- A large study found that three servings of French fries per week were linked with a 20% higher risk of type 2 diabetes.
- Boiled, baked and mashed potatoes were not linked with the same significant increase in risk.
- Replacing potatoes with whole grains was linked with lower diabetes risk, while replacing them with white rice was linked with higher risk.
Potatoes often get blamed for raising diabetes risk, but a new study suggests the cooking method matters.
Researchers analysed data from more than 205,000 US health professionals followed for nearly 40 years.
At the start, participants did not have diabetes, heart disease or cancer.
Their diets were assessed every four years.
During follow-up, 22,299 people developed type 2 diabetes.
Overall, every three servings of potatoes per week were linked with a 5% higher rate of type 2 diabetes.
But when researchers looked at preparation method, French fries stood out.
Three weekly servings of French fries were linked with a 20% higher risk of type 2 diabetes.
Boiled, baked or mashed potatoes were not linked with a statistically significant increase.
That is an important difference.
A boiled potato and a portion of fries are not the same food in practice.
French fries are usually cooked in oil, often eaten with salt and may come as part of a wider fast-food pattern.
The study also looked at what people ate instead of potatoes.
Replacing potatoes with whole grains was linked with lower type 2 diabetes risk.
Replacing French fries with whole grains was linked with a 19% lower rate.
But replacing potatoes with white rice was linked with higher diabetes risk.
This suggests the question should not just be “are potatoes good or bad?”
It should be “how are they cooked and what are they replacing?”
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The study was observational, so it cannot prove French fries directly cause diabetes.
But the pattern is plausible.
For people worried about diabetes risk, the advice is not to fear all potatoes.
It is to keep fries occasional and prioritise whole grains, vegetables and less processed carbohydrate sources.
