Vitamin B2 in a nutshell:
Vitamin B2 (also called riboflavin) is used to covert Vitamin B6 into its active form as well as an important factor in other vitamins. It is a component of enzymes responsible for DNA repair and removal of damaged cells. It’s also an antioxidant.
What Is Vitamin B2?
Vitamin B2, also known as riboflavin, is a readily absorbed water-soluble micronutrient that is critical to the generation of energy. In foods and supplements, vitamin B2 is resistant to heat but easily destroyed by light.
Alternate names: Vitamin B2; riboflavin.
Vitamin B2 is a nutrient for almost all living things. It is an essential component of two enzyme cofactors, FAD (flavin adenine dinucleotide) and FMN (flavin mononucleotide). In plants, FAD and FMN are critical for photosynthesis. In animals and in people, they are involved in DNA repair, in the process of apoptosis that removes damaged cells, and in chemical reactions involving carbohydrates, fats, proteins, and ketones. Vitamin B2 also acts as an antioxidant.
What Does Vitamin B2 Do in the Human Body?
In human beings, vitamin B2 is essential for converting other vitamins into their useful forms:
- Vitamin B2 is needed to make FAD to recharge vitamin A from its retinal form to its retinoic form in the retina, enabling vision under low light.
- Vitamin B2 is needed to make FAD to change folic acid into its active form, 5-methyl THF.
- Vitamin B2 is needed to make FAD so the liver can make vitamin B3 (niacin) from the amino acid tryptophan.
- Vitamin B2 is needed to make FMN to transform vitamin B6 into a coenzyme, pyridoxal phosphate, which enables muscles and the liver to use stored glycogen for energy.
If you don't have enough vitamin B2, your body can't use vitamin A, folic acid, or vitamin B6, and it can't make vitamin B3 (niacin). Nor can you body make glutathione reductase, which protects red blood cells from the effects of free radicals of oxygen and high blood sugar levels.
What Happens When We Don't Get Enough Vitamin B2?
Vitamin B2 deficiency is so deleterious to health that there is a special term for it, ariboflavinosis. The symptoms of vitamin B2 deficiency are very similar to those of vitamin B3 deficiency, the condition known as pellagra.
Vitamin B2 deficiency can cause swelling and reddening of the tongue and cracking and blistering on the lips and at the corners of the mouth that are very similar to pellagra. Vitamin B2 deficiency can also cause seborrhea, the accumulation of large amounts of the waxy skin oil known as sebum, especially on the vulva in women and on the scrotum in men. It can cause a low red blood cell count, although the red blood cells will have normal amounts of hemoglobin and will have normal shapes.
In parts of the world where vitamin B2 deficiency is relatively common, women are at high risk of a potentially fatal condition of high blood pressure during pregnancy known as preeclampsia. Both men and women who are deficient in B2 are at unusually high risk of esophageal cancer.
Are You at Risk of Vitamin B2 Deficiency?
Unlike most water-soluble vitamins, vitamin B2 is most abundant not in plant foods but in milk, fish, and meat. In the United Kingdom, for example, most people get about half of their B2 from dairy products. People who do not have access to milk, meat, and fish or who choose not to eat milk, meat, and fish are at the greatest risk for developing a vitamin B2 deficiency. Vitamin B2 deficiency can also occur in people who are lactose intolerance.
Hypothyroidism and adrenal insufficiency can interfere with the body's ability to use vitamin B2. People who are physically active need more vitamin B2, although taking supplemental vitamin B2 will not necessary increase physical endurance.
There are also several drugs that interfere with the body's ability to use vitamin B2:
- The cancer drug Adriamycin (doxorubicin), the antidepressant Elavil (amitriptyline, now mostly used to treat diabetic neuropathy), the antipsychotic drug Thorazine (chlorpromazine), and the anti-malaria drug Atabrine (quinacrine) interfere with the production of FAD and FMN.
- The anticonvulsant drug phenobarbitol can accelerate the rate at which the liver breaks down vitamin B2.
- There have been some reports that oral contraceptive use can lower vitamin B2 levels in the bloodstream but these results of studies have not been consistent.
How Much Vitamin B2 Is Enough?
The Institute of Medicine has set recommended daily allowances (RDAs) of vitamin B2 as follows:
- Infants aged 0 to 6 months need 0.3 mg per day.
- Infants aged 7 to 12 months need 0.4 mg per day.
- Children aged 1 to 3 years need 0.5 mg per day.
- Children aged 4 to 8 years need 0.6 mg per day.
- Children aged 9 to 13 years need 0.9 mg per day.
- Teenaged girls aged 14 to 18 need 1.0 mg per day.
