That includes French fries, potato chips and hash browns.
It may be the heated vegetable fats that are to blame. Dr. Bruce Holub of the University of Guelph often assigned students to collect frying fat from fast-food restaurants to feed to rats that promptly died.
The study says there’s nothing wrong with potatoes. It’s the frying that increases health risks.
The United States potato industry countered that the study is misleading because it involved only people with osteoarthritis.
"Fried potatoes consumption is increasing worldwide," warned Dr. Nicola Veronese, lead author of the study and a scientist at the National Research Council in Padova, Italy.
Veronese and his colleagues have been tracking 4,440 people aged 45 to 79 over a period of eight years to study osteoarthritis.
This research team decided to momentarily set aside the main issue of osteoarthritis and look at participants' consumption of potatoes.
Even though most of us may have assumed that fried potatoes could be unhealthy for us, there is "very limited" scientific data on this issue, Veronese said.
Age or sex of participants did not influence the result, but the data showed men were more likely than women and younger participants were more likely than older participants to enjoy the fried food.
The study is observational, meaning the researchers simply tracked the behavior of a group of people and found an association between one behavior -- eating fried potatoes -- and another factor -- early death.
Because it is an observational study, Veronese and his co-authors note it cannot be said that eating fried potatoes directly causes an early mortality -- it would require more research to draw such a firm conclusion.
"Even if it is an observational study, we believe that the cooking oil, rich in trans-fat, is an important factor in explaining mortality in those eating more potatoes," said Veronese.
Yet, he also added that "other important factors," including obesity, a sedentary lifestyle and use of high quantities of salt might also play a role in the early death of those eating two or more portions of fried potatoes each week.
National Potato Council chief executive officer John Keeling, noting that the study was for osteoarthritis and not the general populations, said potatoes are a good food.
He said a medium-sized potato is 110 calories, has no fat, no sodium, no cholesterol, and provides nearly a third of the daily vitamin C requirement with more potassium than a banana.
"How the potato is prepared will impact the calorie, fat and sodium content," said Keeling, however the basic nutrients remain "no matter how it is prepared."
Based on the data in the study, Keeling said, "it is very much a stretch to brand fried potatoes, or any other form of potato, as unhealthy."