New research reveals that the portfolio diet can boost heart health through everyday food choices, reducing the risk of heart disease and helping you live longer.
Study: The portfolio dietary pattern and risk of cardiovascular disease mortality during 1988–2019 in US adults: a prospective cohort study. Image credit: Rimma Bondarenko/Shutterstock.com
In a recent study published in BMC Medicine, researchers investigated the long-term impacts of the portfolio diet on cardiovascular outcomes and all-cause mortality.
Background
Cardiovascular diseases (CVDs), particularly coronary heart disease (CHD) and stroke, are the leading causes of disability and mortality worldwide, accounting for an estimated 17.9 million human deaths annually. The financial burden of CVDs is similarly alarming, accounting for 11% and 15% of all health-associated expenditures in the Group of Twenty (G20) nations.
Poor environmental (e.g., pollution) and behavioral (e.g., dietary, sleep, and physical activity) trends are expected to further increase the burden of CVD, prompting ongoing research into preventive strategies. Noninvasive behavioral interventions, especially dietary modifications, represent a leading strategy to mitigate CVD risk and manage its risk factors (e.g., dyslipidemia).
While the physiological advantages of popular ‘healthy’ dietary patterns (e.g., the Mediterranean diet) over their ‘unhealthy’ alternatives (e.g., the Western style dietary pattern) are established, the impacts of lesser-known CVD prevention diets (e.g., the portfolio diet) have been less well-studied, particularly for long-term mortality outcomes in diverse populations.
The portfolio diet is a novel plant-based diet that incorporates increased soy protein, nuts, soluble fiber, and plant sterols to mitigate cholesterol and lipids, thereby promoting long-term cardiovascular health.
About the study
The study aimed to investigate the impact of portfolio diet adherence on CVD, CHD, and all-cause mortality in an extensive cohort of adult US participants, informing future public health and dietary recommendations.
Study data were obtained from the National Health and Nutrition Examination Survey (NHANES 1988–1994), with methodology approved by the US Centers for Disease Control and Prevention (CDC).
Participant inclusion criteria included non-pregnant adults (20+ years) with baseline first-day 24-hour dietary recall and mortality follow-up data (22 years). Individuals with missing sociodemographic data, a food frequency questionnaire (FFQ), or a low body mass index (BMI < 18.5 kg/m²) were excluded from subsequent analyses.
Study outcomes focused on CVD mortality (primary outcome) alongside stroke, CHD, and all-cause mortality (secondary outcomes). Dietary evaluations were conducted using 24-h dietary recall interviews combined with FFQs, which were used together to calculate a portfolio diet Score (PDS; 6-30 points), indicating the relative impact of soy protein, nuts, and soluble fiber on participants’ long-term mortality risk. Notably, FFQs are not designed to assess plant sterols (phytosterols) metrics, restricting phytosterol analyses to only 24-h recall estimates.
PDS was used to categorize participants into three groups. Cox proportional hazard models were used to compute hazard ratios (HRs), adjusting for potential confounds (e.g., demographic factors, physical activity, socioeconomic status, smoking, alcohol use, clinical risk factors, and BMI).
It is important to note that dietary exposures were measured at a single baseline time point using self-reported methods, including a single 24-hour recall and FFQ, which are subject to under- and over-reporting and may not fully capture participant habits, introducing the potential for bias and measurement error.
Study findings
The study's inclusion criteria identified 14,835 participants with complete data. The median follow-up (22 yrs) revealed 6,238 all-cause deaths, including 2300 CVD-associated, 1,887 CHD-associated, and 413 stroke-associated.
Portfolio diet evaluations (leveraging PDS metrics) showed a strong inverse association between dietary adherence and mortality risk. Every 8-point increase in PDS resulted in lower CVD mortality (-12%), CHD mortality (-14%), and all-cause mortality (-12%).
Participants categorized into the highest group of PDS demonstrated a 16% lower risk of CVD death, an 18% lower risk of CHD death, and a 14% lower all-cause mortality compared to those assigned to the lowest group. These associations remained significant after statistical adjustments for various demographic, lifestyle, and clinical confounders.
Subgroup and sensitivity analyses confirmed these results, suggesting that even partial adherence to a portfolio diet may yield meaningful long-term cardiovascular benefits.
Surprisingly, the study was unable to identify a relationship between the portfolio diet and strokes, suggesting that alternate, currently unknown pathophysiological mechanisms determine stroke risk. This may reflect limited statistical power due to the number of stroke events in the cohort, and other studies have shown possible associations.
Furthermore, subgroup analyses revealed an association between race/ethnicity and mortality outcomes, suggesting that population-specific effects exist, which future research should explore. These subgroup findings are exploratory and inconclusive and are not for tailored intervention recommendations.
In addition to mortality outcomes, greater portfolio diet adherence is associated with favorable changes in several cardiometabolic biomarkers, including LDL cholesterol, non-HDL cholesterol, C-reactive protein, and hemoglobin A1c.
Still, as with all observational studies, causality cannot be established, and the findings could be affected by confounding and measurement limitations.
Conclusions
The large cohort study demonstrates a long-term association with cardiovascular benefits and greater adherence to a portfolio diet, supporting the diet as a non-invasive behavioral intervention for reducing cardiovascular and all-cause mortality.
However, the study’s observational design, reliance on single-time-point dietary recall, and focus on the US population mean that the results are not definitive for the broader population. Despite this, the portfolio diet may offer benefits with partial adherence, but its broader applications require further investigation.
Further research, including prospective and intervention studies in diverse populations and tailoring of this diet, is needed to better understand the portfolio diet's full potential and limitations.
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