Diabetes risk hinges on how you cook potatoes

By Dr. Priyom Bose, Ph.D.Reviewed by Lauren HardakerAug 11 2025

New evidence from decades of data reveals why your method of potato cooking, or what you swap it for, could make a big difference to your long-term diabetes risk.

Study: Total and specific potato intake and risk of type 2 diabetes: results from three US cohort studies and a substitution meta-analysis of prospective cohorts. Image credit: Alexeysun/Shutterstock.com

A study in the BMJ evaluated whether total and individual potato intake differentially impacts type 2 diabetes (T2D) and assessed the effect of replacing potatoes with whole grains and other major carbohydrate sources on T2D.

Potato consumption and T2D risks

Potatoes are the third most consumed food, providing substantial daily energy. They contain various nutrients, such as vitamin C, fiber, potassium, polyphenols, and magnesium. However, the high starch content of potatoes can increase the glycemic index, thereby elevating the risk of metabolic diseases. Furthermore, specific cooking methods also decrease their nutrient content.

Although previous studies have investigated the association between potato consumption and T2D, their findings have remained inconclusive. For instance, some studies have shown a positive correlation between potato consumption and T2D, while others have observed an inverse association. A US-based individual participant data (IPD) meta-analysis revealed no association between T2D and total potato intake but a modest increased risk with fried potato intake.

Inconsistency in the effect of T2D was observed when potatoes were replaced with alternative carbohydrates, whole grains, and non-starchy vegetables. These inconsistencies in research findings could stem from variations in methodology, regional differences in potato consumption, and inadequate control for confounding variables.

Considering the contradictory findings regarding the association between potato consumption and T2D, long-term observational studies with standardized methodologies and high-quality data are needed.

About the study

In the last four decades, the Nurses’ Health Study (NHS), Nurses’ Health Study II (NHSII), and Health Professionals Follow-up Study (HPFS) have repeatedly assessed the impact of diet and other variables on health.  The current study utilized the above three cohorts to evaluate the effects of total and specific potato intake and T2D risk and compare the associations of potatoes and whole grains with T2D risk.

The NHS, NHSII, and HPFS cohorts were initiated in 1976, 1989, and 1986. They contain a sample of male and female registered nurses between 25 and 75.

Participants in these cohorts were initially surveyed using questionnaires, which obtained information about their new diagnosis of T2D, lifestyle, diet, and health. Dietary intake was reassessed every two to four years, and cumulative average intake was used in the main analysis to better capture long-term patterns. Those with incomplete information about age or potato intake were excluded.

Participants were asked whether they consumed potatoes as baked, boiled, mashed, French fries, or as potato or corn chips. Portion sizes were adjusted over time using weights from the National Health and Nutrition Examination Survey (NHANES). Total potato intake was measured by adding the servings of baked, boiled, or mashed potatoes and French fries, excluding potato or corn chips because they were grouped in the questionnaire and could not be separated.

Study findings

A total of 22,299 individuals were diagnosed with T2D. Men and women who reported higher potato intake were found to be less likely to be physically active, take supplements, and have a higher total energy intake. In all three cohorts, the average frequency of consuming boiled, baked, or mashed potatoes was considerably higher than that of French fries. A pooled analysis revealed a positive but modest association between total potato intake and a higher risk of T2D.

Participants who reported consuming seven or more servings of total potatoes weekly had a 12% higher risk of T2D than those with less than one serving weekly. An increase of three servings weekly of total potatoes elevated the risk of developing T2D by 5%. However, this risk varies depending on the cooking method.

Compared to those who almost never consumed French fries, those who consumed five or more servings weekly showed a 27% increased risk of T2D. Every three additional servings of French fries weekly was associated with a 20% higher incidence of T2D. Dose-response analysis revealed a linear association, indicating that a steady increase in French fry intake increases the risk of T2D.

After multivariable adjustment, no increase in T2D incidence could be linked to baked, boiled, or mashed potato intake or potato or corn chip intake. An increased weekly intake of baked, boiled, or mashed potatoes and potato or corn chips also exhibited a statistically null T2D risk.

Replacing three servings of total potatoes per week with whole grains resulted in an 8% lower T2D rate. More specifically, substituting baked, boiled, or mashed potatoes with whole grains was estimated to lower T2D incidence by 4%. The current study also indicated that substituting total potatoes with non-starchy vegetables, replacing French fries with legumes, starchy and non-starchy vegetables, and even refined grains, leads to a reduced T2D incidence. Replacing total or baked, boiled, or mashed potatoes with white rice was associated with an increased risk of T2D.

The current study conducted a meta-analysis that included 13 prospective cohort studies (out of 503 screened) related to potato intake and the risk of T2D. Out of 587,081 participants across the selected studies, 43,471 individuals were diagnosed with T2D during follow-up, ranging from 4 to 27 years. The T2D risk increased by 16% for each three-serving-per-week increment of fried potatoes. A much weaker association was observed between T2D incidence and the consumption of non-fried potatoes.

Additional analyses showed that body mass index (BMI) mediated about 50% of the association between French fry intake and T2D risk. The association between total potato intake and T2D was strongest 12 to 20 years before diagnosis, and results were more robust when using cumulative average dietary intake rather than baseline-only measurements.

Conclusions

The current study found that French fry consumption primarily drove the association between total potato intake and the risk of T2D. Substitution analysis indicated that replacing total potatoes with whole grains reduces the risk of T2D. However, replacing boiled, baked, or mashed potatoes with white rice increased the risk of T2D. These findings highlight that risk varies by cooking method, the food replacing the potatoes, and individual factors such as BMI.

Download your PDF copy now!