Daily reference value of vitamin B2 is 1.7 mg according to the 2013 FDA food-labeling guidelines.
What Are the Recommended Dietary Allowances for Vitamin B2?
| 1–3 years | 0.5 mg |
| 4–8 years | 0.6 mg |
| 9–13 years | 0.9 mg |
| 14–18 years | 1.2 mg (boys); 1.0 mg (girls) |
| 19 years and older | 1.2 mg (men); 1.1 mg (women) |
There is currently no known toxicity of vitamin B2 and no upper intake limit for vitamin B2.
Vitamin B2 Supplements
• Dosage. The most common dosages of vitamin B2 supplements are 50–100 mg, which is much higher than the recommended dietary allowance of 1.2 mg. Nevertheless, vitamin B2 is relatively safe, even when taken at high doses. Various B vitamins seem to act in synchrony and exert complementary effects in the body. If you are a vegetarian and need to take vitamin B2, you may consider taking a vitamin B complex supplement. Vitamin B is bright-yellowish in color, so you should expect your urine to turn bright yellowish when taking a vitamin B2 supplement.
• Hypertension. The MTHFR gene encodes methylenetetrahydrofolate reductase, an enzyme that is critical for folate metabolism, and vitamin B2 is required as its cofactor. Globally, about 10% of people have MTHFR gene polymorphic variants, while 20% of the people in northern China and 32% of all Mexicans carry variants of this gene. Certain MTHFR gene variants cause congenital hypertension, a condition that cannot be controlled by antihypertensive drugs alone. Clinical studies have shown that a combination therapy consisting of antihypertensive drugs and vitamin B2 lowered systolic pressure by 9.2 mmHg and diastolic pressure by 6.0 mmHg in patients with congenital hypertension. The suggested vitamin B2 dose is 1.6 mg daily for 16 months.
• Migraine. Vitamin B2 may mitigate symptoms during a migraine attack. Randomized controlled trials have shown that taking vitamin B2 reduced the incidence of migraine attacks and pain by 50%. In this case, the suggested vitamin B2 dosage is 400 mg daily for three months.
What Types of Drugs May Interact with Vitamin B2?
• Anticonvulsant drugs that prevent seizures and Adriamycin (doxorubicin), used to treat breast cancer, reduce the blood level of vitamin B2.
Vitamin B3 is also known as niacin. Vitamin B3 deficiency can cause pellagra, which comes from the Italian word for “rough skin.” In the late 15th century, Christopher Columbus and his fleets reached South America. Among other things, he brought corn seeds back to Europe. Corn became the main food in Spain, Italy, Egypt, and many other Southern European countries in subsequent centuries. Corn contains niacin, but it is tightly bound to its fibers. Cooking corn in boiled water does not release niacin from the fibers. For thousands of years, American Indians living in South America had developed ways to prepare corn by soaking and cooking it in alkaline lime water. At that time, they had no way of knowing that cooking corn in alkaline lime water released niacin from the corn fibers. Because Columbus brought back corn but not the native Indians’ recipes, the consumption of niacin-poor corn caused vitamin B3 deficiency and thus a pellagra epidemic in southern Europe. Up until the 19th century, many Southern Europeans suffered from pellagra. In 1937, scientists discovered that niacin was effective in treating pellagra and called it “vitamin B3.”
Niacin is involved in the synthesis of NAD and NADP coenzymes. These two coenzymes are essential for enzymatic reactions that convert proteins, lipids, and carbohydrates to energy in the cell. Without NAD and NADP, the body will not be able to produce the energy needed for maintaining the brain, heart, and muscles, as well as other bodily functions.
What Are the Symptoms of Vitamin B3 Deficiency?
• Pellagra. The major symptoms of pellagra are dermatitis, dementia, and diarrhea. Severe diarrhea exacerbates deficiencies in niacin and other nutrients. Pellagra patients with dermatitis generally avoid sun exposure and thus are inclined to stay indoors. Niacin deficiency–induced dementia was often misdiagnosed as psychosis. During the 17th–19th centuries, many pellagra patients in Europe were confined to madhouses. There, these patients continued consuming niacin-poor corn, further aggravating pellagra.
• Tryptophan. Tryptophan can be converted into vitamin B3 in the body. Tryptophan is a common amino acid found in all protein-rich foods. Many animal-based foods and plant-based foods not only are rich in vitamin B3 but also contain tryptophan. Nowadays, instances of vitamin B3 deficiency are rare.
Prevention and Treatment of Diseases
• Prevention. Vitamin B3 may alleviate osteoarthritis.
• Treatment. Vitamin B3 may decrease LDL and triglycerides and increase HDL.
Which Food Items Are Vitamin B3 Rich?
A variety of foods contain vitamin B3, including nuts, brown rice, whole wheat, oats, and legumes. Meat, milk, and fish are also excellent sources of tryptophan. Vitamin B3–fortified foods may include breakfast cereals, bread, rice, and baked goods.
This list of vitamin B3–rich food items is adapted from information provided by the USDA.
| FOOD | PORTION | VITAMIN B3 CONTENT, MG |
% DAILY REFERENCE VALUE
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