Riboflavin (vitamin B2) was initially characterized by English researcher Blyth in 1879 as a yellow-colored factor (lactochrome) in whey.  Years later, the biological functions of the new factor were discovered, and chemical synthesis was accomplished in 1934-by Swiss researchers Kuhn and Karrer.  Good dietary sources of riboflavin include yeast, liver, eggs, milk, most animal products and leafy greens. Poor sources of this water-soluble B vitamin include corn and oilseeds, which is why riboflavin is so important to supplement, especially to non-ruminants.

Riboflavin is involved in many metabolic reactions of carbohydrate, fat, and protein metabolism, some of which help to maintain antioxidant status.  In fact, the accepted assay for human riboflavin status involves measurement of an antioxidant enzyme in red blood cells.  An unselfish vitamin, riboflavin helps in the biosynthesis of niacin, and assists in converting B6 and folic acid to their active forms.  Although relatively stable to heat, riboflavin is sensitive to destruction by UV light, which is important in storage and in human supplemental applications.

Industrial synthesis of riboflavin has almost entirely converted from chemical synthesis to fermentative biosynthesis.  In a 9-step process, dsm-firmenich ferments riboflavin, extracts the active vitamin in pure form, and then spray dries riboflavin with maltodextrin, resulting in an 80% pure, non-dusty, free-flowing product. Size, uniformity and shape of the resulting beadlets are critical to the ease of handling of the straight vitamin, as shown below.  Half the world’s supply of B2 is used in animal feeding.

Deficiency symptoms

Similar to other B vitamins, riboflavin deficiency results in dermatitis, accompanied by more specific signs such as mouth sores (human), and leg weakness in growing chicks, followed by a specific curled toe paralysis.  Riboflavin supplementation is widespread in the feed industry, resulting in relatively rare occurrence of deficiency symptoms.

OVN Optimum Vitamin Nutrition® Supplemental Recommendations for Riboflavin (mg B2/kg feed)

• Broiler starter                    8.4-10.5
• Broiler breeders                13-20
• Laying hens                        5.5-7.5
• Pig starter                          10.5-16
• Dairy calf                            2.5-4.5