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Researchers compared participants who ate non-fried potatoes with those who ate refined grains, to find out whether potatoes are bad carbs.
In many popular diet plans, such as keto and paleo, the plain white potato gets a bad rap. Deemed as a “starchy” vegetable, they are either prohibited in these diet plans altogether or are at least limited to one serving per day – are potatoes really so-called “bad” carbs, or are they good for you?
How are the potatoes prepared?
Of course, the most popular form of potatoes, French fries, is obviously not the healthiest. Potato chips will not rank very high in the list of diet foods either. But these forms of potato are deep fried and full of calories and the unhealthy type of fat. Studies show that diets with a higher intake of fried potatoes are associated with a higher incidence of diabetes and heart disease.
Just how unhealthy is the tasty tater? Are potatoes bad carbs?
Researchers at Pennsylvania State University recently assessed the potatoes’ nutritional value against diets that contain refined grains such as bread, pasta, and rice. The study was published in the British Journal of Nutrition.
Researchers recrutied 50 generally healthy adults between 25 and 75 years of age to participate in the study. There were 34 females and 16 males. The study consisted of two four-week diet periods followed by a two-to-four-week rest period.
Before the study, the participants’ weight, pulse rate, and blood sugar data were collected. Also, at the beginning of the study and after each diet period, blood pressure data were monitored. Participants were randomly assigned to a ‘refined grain diet’ group or a ‘potato diet group’.
In the potato diet group, participants replaced one of their normal starchy side dishes with either a steamed or a baked potato. Boiled potatoes were not used because boiling removes nutrients. Each potato side dish contained about 200 calories.
In the refined grain diet group, participants ate a refined grain side-dish such as pasta, rice, or white bread with their main meal once per day. When the four-week diet period was over, the participants had a two-week rest period. They then switched to the opposite diet group for four weeks and then a four-week rest period.
Steamed or baked potato didn’t increase blood sugar
The researchers found that daily consumption of a steamed or baked potato did not increase participants’ blood sugar and had no effect on their risk for heart disease. The diet quality of the potato diet was better than that of refined grains. Potassium and fiber consumption was also higher for participants in the potato diet. The researchers also found no evidence that the potato diet caused its participants to gain weight.
The study was limited by the number of participants, intervention time, and the participants self-reporting their data. The results of the study do suggest that not only can potatoes be part of a balanced and healthy diet, but they might not be bad carbs either.
Reference: Johnston E, Petersen K, Kris-Etherton P. Daily intake of non-fried potato does not affect markers of glycemia and is associated with better diet quality compared to refined grains: A randomized, crossover study in healthy adults. British Journal of Nutrition. 2020:1-29. doi:10.1017/s0007114520000252;
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