A new study suggests that eating four to six servings of whole grains every day can improve several key risk factors for heart disease. The research was published in the European Heart Journal.
The study is a systematic review and meta-analysis. This means researchers combined the results of many existing studies to get a clearer picture. In this case, they looked at 87 clinical trials. These trials examined how eating whole grains affects the risk of cardiovascular disease.
The findings show that a diet rich in whole grains may help prevent heart disease. It does this by lowering body weight, blood pressure, and levels of cholesterol and blood sugar.
Who Led the Research
Dr. Helda Tutunchi from Tabriz University of Medical Sciences in Iran led the study. She explained that earlier population studies had already linked whole grains to better heart health. However, results from clinical trials had been inconsistent. This left a key question unanswered: how much whole grain should a person eat to actually see benefits?
To find out, her team combined data from every relevant randomized controlled trial they could locate. Their goal was to pinpoint the amount of whole grain linked to the biggest health improvements.
What the Data Showed
The analysis covered more than 6,500 people. These participants came from trials conducted in Asia, Europe, the United States, Canada, Australia, and Brazil.
The results were clear. Eating more whole grains was linked to lower body weight, smaller waist size, and reduced blood pressure. It was also linked to lower total cholesterol, lower LDL cholesterol (often called “bad” cholesterol), and lower triglycerides. In addition, participants showed improved blood sugar levels and reduced interleukin-6, a marker of inflammation in the body.
Some benefits appeared in people eating just 30 to 40 grams of whole grain per day. But the most significant improvements showed up in people eating 60 to 100 grams daily. That amount is roughly equal to four to six servings. Examples include a bowl of oatmeal, a sandwich made with whole-grain bread, and a serving of brown rice.
Dr. Tutunchi described this as the largest and most thorough review of randomized trials on whole grains and heart health to date. Unlike earlier reviews, her team focused specifically on identifying the ideal daily amount. They also assessed how reliable the evidence was. For several outcomes, including body weight, waist size, and total cholesterol, the evidence was rated as highly reliable.
However, she noted an important limitation. Most trials in the review lasted only about eight weeks on average. Because of this short timeframe, it’s unclear whether these benefits last over many years. She also pointed out that few studies tested very high intakes, above 140 grams per day. This means the effects of eating that much whole grain remain unknown.
Dr. Tutunchi added that increasing whole grain intake is a simple, low-cost strategy. It could work alongside other lifestyle changes and medical treatments. She emphasized that current intake levels, around 60 to 100 grams daily, sit near the upper range of existing dietary guidelines. This doesn’t necessarily mean guidelines need to change. But it does support efforts to help people eat more whole grains and reach the higher end of current recommendations.
She also highlighted an intriguing pattern. Whole grains don’t seem to work through one single powerful effect. Instead, they appear to offer many small improvements across different areas, including cholesterol, blood pressure, blood sugar, body fat, and inflammation. On their own, each improvement seems modest. However, when combined, these improvements could lead to a significant decrease in the risk of long-term heart disease. However, longer studies are necessary to confirm these findings, as the trials did not directly track heart attacks or strokes.
An editorial published alongside the study, written by Dr. Cecilie Kyrø of the Danish Cancer Institute and colleagues, added further context. They noted that researchers have suspected a link between refined grains and Western diseases for more than fifty years. Whole grains, they explained, retain all three parts of the grain kernel: the bran, the germ, and the endosperm.
The editorial praised the new study for including a dose-response analysis. This analysis identifies the precise amount required to achieve results. According to the commentary, intakes of 60 to 100 grams per day were clearly tied to better heart health markers.
The authors also noted that current US dietary guidelines recommend two to four servings per day. Based on this new evidence, that number may need to move higher. They stressed that making whole grain foods affordable and accessible should be a public health priority, while avoiding heavily processed foods that simply add whole grains as a marketing feature.
