THE ALLIANCE FOR POTATO RESEARCH AND EDUCATION (APRE)
A new study recently published in Frontiers in Nutrition has challenged the tendency in nutrition research to separate starchy vegetables from their non-starchy counterparts and categorize them with foods delivering lower nutritional value.
Whole grains, legumes, non-starchy vegetables, and fresh fruit are typically considered to be higher quality carbohydrate foods, yet starchy vegetables, including white potatoes, are typically categorized in nutrition studies with sweets, candy, and soda, when researchers assess subjects’ food intake and associations with health outcomes. This new study used five separate indices to assess carbohydrate quality to determine if this categorization of starchy vegetables is an accurate reflection of the foods’ nutritional value.
Four of those carbohydrate quality indices (CQIs), based on carbohydrate to fiber and sugar ratios, had been developed and validated in 2021 by researchers at Tufts University. The fifth index, the new carbohydrate food quality scoring system (CFQS-4) recently developed by scientists working with the Quality Carbohydrate Coalition, also incorporated potassium and sodium. All five indices had been previously published.
The new study screened more than 2,400 carbohydrate-containing foods for carbohydrate quality. Recognizing that carbohydrates are present in a great variety of plant-based foods, the study expanded the range of food groups to include refined and whole grains, snacks and sweets, but also starchy and non-starchy vegetables, legumes and whole fruit. Starchy vegetables had not been tested before using the new carbohydrate quality metrics.
“Starchy vegetables are often not even viewed as vegetables and are routinely removed from high-quality food categories in nutrition research. That view is now challenged by the new nutrient profiling methods” said lead author Adam Drewnowski, PhD, researcher at the Center for Public Health Nutrition at the University of Washington. “Now that we have formal measures of carbohydrate quality that we can agree on, it is time to put starchy vegetables back where they belong. There is no need to demonize ‘bad’ vegetables when the American diet could do with more produce of all kinds.”
“I certainly hope that the Dietary Guidelines Advisory Committee take note as they design a healthy diet at an affordable cost,” Dr. Drewnowski added
The four CQIs and the CFQS-4 had been published before but had not been applied to evaluating carbohydrate quality of legumes, vegetables and fruit. The five indices were based on specific rations of carbohydrate, fiber, free sugar, potassium and sodium. Whereas potassium is under-consumed, sodium is consumed to excess. Both nutrients are recognized as ‘nutrients of public health concern’ in the Dietary Guidelines for Americans.
Based on the four CQI scores, nearly half of the 210 starchy vegetable foods analyzed in the study met the CQI definitions for high-quality carbohydrates, which were defined as those with evidence-based cut-off values for fiber and free sugar. Meanwhile, extremely few snacks and sweets (1-5%), candy and desserts (0-5%) and refined grain foods (10-12%) could be considered high-quality, according to the same CQI measures.
Based on the more comprehensive CFQS-4 model, which also accounts for foods’ potassium and sodium content, starchy vegetables scored most closely to non-starchy vegetables and fruit versus sweets and soda.
“I hope that this simple application of existing carbohydrate quality metrics to a wide spectrum of carb-containing foods will show that starchy vegetables belong with the high-quality carbohydrate foods” said Drewnowski. “Our application of other nutrient profiling has previously shown that potatoes and beans led the pack in terms of nutrients per penny. This latest demonstration clearly shows that all vegetables should remain together when it comes to both research and dietary guidance.”
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