from aiding in metabolism to promoting cell growth and red blood cell production.

A deficiency in these B vitamins can disrupt these crucial processes, leading to various health problems.

For instance, a shortage of B12 can lead to pernicious anemia, while a lack of B1 can result in beriberi, a condition characterized by weakness and nerve damage. B3 deficiency can lead to pellagra, causing skin problems, mental confusion, and digestive issues.

It’s worth noting that these deficiencies can occur individually, although it’s more common for multiple B vitamin deficiencies to occur simultaneously due to their overlapping dietary sources.

For this reason, the term ‘vitamin B complex deficiency’ is commonly used to refer to a deficit in any of the B vitamins.

What is the main cause of vitamin B complex deficiency?

What is the main cause of vitamin B complex deficiency?

Certain individuals are at a higher risk of developing a vitamin B complex deficiency due to various factors like diet, age, medical conditions, and lifestyle habits.

Poor diet

Individuals who consume a diet low in fruits, vegetables, whole grains, and lean proteins—primary sources of B vitamins—are at risk. This includes people who consume highly processed foods or have eating disorders.


Older adults are at risk as the body’s ability to absorb vitamins from food decreases with age.

Medical conditions

People with certain medical conditions such as celiac disease, Crohn’s disease, HIV, or alcohol dependence can have malabsorption issues, reducing the body’s ability to absorb B vitamins from food [2].


Certain medications like proton pump inhibitors and metformin can interfere with B vitamin absorption.


Pregnant women have a higher risk due to increased nutrient demands. Particularly, deficiencies in B9 (folic acid) and B12 can lead to serious birth defects.

Vegetarian or vegan diets

As B12 is predominantly found in animal products, those on strict vegetarian or vegan diets can be susceptible to B12 deficiency unless they take a supplement or consume fortified foods.

In general, maintaining a balanced diet, regular health check-ups, and addressing underlying health issues are vital to prevent vitamin B complex deficiencies.

Featured product offer
Elm & Rye Vitamin B12
  • Has lab-created Vitamin B12, ensuring consistent quality and effectiveness.
  • Also contains dicalcium phosphate, microcrystalline cellulose, and other ingredients.
  • Convenient dosage options for gummies or capsule.

What are the symptoms of a lack of B vitamins?

The symptoms of vitamin B complex deficiency depend on the specific type of B vitamin the body is lacking. Deficiencies in different B vitamins can lead to different health issues. Here we explore early and advanced symptoms associated with vitamin B complex deficiency.

Early signs of vitamin B complex deficiency

1. Fatigue and weakness

A common early sign of several types of vitamin B deficiency, particularly B12, B6, and B9, is fatigue or weakness [3]. These vitamins are vital in energy production, and their shortage can lead to reduced stamina.

2. Mood changes

Deficiencies in B vitamins, especially B6, B9, and B12, can cause mood swings, depression, and anxiety as these vitamins play a crucial role in producing brain chemicals that affect mood.

3. Skin problems

Deficiency in B2, B3, and B7 can cause skin problems such as dermatitis, rashes, dry or scaling skin [4].

4. Digestive issues

A lack of B3, B7, and B9 can lead to digestive problems like nausea, vomiting, abdominal cramps, and diarrhea.

5. Glossitis and stomatitis

Swelling, inflammation or soreness of the tongue [4] (glossitis) or mouth (stomatitis) can result from deficiencies in multiple B vitamins like B2, B3, B6, and B12.

Advanced symptoms of vitamin B complex deficiency

If left untreated, vitamin B complex deficiency can lead to more severe symptoms, which may include:

1. Anemia

Vitamin B12 and B9 are crucial for producing red blood cells. Deficiencies in these vitamins can lead to different forms of anemia, characterized by symptoms such as fatigue, weakness, pale skin, shortness of breath, and dizziness.

2. Neurological disorders

Severe vitamin B deficiencies, particularly B1, B6, and B12, can lead to neurological problems. Symptoms can include numbness and tingling in the hands and feet, muscle weakness, and in severe cases, mental confusion or memory loss [5].

3. Seborrheic dermatitis

A deficiency in several B vitamins, including B2, B3, B6, and B7, can cause this skin disorder, which leads to scaly patches, red skin, and stubborn dandruff.

4. Glossitis

A severe form of this condition, resulting in a smooth, swollen tongue, can occur with deficiencies in B2, B3, B6, and B12.

It’s essential to be aware that these symptoms can indicate various health conditions, not just vitamin B complex deficiencies. If you experience these symptoms, it’s important to seek medical advice.

How is vitamin B complex deficiency diagnosed?

Identifying vitamin B complex deficiency often requires a two-step process: a review of the patient’s medical history and symptoms, followed by specific diagnostic tests.

1. Medical history and physical examination

The doctor typically begins by reviewing the patient’s diet, medication use, alcohol consumption, and potential symptoms. They may also ask about any family history of deficiency. A physical examination might reveal signs such as pale skin, a smooth tongue, or neurological problems.

2. Blood tests

If the doctor suspects a vitamin B deficiency, they will order blood tests. These tests measure the amount of specific B vitamins in the blood or the overall level of all B vitamins. 

