Determinação da ingestão de metionina e ácidos gordos polinsaturados e sua relação com os níveis plasmáticos de homocisteína e cisteína em diabéticos do tipo 2

Título em inglês: Methionine and polyunsaturated fatty acids intake assessed by food frequency questionnaire in relation with plasma homocysteine and cysteine in type 2 diabetic patients

INTRODUCTION: Diabetes mellitus is a major public health threat in the World. In Portugal, there are around 1 million type 2 diabetic patients. This chronic disease, hyperhomocysteinaemia and hypercysteinaemia are known as cardiovascular risk factors. Homocysteine (Hcy) is a sulphur containing amino acid that is derived from methionine, an essential amino acid found in abundance in protein of animal origin. Diet plays a vital role in the risk factors of chronic disease. In observational studies, higher intakes of n-3 fatty acids appear to reduce the risk of coronary artery disease, hypertension and diabetes. Other studies have shown that diets rich in n 6 fatty acids may increase the risk of disease. Recent evidence suggests that a balanced ratio of these 2 types of fatty acids may be necessary for the prevention of chronic diseases. AIM: To study a possible relationship between methionine, n-3 and n-6 intakes and plasma Hcy and Cys levels in type 2 diabetic patients with and without angiopathy. METHODS: Study population was composed by 150 Portuguese type 2 diabetic patients, aged between 40-75 years. The participants were divided in two groups: I - 75 diabetics with angiopathy; II - 75 diabetics without angiopathy. Nutrients intake were estimated from a food-frequency questionnaire previously validated for Portuguese adults with cardiovascular disease by the Epidemiology Department, Faculty of Medicine, University of Porto. Plasma Hcy and Cys levels were analyzed using a previously validated HPLC method. The n-6/n-3 ratio was calculated for all participants. Hyperhomocysteinaemia was defined for Hcy levels ≥15 µM. A statistical analysis was performed by unpaired two-tailed z-test and Pearson's Correlation Coefficient. RESULTS: The prevalence of hyperhomocysteinaemia was 20% for group I and 8% for group II. The mean values for Hcy plasma levels in group I (10.6 ± 4.7 µM) was slightly higher compared to group II (9.4 ± 4.5 µM). The mean levels for Cys were also higher in group I (246.5 ± 55.6 µM) compared to group II (229.4 ± 48.1 µM). The dietary intakes of methionine, n-3 and n-6 were higher in diabetic patients with angiopathy compared to those without angiopathy. The coefficients of correlation between the different parameters under study were not significant. CONCLUSION: The prevalence of hyperhomocysteinaemia and Cys plasma levels are associated with the presence of angiopathy. The dietary intake of methionine, n-3 and n-6 fatty acids are not related with Hcy and Cys plasma levels in type 2 diabetic patients.

This study was funded by PIC/IC/82957/2007 from “Fundação para a Ciência e a Tecnologia” (FCT) and Ana Valente is grateful for the PhD grant, number (SFRH/DB/16166/2004/5E4M) and the research grant, both supported by FCT.