- Teenaged boys aged 14 to 18 need 1.3 mg per day.
- Pregnant women need 1.4 mg per day.
- Breastfeeding women need 1.6 mg per day.
Most people in the US, UK, Canada, Australia, New Zealand, and Europe get considerably more than the RDA.
How You Can Be Sure You Get Enough Vitamin B2
It's not hard to get enough vitamin B2. A cup of vitamin-fortified cereal contain as much as 2.2 mg of vitamin B2, more than a full day's supply. A glass of milk or a single egg contains about 0.3 mg. A handful of almonds or a serving of dark meat chicken or beef contains about 0.2 mg. White bread, because of fortification of flour, usually contains about 30% more vitamin B2 than wheat bread in the United States and Canada.
A serving of vegetables usually contains about 0.1 mg of vitamin B2, although spinach contains about twice that amount. If you do not consume meat or dairy, you need to eat about nine servings of fruits and vegetables every day to be sure you get your vitamin B2.
Just be sure that the food you consume for vitamin B2 is not exposed to sunlight. Just two hours exposure to sun can destroy 50% of the vitamin B2 in a bottle of milk in a clear container.
Using Vitamin B2 to Prevent Migraines
The way vitamin B2 may help prevent migraines is by helping the brain maintain energy reserves. Taking supplemental vitamin B2 may help reduce the frequency of migraines in a way that complements the medications designed to prevent constriction of blood vessels leading to the brain that can cause excruciating pain.
In clinical trials of vitamin B2 for migraines, the best results were obtained in a small group of migraine sufferers who took 400 mg of B2 per day. (This amount of riboflavin will dye the urine neon yellow.) Taking vitamin B2 did not eliminate migraines, but it reduced the number of days per month participants in the study had migraines. A follow-up study found taking just 25 mg of vitamin B2 per day more beneficial than taking magnesium or feverfew supplements, which are more commonly used by migraine sufferers.
Vitamin B2 and Cataracts
The clouding of the lens of the eye called a cataract is the leading cause of blindness among people over the age of 60 all over the world. Australian nutritional researchers have found that people who consume the highest amounts of vitamin B2 per day (1.5 mg per day or more) are 33% less likely to develop cataracts than people who consume the lowest amounts of vitamin B2 (less 0.1 mg per day). However, even consuming especially high amounts of vitamin B2 is not a guarantee that cataracts will not occur.
Riboflavin Added to Fruit and Vegetable Juices
Riboflavin is the water-soluble vitamin also known as vitamin B2. It is also identified in the European Union as E101 when it is added to beverages or foods. There is abundant natural riboflavin in juices made from green leafy vegetables, but the vitamin breaks down when it is exposed to sunlight. Since marketers want to be able both to display a vibrantly green bottled juice and to claim vitamin content for the beverage, they often add vitamin B2. In North America they may not have to disclose that they added the vitamin, and in the European Union there will be just a mention of “E101” on the label.
Vitamins are vital, so what could possibly go wrong by adding vitamin B2? The issue with added vitamin B2 is that it is usually made through genetic engineering. The probiotic bacterium Bacillus subtilis is genetically modified so that it produces large amounts of B2. The bacteria are grown in tanks and then harvested for extraction of the vitamin. Many nutritional supplements and even medications such as insulin are manufactured by a similar process.
The problem is that bacteria don't dutifully just sit in their tank and make vitamin B2. Just as bacteria in the natural world can mutate and develop resistance to antibiotics, bacteria in a vat can also mutate and develop resistance to antibiotics—even if the antibiotics are not physically present in the tank. Although bacteria reproduce by fission, each offspring genetically identical to its “parent,” bacteria are capable of exchanging segments of DNA, including the segments of DNA that can confer resistance to antibiotics. And it turns out that using genetically modified Bacillus subtilis bacteria to make vitamin B2 sometimes generates resistance to an antibiotic called ampicillin. The bacteria are killed as the vitamin is extracted by the DNA that carries resistance can find its way into the additive. The bacteria in your body can develop resistance to ampicillin when they absorb the strand of DNA.
If you never develop an infection that your doctor has to treat with ampicillin, that's not a problem. But you don't really want to find out that you suddenly have a life-threatening and untreatable infection sometime far into your future. It's not that the vitamin additive gives you an infection. The problem is that the vitamin additive—in this form—may counteract a future antibiotic treatment for an infection.
And do you really need to buy pasteurized and bottled green juices when they are fresher and tastier made at home? It costs a little more up front, but a macerating juicer will give your green juices that have all their natural vitamin content because you make them fresh and drink them fresh. Don't drink juice that sits on a shelf for months and has to have its vitamins added back in. Drink fresh juice and get safe and natural vitamins including B2.