Sensory Peripheral Nerve Function in Chilean Elderly Consuming Folic Acid Fortified Flour: Relationship to Plasma Folate and a Novel Combined Biomarker of B12 Status
Alex Brito *
Institute of Nutrition and Food Technology, University of Chile, Santiago, Chile and USDA, ARS, Western Human Nutrition Research Center, UC Davis, Davis, Ca, USA.
Joshua W. Miller
Department of Nutritional Sciences, Rutgers University, NJ, USA.
Sergey N. Fedosov
Department of Engineering Science, University of Aarhus, Aarhus, Denmark.
Setareh Shahab-Ferdows
USDA, ARS, Western Human Nutrition Research Center, UC Davis, Davis, Ca, USA.
Hugo Sanchez
Institute of Nutrition and Food Technology, University of Chile, Santiago, Chile.
Cecilia Albala
Institute of Nutrition and Food Technology, University of Chile, Santiago, Chile.
Renato Verdugo
Department of Neurologic Sciences, Faculty of Medicine, University of Chile, Santiago, Chile.
Ricardo Uauy
Institute of Nutrition and Food Technology, University of Chile, Santiago, Chile and London School of Hygiene and Tropical Medicine, London, UK.
Lindsay H. Allen
USDA, ARS, Western Human Nutrition Research Center, UC Davis, Davis, Ca, USA and Program in International and Community Nutrition, UC Davis, Davis, Ca, USA.
*Author to whom correspondence should be addressed.
Abstract
Objectives: It has been reported that low vitamin B12 status and high serum folate is associated with anemia and cognitive impairment. However, few data are available on neurophysiological outcomes, such as peripheral neurophysiology. The objective was to assess associations between folate, B12 and sensory peripheral nerve conduction in Chilean elderly exposed to folic acid fortification.
Methods: The average of the left and right distal sensory conduction latency of the sural nerve, and conduction velocity of the right peroneus nerve were measured in 159 community-dwelling older Chilean. Serum folate, B12, Hcy, MMA, and holoTC were determined. B12 status was defined based on: w=log_10 (holoTC*B12)/(MMA*Hcy)-(age factor) (Fedosov SN, Clin. Chim. Acta. 2013). Nerve conduction, folate and B12 status were divided into tertiles.
Results: Age was 70-78y (57% women). 62.9%, 10.7% and 26.4% were classified as having B12 adequacy (w>-0.5), transitional status (-1.5< w<-0.5) and deficiency (w<-1.5) respectively, while 15.1% presented high folate (>45.3 nmol/L). Nerve conduction velocity of the right peroneus nerve positively correlated with B12 status (r=0.21, p<0.05). In the highest tertile of both B12 (w) and folate only 6% were in lowest tertile of sural nerve conduction vs. 31.5% (p<0.001) with low B12 and high folate. In the highest tertile of both B12 (w) and folate 25% were in lowest tertile of peroneal nerve conduction velocity as compared with 63.2% with low B12 and high folate (p<0.001).
Conclusions: Elderly with both high B12 and folate status were less likely to have poor sensory peripheral nerve conduction than those with low B12 and high folate.