Functions of Vitamin B2
Vitamin B2, also called riboflavin, is one of the eight essential B complex vitamins. It’s a water-soluble vitamin, meaning excess amounts are not stored in the body like fat-soluble vitamins but are excreted out via urine. Gut bacteria produce small amounts of riboflavin, but not nearly enough to meet the daily recommended amount. Due to these factors, it’s important to intake vitamin B2 every day to avoid deficiency.
Like all B vitamins, B2 plays a role in energy production by breaking down proteins, fats, and carbohydrates to make energy. Its also involved in skin development, digestive tract lining functioning, blood cell production, brain health, oxidative stress, and the metabolism of many different compounds.
Vitamin B2 is important for healthy skin. It’s involved in cell turnover and collagen maintenance. It also helps secrete mucus in the skin, which moisturizes it. This is why riboflavin deficiency symptoms often involve dryness issues like cracked lips or dry eyes.
Vitamin B2 plays a role in regulating inflammation levels, which is important for skin conditions like acne, dermatitis, eczema, and rosacea. The mechanisms of B2 and inflammation are discussed in greater detail in a later section.
Vitamin B2 also plays a role in wound healing. In a study measuring riboflavin and healing time, riboflavin deficiency was found to slow the rate of wound healing and decrease collagen formation by 25% . However, this was an animal study and results would need to be replicated in humans to back-up these claims.
In addition to keeping the skin healthy, it supports other connective tissue health like hair, nails, and eyes. Vitamin B2 aids in vision has been linked to cataract prevention .
Digestive tract function
B2 is important in maintaining mucous membranes in the GI tract . The mucosa, or mucous membrane layer, is the innermost wall that lines the small intestine. It comes into contact with microorganisms, digested food, toxins, byproducts, and is responsible for nutrient absorption. A healthy mucosa membrane is part of the foundation of good health.
The mucosa is responsible for protecting the body from harmful external pathogens by acting as a physical barrier and secreting mucous. This mucous, produced by goblet cells, contains defensins, which are natural antibiotics. This keeps harmful pathogens from entering into the bodies’ blood stream.
The digestive mucous membrane also aids in the absorption of nutrients and transfers them to other systems in the body. B2, along with many other nutrients, supports the health of this tissue.
Blood cell function
B2 plays a role in iron absorption, which is critical for red blood cell health. A reduced version of B2 can “reduce and mobilize” ferritin iron is several body tissues. In a study where animals were fed a vitamin B2 deficient diet, they were less efficient at transporting iron, indicating B2 is important for adequate iron transportation .
It’s also involved in red blood cell production in the bone marrow and transporting oxygen molecules to cells. Increased amounts of vitamin B2 in the body are linked with increased circulating hemoglobin, a protein in red blood cells that carries oxygen, and increased red blood cell production.
B2 has neuroprotective properties by decreasing oxidative stress, mitochondrial dysfunction, neurogenic inflammation, and homocysteine neurotoxicity, all of which are part of neurodegenerative diseases .
Oxidative stress is an imbalance between free radicals and antioxidants that causes cellular damage. Neural tissue has a higher susceptibility to oxidative stress compared to other tissues because the brain has lower antioxidant activity and uses 20% of total body oxygen . Due to this, a healthy nervous system needs plenty of antioxidants to balance out the oxidation that occurs in oxygen reactions.
B2 supports antioxidant function
Glutathione, a protein-like molecule and strong antioxidant, prevents cell damage by decreasing circulating free radicals. After absorbing a free radical, glutathione must be converted back into its active form so it can continue to work. Vitamin B2 helps with this conversion as it’s a cofactor for the enzyme glutathione reductase, a catalyst that coverts the oxidized form of glutathione back into its active form .
Vitamin B2 is also required to form PLP, or pyridoxal phosphate, the active form of B6 which has antioxidant properties.
FAD and FMN
Two of B2's biologically active forms, flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), aid a range of redox reactions that support the health of cells.
Thus, riboflavin impacts several antioxidant pathways and plays an important role in decreasing oxidative stress.
Riboflavin deficiency can lead to deficiencies in its flavoco-enzymes, FAD and FMN, which can increase mitochondrial dysfunction. Without these enzymes present to support redox reactions, a molecule called reactive oxygen species (ROS), a free radical that contains oxygen, can cause increased mitochondrial damage.
B2 plays a role in regulating bodily inflammation levels. It has anti-inflammatory effects through its ability to inhibit NF-κB and high-mobility group protein B1 (HMGB1), factors involved in inflammatory processes .
