Vitamin B2 (Riboflavin) Blood Test: Normal Ranges, Causes & What Your Results Mean

What Is Vitamin B2 (Riboflavin)?

Vitamin B2, also known as riboflavin, is an essential water-soluble vitamin that serves as a building block for two critical coenzymes: flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). These coenzymes are involved in over 100 enzymatic reactions in the body, including energy production from carbohydrates, fats, and proteins, as well as the metabolism of other vitamins (particularly B6, folate, and niacin).

Riboflavin also acts as an antioxidant, helping to neutralise free radicals and reduce oxidative stress. It plays a role in maintaining healthy skin, eyes, and nerve function. Unlike fat-soluble vitamins, the body stores very little riboflavin, so regular dietary intake is essential.

Why Is Vitamin B2 Tested?

• Investigate symptoms of riboflavin deficiency: cracked lips (cheilosis), sore throat, mouth ulcers, or red swollen tongue
• Assess nutritional status in patients with restricted diets, eating disorders, or malabsorption conditions
• Evaluate patients with persistent migraines — riboflavin supplementation is an evidence-based prophylactic
• Monitor patients on certain medications that interfere with riboflavin metabolism (tricyclic antidepressants, some antimalarials)
• Investigate unexplained anaemia or skin conditions
• Screen for deficiency in alcoholism, pregnancy, or elderly patients

Normal Ranges

EGRAC is considered the gold standard functional test for riboflavin status. A coefficient above 1.4 indicates significant deficiency.

Causes of Low Vitamin B2

• Poor dietary intake: Diets low in dairy, meat, and green vegetables — riboflavin's best sources
• Alcohol use: Alcohol reduces riboflavin absorption and increases urinary excretion
• Malabsorption: Coeliac disease, inflammatory bowel disease, or short bowel syndrome
• Eating disorders: Anorexia and bulimia frequently lead to B-vitamin deficiencies
• Medications: Tricyclic antidepressants, phenytoin, oral contraceptives, and some antimalarials
• Pregnancy and lactation: Increased demand can deplete stores
• Hypothyroidism: Impairs riboflavin metabolism
• Elderly population: Reduced intake and absorption with age

Causes of High Vitamin B2

Elevated riboflavin is generally harmless, as excess is efficiently excreted in urine (which turns bright yellow). High levels may be seen with:

• Supplementation with B-complex or multivitamin preparations
• High dairy or fortified food consumption

How to Maintain Healthy Vitamin B2 Levels

• Eat riboflavin-rich foods: Milk, yoghurt, eggs, lean meats, almonds, spinach, and fortified cereals
• Don't expose milk to light: Riboflavin degrades rapidly when exposed to UV light — store milk in opaque containers
• Consider supplementation: A B-complex supplement provides adequate riboflavin for most people
• For migraine prevention: 400mg daily of riboflavin has been shown to reduce migraine frequency by up to 50%
• Limit alcohol: Excessive alcohol impairs riboflavin absorption
• Include dairy: Dairy products are the single best dietary source of riboflavin in the UK diet

When Should You Get Tested?

• You have persistent cracked lips, mouth ulcers, or sore tongue that doesn't resolve
• You follow a restrictive diet (dairy-free, vegan) without supplementation
• You suffer from frequent migraines and want to explore nutritional approaches
• You have a malabsorption condition or have had gastrointestinal surgery
• You consume alcohol regularly

Which Lola Health Tests Include Vitamin B2?

• Peak Insights — our most comprehensive panel including B vitamins and 70+ biomarkers