The need for nuance in carbohydrate recommendations

A more complex, holistic and non-reductionist approach to defining carbohydrate quality is needed

Peer-Reviewed Publication



Carbohydrates have traditionally been the largest source of energy intake for much of the world’s population1. However, without a standard definition for carbohydrate quality, some foods that contain carbohydrates are often stigmatized based on isolated and reductionist assessment methods that fail to consider their contributions to nutrient intakes and balanced, healthy diets. A new perspective piece, published in Advances in Nutrition, brings to light the pressing need to define carbohydrate quality, to better assess the value of nutrient-dense carbohydrate-containing foods in healthy lifestyles. Ultimately, the authors call for a more holistic approach to carbohydrate guidance to address the complex needs of both people and the planet.

“To date, terms like ‘good carbs’ and ‘bad carbs’ have been inconsistently assigned to a plethora of foods based on overly simplistic and narrowly focused measures, like glycemic index (GI) or fiber content,” states Rebekah Schulz of University of Minnesota and perspective piece coauthor. “While these aspects can be individual pieces of the puzzle, they don’t reflect the full picture of carbohydrate quality. For example, while GI may be a useful index in isolation, it is not representative of real-life dietary intake when carbohydrates are consumed with other foods, nor does it account for a food’s overall nutrient content or planetary impact.”

This paper addresses the strengths and weaknesses of current methods used to assess carbohydrate quality, proposes additional indices to include in a standardized quality carbohydrate definition, and defines research questions for further exploration. Within the perspective piece, authors analyzed various existing frameworks for carbohydrate quality and weighed the pros and cons of indexing based solely on measures such as GI, whole grain foods, fiber and added sugar.

The authors concluded that, “for truly relevant and applicable dietary guidance, the framework should focus on nutrient contributions and take into account various ways to measure and analyze nutrients, as well as be nimble to adjust for new research findings and data.”

Carbohydrate Quality: Spotlight on Fruits & Vegetables

The authors also note that current approaches to assessing carbohydrate quality may lead to even greater consumer confusion of nutritional recommendations for specific foods, including fruits and vegetables. Given that one in 10 Americans fall short of meeting their fruit and vegetable requirements2, it’s important that a holistic and standardized approach to dietary carbohydrate guidance is established to promote both human and planetary health as effectively as possible.

“Potatoes are one example of a food that tends to be misclassified or misunderstood based significantly on their GI value – even though preparation techniques and common consumption methods are not reflected accurately within a GI value,” points out Joanne Slavin, PhD, RD of University of Minnesota and perspective piece coauthor. “Potatoes are a nutrient-dense vegetable that provide several important nutrients – like fiber, potassium, Vitamin C and resistant starch – to Americans’ diets and have been consumed for centuries as a main staple in various cultures. Additionally, potatoes serve an important role in food security in developing countries.”

A Forward-Looking Solution: Establishing a Standardized Carbohydrate Quality Metric

Overall, there is a general shift away from one-directional and overly simplified dietary guidance, as any food or nutrient can have a place as part of a healthy lifestyle. Thus, to best define high quality carbohydrates, the authors call for a standardized carbohydrate quality metric, such as an algorithm that encompasses a broader spectrum of factors.

“There is a need to provide easy tools grounded in strong science,” added Schulz. “When consumers need to make a quick choice about carbohydrate-containing foods, they should feel comfortable knowing that there is a comprehensive, science-backed formula or algorithm behind-the-scenes helping guide this decision.”

The authors propose several potential quality indices to be considered when assessing carbohydrate quality:

  • Whole-grain, fiber, and added-sugar content
  • Ratios of total carbohydrate to fiber and added sugar to fiber in a food
  • Protein quality
  • Degree of processing
  • Environmental impact of a food

“As dietary guidance rightly moves away from isolated nutrient recommendations toward broader and more flexible dietary patterns, it’s clear we need to better define the quality underpinnings of these patterns, including carbohydrates,” notes Slavin. “By establishing an algorithm to assess carbohydrate quality, the result would positively impact both health and environmental outcomes and create consistent ways to measure intake across populations.”


The perspective piece, “Perspective: Defining Carbohydrate Quality for Human Health and Environmental Sustainability,” is published in Advances in Nutrition (https://doi.org/10.1093/advances/nmab050). Authors include Rebekah Schulz and Joanne Slavin, PhD, RD, University of Minnesota. The authors reported no funding received for this work. Joanne Slavin has received prior funding from Potatoes USA.