It also fights inflammation by metabolizing homocysteine, an amino acid that is linked with cardiovascular disease and increased inflammation. B2, along with several other B vitamins, breaks down homocysteine in the body and converts it to other compounds like methionine, an essential amino acid and antioxidant.
Dietary riboflavin is the precursor of two metabolically active flavocoenzymes. These enzymes, as either flavin adenine dinucleotide (FAD) or flavin mononucleotide (FMN), are a part of reactions in the mitochondrial electron transport chain, oxidation of fatty acids, citric acid cycle, and redox homeostasis. They also help with DNA repair, protein folding, apoptosis (cell death), biosynthesis of other cofactors and hormones, and metabolism of other B vitamins (folate, pyridoxine, and niacin) as well as zinc and iron .
Being deficient in vitamin B2 can affect iron absorption, metabolism of tryptophan, mitochondrial function, the gastrointestinal tract, brain function, and the metabolism of other vitamins. It’s also associated with skin disorders, like eczema and rosacea .
There are two types of B2 deficiency: primary and secondary. Primary deficiency happens when dietary intake of B2 is low, and secondary deficiency occurs with adequate intake but either you don't absorb it properly or excrete it too quickly.
Signs of a deficiency can be cracked lips, dry skin, inflammation of the tongue, mouth ulcers, red lips, sore throat, iron-deficiency anemia, or eye sensitivity to light.
There are several medications that can interfere with riboflavin levels in the body.
1. Oral contraceptives- Birth control pills can interfere with riboflavin absorption.
2. The antibiotic tetracycline- Riboflavin interferes with its absorption.
3. Tricyclic antidepressants- Tofranil, norpramin, Elavil, or Pamelor may reduce levels of riboflavin in the body.
4. Methotrexate- Typically used to treat cancer or autoimmune disease. It can also inhibit the body from using riboflavin.
5. Doxorubicin- This medication is used to treat cancer; riboflavin can potentially deactivate doxorubicin.
6. Probenecid- Used to treat gout; may decrease the absorption of riboflavin from the digestive tract and increase excretion via urine.
If you’re prescribed any medications, talk with health professionals first before taking any dietary supplements .
Vitamin B2 can help treat headaches, anemia, cancer, hyperglycemia, hypertension, diabetes, oxidative stress, and other health conditions.
Preventing migraine headaches
Because riboflavin fights oxidative stress and mitochondrial dysfunction, two contributors to migraine headaches, riboflavin is a potential aid to treat migraine headaches. In a study with adults who experience migraines, the patients were given a large dose of riboflavin daily. Compared with the control group, who received placebo pills with nothing in them, riboflavin supplementation was found to reduce the frequency of migraine attacks by two a month .
Recent evidence indicates riboflavin has a "genotype-specific effect on blood pressure in (MTHFR) 677C→T patients" . In three randomized controlled trials studying hypertension in patients with this genotype, daily supplementation with 1.6 mg of riboflavin decreased blood pressure 6 to 13 mm.
Treatment with commonly used blood pressure medications may not work in specific patients, especially the cases with a genetic factor. With riboflavin being both cost-effective and having minimal side effects, it may be a promising future solution to part of the hypertension crisis.
Dietary reference intakes
The recommended dietary allowance (RDA) are the optimal levels of a nutrient you should aim for. It factors in both biological gender and age. To get enough riboflavin, adult men should intake 1.3 mg and adult women 1.1 mg of the vitamin daily . For breastfeeding or pregnant women, that amounts increases to 1.4-1.6 mg daily.
Upper intake level
A tolerable upper intake level (UL) is the maximum safest dosage amount of a nutrient. Many vitamins can cause adverse side effects if too much is taken, which is why the USDA created this set of guidelines. Since it's a water soluble vitamin and excess riboflavin is excreted out in urine fairly quickly, no UL has been set. A large amount of riboflavin being excreted can cause urine to appear bright yellow, but other than that no adverse side effects have been reported.
Riboflavin is naturally present in both plant and animal based food sources.
Plant foods with high riboflavin content are almonds, whole grains, mushrooms, soybeans, wild rice, and green vegetables like broccoli, brussels sprouts and spinach.
Animal sources of B2 are organ meats, and dairy products like milk, yogurt, and eggs.
Most fortified foods, like cereals and items made with enriched flour (pasta, bread, crackers, etc.) have B2 added into them.
Between a balanced diet of whole foods and enriched processed foods, riboflavin deficiency is rare in developed countries like the United States. However, it can still occur. Rootine makes a high-quality vitamin supplements in microbead form that release over 6+ hours, providing enhanced absorption and maintenance of optimal blood nutrient levels. For those that struggle with absorption issues, a supplement can be very helpful in preventing nutrient deficiencies.
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