Riboflavin May Be an Effective Biomarker for Vitamin B-6 Status

Riboflavin may be essential for healthy vitamin B-6 levels, especially in adults aged 60 years or older, according to the results of a recent study.

“Riboflavin is required to generate the active form of vitamin B-6 (pyridoxal 5′-phosphate; PLP) in tissues, but the relevance of this metabolic interaction for nutritional status of vitamin B-6 is unclear because riboflavin biomarkers are rarely measured in human studies,” the study authors wrote.

In effort to fill this knowledge gap, the researchers conducted an observational study in which they assessed 407 healthy adults. All participants were between the ages of 18 to 92 years and did not use vitamin-B supplements. The status of vitamin B-6 was measured through the use of plasma PLP concentrations. Erythrocyte glutathione reductase activation coefficient (EGRac) was also used as a functional indicator of riboflavin status.

Suboptimal levels of vitamin B-6 intake were defined as a PLP level of less than or equal to 30.0 nmol/L and suboptimal levels of riboflavin were defined as an EGRac level of 1.40 or higher.

The results indicated that not only was vitamin B-6 intake below the average requirements for dietary intake in 10% of participants, but riboflavin intake was below average for 29% of participants as well.

These vitamin B-6 results were more prevalent in adults aged 60 years or older (14%) than in participants of a younger age group (5%). However, both age groups were observed to have a high rate (37%) of deficient riboflavin status.

“Plasma PLP showed a stepwise decrease across riboflavin status categories from optimal (EGRac ≤1.26) to low (EGRac 1.27–1.39) to deficient status (P = 0.001), independent of dietary vitamin B-6 intake,” the researchers wrote.

In addition, significant determinants of plasma PLP include EGRac (P = .019), dietary vitamin B-6 intake (P = .003), age (P < .001), body mass index (P = .031), and methylenetetrahydrofolate reductase (MTHFR) genotype (P < .001). Similarly, significant determinants of EGRac include dietary riboflavin intake (P < .001), age (P < .001) and MTHFR genotype (P = .020).

“The findings are consistent with the known metabolic dependency of vitamin B-6 on riboflavin status and indicate that riboflavin may be the limiting nutrient, particularly in older people, for maintaining adequate vitamin B-6 status,” the researchers concluded.

—Leigh Precopio

Reference:

Jungert A, McNulty H, Hoey L, et al. Riboflavin is an important determinant of vitamin B-6 status in healthy adults. J Nutr. 2020;150(10):2699-2706. doi:10.1093/jn/nxaa225