Heart disease and type 2 diabetes are among the top causes of death and disability in the United States. Eating a healthy diet rich in plant-based foods can help prevent or delay these diseases. New research highlights a specific component in these foods, called phytosterol, as a key factor in reducing risk.
The study found that people who ate more phytosterols—a plant compound similar in structure to cholesterol—had a significantly lower risk of heart disease and type 2 diabetes. Higher phytosterol intake also linked to better insulin regulation, less inflammation, and changes in the gut microbiome that may support a healthy metabolism.
Fenglei Wang, a research associate at Harvard T.H. Chan School of Public Health, said, “Our findings support the advice to follow a plant-based diet rich in vegetables, fruits, nuts, and whole grains. This information can help people make healthier food choices.”
Wang presented the study at NUTRITION 2025, the annual meeting of the American Society for Nutrition, held May 31 to June 3 in Orlando, Florida.
Previous studies showed that phytosterols can lower LDL, or “bad,” cholesterol. However, those studies often involved high doses of phytosterols beyond normal dietary intake. This new research is among the first to show benefits from typical dietary levels of phytosterols.
The researchers combined data from three long-term studies with over 200,000 U.S. adults, mostly nurses and health professionals, about 80% of whom were women. Over a follow-up of up to 36 years, more than 20,000 participants developed type 2 diabetes, and nearly 16,000 developed heart disease.
Using food questionnaires, the team estimated how much phytosterol each participant consumed. Those in the highest group for phytosterol intake typically ate about 4-5 servings of vegetables, 2-3 servings of fruit, two servings of whole grains, and half a serving of nuts daily.
Compared to those in the lowest group, people in the highest phytosterol group were 9% less likely to develop heart disease and 8% less likely to develop type 2 diabetes. Similar results were found for the specific phytosterol β-sitosterol, but not for other types like campesterol or stigmasterol.
The study also analyzed blood samples from over 11,000 participants for metabolites, and from over 40,000 for metabolic markers. They found that total phytosterols and β-sitosterol were linked to positive metabolic changes related to heart disease and diabetes, suggesting how phytosterols might protect health.
Wang explained, “Our results suggest phytosterols may reduce risk by improving insulin activity, lowering inflammation, and affecting metabolism related to diabetes and cardiovascular disease.”
In a smaller group of 465 participants, researchers studied the gut microbiome and found certain microbial species and enzymes connected to higher phytosterol intake. One species, Faecalibacterium prausnitzii, may help break down phytosterols, influencing metabolism and disease risk.
The researchers noted the study is observational and cannot prove cause and effect. However, the combined evidence from diet data, biomarkers, and microbiome analysis makes the findings more convincing.
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