Zach Pfirrman
Tristan Pursley
KNH 304
Vitamin B2: Riboflavin
Vitamin B2, also known as riboflavin is a water- soluble vitamin that is essential for the
human body's function. It's history, function in the body, Recommended Daily Allowance,
toxicity, and deficiencies will be discussed.
Riboflavin was first observed by English chemist Alexander Wynter Blyth in 1872, when
he noted the Yellow-green fluorescence pigment in milk. It was first described as riboflavin or
B2 in 1930s. Efforts to identify this compound were begun in the early 1900s. “Riboflavin was
the second vitamin to be isolated and the first from the vitamin B-2 complex; the essential nature
of the vitamin as a food constituent for man was shown in 1939” (/www.ncbi.nlm.nih.gov/).
Riboflavin can be found in small quantities in most plant and animal derived foods.
Commonly found in milk, eggs, malted barley, liver, kidney, heart, and leafy vegetables. Its
principal forms in tissues and cells are as Flavin Mononucleotide or FMN and Flavin-Adenine
Dinucleotide or FAD. “While riboflavin is not destroyed by heat, it can be lost in water when
foods are boiled or soaked. During cooking, roasting, and steaming preserves more riboflavin
than frying or scalding” (umm.edu/health). Riboflavin is easily destroyed by exposure to light.
For instance, up to 50% of the riboflavin in milk contained in a clear glass bottle can be
destroyed after two hours of exposure to bright sunlight.
Riboflavin is essential for normal cellular functions, growth, and development. “Primary
absorption of riboflavin occurs in the small intestine via a rapid, saturable transport system. A
small amount is absorbed in the large intestine. The rate of absorption is proportional to intake,
and it increases when riboflavin is ingested along with other foods and in the presence of bile
salts”(Absorption, Distribution and Excretion).
Food
Serving
Fortified cereal
1 cup
Milk (nonfat)
1 cup (8 ounces)
Cheddar cheese
1 ounce
Egg (cooked)
1 large
Almonds
1 ounce
Salmon (cooked)
3 ounces*
Halibut (broiled)
3 ounces
Chicken, light meat (roasted)
3 ounces
Chicken, dark meat (roasted)
3 ounces
Beef (cooked)
3 ounces
Broccoli (boiled)
1/2 cup chopped
Asparagus (boiled)
6 spears
Spinach (boiled)
1/2 cup
Bread, whole wheat
1 slice
Bread, white (enriched)
1 slice
http://lpi.oregonstate.edu/infocenter/vitamins/riboflavin/
Riboflavin (mg)
0.59 to 2.27
0.34
0.11
0.27
0.23
0.12
0.08
0.08
0.16
0.16
0.10
0.13
0.21
0.06
0.08
When too much riboflavin is absorbed, a very little amount is stored in the body's tissues.
The excess is excreted, almost entirely in the urine. “A markedly increased excretion of
riboflavin has been noted at intakes exceeding 0.8 to 0.9 mg/day for women and 1.0 to 1.1
mg/day for men”(Absorption, Distribution and Excretion).
Flavocoenzymes are critical for the metabolism of carbohydrates, fats, and proteins.
Flavin-Adenine Dinucleotide (FAD) is part of the electron transport chain, which is central to
energy production. Because flavoproteins are involved in the metabolism of several other
vitamins like vitamin B6, niacin, and folic acid, severe riboflavin deficiency can have a negative
impact on many of the enzyme systems.
As far as toxicity goes, there is none. One of the only know side effects from high levels
of riboflavin is the color of one's urine becoming bright yellow, which is as harmless as side
effects come. “The Food and Nutrition Board did not establish a tolerable upper level of intake
(UL) when the RDA was revised in 1998”
(http://lpi.oregonstate.edu/infocenter/vitamins/riboflavin/ ).
Recommended Dietary Allowance (RDA) for Riboflavin
Life Stage
Age
Males (mg/day)
Females (mg/day)
Infants
0-6 months
0.3 (AI)
0.3 (AI)
Infants
7-12 months
0.4 (AI)
0.4 (AI)
Children
1-3 years
0.5
0.5
Children
4-8 years
0.6
0.6
Children
9-13 years
0.9
0.9
Adolescents
14-18 years
1.3
1.0
Adults
19 years and older
1.3
1.1
Pregnancy
all ages
1.4
Breast-feeding
all ages
1.6
http://lpi.oregonstate.edu/infocenter/vitamins/riboflavin/
Ariboflavinosis is the name for clinical riboflavin deficiency. Riboflavin deficiency is
rarely found in isolation. When it occurs, it will normally occur in combination with deficiencies
of other water-soluble vitamins. “The following may also be manifestations of riboflavin
deficiency: red, itchy eyes, night blindness, cataracts, migraines, peripheral neuropathy anemia,
fatigue, malignancy” (Riboflavin Deficiency). Riboflavin deficiency also alters iron metabolism.
In humans, improving nutritional status of riboflavin has been found to increase circulating
hemoglobin levels. Correction of vitamin B2 deficiency in individuals who are both riboflavin
and iron deficient improves the response of iron-deficiency anemia to iron therapy.
Alcoholics are at increased risk for riboflavin deficiency due to a decrease in intake,
decreased ability to absorb it, and impaired utilization throughout the body. Additionally, those
who are anorexic rarely consume enough riboflavin, and individuals with lactose intolerance
may not consume milk or other dairy products which are good sources of vitamin B2. Further,
people who are very active physically may have a slightly increased need for riboflavin.
However, B2 supplementation have not been found to improve exercise tolerance or
performance.
There is research being done on riboflavin and it's possible help in preventing cataracts.
“People who took a niacin and riboflavin supplement had fewer cataracts than people who took
other vitamins and nutrients. However, researchers don't know whether that was due to
riboflavin, niacin, or the combination of the two”(umm.edu/health). Another study was done
based on riboflavin's effect on migraine headaches and how it can prevent them and treat them.
As an essential nutrient, Riboflavin is critical for many body processes and many other
nutrients are dependent upon its presence. It is in so many foods that people eat regularly, so one
does not need to go out of their way to get proper amounts of this vitamin from their diet. It is
highly encouraged that the RDA for riboflavin is met and that education on its importance is
stressed both clinically and personally. There are no excuses for not reaching the nutrient's RDA.
Drink some milk.
Work Cited
Absorption, Distribution and Excretion. (n.d.). pubchem.ncbi.nlm.nih.gov.opac.acc.msmc.edu.
Retrieved September 23, 2013, from http://0pubchem.ncbi.nlm.nih.gov.opac.acc.msmc.edu/toc/summary_toc.cgi?tocid=332&sid=91
487&numsections=1
Linus Pauling Institute at Oregon State University. (n.d.). Linus Pauling Institute at Oregon State
University. Retrieved September 23, 2013, from
http://lpi.oregonstate.edu/infocenter/vitamins/riboflavin/
Riboflavin Deficiency. (n.d.). /emedicine.medscape.com. Retrieved September 22, 2013, from
http://emedicine.medscape.com/article/125193-overview#aw2aab6b4
The discovery and characterization of riboflavin [Ann Nutr Metab. 2012] - PubMed - NCBI.
(n.d.). National Center for Biotechnology Information. Retrieved September 23, 2013,
from http://www.ncbi.nlm.nih.gov/pubmed/23183293
Vitamin B2 (Riboflavin) | University of Maryland Medical Center. (n.d.). Home | University of
Maryland Medical Center. Retrieved September 23, 2013, from
http://umm.edu/health/medical/altmed/supplement/vitamin-b2-riboflavin