American, British, and Kuwaiti researchers conducted a meta-analysis of prospective cohorts and found that regular consumption of French fries, but not other potato dishes, was associated with a dose-dependent increase in the risk of developing type 2 diabetes. The study was published in BMJ.
Potatoes are the third most consumed food crop (and the first among non-grain crops). Like other vegetables, they contain a variety of nutrients (vitamins, microelements, dietary fiber, polyphenols). However, due to their high starch content, they have a high glycemic index and glycemic load. Various cooking methods can reduce micronutrient content and lead to the formation of hazardous compounds. All this raises concerns about the potential negative impact of potato consumption on health, but this issue has not been sufficiently studied.
Walter Willett of the Harvard T.H. Chan School of Public Health and colleagues used data from more than 205,000 adult participants from the prospective US cohorts NHS (1984–2020), NHS II (1991–2021), and HPFS (1986–2018). They were free of cancer, angina, heart attacks, strokes, coronary artery bypass grafting, and diabetes at enrollment and had complete dietary data collected every 2–4 years of follow-up (a total of 5.1755 million person-years). Potato and potato product consumption was categorized into nine categories, ranging from "never or less than once a month" to "six or more servings per day." A serving was defined as a medium-sized potato, an equivalent amount of mashed potatoes, and 115–170 grams of French fries. Chips were not included in the analysis, as the questionnaires combined potato and corn chips. Data were processed using Cox proportional hazards models, adjusting for confounding factors.
The researchers also conducted a meta-analysis of publications on the topic from the PubMed/Medline, Web of Science, and Embase databases up to July 2024. They included 10 prospective cohort studies, to which the three aforementioned cohorts were added. Five of these were from the United States, four from Europe, and two each from Asia and Australia. Three included only women, one included only men, and the remaining included people of both sexes. The total number of participants exceeded 587,000, with follow-up periods ranging from four to 27 years.
During the observation period, type 2 diabetes developed in nearly 22,300 participants in three American cohorts. The analysis of the American cohorts showed that for every three servings per week of any potato consumed, the risk of developing type 2 diabetes increased by 5%. This increase was driven by French fries, with every three servings per week increasing consumption associated with a 20 percent increase in risk. Baked, boiled, and mashed potato consumption were not significantly associated with risk. The researchers also calculated that replacing three servings of potatoes per week with whole grain products of similar calorie content (but not white rice) could reduce the risk of diabetes by 8 percent for potatoes overall, by 4 percent for baked, boiled, and mashed potatoes, and by 19 percent for French fries.
In 13 global cohorts included in the meta-analysis, type 2 diabetes was diagnosed in 43,500 participants, and the results were similar. For every three servings per week consumed in any potato, the risk of developing diabetes increased by three percent, and for every three servings per week consumed in fried potatoes, including French fries, the risk increased by 16 percent. When replacing three servings per week of any, unfried, and fried potatoes with whole grains, the risk of developing the disease decreased by seven, five, and 17 percent, respectively.
Thus, regular consumption of French fries, but not baked, boiled, or mashed potatoes, is associated with a significantly increased risk of developing type 2 diabetes. This risk depends on what a person eats instead of potatoes: it decreases with whole grains and increases slightly with white rice.
Previously, Norwegian scientists conducted a long-term prospective cohort study and found that frequent consumption of potatoes, primarily boiled, is associated with a significant reduction in overall and cardiovascular mortality.
