Riboflavin (Vitamin B2), MTHFR, and Deficiency Symptoms

Key takeaways:

• Riboflavin (vitamin B2) is a water-soluble vitamin that is a cofactor for many enzymes in the body.
• It is vital for energy production in the mitochondria and is also a key component of your body’s detoxification system.
• Genetic variants can increase your need for riboflavin. For example, research shows that riboflavin is important for people with MTHFR variants.

Members will see their genotype report below, plus additional solutions in the Lifehacks section. Consider joining today. 

What is riboflavin, and why is it important?

Riboflavin, also known as vitamin B2, is synthesized from a ribose sugar bound to a flavin molecule. Thus, the name ribo-flavin.

This is an essential vitamin for many important cellular functions. Riboflavin is the precursor to FMN (flavin mononucleotide) and FAD (flavin adenine dinucleotide), which are coenzymes involved in numerous vital functions in our bodies, including redox reactions involved in transferring electrons.

FAD is an essential component of the electron transport chain, which is how your body produces energy in the mitochondria.

• FAD is important for producing energy both from carbohydrates and through fatty-acid oxidation in the mitochondria.[ref]
• FAD is also involved in detoxification as a cofactor for some CYP450 enzymes, as well as for glutathione recycling.
• FAD can participate in many different reactions in the body because it can easily donate and accept electrons. It can exist in different redox states (FADH2, FADH).[ref]

Within the mitochondria, FAD and FMN also act as antioxidants, integral to activating the various enzymes that protect cells from oxidative stress, thus making adequate riboflavin essential for healthy mitochondria. Conditions that are related to mitochondrial dysfunction and reliant on FAD and FMN include Parkinson’s disease, Alzheimer’s, migraines, Complex I deficiency, Alper’s syndrome, multiple sclerosis, and Kearns Sayre syndrome.[ref]

Nutrient interactions:

• Riboflavin also helps convert tryptophan to niacin (vitamin B3), which in turn activates vitamin B6.[ref]
• It is also essential for the methylation cycle and folate-related metabolism. FAD is a required cofactor for MTHFR.
• Riboflavin is also important in the metabolism of iron.

Related articles: Methylation cycle and MTHFR Explained

What are the symptoms of riboflavin deficiency?

A lack of riboflavin can show up as:

• angular cheilitis (cracks at the corners of the mouth)
• anemia
• burning mouth
• sore throat
• cataracts

Riboflavin deficiency can also cause problems with iron absorption, leading to iron-deficiency anemia. It can also play a role in mitochondrial dysfunction in the development of cardiovascular problems.[ref]

Riboflavin is central to many pathways in health, with insufficiency affecting hair, skin, nails, energy, cognitive function, and reproductive health.

Who is at risk of riboflavin deficiency?

For most people who are eating a balanced diet, full-on riboflavin deficiency is considered rare. The majority of the population meets the recommended daily allowance of 0.9-1.3 mg/day.[ref]

People more likely to suffer from riboflavin deficiency include:

• The elderly, women on birth control, vegans, and alcoholics are more likely to have a deficiency.[ref]
• People who exercise a lot are at a risk of deficiency if their intake isn’t increased to meet the energy demand.[ref]
• Mothers who are breastfeeding may need more riboflavin because breast milk contains a lot of riboflavin and FAD.[ref]
• The need for riboflavin increases significantly in pregnancy.[ref]

However, there is a difference between not having a severe deficiency and getting what is optimal for your specific needs, taking into account genetics and lifestyle. Even without frank deficiency, dialing in riboflavin can help with energy, cognitive function, and overall wellness if you are on the edge of your optimal range.

Riboflavin absorption from foods and transport:

The US RDA is 1.6mg for adults, and the majority of people eating a varied diet are estimated to meet this level. Riboflavin is found in dairy products, eggs, liver, enriched flour, and in minor amounts in other foods.

Riboflavin is absorbed from foods as they are broken down in the upper part of the small intestines, so people with intestinal disorders that inhibit absorption could have problems with riboflavin deficiency.