1 FAO. FAOSTAT. Available from: http://www.fao.org/faostat/en/#data/QC

2 Lee-Kwan SH, Moore LV, Blanck HM, Harris DM, Galuska D. Disparities in State-Specific Adult Fruit and Vegetable Consumption — United States, 2015. MMWR Morb Mortal Wkly Rep 2017;66:1241-1247. DOI: http://dx.doi.org/10.15585/mmwr.mm6645a1 external icon


Advances in Nutrition



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People with type 2 diabetes need not avoid eating potatoes based on glycemic index

New study findings show that people with type 2 diabetes can better maintain overnight glycemic control when high Glycemic Index (GI) potatoes are included in an evening meal versus low GI basmati rice

Peer-Reviewed Publication


People with type 2 Diabetes (T2D) are frequently told to avoid eating potatoes, and other high Glycemic Index (GI) foods, because of the longstanding perception that these foods make it difficult to control blood sugar levels. This is especially problematic during the night when blood sugar tends to spike — a phenomenon that has been associated with cardiovascular disease and endothelial disfunction. However, for the first time, a rigorously controlled clinical trial, including 24 adults with T2D, demonstrates that GI is not an accurate surrogate for an individual’s glycemic response (GR) to a food consumed as part of an evening meal. Specifically, the findings published in Clinical Nutrition show that participants had a better ‘nocturnal’ GR when they ate a mixed meal with skinless white potatoes compared to an isoenergetic and macronutrient-matched mixed meal that included a low GI carbohydrate food — basmati rice.

“Despite its frequent use among nutrition researchers, GI is not an appropriate tool for understanding how a meal impacts glycemic control; it is a very specific measurement for foods consumed in isolation, typically conducted under controlled laboratory conditions,” says Dr. Brooke Devlin, PhD, the primary investigator, at Australian Catholic University in Melbourne. “It’s rare that people eat foods in isolation, and findings from this study demonstrate how other factors, such as the time of day or food pairings, need to be considered when investigating the GR of mixed meals in individuals with T2D.”

Participants were provided the same breakfast and lunch, but they were randomly assigned to one of four dinners, each including either skinless white potatoes (test meal) prepared in three different ways (boiled, roasted, boiled then cooled then reheated) or basmati rice (control meal). Participants repeated the experiment, with a 9-day break in between each trial, to cycle through all test meals and the control. In addition to having blood samples collected regularly (both immediately after the meal and again every 30 minutes, for 2 hours), participants also wore a continuous glucose monitor overnight to track changes in blood sugar levels while sleeping.

There were no differences between meals in glucose response following the dinner that contained any of the potato dishes or basmati rice. Moreover, participants’ overnight GR was more favorable after eating the evening meal that included any of the high GI potato side dishes compared to low GI basmati rice.

“These findings are contrary to that of observational research and traditional dietary guidance that has led some to believe potatoes are not an appropriate food choice for people with T2D,” added Devlin. “Our study shows high GI foods, like potatoes, can be consumed as part of a healthy evening meal without negatively affecting GR — and while delivering key nutrients in relatively few calories, which is essential for people with T2D.”

This study followed a rigorous methodology by using a randomized crossover design and measuring glucose levels both immediately post-meal and overnight to obtain a better picture of the potatoes’ impact on GR. However, the researchers noted a few limitations: study participants’ baseline GR was assessed for only one evening meal, the dinner provided was larger than what is typically recommended for people with T2D (but in line with Australian eating patterns, at 40 percent of an individual’s total energy intake), and the potatoes’ impact on long-term glycemic control was not assessed.

Despite such limitations, the researchers concluded that “potatoes are a vegetable that is sustainable, affordable and nutrient-dense, and thus, they can play an important role in modern diets irrespective of metabolic health status.”


The article, “Lower nocturnal blood glucose response to a potato-based mixed evening meal compared to rice in individuals with type 2 diabetes,” is published in Clinical Nutrition (doi: https://doi.org/10.1016/j.clnu.2020.09.049.) Authors include Brooke L. Devlin, Evelyn B. Parr, Bridget E. Radford, and John A. Hawley of Australian Catholic University. Funding was provided by the Alliance for Potato Research and Education.


Clinical Nutrition



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Looking for New Ways to Fuel Athletic Performance? Try A Potato

White potatoes are as effective as commercial sports products in exercise fueling, performance and recovery, according to research funded by the Alliance for Potato Research & Education


The Alliance for Potato Research & Education 

Oct 15, 2020, 08:36 ET

CHICAGO, Oct. 15, 2020 /PRNewswire/ — Lab-manufactured sports products are a go-to supplement for many athletes today to maximize performance. But as consumers seek out simpler foods, there is an opportunity to find more diverse, whole food options for athletes. A series of recent studies published in NutrientsJournal of Applied Physiology and European Journal of Applied Physiology, shows promising results for one whole food option – the potato. These three studies demonstrate that whether consumed before, during or after workouts, potatoes positively impact performance and recovery as effectively – and sometimes more effectively than – traditional commercial sports products, such carbohydrate gels.

Nicholas Burd, PhD, primary investigator of the study published in the Journal of Applied Physiology explained, “While ingestion of concentrated carbohydrate gels is commonplace, my study indicates that whole food alternatives – like potatoes – when fed during exercise, are equally effective in supporting athletes’ performance. These promising results complement two studies from my peers, demonstrating that potatoes can also support muscle building and recovery. Collectively, these are important findings as they provide a new wholesome, nutrient-dense and cost-effective option for athletes.”

