What Causes Low B2 Levels in the Body?

November 1, 2025 •

3 min read

According to the National Institutes of Health, while severe vitamin B2 (riboflavin) deficiency is rare in the developed world, suboptimal levels are more common among specific populations. This article explores the primary factors that cause low B2 levels in the body, ranging from dietary issues to underlying health conditions.

Quick Summary

Low B2 levels, or riboflavin deficiency, can result from inadequate diet, malabsorption issues, certain medications, chronic health conditions, and increased bodily needs. At-risk groups include vegans, alcoholics, pregnant women, and people with specific genetic disorders.

Key Points

Dietary Insufficiency: The most common cause is a diet low in dairy, meat, eggs, and fortified grains.
Malabsorption Disorders: Conditions like celiac disease, Crohn's disease, and chronic diarrhea prevent proper nutrient absorption in the small intestine.
Alcohol Abuse: Chronic alcoholism significantly impairs riboflavin absorption and utilization within the body.
Certain Medications: Long-term use of drugs like oral contraceptives, specific antidepressants, and chemotherapy agents can lower B2 levels.
Increased Physiological Needs: Higher demands for riboflavin during pregnancy, breastfeeding, intense exercise, or chronic illness can lead to deficiency if not met.
Genetic Factors: Rare genetic disorders, such as riboflavin transporter deficiency, can impair the body's ability to transport and absorb the vitamin.
Underlying Health Conditions: Liver disorders, thyroid dysfunction, and renal issues requiring dialysis can disrupt riboflavin metabolism.
Water Solubility: Because riboflavin is water-soluble, excess is excreted, meaning the body needs a consistent supply and cannot store it for long periods.

Dietary Factors and Insufficient Intake

One of the most straightforward causes of low B2 levels is insufficient dietary intake. Riboflavin is a water-soluble vitamin that the body doesn't store in large amounts, necessitating a consistent intake from food. Diets lacking in key B2-rich foods are a primary risk factor.

Inadequate Food Sources

Certain groups are more likely to have a low dietary intake, including vegans and vegetarians who may not consume enough fortified foods, as dairy, meat, and eggs are major sources. Individuals with lactose intolerance or those on restricted diets, such as those with anorexia nervosa, are also susceptible.

Poor Food Preparation

Riboflavin is sensitive to light and is water-soluble. Improper cooking methods, such as boiling vegetables, can lead to nutrient loss. Packaging milk in opaque cartons helps prevent light-induced degradation.

Health Conditions and Malabsorption

Even with an adequate diet, health conditions can impair the body's ability to absorb or utilize riboflavin.

Gastrointestinal and Malabsorptive Disorders

Diseases affecting the small intestine, like celiac disease or Crohn's disease, can hinder nutrient absorption. Chronic diarrhea can also lead to poor absorption.

Chronic Health Issues

Chronic alcohol abuse impairs absorption and metabolism. Liver disorders disrupt metabolism and storage. Thyroid hormone insufficiency can affect the conversion of riboflavin into its active forms. Individuals with diabetes or those undergoing dialysis are also at higher risk.

Medical Treatments and Medications

Some medical treatments and medications can interfere with riboflavin levels.

Pharmaceutical Interference

Oral contraceptives may reduce absorption. Certain antidepressants (like imipramine) and antipsychotics (like chlorpromazine) can interfere with utilization or increase excretion. Chemotherapy drugs and long-term use of barbiturates can also deplete riboflavin.

Genetic and Increased Physiological Needs

Genetic conditions or increased bodily demands can also lead to low B2 levels.

Rare Genetic Disorders

Riboflavin transporter deficiency is a rare genetic disorder where mutations impair the absorption and transport of riboflavin, requiring high-dose supplementation.

Increased Demands for Riboflavin

Needs increase significantly during pregnancy and lactation. Athletes, especially vegetarian athletes, have increased metabolic demands. Elderly individuals may experience decreased absorption and intake.

Causes of Low B2 Levels: At-a-Glance


Cause Category	Primary Examples	Impact on Riboflavin	Affected Individuals
Dietary	Veganism, low dairy, restricted diets	Insufficient direct intake from food	Vegans, lactose-intolerant, individuals with eating disorders
Malabsorption	Celiac disease, Crohn's disease, chronic diarrhea	Impaired intestinal absorption of the vitamin	Individuals with GI disorders, alcoholics
Medication	Oral contraceptives, certain antidepressants, chemo drugs	Reduced absorption, increased excretion, metabolic interference	Patients on specific long-term medications
Chronic Disease	Alcoholism, liver disease, thyroid issues, dialysis	Disrupted metabolism, storage, or increased needs	Chronic alcohol users, individuals with specific chronic illnesses
Genetic	Riboflavin transporter deficiency	Impaired cellular transport and absorption	Individuals with specific inherited genetic mutations
Increased Needs	Pregnancy, lactation, intense athletic training	Higher metabolic demand for the nutrient	Pregnant/lactating women, endurance athletes

Conclusion

Low B2 levels result from various factors, including inadequate diet, malabsorption issues, chronic health conditions, medications, genetic predispositions, and increased physiological demands. While dietary intake is a common cause, particularly for those with restrictions, other factors highlight the complexity of riboflavin deficiency. Identifying and addressing these causes is crucial, especially for high-risk individuals. Anyone concerned about their B2 status should seek medical advice.

What are the most common symptoms of riboflavin deficiency?

Symptoms often include oral issues like cracked mouth corners and lips, and a sore, swollen tongue. Skin problems, eye irritation, light sensitivity, fatigue, headaches, and even anemia can occur. In severe cases, nerve degeneration is possible.

Frequently Asked Questions

Riboflavin, or vitamin B2, is one of the eight B-vitamins crucial for energy production and cellular functions. It acts as a coenzyme in metabolic processes that convert food into energy and helps maintain healthy skin, vision, and red blood cells.

High-risk groups include individuals with chronic alcohol use disorder, those on restricted diets (especially vegans who do not supplement), pregnant and lactating women, people with malabsorption disorders, and those with certain chronic diseases.

Yes. Some medications can cause low B2 levels by interfering with absorption or increasing excretion. Examples include oral contraceptives, tricyclic antidepressants, and some chemotherapy drugs.

A key sign is often seen in the mouth, with symptoms like angular stomatitis (cracks at the corners of the mouth), cheilosis (cracked lips), and a painful, swollen tongue.

Diagnosis is typically based on a clinical assessment of symptoms. A doctor may also perform laboratory tests, such as measuring urinary excretion of riboflavin, and monitor the patient's response to riboflavin supplements.

Treatment usually involves oral supplements of riboflavin. Because deficiencies often occur with other B vitamins, a multivitamin or B-complex supplement is often recommended. In severe cases, injections may be used.

Yes, a rare neurological disorder called riboflavin transporter deficiency is caused by a genetic mutation that prevents the body from properly absorbing and transporting riboflavin. This requires high-dose oral supplementation.