Additionally, riboflavin must be transported within cells and into the mitochondria. Riboflavin-specific transporters are found on the outer membrane of the mitochondria. Rare mutations in this transporter (SLC52A2 gene) cause Brown-Vialetto-Van Laere syndrome, which is a rare neurological disorder that may be helped by riboflavin supplementation in some cases.[ref]

MTHFR and vitamin B2 benefits:

The MTHFR gene codes for the enzyme needed to convert folate to methylfolate, a key component in the methylation cycle. The MTHFR C677T variant causes a change in the shape of the MTHFR enzyme and decreases its ability to bind to FAD.[ref] If you have high homocysteine (a marker for heart disease risk), several studies show that increasing riboflavin lowers homocysteine levels in those with the A/A genotype.[ref][ref] Other research points to riboflavin lowering homocysteine levels only if vitamin B6 levels are adequate.[ref]

Bone health:
Low riboflavin status in women with MTHFR C677T increases the risk of fractures in osteoporosis.[ref][ref]

Related article: Osteoporosis risk factors and genetic variants

Heart health:
The C677T variant causes a change in the shape of the MTHFR enzyme and decreases its ability to bind to FAD.[ref] If you have high homocysteine (a marker for heart disease risk), several studies show that increasing riboflavin lowers homocysteine levels in those with the A/A genotype.[ref][ref] A 2025 study found that low riboflavin levels combined with the MTHFR C677T homozygous genotype were at an increased risk of hypertension.[ref] Other research indicates that riboflavin lowers homocysteine levels only when vitamin B6 levels are adequate.[ref]

Related Articles: MTHFR, Riboflavin, and Blood Pressure |  Vitamin B6 Genes

Riboflavin affects gene expression:

In people with MTHFR C677T (AA genotype, below in genotype report), researchers found that there was higher DNA methylation of NOS3. Higher DNA methylation means that there will be lower expression of the NOS3 enzyme and lower endothelial nitric oxide. Supplementing with riboflavin altered the DNA methylation in people with MTHFR C677T, causing a decrease in methylation of the ACE gene.[ref]

Benefits of supplemental riboflavin: Clinical trial data

Clinical trials are an excellent way to know if a supplement is effective for most people. Genetic variants (below) can also clue you in as to whether you may need more riboflavin than normal.

Here’s what randomized clinical trials show:

Concussion recovery:
A randomized placebo-controlled trial investigated the efficacy of supplemental riboflavin for concussions. The trial involved 52 participants with sports-related concussions. Half took 400 mg/day of riboflavin and half received a placebo. The riboflavin group recovered twice as fast (10 days vs. 22 days).[ref]

Migraines:
Numerous studies and clinical trials have investigated high-dose riboflavin supplementation for migraines. While riboflavin may not be a panacea for everyone with migraines, it is inexpensive, non-toxic, safe, and effective for some migraine sufferers. For example, one study found that 400 mg/day of riboflavin cut migraine frequency in half after three months of treatment. (This is better than trial outcomes for many expensive migraine prescription medications and injections that have serious side effects!).[ref][ref][ref]

Related article: Migraines, root causes and genetic pathways

Eye health:
Riboflavin is also being investigated and used for preventing cataracts.[ref][ref]

Throat health:
Riboflavin is also important in the esophageal mucosa. A study in China examined the effects of using riboflavin-fortified salt in certain townships. The groups that received the riboflavin-fortified salt had lower rates of esophageal cancer.[ref]

Inflammatory Bowel Disease (IBD):
In patients with Crohn’s disease, riboflavin (100mg/day) decreased inflammatory markers significantly in three weeks.[ref]

Related article: IBD and Genetic Connections

Inflammation:
A randomized, placebo-controlled trial of supplemental riboflavin found that it reduced inflammation based on a lower CRP level.[ref]

Related article: Inflammation and chronic disease

Gut microbiome interactions with riboflavin:

Certain gut microbes can produce riboflavin, part of which is then absorbed into the body. However, other gut bacteria that can’t produce riboflavin may utilize dietary or supplemental riboflavin.

