High dietary folate supplementation: effects on diet utilization and methionine metabolism in aged rats
Achon, M.; Alonso-Aperts, E.; Varela-Moreiras, G.
Journal of Nutrition Health and Aging 6(1): 51-54
2002
ISSN/ISBN: 1279-7707 PMID: 11813082 Document Number: 549519
Background: Folate supplementation or food fortification is being nowadays recommended because of its effect on the prevention of neural tube defects and the lowering of homocysteine levels. We have previously reported a negative effect of high dose folate supplementation on dietary metabolic protein utilization in pregnant and virgin rats. Objectives: To determine the effects of folate supplementation on nutritional and some biochemical markers in aged rats. Design: Aged male Wistar rats were given free access either to a folate supplemented diet (40 mg/kg diet) or a control diet (1 mg/kg diet) for 29 days following a week adaptation period. Two critical periods were used for metabolic balance studies (experimental days 1-8 and 22-29), involving the determination of digestive and metabolic protein utilization. Several biochemical markers involved in the methylation cycle were also determined. Results: Data showed that long term high folate supplementation reduced nitrogen digestive function in aged rats (P<0.03) during the second metabolic period (days 22-29). However, supplementation did not alter metabolic protein utilization. Plasma homocysteine and serum vitamin B6 and B12 levels, hepatic S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) concentrations, and methylation ratio (SAM:SAH) were neither affected by folate supplementation. Conclusion: Folate supplementation at high doses may have a negative effect on diet utilization related to protein status.