A new 12-week study will test whether combining two plant-based diets (DASH and Portfolio) lowers blood pressure better than standard care in 300 adults with high blood pressure and obesity. Researchers will also compare whether using whole soy foods works as well as processed soy products for blood pressure reduction. According to Gram Research analysis, this randomized controlled trial will provide high-quality evidence on the best plant-based dietary approach for managing heart disease risk factors.
Researchers are launching a major study to test whether combining two popular heart-healthy diets can better lower blood pressure in people with high blood pressure and obesity. The study, called SWITCH, will compare three different eating approaches over 12 weeks: a combined DASH and Portfolio diet with highly processed soy foods, the same diet with less processed soy foods, and standard care. According to Gram Research analysis, this trial will help doctors understand if plant-based diets work better when they focus on whole foods rather than ultra-processed versions, potentially offering clearer guidance for millions managing heart disease risk.
Key Statistics
A 2026 randomized controlled trial called SWITCH will enroll 300 adults with hypertension and obesity, including 50% with type 2 diabetes, to test whether a combined DASH-Portfolio diet reduces blood pressure over 12 weeks.
The SWITCH trial will compare three approaches: a DASH-enhanced Portfolio diet with highly processed soy proteins, the same diet with whole soy foods, and standard care, measuring systolic blood pressure as the primary outcome.
Research shows the DASH diet alone reduces blood pressure by 8 to 14 millimeters of mercury in people with hypertension, while the Portfolio diet reduces LDL cholesterol by up to 30%, but no previous trial has combined both diets in a rigorous study design.
The Quick Take
- What they studied: Whether combining two plant-based diets (DASH and Portfolio) can lower blood pressure better than usual care, and whether using less processed soy foods works as well as using more processed soy foods
- Who participated: 300 adults with high blood pressure and obesity, with about half also having type 2 diabetes, randomly assigned to three different eating groups
- Key finding: This is a planned study that hasn’t produced results yet, but it will test if a combined plant-based diet approach can achieve meaningful blood pressure reductions over 12 weeks
- What it means for you: If successful, this research could provide clearer guidance on which plant-based foods work best for managing blood pressure and heart disease risk, helping people make better food choices
The Research Details
The SWITCH trial is a carefully designed experiment that will randomly assign 300 people into three groups. One group will eat a combined DASH and Portfolio diet using highly processed soy products. A second group will eat the same diet but with less processed, whole soy foods. A third group will receive standard care advice. All participants will follow their assigned eating plan for 12 weeks. Researchers will measure blood pressure, cholesterol, and body weight at the start and end to see which approach works best.
This type of study design, called a randomized controlled trial, is considered the gold standard in nutrition research. By randomly assigning people to groups, researchers can be more confident that any differences in results come from the diet itself rather than other factors. The study is open-label, meaning participants know which diet group they’re in, which is practical for long-term eating studies.
The researchers chose to combine two well-established diets because each targets different heart disease risk factors. The DASH diet is proven to lower blood pressure, while the Portfolio diet is known for reducing cholesterol. By combining them, the researchers hope to address multiple risk factors at once.
This research matters because cardiovascular disease is the leading cause of death worldwide, and many people struggle to manage their blood pressure and weight. The study addresses a real-world question: do plant-based diets work better when people eat whole foods instead of processed versions? This is important because many soy-based meat and dairy replacements are highly processed, and doctors aren’t sure if they’re as healthy as whole plant foods. The findings will help create clearer dietary guidelines that people can actually follow.
This study has several strengths that make it reliable. It’s being conducted by researchers at major institutions and published in a respected journal focused on heart health. The study uses a large sample size (300 people), which gives results more statistical power. It includes a diverse population with 50% having type 2 diabetes, making findings more applicable to real patients. However, the study is relatively short (12 weeks), so it shows short-term effects rather than long-term benefits. The open-label design means participants know which diet they’re following, which could influence their behavior, though this is unavoidable in diet studies.
What the Results Show
This is a protocol paper describing a planned study, so final results are not yet available. The primary outcome the researchers will measure is systolic blood pressure (the top number in a blood pressure reading). The study will determine whether the combined DASH-Portfolio diet produces clinically meaningful reductions in blood pressure compared to standard care. Clinically meaningful means the reduction is large enough to actually improve health outcomes, not just a tiny statistical difference.
The researchers will also compare whether using less processed soy foods works as well as using more processed soy foods. This is important because it will help answer whether the processing method matters for health benefits. If both approaches work equally well, it gives people more food choices. If whole soy foods work better, it suggests people should prioritize them.
The study will track multiple heart disease risk factors beyond just blood pressure. These include non-high-density lipoprotein cholesterol (a type of cholesterol linked to heart disease), body weight, and other cardiometabolic markers. This comprehensive approach will show whether the diet benefits multiple aspects of heart health or just one.
Secondary outcomes include changes in non-high-density lipoprotein cholesterol and body weight. These are important because high cholesterol and excess weight are major risk factors for heart disease. The study will also measure other cardiometabolic risk factors, which may include blood sugar control, inflammation markers, and kidney function. These additional measurements will provide a complete picture of how the diet affects overall heart and metabolic health.
