According to a new UK study improving riboflavin status increases circulating red blood cell numbers and hemoglobin concentrations for young women.
In the randomized controlled trial, 119 healthy women, aged between 19 and 25 years, were assigned to receive a supplement with 2 mg or 4 mg riboflavin or placebo for eight weeks (1). The study results showed that the use of the riboflavin supplement elicited a significant improvement in riboflavin blood concentration with a dose response. In turn, improving riboflavin status led to an increase in the number of circulating red blood cells and hemoglobin concentrations: the poorer the riboflavin status at the beginning of the study, the greater the beneficial effect with supplementation. Dietary iron intake and iron absorption did not change during the study.
According to the researchers these results indicate that poor riboflavin status among this group of women impaired iron handling and improving their riboflavin status would lead to an increase in hemoglobin, independent of any change in dietary iron. The mechanisms by which riboflavin status influences blood characteristics are uncertain. It has been suggested that an improved riboflavin status may increase the mobilization of the body’s own stores of iron. The scientists concluded that these findings are also relevant for other age groups for which high prevalence of riboflavin deficiency has been reported, including in adolescents and the elderly. While overt riboflavin deficiency is rare in developed countries because it is found in many foodstuffs, and wheat flour is often fortified with riboflavin, an insufficient vitamin B2 status (without obvious symptoms) however may be widespread. Furthermore, current recommendations for marginal deficiency cut-offs may need to be revised.
Riboflavin deficiency is endemic in many populations with diets low in meat and dairy products. More surprisingly, a high prevalence of riboflavin deficiency was reported in various apparently healthy population groups in affluent countries, including the United States, France, and the United Kingdom (2–4). Recent National Diet and Nutrition Surveys of the UK have revealed a high prevalence of riboflavin deficiency in 41% of free-living elderly people (5) and in 95% of adolescent girls (6).