Riboflavin

Factors affecting requirements

Several studies reported modest effects of physical activity on the erythrocyte glutathione reductase AC. A slight increase in the AC and decrease in urinary flavin of weightreducing women and older women undergoing exercise training were “normalised” with 20 percent additional riboflavin. However, riboflavin supplementation did not lead to an increase in work performance when such subjects were not clinically deficient.

Bio-availability of riboflavin in foods, mostly as digestible flavoco-enzymes, is excellent at nearly 95 percent, but absorption of the free vitamin is limited to about 27 mg per single meal or dose in an adult. No more than about 7 percent of food flavin is found as 8α-FAD covalently attached to certain flavoprotein enzymes. Although some portions of the 8α-(amino acid)-riboflavins are released by proteolysis of these flavoproteins, they do not have vitamin activity. 

A lower fat-to-carbohydrate ratio may decrease the riboflavin requirements of the elderly. Riboflavin interrelates with other B vitamins, notably niacin, which requires FAD for its formation from tryptophan, and vitamin B6, which requires FMN for conversion of the phosphates of pyridoxine and pyridoxamine to the co-enzyme pyridoxal 5'-phosphate (PLP). Contrary to earlier reports, no difference was seen in riboflavin status of women taking oral contraceptives when dietary intake was controlled by providing a single basic daily menu and meal pattern after 0.6 mg riboflavin/418 kJ was given in a 2-week acclimation period.

Findings by age and life stage

As reviewed by Thomas et al., early estimates of riboflavin content in human milk showed changes during the post-partum period. More recent investigations of flavin composition of both human  and cow  milk have helped clarify the nature of the flavins present and provide better estimates of riboflavin equivalence. For human milk consumed by infants up to age 6 months, the riboflavin equivalence averages 0.35mg (931 nmol) /l (6) or 0.26 mg (691nmol) /0.75 l of milk per day. For low-income Indian women with erythrocyte glutathione reductase activity ratios averaging 1.80 and a milk riboflavin content of 0.22 mg/l, breast-fed infants averaged AC ratios near 1.36. Hence, a deficiency sufficient to reduce human-milk riboflavin content by one-third can lead to a mild sub-clinical deficiency in infants.

Studies of riboflavin status in adults include those by Belko et al. in modestly obese young women on low-energy diets, by Bates et al. on deficient Gambians, and by Kuizon et al. on Filipino women. Most of a 1.7-mg dose of riboflavin given to healthy adults consuming at least this amount was largely excreted in the urine. Such findings corroborate earlier work indicating a relative saturation of tissue with intakes above 1.1 mg/day. Studies by Alexander et al.  on riboflavin status in the elderly show that doubling the estimated riboflavin intakes of 1.7 mg/day for women aged 70 years and over, with a reductase AC of 1.8, led to a doubling of urinary riboflavin from 1.6–3.4 μg (4.2 to 9.0 nmol) /mg creatinine and a decrease in AC to 1.25. Boisvert et al.  obtained normalisation of the glutathione reductase AC in elderly Guatemalans with approximately 1.3 mg/day of riboflavin, with a sharp increase in urinary riboflavin occurring at intakes above 1.0–1.1 mg/day.

Pregnant women have an increased erythrocyte glutathione reductase AC. Kuizon et al. found that riboflavin at 0.7 mg /4184 kJ was needed to lower the AC of four of eight pregnant women to 1.3 within 20 days, whereas only 0.41 mg/4184 kJ was needed for five of the seven non-pregnant women. Maternal riboflavin intake was positively associated with foetal growth in a study of 372 pregnant women. The additional riboflavin requirement of 0.3 mg/day for pregnancy is an estimate based on increased growth in maternal and foetal compartments. For lactating women, an estimated 0.3 mg riboflavin is transferred in milk daily and, because utilisation for milk production is assumed to be 70 percent efficient, the value is adjusted upward to 0.4 mg/day.

References:

Belko, A.Z., Obarzanek, E., Kalkwarf, H.J., Rotter, M.A., Bogusz, S., Miller, D., Haas, J.D. & Roe, D.A. 1983. Effects of exercise on riboflavin requirements of young women. Am. J. Clin. Nutr., 37: 509-17.

Belko, A.Z., Obarzanek, E., Roach, R., Rotten, M., Urban, G., Weinberg, S. & Roe, D.A. 1984. Effects of aerobic exercise and weight loss on riboflavin requirements of moderately obese, marginally deficient young women. Am. J. Clin. Nutr., 40: 553-61.

Belko, A.Z., Meredith, M.P., Kalkwarf, H.J., Obarzanek, E., Weinberg, S., Roach, R., McKeon, G. & Roe, D.A. 1985. Effects of exercise on riboflavin requirements: biological validation in weight reducing women. Am. J. Clin. Nutr., 41: 270-7.