The DASH diet has strong evidence from previous research showing it lowers blood pressure by 8 to 14 millimeters of mercury (mmHg) in people with high blood pressure. The Portfolio diet has proven effective at reducing LDL cholesterol by up to 30%. However, no previous study has combined these two diets in a rigorous trial. This study builds on decades of research by testing whether combining proven approaches produces even better results. The focus on ultra-processed versus whole soy foods addresses a newer concern in nutrition science about whether processing affects the health benefits of plant-based foods.
This is a protocol paper, so the main limitation is that results don’t exist yet. When results do come, several limitations will apply. The 12-week duration is relatively short for evaluating long-term dietary changes. The open-label design means participants know which diet they’re following, which could influence their motivation and adherence. The study focuses on adults with high blood pressure and obesity, so results may not apply to people without these conditions. Additionally, the study doesn’t include a long-term follow-up period, so researchers won’t know if benefits persist after people stop the structured diet.
The Bottom Line
This is a planned study, so specific recommendations await results. However, current evidence strongly supports the DASH diet for blood pressure management and the Portfolio diet for cholesterol reduction. People with high blood pressure and obesity should discuss plant-based dietary approaches with their doctor. When results from this trial become available, they may provide clearer guidance on whether combining these diets offers additional benefits and whether whole soy foods should be prioritized over processed versions. Confidence in these future recommendations will be high because the study uses rigorous methodology.
Adults with high blood pressure and obesity should pay attention to this research, especially those interested in plant-based eating. People with type 2 diabetes will find this particularly relevant since half the study participants have diabetes. Healthcare providers managing cardiovascular disease risk will use these findings to update dietary recommendations. People looking to reduce processed foods in their diet will benefit from clarity on whether soy-based meat replacements are as healthy as whole plant foods. However, people without high blood pressure or obesity may not see the same benefits, and the study doesn’t address other populations.
The study runs for 12 weeks, so researchers expect to see measurable changes in blood pressure and other markers within this timeframe. Blood pressure typically responds to dietary changes within 2 to 4 weeks, so meaningful improvements should appear by the end of the study. Weight loss and cholesterol changes may take the full 12 weeks to become apparent. However, these are short-term results. Long-term benefits and whether people can maintain these diets for years remain unknown and would require additional research.
Frequently Asked Questions
What is the difference between the DASH diet and the Portfolio diet?
The DASH diet focuses on lowering blood pressure through foods like vegetables, fruits, whole grains, lean proteins, and low-fat dairy while limiting salt and sugar. The Portfolio diet targets cholesterol reduction using plant sterols, soy protein, nuts, and soluble fiber. The SWITCH trial combines both approaches to address multiple heart disease risk factors simultaneously.
Are ultra-processed soy foods as healthy as whole soy foods?
This study will directly answer that question. Current research suggests whole soy foods may offer more nutrients, but processed soy products still contain beneficial protein and plant compounds. The SWITCH trial will determine whether the processing method affects blood pressure and cholesterol outcomes over 12 weeks.
How quickly does the DASH diet lower blood pressure?
Research shows blood pressure typically begins dropping within 2 to 4 weeks of following the DASH diet, with maximum benefits appearing around 8 to 12 weeks. The SWITCH trial will measure changes at the 12-week mark to see if combining DASH with the Portfolio diet produces faster or greater reductions.
Who should follow a plant-based diet for heart health?
People with high blood pressure, high cholesterol, obesity, or type 2 diabetes benefit most from plant-based diets like DASH and Portfolio. However, anyone concerned about heart disease risk can benefit from increasing plant foods. Talk with your doctor about whether these diets suit your specific health conditions and medications.
Will results from this study apply to people without obesity or diabetes?
The SWITCH trial specifically enrolls adults with high blood pressure and obesity, so results will be most reliable for this population. People without these conditions may still benefit from plant-based diets, but this study won’t directly test that. Existing research on DASH and Portfolio diets includes broader populations.
Want to Apply This Research?
- Track systolic blood pressure (top number) daily at the same time each morning before eating, recording the reading in the app. Also log weekly body weight and note which soy foods you consume (processed versus whole options) to identify patterns between food choices and blood pressure changes.
- Users can use the app to log meals following either the DASH or Portfolio diet guidelines, with specific tracking for soy protein sources. The app could provide daily reminders to eat recommended plant-based foods like beans, nuts, whole grains, and either whole soy foods or processed soy alternatives, depending on which approach they’re testing.
- Set up weekly blood pressure trend reports in the app to visualize changes over the 12-week period. Create a food diary that categorizes soy products as processed or whole, allowing users to see correlations between food choices and health markers. Generate monthly summaries comparing blood pressure, weight, and dietary adherence to identify which approach works best for the individual.
This article describes a planned research study that has not yet produced results. The findings discussed are based on the study protocol and design, not actual outcomes. This information is for educational purposes only and should not replace professional medical advice. Anyone with high blood pressure, obesity, or heart disease should consult with their healthcare provider before making significant dietary changes. Results from this trial, when available, should be discussed with a doctor to determine if the recommended diet is appropriate for your individual health situation. This research is not a substitute for medical treatment or medication prescribed by your healthcare provider.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.