French fries are a favorite food of Americans. However, a recent large study found that eating 3 or more servings of French fries a week is associated with a 20% increased risk for developing type 2 diabetes. The same risk is not found with eating other forms of potatoes, such as mashed, baked, or boiled.
There was a dose response effect with French fry consumption - the more servings a person ate per week, the greater the risk of developing type 2 diabetes. For 3 servings per week, there was a 20% increase in type 2 diabetes, but consuming 5 or more servings of French fries weekly was associated with a 27% higher rate of type 2 diabetes (when compared to people who rarely ate French fries, that is, less than 1 serving per week).
Also, replacing 3 servings per week of any form of potatoes with whole grains lowers the risk of developing type 2 diabetes, but not replacing potatoes with white rice. White rice is linked to an increased risk for type 2 diabetes.
Why is that? There is lots of fiber in whole grains and in whole potatoes (especially the skin), which is not present in French fries and white rice. Whole potatoes are also a good source for a number of nutrients, such as vitamin C, potassium, polyphenols, and magnesium. Many studies find that eating a diet rich in fruits, vegetables, whole grains, legumes, and nuts is linked to a lower incidence of type 2 diabetes.
From Science Daily: What scientists discovered about french fries and diabetes
Eating three servings of French fries a week is associated with a 20% increased risk of developing type 2 diabetes, but eating similar amounts of potatoes cooked in other ways -- boiled, baked or mashed -- does not substantially increase the risk, finds a study published by The BMJ on August 6.
What's more, replacing any form of potatoes with whole grains was associated with a lower type 2 diabetes risk, but swapping them for white rice was linked to an increased risk, the results show.
... researchers investigated the association between intake of potatoes prepared by different methods (boiled, baked, or mashed versus French fries) and risk of type 2 diabetes. They also looked at the impact on health of replacing potatoes with other major carbohydrates, such as whole grains and rice.
Their findings are based on more than 205,000 health professionals from three large US studies carried out between 1984 and 2021. Participants were free of diabetes, heart disease or cancer and completed detailed food questionnaires every four years. During almost 40 years of follow up, 22,299 people were diagnosed with type 2 diabetes.
After adjusting for lifestyle and dietary factors related to diabetes risk, the researchers found that for every three weekly servings of total potato, the rate of type 2 diabetes increased by 5% and for every three weekly servings of French fries, the rate increased by 20%. However, similar intake of baked, boiled, or mashed potatoes was not associated with a significantly increased risk.
Replacing three weekly servings of total potato with whole grains lowered the type 2 diabetes rate by 8%. Substituting baked, boiled, or mashed potatoes with whole grains lowered the rate by 4%, and replacing French fries lowered the rate by 19%.
In contrast, replacing total potatoes or baked, boiled, or mashed potatoes with white rice was associated with an increased risk of type 2 diabetes.
Nevertheless, they conclude: "Our findings underscore that the association between potato intake and type 2 diabetes risk depends on the specific foods used as replacement. The findings also align with current dietary recommendations that promote the inclusion of whole grains as part of a healthy diet for the prevention of type 2 diabetes."