US scientists show how many portions of French fries a week appear to be harmful to our health and give a raft of advice on how we should get our carbs
French fries increase our diabetes risk while baked and mashed potatoes do not, research shows.
A study tracking the diet of 205,000 US health workers has indicated how we consume potatoes dictates whether they could be healthy or not. The findings, published in the British Medical Journal, relied on repeated diet surveys conducted over four decades, during which 22,000 people were diagnosed with type 2 diabetes.
High intake of baked, boiled or mashed potatoes were not linked to an increased risk of type 2 diabetes, but people who had a higher consumption of French fries – at least three weekly servings – had a 20% increased risk. And those who eat fries five times a week had a 27% increased risk.
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Research author Seyed Mohammad Mousavi, of the Harvard T.H. Chan School of Public Health in Boston, said: “The risks associated with potato intake varied by cooking method. The association between higher potato intake and increased Type 2 diabetes risk is primarily driven by intake of French fries. Higher intake of French fries, but not combined baked, boiled, or mashed potatoes, was associated with a higher risk.”
The international team of researchers, including an expert from Cambridge University, suspect the reason for the difference is in the cooking processes involved.
French fries are made by cutting potatoes into strips, frying them in oil and then seasoning them. Often they are blanched in hot oil to remove excess moisture and enhance crispiness before being fried again. Additives like dextrose and sodium acid pyrophosphate may be used to maintain colour and prevent browning during processing.
Commenting on the findings, Associate Professor Daniel Ibsen, of Aarhus University in Denmark, said: “This finding also corresponds to the observed associations between high intake of ultra-processed foods and high risk of type 2 diabetes – French fries are often ultra-processed whereas baked, boiled, or mashed potatoes are often minimally processed.”
The research team also found that replacing three servings of potatoes each week with whole grains was found to lower the risk of type 2 diabetes by 8%. Examples of whole grains include brown rice, whole wheat bread, oats, barley, quinoa and buckwheat. But replacing potatoes with white rice was associated with an increased risk of type 2 diabetes, they found.
Study author Seyed Mohammad Mousavi added: “Replacing any form of potatoes, particularly French fries, with whole grains is estimated to lower the risk of Type 2 diabetes, reinforcing the importance of promoting whole grains as an essential part of a healthy diet.
“With their relatively low environmental impact and their health impact, potatoes can be part of a healthy and sustainable diet, though whole grains should remain a priority.”
Dr Faye Riley, a spokeswoman at charity Diabetes UK, said: “This research shows that the link between potatoes and type 2 diabetes isn’t as clear-cut as it might seem. Type 2 diabetes is a complex condition, with many factors influencing its development, including genetics, age and ethnicity.
“Diet is just one part of the picture, but this study suggests that how food is prepared can make a difference and reinforces the advice to prioritise whole grains and cut back on fried or heavily processed foods as a way to support a balanced diet and reduce your risk.”