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Is More Fiber the Heart’s Ally?

A long-term U.S. study found that greater adherence to a plant-based cholesterol-lowering diet was linked to lower cardiovascular, coronary heart disease, and all-cause mortality.

Conexiant

In a large, long-term study of U.S. adults, investigators found that higher adherence to the Portfolio dietary pattern—a plant-based cholesterol-lowering diet—was associated with lower risks of cardiovascular disease, coronary heart disease, and all-cause mortality over 22 years.

The investigators analyzed data from 14,835 adults aged 20 years and older who participated in the National Health and Nutrition Examination Survey (NHANES) III, conducted between 1988 and 1994. The cohort represented a racially diverse sample, with intentional oversampling of non-Hispanic Black and Mexican American adults. Mortality outcomes were tracked through 2019, yielding 326,544 person-years of follow-up.

During this period, 2,300 participants died from cardiovascular disease (CVD), including 1,887 from coronary heart disease (CHD) and 413 from stroke, while 6,238 experienced all-cause mortality.

Adherence to the Portfolio diet was quantified using the Portfolio Diet Score (PDS), which ranges from 6 to 30 points. Higher scores reflected greater intake of nuts, plant proteins, viscous fiber, phytosterols, and plant-based monounsaturated fats, and lower intake of saturated fats and cholesterol. Dietary intake was assessed through 24-hour dietary recalls combined with a food frequency questionnaire to capture episodically consumed foods.

After adjusting for a wide range of confounders—including age, sex, race/ethnicity, education, income, smoking, alcohol use, physical activity, body mass index (BMI), comorbidities, family history, and sodium intake—each 8-point increase in PDS was associated with a:

  • 12% lower risk of CVD mortality (HR = 0.88; 95% CI = 0.78–0.99),

  • 14% lower risk of CHD mortality (HR = 0.86; 95% CI = 0.78–0.96), and

  • 12% lower risk of all-cause mortality (HR = 0.88; 95% CI = 0.82–0.95).

No statistically significant association was found for stroke mortality, with an HR of 1.03 (95% CI = 0.75–1.44) per 8-point increase in PDS.

When comparing the highest versus lowest tertile of adherence, individuals in the highest tertile had a:

  • 16% lower risk of CVD mortality (HR = 0.84; 95% CI = 0.73–0.98),

  • 18% lower risk of CHD mortality (HR = 0.82; 95% CI = 0.72–0.95), and

  • 14% lower risk of all-cause mortality (HR = 0.86; 95% CI = 0.78–0.96).

Subgroup analyses revealed differences by race and ethnicity. Among non-White participants (including non-Hispanic Black, Mexican American, and others), the inverse associations were stronger:

  • CVD mortality: HR = 0.57 (95% CI = 0.45–0.72)

  • CHD mortality: HR = 0.53 (95% CI = 0.41–0.69)
    In comparison, White participants showed smaller, non-significant associations.

In biomarker analyses, each 8-point increase in PDS was associated with reductions in:

  • LDL cholesterol (−2.93 mg/dL),

  • non–HDL cholesterol (−2.90 mg/dL),

  • total cholesterol (−3.3 mg/dL),

  • C-reactive protein (−6.05%), and

  • HbA1c (−0.06%).

No significant changes were observed for triglycerides, HDL cholesterol, or blood pressure.

The Portfolio diet was originally designed to lower LDL cholesterol by combining plant-based foods with known lipid-lowering effects. Previous research has shown it can reduce LDL cholesterol by approximately 30%, comparable to early statins. However, in this cohort, most participants showed low adherence to the full dietary targets. Notably, even modest adherence levels—as low as ~19% of the targets in the highest tertile—were associated with meaningful mortality benefits. Translating this to food servings, such adherence could be achieved by adding a combination of small portions of nuts, legumes, fiber-rich fruits, and healthy oils to the daily diet.

Study limitations included reliance on a single baseline dietary assessment, self-reported intake, and potential measurement error. While sophisticated error correction methods were not applied due to data constraints, the combination of dietary recall and FFQ was used to minimize bias.

Despite these limitations, the findings suggest that even partial adherence to the Portfolio diet may help reduce long-term risks of CVD and premature death—particularly among racially and ethnically diverse populations.

Full disclosures can be found in the published study.

Source: BMC Medicine