What is the relationship between adherence to dietary guidelines/recommendations or specific dietary patterns, assessed using an index or score, and risk of cardiovascular disease?
ConclusionThere is strong and consistent evidence that in healthy adults increased adherence to dietary patterns scoring high in fruits, vegetables, whole grains, nuts, legumes, unsaturated oils, low-fat dairy, poultry and fish; low in red and processed meat, high-fat dairy, and added sugars; and moderate in alcohol is associated with decreased risk of fatal and non-fatal cardiovascular diseases, including coronary heart disease and stroke.
GradeI – Strong
- Three major categories of dietary pattern scores were identified related to cardiovascular disease (CVD) risk: dietary exposure based on adherence to (1) a Mediterranean dietary pattern, (2) dietary guidelines recommendations, or (3) a DASH diet.
- The preponderance of the evidence from studies carried out in large, well-characterized prospective cohorts from the United States, Europe, Japan, and Australia showed that, in healthy adults, an increase in a Mediterranean diet score or dietary guidelines-related score was associated with decreased risk of fatal and non-fatal CVD, defined as coronary heart disease (CHD) and stroke, as well as decreased risk of CHD and stroke as individual clinical outcomes. Fewer studies assessed the association between adherence to a DASH diet and CVD, CHD, or stroke outcomes, using an index or score, and their findings were inconsistent.
- Scores that were most frequently associated with decreased risk of CVD, CHD, or stroke, in categorical comparisons of adherence, were the original Mediterranean Diet Score (MDS), the Alternate Mediterranean Diet Score (aMed), the Healthy Eating Index (HEI)-2005, the Alternate HEI (AHEI) and updated AHEI-2010, the Recommended Food Score (RFS), and one of the DASH scores.
- Positive food components of scores that were associated with decreased CVD risk were fruits, vegetables, whole grains, nuts, legumes, unsaturated fats, and fish. Alcohol was included as a positive component when consumed in moderation, but not in all scores. Red and processed meats were negative components in the Mediterranean scores, AHEI scores, and DASH; whereas, poultry was included as a positive component in the original AHEI and RFS scores. Total high-fat dairy was a negative component in the MDS, but dairy was a positive component when meeting recommended intakes for the HEI-2005 or as low-fat dairy in the RFS and DASH scores. Certain scores also included sugars or sugar-sweetened beverages as negative components.
- Studies that assessed the association between individual food components of scores and CVD risk were consistent with the identified food components from comparisons across predictive scores.
- A smaller number of studies examined intermediate, secondary outcomes and other individual clinical endpoints outcomes with mixed results.
The studies covered in this systematic review provide results that improve some of the problems involved in dietary patterns research. For example, the need for consensus on a single score or index that is applicable across populations is less problematic in this body of evidence than for some other outcomes, as a relatively small number of uncomplicated scores have been used to successfully predict CVD risk in large U.S. and European populations. Further quantitative analysis/comparisons of these scores and their respective components by meta-analysis would be particularly useful. Although a large number of the studies assessed food group components and their association with CVD outcomes, many did not, and more precise determination of the benefits and risks of individual components (e.g., alcohol) would be helpful for policy recommendations. In addition, component analysis could be improved by determining interaction terms across components that would be needed to maintain a dietary patterns approach. Methodologically, research in this area could be improved by measuring dietary intake at regular intervals over the course of a prospective study, rather than just at baseline (although a few of the large cohort studies in this body of evidence did this). Determining the best approach to weighing and scoring individual food components would also improve the rigor in application of scores to assess dietary pattern adherence. Additionally, studies in this body of evidence that assessed gender differences in the relationship between adherence to a dietary pattern and CVD risk found inconsistent results. Further research is needed to clarify this. There were also very few studies that identified racial/ethnic subgroups within their cohorts and analyzed these groups separately related to CVD risk and this warrants additional research. Assessment of dietary patterns at earlier and later stages of the life cycle is also recommended. Lastly, behavioral issues related to timing, frequency, and size of meals need further consideration.
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Search Plan and Results
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