Mrs. B is a 56-year-old African American woman with a past medical history significant for type 2 diabetes (HbA1C 7.6) and hypercholesterolemia. Her calculated ASCVD risk score today is 12.5% and her BMI is 24kg/m2. She is concerned about her high cholesterol levels despite being on a statin and feels that her diet is “not healthy enough.” She is interested in making dietary changes to help reduce her ASCVD risk. Which of the following recommendations is appropriate?

A. Sodium restriction to <3g /day will be of no benefit because she is not hypertensive.
B. Isocaloric substitution of saturated fat with polyunsaturated fat is associated with reduction of CHD risk.
C. Dietary fiber intake is associated with GI benefits but has no CV risk reduction benefit.
D. Supplementing diet with vitamins A, B, C and E helps reduce ASCVD risk.

The correct answer is B.

Risk of CHD is reduced when dietary saturated fats are replaced with other foods having similar caloric values. The greatest reduction was observed when saturated fats were isocalorically replaced with polyunsaturated fats (↓25%), followed by monounsaturated fats (↓15%) and carbohydrates from whole grains (↓9%). This is a class 1a recommendation in the ESC guidelines and a class IIa recommendation in the 2019 ACC/AHA guidelines. Conversely, increased trans fatty acid intake is associated with increased CHD risk. A regulation of the European Union (EU) Commission has set the upper limit of trans fats to 2 g per 100 g of fat. The ACC/AHA guidelines recommend that the intake of trans fats should be avoided (a class III: harm).

Choice A is incorrect because dietary sodium restriction is recommended not only for control of blood pressure, but also for reduction of ASCVD risk. In a meta-analysis, salt reduction of 2.5 g/day resulted in a 20% reduction of ASCVD events (RR 0.80). Reduction of salt intake is a class 1 recommendation in the ESC guidelines compared to a class IIa recommendation in the 2019 ACC/AHA guidelines.

Choice C is incorrect because a 10 g/day higher fiber intake was associated with a 16% lower risk of stroke (RR 0.84) and a 6% lower risk of type 2 DM (RR 0.94). A high fiber intake may reduce postprandial glucose responses after carbohydrate-rich meals and also lower triglyceride levels. The Mediterranean diet is rich in fiber (it includes high intakes of fruits, vegetables, pulses and wholegrain products) and is a class I recommendation.

Choice D is incorrect because while vitamin supplementation has been associated with reduction in ASCVD risk in observational studies, intervention trials have failed to show any benefit. 

Main Takeaway:

A healthy diet is recommended as a cornerstone of CVD prevention in all individuals, independent of their underlying co-morbidities. Replacing saturated with unsaturated fats, reducing salt intake, and choosing a more plant-based diet that is rich in fiber can lower risk of CVD.

Guideline Location
Section 4.3.2, Page 3270