Low-Fiber Diets Linked To High-Risk Plaques That Can Trigger Heart Attacks

Heart attacks are no longer the leading cause of death from heart disease. (Carlos_Pascual/Shutterstock)

LUND, Sweden — If your diet lacks fiber-rich foods and includes plenty of red meat, your heart might be paying a price you can’t see. A study of nearly 25,000 middle-aged adults has uncovered a striking association between poor dietary patterns and the development of coronary artery plaques, especially the kind that can raise the risk of sudden heart attacks.

Researchers from Sweden’s largest heart imaging project found that people who ate diets low in fiber and high in red meat were more likely to develop what doctors classify as “high-risk” coronary plaques. These are soft, rupture-prone deposits that can trigger heart attacks even when they don’t significantly block blood flow.

The researchers also identified waist circumference, triglyceride levels, and hypertension as potential mediators of this relationship, suggesting that diet may influence heart health partly through these metabolic pathways.

The study, published in Cardiovascular Research, focused on people who appeared generally healthy. None had been diagnosed with heart disease. Yet advanced imaging revealed clear differences in their coronary arteries depending on what they ate.

How Dietary Patterns Impact Coronary Plaque

The research team used a detailed food questionnaire and assigned each participant a dietary inflammation score. People earned points for regularly consuming foods considered anti-inflammatory, such as fruits, vegetables, whole grains, nuts, olive oil, tea, and even coffee. They received no points for eating foods with pro-inflammatory potential, including red and processed meats, offal, potato chips, and sugary drinks.

The researchers grouped participants into three dietary categories based on their scores. Those in the lowest-scoring group (representing the poorest diets) were significantly more likely to have high-risk coronary plaque features, including non-calcified plaques that narrowed the artery by 50% or more.

People with poor diets also had coronary plaques more often overall (44.3% versus 36.3% in the highest diet-quality group), higher calcium buildup in their arteries, and more segments affected by disease.

The Hidden Danger in Your Arteries

Most heart attacks aren’t caused by heavily narrowed arteries that build up slowly over time. Instead, many result from softer, more vulnerable plaques that suddenly rupture, creating clots that can block blood flow to the heart.

These plaques are called “non-calcified” because they haven’t hardened with calcium deposits. On CT scans, they show up as darker, low-density areas embedded in artery walls. They may not cause noticeable symptoms, but they’re considered more unstable and more dangerous.

In the Swedish study, people with the poorest dietary scores were significantly more likely to have these high-risk plaque types. In fact, after adjusting for age and sex, those in the lowest diet group had 67% higher odds of having non-calcified plaques with significant narrowing compared to those with the best diets.

Diet doesn’t influence heart health in isolation. Poor eating patterns were also linked to a series of metabolic problems that may help explain the buildup and instability of dangerous plaques.

Participants with the worst diets had larger waistlines, higher triglyceride levels, and were more likely to have high blood pressure, all established risk factors for heart disease. When researchers factored in these variables, the direct link between diet and plaque features became less pronounced, indicating that these metabolic issues may be part of the pathway connecting food to heart health.

The study also found that people with the lowest diet scores had higher levels of C-reactive protein (CRP), a marker of chronic inflammation. While CRP wasn’t the strongest contributor in the analysis, its presence adds biological support to the idea that poor dietary choices may fuel systemic inflammation, a known driver of plaque instability.

The poorest diets were more common among men (62.2% of the lowest diet group were male versus 32.9% in the highest group) and among people with less formal education. These individuals also tended to smoke more, drink more alcohol, and get less exercise, highlighting how diet often clusters with other lifestyle risk factors.

Advanced Scans Reveal What Traditional Tests Miss

The study used coronary computed tomography angiography (CCTA), a cutting-edge imaging technique that allows doctors to see not just whether arteries are narrowed, but also what kind of plaques are present. Unlike older methods that primarily detect blockages, CCTA can differentiate between hardened, stable plaques and the softer, more rupture-prone ones.

All participants were scanned at six Swedish medical centers, with 36 trained professionals evaluating the results using consistent protocols.

While this cross-sectional study can’t prove that poor diet causes dangerous plaques, the researchers say their findings add to decades of evidence linking diet and cardiovascular risk. More importantly, it shows that not all plaque is created equal—what matters most may be its composition, not just its size.

For the average person, the takeaway is simple: eating more fiber-rich, plant-based foods and cutting back on red meat and processed snacks may not just lower your cholesterol, it might also influence whether your arteries develop the kind of plaques that are most likely to trigger heart attacks.