Soares, M.J., Satyanarayana, K., Bamji, M.S., Jacob, C.M., Ramana, Y.V. & Rao, S.S. 1993. The effect of exercise on the riboflavin status of adult men. Br. J. Nutr., 69: 541-51.

Winters, L.R., Yoon, J.S., Kalkwarf, H.J., Davies, J.C., Berkowitz, M.G., Haas, J. & Roe, D.A. 1992. Riboflavin requirements and exercise adaptation in older women. Am. J. Clin. Nutr., 56: 526-32.

Powers, H.J., Bates, C.J., Eccles, M., Brown, H. & George, E. 1987. Bicycling performance in Gambian children: effects of supplements of riboflavin or ascorbic acid. Human. J. Clin. Nutr., 41: 59-69.

Prasad, A.P., Bamji, M.S., Lakshmi, A.V. & Satyanarayana, K. 1990. Functional impact of riboflavin supplementation in urban school children. Nutr Res., 10: 275-81.

Tremblay, A., Boilard, M., Bratton, M.F., Bessette, H. & Roberge, A.B. 1984. The effects of a riboflavin supplementation on the nutritional status and performance of elite swimmers. Nutr Res., 4: 201-8.

Weight, L.M., Myburgh, K.H. & Noakes, T.D. 1988. Vitamin and mineral supplementation: effect on the running performance of trained athletes. Am. J. Clin. Nutr., 47: 192-5.

Zempleni, J., Galloway, J.R. & McCormick, D.B. 1996. Pharmacokinetics of orally and

intravenously administered riboflavin in healthy Humans. Am. J. Clin. Nutr., 63: 54-66.

Chia, C.P., Addison, R. & McCormick, D.B. 1978. Absorption, metabolism, and excretion of 8a-(amino acid)-riboflavins in the rat. J. Nutr., 108: 373-81.

Boisvert, W.A., Mendoza, I., Castañeda, C., DePortocarrero, L., Solomons, N.W., Gershoff, S.N. & Russell, R.M. 193. Riboflavin requirement of healthy elderly Humans and its relationship to macronutrient composition of the diet. J. Nutr., 123: 915-25.

McCormick, D.B. 1989. Two interconnected B vitamins: riboflavin and pyridoxine. Physiol. Revs., 69: 1170-98.

Roe, D.A., Bogusz, S., Sheu, J. & McCormick, D.B. 1982. Factors affecting riboflavin requirements of oral contraceptive users and nonusers. Am. J. Clin. Nutr., 35: 495-501.

Thomas, M.R., Sneed, S.M., Wei, C., Nail, P.A., Wilson, M. & Sprinkle, E.E., III. 1980. The effects of vitamin C, vitamin B6, vitamin B12, folic acid, riboflavin, and thiamin on the breast milk and maternal status of well-nourished women at 6 months postpartum. Am. J. Clin. Nutr., 33: 2151-6.

Roughead, Z.K. & McCormick, D.B. 1990. Flavin composition of Human milk. Am. J. Clin. Nutr., 52: 854-7.

Roughead, Z.K. & McCormick, D.B. 1990. A qualitative and quantitative assessment of flavins in cow's milk. J. Nutr., 120: 382-8.

Bamji, M.S., Chowdhury, N., Ramalakshmi, B.A. & Jacob, C.M. 1991. Enzymatic evaluation of riboflavin status of infants. Eur. J. Clin. Nutr., 45: 309-13.

Bates, C.J., Powers, H.J., Downes, R., Brubacher, D., Sutcliffe, V. & Thurnhill, A. 1989. Riboflavin status of adolescent vs. elderly Gambian subjects before and during supplementation. Am. J. Clin. Nutr., 50: 825-9.

Kuizon, M.D., Natera, M.G., Alberto, S.P., Perlas, L.A., Desnacido, J.A., Avena, E.M., Tajaon, R.T. & Macapinlac, M.P. 1992. Riboflavin requirement of Filipino women. Eur. J. Clin. Nutr., 46: 257-64.

Alexander, M., Emanuel, G., Golin, T., Pinto, J.T. & Rivlin, R.S. 1984. Relation of riboflavin nutriture in healthy elderly to intake of calcium and vitamin supplements: evidence against riboflavin supplementation. Am. J. Clin. Nutr., 39: 540-6.

Bates, C.J., Prentice, A.M., Paul, A.A., Sutcliffe, B.A., Watkinson, M. & Whitehead, R.G. 1981. Riboflavin status in Gambian pregnant and lactating women and its implications for recommended Dietary Allowances. Am. J. Clin. Nutr., 34: 928-35.

Vir, S.C., Love, A.H. & Thompson, W. 1981. Riboflavin status during pregnancy. Am. J. Clin. Nutr., 34: 2699-705.

Badart-Smook, A., van Houwelingen, A.C., Al, M.D., Kester, A.D. & Hornstra, G. 1997. Foetal growth is associated positively with maternal intake of riboflavin and negatively with maternal intake of linoleic acid. J. Am. Diet. Assoc., 97: 867-70.