Article - Effects of Diet on 10-Year Atherosclerotic Cardiovascular Disease Risk (from the DASH Trial).

Plain Language Summary

Determining the 10-year risk of heart disease can be used as tool to determine appropriate treatment plans. This study of 459 adults aged 22-75 years with obesity aimed to compare the effects on the 10-year risk for the development heart disease of an 8-week dietary approaches to stop hypertension (DASH) diet, with the standard American diet (AD) and a diet high in fruits and vegetables (F/V). The results showed that the DASH diet significantly improved risk factors such as systolic blood pressure and total cholesterol. However, the F/V diet had an improvement in good cholesterol, which the DASH diet did not. This equated to a similar 10% reduction in the 10-year heart disease risk compared to the AD. It was concluded that compared to a typical AD, DASH and F/V diets reduced the risk for heart disease over a 10-year period. However, the actual risk reduction was only small and individuals with obesity may need to reduce their risk further with other therapies. This study could be used by healthcare professionals to recommend a DASH diet or a diet high in fruits and vegetables to reduce the long-term risk for heart disease alongside other proven therapies or methods to reduce risk.

Expert Review

Reviewer: Chloe Steele

18th Mar 2024

Conflict of interest

None

Take home message

DASH and F/V diets may be of benefit to obese individuals to decrease their risk for ASCVD
The DASH diet did reduce HDL cholesterol and recommendations should be made to limit this effect (e.g. exercise and more fruit and vegetables in the diet).

Evidence category

A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)

Summary review

Introduction

This study aimed to determine the effect of the Dietary Approaches to Stop Hypertension (DASH) diet compared to a standard American diet (AD) and a diet emphasising fruits and vegetables (F/V) on the 10-year risk of atherosclerotic cardiovascular disease (ASCVD) and how adopting these diets affect specific risk factors (e.g systolic blood pressure (SBP), diastolic blood pressure (DBP) and blood lipids).

Methods

Secondary analysis from the DASH trial which ran for 8 weeks in 459 adults aged 22-75 years with obesity
All meals were provided and dietary intake was adjusted to prevent weight loss
The primary outcome was an absolute and relative difference in 10-year ASCVD risk from baseline.

Participants were randomised to one of three diets: 1) DASH diet 2) F/V diet, similar to AD but with more fruits and vegetables and higher potassium and magnesium 3) Standard AD.

Results

DASH significantly lowered SBP, total cholesterol, and HDL cholesterol compared to F/V (absolute difference SBP: -2.8, (95% confidence interval [CI]-4.5, -1.2), total cholesterol: 9.3 (-14.7, 3.9), and HDL cholesterol: -3.5 (-5.0, -2.1) P=<0.05 for all)
DASH significantly lowered SBP, total cholesterol, and HDL cholesterol compared to AD (absolute difference SBP: -5.3 (-7.0, -3.7), total cholesterol: -13.1 (-18.5, -7.7), and HDL cholesterol: -3.8 (-5.2, -2.4) P=<0.05 for all)
Compared to AD, DASH and F/V diets reduced 10-year ASCVD relative risk by -10.3% ( −14.4 to −5.9) and −9.9% ( −14.0 to −5.5) respectively
This translated into low actual risk reductions of -0.21% for the F/V diet and -0.17% for the DASH diet
Although DASH improved SBP, and total cholesterol compared to F/V, no differences in ASCVD risk between DASH and F/V were apparent. This was attributable to the detrimental effect of the DASH diet on HDL cholesterol, which was not seen in the F/V diet
The effects of the DASH diet were more pronounced in black participants and in women.

Conclusion

Compared to the AD, DASH and F/V reduced 10-year ASCVD risk by approximately 10% over 8-weeks. The DASH diet was more effective for women and black adults.

Clinical practice applications

DASH and F/V diets decrease risk factors and an individual’s risk of ASCVD, and should be encouraged in individuals with obesity, especially women and black adults
However, these diets do still leave obese individuals at risk for ASCVD.

Considerations for future research

Research on these diets in combination with weight loss regimes may give more pronounced results
It may also be interesting to understand the mechanisms behind why the DASH diet reduces HDL cholesterol.

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Abstract

Although modern risk estimators, such as the American College of Cardiology/American Heart Association Pooled Cohort Equation, play a central role in the decisions of patients to start pharmacologic therapy to prevent atherosclerotic cardiovascular disease (ASCVD), there is limited evidence to inform expectations for 10-year ASCVD risk reduction from established lifestyle interventions. Using data from the original DASH (Dietary Approaches to Stop Hypertension) trial, we determined the effects of adopting the DASH diet on 10-year ASCVD risk compared with adopting a control or a fruits and vegetables (F/V) diet. The DASH trial included 459 adults aged 22 to 75 years without CVD and not taking antihypertensive or diabetes mellitus medications, who were randomized to controlled feeding of a control diet, an F/V diet, or the DASH diet for 8 weeks. We determined 10-year ASCVD risk with the American College of Cardiology/American Heart Association Pooled Cohort Equation based on blood pressure and lipids measured before and after the 8-week intervention. Compared with the control diet, the DASH and F/V diets changed 10-year ASCVD risk by -10.3% (95% confidence interval [CI] -14.4 to -5.9) and -9.9% (95% CI -14.0 to -5.5) respectively; these effects were more pronounced in women and Black adults. There was no difference between the DASH and F/V diets (-0.4%, 95% CI -6.9 to 6.5). ASCVD reductions attributable to the difference in systolic blood pressure alone were -14.6% (-17.3 to -11.7) with the DASH diet and -7.9% (-10.9 to -4.8) with the F/V diet, a net relative advantage of 7.2% greater relative reduction from DASH compared with F/V. This was offset by the effects on high-density lipoprotein of the DASH diet, which increased 10-year ASCVD by 8.8% (5.5 to 12.3) compared with the more neutral effect of the F/V diet of -1.9% (-5.0 to 1.2). In conclusion, compared with a typical American diet, the DASH and F/V diets reduced 10-year ASCVD risk scores by about 10% over 8 weeks. These findings are informative for counseling patients on both choices of diet and expectations for 10-year ASCVD risk reduction.