A new study published in the British Medical Journal has found that consuming three portions of French fries per week increases the risk of developing type 2 diabetes by around 20 percent. The research, led by teams from Harvard University and the University of Cambridge, analyzed decades of dietary and health data, revealing that fried potatoes are significantly more harmful than other forms of potato consumption.
Type 2 diabetes, often associated with obesity and physical inactivity, affects millions worldwide and can lead to serious health complications. While potatoes are rich in vitamin C, magnesium, and fiber, they also contain high levels of starch. Previous research has linked potato consumption in general to diabetes risk, but few studies have closely examined how preparation methods impact that risk.
Large-Scale Analysis Reveals Preparation Matters
The researchers examined data from U.S. cohort studies conducted between 1984 and 2021, involving over 205,000 initially healthy healthcare workers. Participants completed detailed dietary surveys every four years, and during nearly 40 years of follow-up, approximately 22,300 developed type 2 diabetes.
When all forms of potato preparation were considered together, eating three portions per week was linked to only a 5% increase in diabetes risk. However, when focusing on French fries alone, the increase jumped to 20%. The authors attribute this difference to the fats, salt, and harmful compounds formed during frying. In contrast, boiled, baked, or mashed potatoes showed no significant association with higher diabetes risk.
The study also included long-term data from other countries, strengthening the findings, though the researchers noted that the results may not apply equally across all population groups.
Whole Grains Recommended as a Healthier Alternative
Replacing potatoes, particularly fried ones, with whole grain foods appears to reduce the risk of type 2 diabetes. The study found that consuming three portions of whole grain products per week was associated with an 8% lower risk compared to potatoes, and a 19% lower risk when replacing French fries specifically. Substituting with white rice, however, did not show the same benefits.
While the researchers cautioned that the observational nature of the study prevents them from establishing a direct cause-and-effect relationship, the results align with current dietary guidelines that recommend prioritizing whole grains over refined carbohydrates or fried foods.
Balanced Approach Still Possible
In an accompanying commentary, Danish researcher Daniel Ibsen of Aarhus University and Yanbo Zhang of the Albert Einstein College of Medicine emphasized that potatoes remain a nutritious and environmentally sustainable carbohydrate source when consumed in less processed forms.
“Potatoes can be part of a healthy and sustainable diet, but whole grain products should take priority,” the authors noted. They stressed that any health benefits from reducing potato consumption depend on replacing them with nutrient-rich alternatives, rather than less healthy substitutes.
The study adds to growing evidence that not all carbohydrates, and not all potatoes, are equal in their impact on long-term health, particularly about type 2 diabetes prevention.
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