Researchers followed nearly 19,000 young Spanish adults for about 16 years to see how different plant-based eating patterns affected their heart health. They found that people who ate more plant-based foods had a 37% lower risk of developing heart disease compared to those who ate the least plants. Interestingly, the type of plant foods mattered—eating healthy plant foods like whole grains and legumes was protective, but eating unhealthy plant foods like processed snacks and sugary drinks actually increased heart disease risk. This suggests that simply eating more plants isn’t enough; the quality of those plant foods is what really counts for protecting your heart.

The Quick Take

  • What they studied: Whether eating more plant-based foods helps protect young people from developing heart disease, and whether the type of plant foods matters.
  • Who participated: 18,560 Spanish university graduates with an average age of 38 years at the start, followed for up to 20 years. Participants were relatively healthy and well-educated.
  • Key finding: Young adults who ate the most plant-based foods had a 37% lower chance of developing heart disease over 16 years compared to those who ate the least. However, this benefit only applied to healthy plant foods—eating unhealthy plant-based foods actually increased heart disease risk by 76%.
  • What it means for you: If you’re a young adult, eating more healthy plant-based foods like vegetables, fruits, whole grains, and beans may help protect your heart. But processed plant-based snacks and sugary foods don’t provide the same benefit. Focus on whole, minimally processed plant foods rather than plant-based junk food.

The Research Details

This was a long-term follow-up study called the SUN Project, which tracked Spanish university graduates over many years. Researchers asked participants detailed questions about what they ate and created three different scoring systems to measure how plant-based their diets were. The first score simply counted how many plant foods versus animal foods people ate. The second score (healthy plant-based) gave extra credit for nutritious plant foods like whole grains, legumes, nuts, and fresh produce. The third score (unhealthy plant-based) tracked consumption of less healthy plant options like refined grains, sugary drinks, and processed plant-based foods. Researchers then followed participants for an average of 16 years and tracked who developed heart disease.

This research approach is valuable because it follows real people over many years in their actual lives, rather than just testing people in a lab. It also looks at the Mediterranean population specifically, which has different eating patterns than other groups studied before. Most importantly, it separates ‘plant-based eating’ into healthy and unhealthy categories, which is more realistic than just counting plants.

This study has several strengths: it included a large number of participants (18,560), followed them for a long time (up to 20 years), and carefully measured their diets. The participants were well-educated and relatively healthy, which means results may not apply equally to all populations. The study found 227 cases of heart disease, which is enough to draw meaningful conclusions. However, because participants were mostly Spanish university graduates, the findings may be most relevant to similar populations.

What the Results Show

The main finding was clear: people who ate the most plant-based foods had significantly lower heart disease risk. Specifically, those in the top quarter of plant-based eating had a 37% lower risk compared to those in the bottom quarter. This protective effect was even stronger for healthy plant-based eating—those eating the most healthy plant foods had a 40% lower risk. The study identified 227 cases of heart disease during the follow-up period, which provided enough data to draw reliable conclusions. The benefits appeared consistent across the study period, suggesting this is a long-term effect rather than a short-term change.

A striking finding was that unhealthy plant-based eating actually increased heart disease risk. People who ate the most unhealthy plant foods (like processed plant-based products and sugary drinks) had a 76% higher risk of heart disease compared to those who ate the least. This is a crucial finding because it shows that not all plant-based foods are equal. The research suggests that the quality and type of plant foods matter more than simply eating ‘more plants.’

Previous research had shown that plant-based eating patterns protect heart health in older adults and non-Mediterranean populations. This study extends those findings to younger adults and Mediterranean populations specifically. However, this is one of the first studies to clearly show that the type of plant foods matters—distinguishing between healthy and unhealthy plant-based options. This adds important nuance to earlier research that didn’t make this distinction.

The study participants were mostly Spanish university graduates, so results may not apply equally to other populations with different genetics, climates, or food availability. All participants self-reported what they ate, which can be inaccurate. The study found only 227 cases of heart disease, which is relatively small for such a large group, meaning some findings could be due to chance. The study couldn’t prove that plant-based eating causes lower heart disease risk—only that the two are associated. Other factors not measured in the study could explain the results.

The Bottom Line

If you’re a young adult, consider eating more healthy plant-based foods like vegetables, fruits, whole grains, legumes, nuts, and seeds. This eating pattern appears to reduce heart disease risk based on moderate-to-good evidence. However, avoid relying on processed plant-based foods and sugary drinks, as these don’t provide the same benefits and may actually increase risk. These recommendations are most confident for people similar to the study participants (relatively healthy, younger adults).

Young and middle-aged adults should pay attention to these findings, especially those with family history of heart disease or other heart disease risk factors. The findings are most relevant to people in Mediterranean regions or with similar food availability, though the principles likely apply more broadly. People already eating healthy plant-based diets can feel confident in their choices. Those eating mostly processed plant-based foods should consider shifting toward whole plant foods.

Heart disease develops over many years, so don’t expect immediate changes. The study followed people for 16 years, suggesting that benefits accumulate over time. You might notice improvements in blood pressure, cholesterol, or weight within weeks to months, but the major heart disease risk reduction appears to develop over years of consistent healthy eating.

Want to Apply This Research?

  • Track daily servings of whole plant foods (vegetables, fruits, whole grains, legumes, nuts) separately from processed plant foods. Aim for at least 5 servings of whole plant foods daily and minimize processed plant-based products to fewer than 2 servings per week.
  • Replace one processed food or animal product per day with a whole plant-based option. For example: swap a processed snack for a handful of nuts, replace white bread with whole grain bread, or add beans to one meal daily. Track these swaps in the app to build momentum.
  • Weekly review of plant food quality—calculate the percentage of plant foods that are whole/minimally processed versus processed. Monthly check-ins on related health markers like energy levels, digestion, and any available biometric data (blood pressure, cholesterol if measured). Long-term tracking of dietary consistency over months and years, as benefits appear to accumulate over time.

This research suggests an association between plant-based eating patterns and lower heart disease risk in young adults, but does not prove cause-and-effect. Results are most applicable to relatively healthy, younger populations similar to study participants. Individual results may vary based on genetics, overall lifestyle, and other health factors. This information is not a substitute for medical advice. Anyone with existing heart disease, taking medications, or with specific health conditions should consult their healthcare provider before making significant dietary changes. Always discuss major dietary changes with a doctor or registered dietitian, especially if you have a family history of heart disease or other cardiovascular risk factors.