Vitamin B2 (Riboflavin)
As with several of the B vitamins, riboflavin caused quite a stir when scientists first discovered it, but this essential nutrient was Soon relegated to the back of the closet as more famous relatives arrived on the scene. Riboflavin makes its presence felt from time to time or, more accurately, its absence, when manufacturers and consumers fail to handle it with care.
The alias for this nutrient, B2, helps to explain its secondrate status. As mentioned in the thiamin section, the disease beriberi was a scourge around the world for centuries, causing damage to the nervous and cardiovascular systems and many deaths. The discovery by a Japanese navy surgeon and the Dutch scientist Eijkmann that certain foods could prevent and cure beriberi seemed to solve the mystery of the disease, and when scientists isolated the nutrient in the late 1920s, they thought they'd discovered the antiberiberi factor.
It didn't take long before they realized their error-the antiberiberi factor was actually two different compounds. This finally led to the discovery of riboflavin, which was labeled B2 in England and vitamin G in the United States. Later, more B vitamins joined the list, some with ascending numbers. Riboflavin's fluorescent orange-yellow color helped the researchers make their discovery, because it was readily detectable in food extracts. The bright color also gave scientists some help with the vitamin's other name: flavus is yellow in Latin. The other part of its name comes from a sugar the vitamin contains, ribitol.
The vitamin is a part of two different coenzymes in the body which, in turn, function in many enzyme systems. Some of the enzyme systems include those involved in energy production and the conversion of the amino acid tryptophan to the B vitamin niacin, a handy reaction if you're short of niacin. Dietary sources of riboflavin include meats, poultry, fish, and particularly dairy products. Whole grain and enriched products supply a large amount of riboflavin to most Americans. Other good sources of riboflavin are leafy green vegetables, although because of its solubility in water, significant amounts are lost in the water used to cook these vegetables. By the same principle, excess amounts are readily excreted in the urine, making it a relatively safe vitamin. Unlike others of its ilk, the vitamin is stable to heat, but it is sensitive to light.
The new DRI for riboflavin is 1.3 mg and 1.1 mg for women and men, respectively. Dietary intake surveys show that most Americans are meeting the recommended levels. Around the world, riboflavin deficiency is common, although it usually occurs in combination with deficiencies of other B vitamins. Signs of the deficiency include fluid retention, sore throat, and inflammation of the tongue and mouth. People who have abnormal hormone levels, especially thyroid hormone, may not metabolize the vitamin properly, and some drugs, including oral contraceptives and barbiturates, can cause problems.
Some groups of Americans may also be at risk for riboflavin deficiency, including athletes, women, alcoholics, and people who don't eat dairy products. Athletes have a greater energy demand and this uses up riboflavin. Women and alcoholics tend to have a less nutrient-dense diet and are more likely to avoid milk. Since milk and dairy products are the best source, eliminating them may lead to a riboflavin deficiency.
Public attention began less than ten years ago, when studies reported major losses of riboflavin from milk in opaque plastic containers. Although scientists had known for decades that riboflavin is sensitive to light, no one gave the new milk cartons much thought when they replaced the old-fashioned paper cartons. Because dairy products are the most concentrated source of the vitamin in the U.S. food supply, however, when the concern surfaced, it seemed well founded. Suddenly, consumers were clamoring for the return of paper cartons to replace the ubiquitous plastic gallon jugs.
The opaque jugs do allow a certain amount of light to pass through, but riboflavin loss is less compared to milk in glass bottles. Many consumers recall the days when the milk delivery man left glass milk bottles on the front doorstep in the morning. This should have accounted for riboflavin deficiency en masse for Americans, but this was not the case. While cartons are preferable, consumers who buy plastic gallons can minimize losses by returning the milk jug to the refrigerator as soon as possible. Those who prefer plastic can take comfort in riboflavin's availability from so many sources in the American diet. Studies have shown that the small loss from plastic jugs probably doesn't adversely affect most people's diets.
Recently, riboflavin made a bit of news when a study on migraine headaches hit the newsstands. Earlier, researchers had theorized that problems in energy metabolism may playa role in the development of migraines, and limited studies suggested that high dose riboflavin was effective in preventing migraines. The authors of the recent study compared a 400 mg dose of riboflavin and placebo for three months in fiftyfive migraine patients.
Riboflavin supplementation beat the placebo in reducing the frequency of migraine attacks, with 59 percent of patients reporting improvement. No serious side effects of the supplement occurred. The researchers concluded that because of its "high efficacy, excellent tolerability, and low cost, riboflavin is an interesting option for migraine prevention." They suggested that more studies be done to compare riboflavin supplements to current drug treatments for migraine.