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 report on the work 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, trace elements, dietary fiber, polyphenols), but due to their high starch content, they have a high glycemic index and load, and various cooking methods can reduce the micronutrient content and lead to the formation of hazardous compounds. All this raises concerns about the possible 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) who 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 divided 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 equal amount of mashed potatoes, and 115–170 grams of French fries. Chips were not included in the analysis, since potato and corn chips were combined in the questionnaires. Data were processed using Cox proportional hazards models adjusted 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. It included 10 prospective cohort studies, to which the three above-mentioned cohorts were added. Five of them 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 rest included people of both sexes. The total number of participants exceeded 587,000, and the observation period ranged from four to 27 years.
During the observation period, type 2 diabetes developed in almost 22.3 thousand participants in three American cohorts. The analysis of American cohorts showed that with an increase in the consumption of any potato for every three servings per week, the risk of developing type 2 diabetes increases by five percent. This was due to French fries, the increase in consumption of which for every three servings per week was associated with a 20 percent increase in risk. The consumption of baked, boiled and mashed potatoes did not significantly correlate with the 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) can reduce the risk of diabetes by eight percent for potatoes in general, by four 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 43.5 thousand participants, and the results were similar. With an increase in the consumption of any potato for every three servings per week, the risk of developing diabetes increased by three percent, and fried potatoes, including French fries, by 16 percent. When calculating the replacement of three servings per week of any, unfried and fried potatoes with whole grain products, the risk of developing the disease decreased by seven, five and 17 percent, respectively.
Thus, systematic consumption of French fries, but not baked, boiled and mashed potatoes, is associated with a significant increase in the risk of developing type 2 diabetes. At the same time, such risk depends on what a person uses instead of potatoes - it decreases with the use of whole grain products and slightly increases with a preference for 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.
