BackgroundAlthough a wealth of literature links dietary factors and coronary heart disease (CHD), the strength of the evidence supporting valid associations has not been evaluated systematically in a single investigation. Methods We conducted a systematic search of MEDLINE for prospective cohort studies or randomized trials investigating dietary exposures in relation to CHD [coronary heart disease]. We used the Bradford Hill guidelines to derive a causation score based on 4 criteria (strength, consistency, temporality, and coherence) for each dietary exposure in cohort studies and examined for consistency with the findings of randomized trials.
ResultsStrong evidence supports valid associations (4 criteria satisfied) of protective factors, including intake of vegetables, nuts, and “Mediterranean” and high-quality dietary patterns with CHD, and associations of harmful factors, including intake of trans–fatty acids and foods with a high glycemic index or load.
Effects of dietary carbohydrate restriction vs low-fat diet on flow-mediated dilation. This study examines the “vascular function” of patients on either a low fat or low carbohydrate diet. Abstract excerpts:
We previously reported that a carbohydrate-restricted diet (CRD) ameliorated many of the traditional markers associated with metabolic syndrome and cardiovascular risk compared with a low-fat diet (LFD). There remains concern how CRD affects vascular function because acute meals high in fat have been shown to impair endothelial function. Here, we extend our work and address these concerns by measuring fasting and postprandial vascular function in 40 overweight men and women with moderate hypertriacylglycerolemia who were randomly assigned to consume hypocaloric diets ( approximately 1500 kcal) restricted in carbohydrate (percentage of carbohydrate-fat-protein = 12:59:28) or LFD [low fat diet] (56:24:20)
After 12 weeks, peak flow-mediated dilation at 3 hours increased from 5.1% to 6.5% in the CRD [carbohydrate restricted diet] group and decreased from 7.9% to 5.2% in the LFD [low fat diet] group (P = .004). These findings show that a 12-week low-carbohydrate diet improves postprandial vascular function more than a LFD in individuals with atherogenic dyslipidemia.