Dietary Cysteine and Other Amino Acids and Stroke Incidence in Women

Abstract

Evidence from animal studies, randomized trials, and observational studies indicates that dietary protein intake is inversely associated with blood pressure 1-3 and the risk of stroke. 4,5 A recent meta-analysis of 7 prospective studies found that intake of total and animal protein, but not vegetable protein, was significantly inversely associated with stroke risk. 4 Proteins in the diet are composed of several amino acids, each with different chemical properties. Cysteine is a nonessential sulfur-containing amino acid that may, at least in part, be responsible for the potential blood pressure and strokereducing effects of a high-protein diet. It is more abundant in animal and cereal proteins than in legume proteins. 6 Foods rich in cysteine include poultry, egg, beef, and whole grains. Cysteine may exert its antihypertensive effects directly or via its storage form, glutathione, by reducing oxidative stress and advanced glycation end products, improving insulin sensitivity and glucose metabolism, and modulating nitric oxide levels. 7 To the best of our knowledge, no study has examined the association between cysteine intake and risk of stroke.In a previous study, based on data from the Swedish Mammography Cohort (SMC), we observed inverse associations of total and animal protein intakes with stroke incidence. 8In this study, we evaluated the a priori hypothesis that cysteine intake is inversely associated with risk of stroke, and that cysteine may have contributed to our previous observed finding for dietary protein. We also provide results for other amino acids, most of which are highly correlated with protein intake, in relation to stroke risk. Methods Study PopulationThis study was based on data from the SMC, which is a populationbased prospective cohort study of Swedish women. 9 In the autumn of 1997, 56 030 participants of the SMC obtained a comprehensive questionnaire that included ≈350 items on diet, other lifestyle factors, etc; 39 227 women (70%) returned a completed questionnaire. We excluded women with an erroneous or a missing personal identification number (n=243), women who did before start of follow-up (January 1, 1998; n=26), women with a diagnosis of cardiovascular disease (n=2492) or cancer (n=1811) before start of follow-up, and women with an implausibly high or low energy intake (ie, 3 SDs from the log e -transformed mean energy intake; n=405). After exclusions, 34 250 women aged 49−83 years remained for analysis. The study was approved by the Regional Ethical Review Board at the Karolinska Institutet in Stockholm.Background and Purpose-Cysteine could potentially lower the risk of stroke through antihypertensive and antioxidant effects. Our aim was to evaluate the hypothesis that cysteine intake is inversely associated with stroke incidence. Methods-We used data from the Swedish Mammography Cohort, a population-based prospective cohort of 34 250 women who were free of cardiovascular disease and cancer and had completed a food-frequency questionnaire about diet and other risk factors for stro...

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Urinary Excretion of Sulfur Metabolites and Risk of Cardiovascular Events and All-Cause Mortality in the General Population

“…In the present study this is confirmed by the strong association with 24-h urinary urea excretion, which roughly reflects dietary protein intake. Diets high in protein or specific SAAs have been associated with decreased risk of CVD and mortality (19,29,31,32,47). However, results have been inconsistent (19,29,31,32,44,47).…”

Validity and reliability of a self-administered food frequency questionnaire for the JPHC study: The assessment of amino acid intake

“…To the best of our knowledge, no other study has assessed the validity of the FFQ for amino acids. While an association has been reported between dietary cysteine intake, which was calculated from the FFQ, and the risk of stroke in a Swedish cohort, this study only evaluated protein intake and not dietary cysteine intake at the amino acid level 1, 15…”

“…Studies assessing the association between dietary amino acids and cardiovascular disease risk have shown that dietary intake of cysteine was inversely associated with the risk of stroke in women 1 . Higher methionine intake was associated with an increased risk of acute coronary events in men 2 .…”