Let’s take a look at both of these scenarios:

Studies show that Lactobacillus and Bifidobacterium species can synthesize some riboflavin. This is one reason these species are beneficial in the gut microbiome and in the vaginal microbiome.[ref]

Other bacteria, such as a major colonic butyrate-producing bacterium called Faecalibacterium prausnitzii, rely on riboflavin from food or other bacteria in the colon. Supplementing with riboflavin can promote these bacteria to produce more butyrate, a short-chain fatty acid that is beneficial for colon health. Butyrate is directly used by the cell lining the gut for energy. A 2023 clinical trial showed that 100 mg/day of supplemental riboflavin in healthy adults increased butyrate production in the colon. The trial was only two weeks long, and of note here is that there weren’t major shifts in the microbial composition, indicating increased butyrate production but not F. prausnitzii overgrowth.[ref]

Riboflavin supplementation and safety:

Vitamin B2, riboflavin, is a water-soluble vitamin. There is no known toxicity for taking too much riboflavin, and no upper limit has been set in the US.[ref]

Heads up: Excess riboflavin is excreted through the kidneys and makes your pee yellow – really yellow – in a way that can be startling.[ref]

Does excess riboflavin just give you ‘expensive pee’?  The maximum amount of riboflavin that can be absorbed tops out at around 27 mg at a time. However, going above that amount may have beneficial impacts on the gut microbiome, as noted above in regard to promoting short-chain fatty acid-producing bacteria. This is one situation where going above what is needed with a water-soluble vitamin may have a beneficial effect separate from its function in the body.

With all of this background information in mind, let’s take a look at how your genes affect how much riboflavin you need.

Lifehacks for boosting riboflavin:

How much riboflavin do you need?

Forms of riboflavin found in supplements:

Riboflavin is available in two forms:

• riboflavin 5′-phosphatase (R5P), the active form that doesn’t need to be converted.
• riboflavin (B2), which must be converted by flavokinase

Both are inexpensive supplements, so it doesn’t cost a lot more to get the R5P active form. There is no known upper limit for riboflavin supplementation.[ref]

Water-soluble vitamin:
Riboflavin is absorbed in the upper small intestine via a riboflavin transporter. The guide for dietary reference intakes indicates that the body can’t absorb larger amounts of riboflavin at one time.

When you take higher doses than your body can absorb, your urine will turn bright yellow.

Stack with other B-vitamins? 

Many people use a B-complex that includes riboflavin in order to get all of their B vitamins together. If you have the MTHFR C677T variant, be sure to look for a B-complex that includes methylfolate instead of folic acid – along with the other active forms of B vitamins. Additionally, check your COMT enzyme function to see if you would be better off steering clear of high doses of methylB-12.

People with alcohol use disorder tend to be deficient in riboflavin and thiamine, another B-vitamin. If you drink a lot on a daily basis, you may also want to include B vitamins.

Related article: Alcohol dependency genes

Riboflavin Absorption: Medications That Interfere

• Birth control pills, antipsychotics, and other drugs affect riboflavin

Vitamin B2 Foods:

The following foods are high in riboflavin. Stacking your diet with them can help you meet the daily RDA.

If you don’t eat dairy, eggs, or liver, you may want to track your daily riboflavin consumption for a few days to see if you are getting the recommended amount. Cronometer is a free online app that is great for keeping track of nutrients.

How can you know if riboflavin is beneficial?

It’s sometimes hard to know if a vitamin is helpful or just a waste of money. Here are some suggestions of outcomes to look at:

☑ If you are deficient in riboflavin, you will absorb a lot more of it. When your urine is bright yellow, you are likely getting more than enough and could back off a bit.

☑ If you normally have migraines on a fairly regular basis (e.g., a couple of times a month), keep track on a calendar to see if your migraine frequency decreases with riboflavin.

☑ If you have high homocysteine, you may want to re-check your homocysteine levels after a month or two of riboflavin supplementation to see if it is lower.

☑ If you carry the FMO3 variants, see if you have less body odor with riboflavin supplementation.

☑ Riboflavin helps with iron absorption if you are deficient in iron. For anemia (as shown on an iron test), try supplementing with riboflavin along with your iron.

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