For instance, a complete blood count (CBC) [6] can detect anemia caused by vitamin B12 or folic acid deficiency. Methylmalonic acid (MMA) [6] levels might be checked for suspected B12 deficiency, as high MMA levels often indicate B12 deficiency.

Other tests can include a homocysteine level test, which can indicate deficiencies of vitamins B6, B12, or folic acid. A urine test for N-methyl nicotinamide can be used to diagnose niacin deficiency.

In some cases, further testing may be needed to determine the exact cause of the deficiency, such as gastrointestinal malabsorption. It’s crucial to get a precise diagnosis, as each type of vitamin B deficiency requires a different treatment approach.

Featured product offer
HelloHealth Vitamin B12 drops
  • GMO-free, USDA certified organic, sugar and gluten-free, and free from common allergens.
  • Laboratory tested for quality and potency.
  • Formulated with vitamins B2, B3, B5, B6 and B12.

How can you treat vitamin B complex deficiency

The treatment for vitamin B complex deficiency primarily involves replenishing the deficient vitamins and addressing any underlying causes contributing to the deficiency.

1. Dietary changes

Increasing the intake of foods rich in B vitamins is often the first step. This includes lean meats, eggs, dairy products, leafy greens, beans, peas, and whole grains. For vegans and vegetarians, fortified foods or supplements may be necessary, especially for vitamin B12.

dietary changes

2. Supplements

In cases where dietary changes are insufficient or impractical, doctors may recommend vitamin B complex supplements. These are available over-the-counter or by prescription in various forms, such as tablets, capsules, or injections.

3. Treating underlying causes

If the deficiency is caused by a medical condition like celiac disease or an alcohol use disorder, treating the underlying condition is crucial to resolving the deficiency.

How to prevent a vitamin B complex deficiency

Preventing a vitamin B complex deficiency typically involves maintaining a balanced diet, practicing good lifestyle habits, and managing underlying health conditions that can affect nutrient absorption. Here are some preventive strategies:

1. Consume a balanced diet that includes a variety of foods rich in B vitamins. These foods include whole grains, lean meats, eggs, dairy products, fruits, vegetables, and legumes. For vegans and vegetarians, fortified foods or supplements might be necessary.

2. Get regular health check-ups to help detect deficiencies early before they lead to severe health problems. This is especially important for at-risk groups like the elderly, pregnant women, and individuals with certain health conditions.

3. Be careful with medication use. Some medications can interfere with the absorption of B vitamins. If you’re prescribed such medications, discuss the risk of vitamin B complex deficiency with your healthcare provider. You may need to take a supplement or adjust your diet.

4. Manage underlying conditions that affect absorption to help prevent deficiencies, these may include Crohn’s disease or celiac disease.

5. Limit alcohol consumption as excessive intake can interfere with B vitamin absorption and metabolism.

Closing thoughts

Understanding the importance of the vitamin B complex for maintaining optimal health is critical. These vitamins play an integral role in various bodily functions, from energy production to cell growth. Deficiencies can lead to a range of symptoms, from mild discomfort to severe health conditions. 

Fortunately, through balanced nutrition, regular health check-ups, and targeted treatment when necessary, vitamin B complex deficiencies can be effectively managed and prevented.

However, any suspected deficiencies should be confirmed and treated under the guidance of a healthcare professional to ensure a safe and effective approach to restoring and maintaining your health.


What happens if vitamin B complex is low?

When vitamin B complex levels are low, it can disrupt vital bodily functions, leading to symptoms like fatigue, mood changes, skin issues, and digestive problems. If left untreated, severe deficiencies can result in anemia, neurological disorders, and other serious health conditions.

Is it OK to take vitamin B complex everyday?

Yes, it’s generally safe to take vitamin B complex supplements daily, as they’re water-soluble vitamins and excess amounts are excreted from the body. However, it’s always recommended to consult with a healthcare professional before starting any new supplement regimen to ensure it’s suitable for your specific health needs.

How do I know if I need more vitamin B?

Symptoms like fatigue, mood changes, skin issues, or digestive problems may indicate a deficiency in vitamin B complex. However, the best way to confirm if you need more vitamin B is through a blood test conducted by a healthcare professional, as these symptoms could be associated with various health conditions.

Does lack of vitamin B make you sleepy?

Yes, a lack of certain B vitamins, specifically B12, B6, and B9, can contribute to feelings of fatigue and sleepiness, as these vitamins are crucial in the body’s energy production process. However, persistent sleepiness can be a sign of various health conditions, so it’s essential to consult a healthcare professional for an accurate diagnosis.

Featured product offer
Future Kind+ Vegan Vitamin B12 Energy Gummies
  • Enhances energy and mental clarity, specially formulated for vegan diets.
  • Easy-to-take, chewable gummies free from common allergens.
  • Supports cognitive functions and immunity with essential Vitamin B12.


The information included in this article is for informational purposes only. The purpose of this webpage is to promote broad consumer understanding and knowledge of various health topics. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition or treatment and before undertaking a new health care regimen, and never disregard professional medical advice or delay in seeking it because of something you have read on this website.