Together, these studies are a foundational turning point for both the sports and nutrition research world – opening up new fueling and recovery sources for active people and novel research hypotheses for scientists. Specifically, the studies found that:

  • As a significant part of a higher protein diet (above the Recommended Dietary Allowance, or RDA), consuming potato protein isolate throughout the day for two weeks – including before resistance exercise – increased muscle protein synthesis in women (Oikawa et al., Nutrients, 2020)
  • Russet potatoes consumed during a cycling trial improved performance and sustained blood glucose concentrations of trained athletes equal to that of a commercial sports gel (Burd et al., J App Physiol2019)
  • Potato-based products consumed after a 90-minute cycling trial helped replenish muscle glycogen stores and support subsequent exercise as effectively as common sports supplements (Flynn et al., Eur J App Physiol, 2020)

According to Brent Ruby, PhD, FACSM, the lead researcher of the study published in the European Journal of Applied Physiology, finding effective and agreeable foods to fuel exercise is important, and potatoes can fit this bill. “Evidence shows many athletes – especially women – have lower energy intakes and consume less than the recommended amount of daily carbohydrates during intensive segments of training and competitions. In our study, there were no differences in post-exercise muscle glycogen recovery and time trial performance when we compared common sport supplements with a potato-based feeding plan. Moreover, participants rated the post-exercise potato meals as more tasty, satisfying and acceptable compared to commercial sports supplement foods. This indicates that potatoes may be a viable and more economical option to help athletes meet their recovery fueling needs,” explained Dr. Ruby.

Stuart Phillips, PhD, lead researcher for the study published in Nutrients, further added that his research is important for consumers leaning towards plant-based lifestyles. According to Dr. Phillips, “Plant-based diets are certainly growing in popularity. But compared to animal-derived proteins, we know much less about how plant-based proteins can support muscle protein synthesis. Our study demonstrates that potato protein – which is a high-quality protein comparable to animal-based sources and better than many plant sources – is an effective option for exercise regimens and muscle protein synthesis.”

While choosing potatoes as an optimal performance food may seem odd and difficult to execute, the trials demonstrate that various potato forms can be used to support athlete’s needs – ranging from a simple puree to potato pancakes or hash browns. According to Dr. Burd, “Potatoes are a versatile ingredient and there are many different forms of this vegetable for consumers today. While we tested a potato puree in our study, athletes can opt for different potato recipes and on-the-go products as their exercise fuel.”

These three studies provide exciting new evidence to the field of sports nutrition, but they are just a start. According to Dr. Phillips, “Our study is the first, to our knowledge, to examine effects of potato protein supplementation in any capacity in humans – and it clearly showed the inadequacy of the protein RDA. Given that recommendations and personal preferences are shifting to more plant-based, whole food options, we need more research around diverse fuels for athletes and active people alike. Researchers should continue this important work and consider other ways in which potato-derived ingredients, in various forms and situations, can support exercise performance.”

All three studies were funded by the Alliance for Potato Research and Education (APRE). APRE is a not-for-profit organization funded by the potato industry, including potato growers and processors, dedicated to advancing the scientific understanding of the role potatoes play in nutrition and health. Learn more at www.apre.org. 

Media Contact:

Laurie Hainley



SOURCE The Alliance for Potato Research & Education

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Potato power: Spuds serve high quality protein that’s good for women’s muscle

Peer-Reviewed Publication


Researchers from McMaster University have found that the potato, primarily known as a starchy vegetable, can be a source of high-quality protein that helps to maintain muscle.

The findings, reported in the journal Nutrients, highlight the potential benefits of what is considered a non-traditional source of protein, particularly as dietary trends change and worldwide demand has increased for plant-based alternatives to animal-derived sources.

“While the amount of protein found in a potato is small, we grow lots of potatoes and the protein, when isolated, it can provide some measurable benefits,” says Sara Oikawa, a former graduate student in the Department of Kinesiology at McMaster and lead author of the research paper.

The researchers recruited young women in their early twenties who consumed diets containing protein at the recommended dietary allowance (RDA) of 0.8 grams of protein/ per kilogram of weight/day, which would be approximately 60g of protein for the average woman or 70g for the average man.

One group of participants consumed additional potato protein isolate – in the form of a pudding–doubling their intake of the RDA to 1.6g/kg/d. Another group received a placebo.

Researchers found the women who consumed the additional potato protein increased the rate at which their muscles made new protein, while the placebo group did not.

“This was an interesting finding that we did not expect,” says Oikawa. “But it is one that shows the recommended daily allowance is inadequate to support maintenance of muscle in these young women.”

Perhaps more interesting, she says, was that a form of plant-derived protein, which has generally been thought to be of lower quality than animal-derived protein, can have such a beneficial effect.

To study the impact of weightlifting, the research team then instructed both groups of women to exercise only one of their legs.

“This method is a little unconventional but allows us to see the effect within the same person and not have to add more people who were exercising,” said the study principal investigator Stuart Phillips, who is a professor in the Department of Kinesiology at McMaster and a leading researcher on protein and exercise.

In the leg the women exercised, scientists did not find any extra benefits from potato protein.

“That finding, which some may find disappointing, is in line with the rather small effect that protein has compared to exercise itself,” explains Phillips. “In other words, exercise is just such a more potent stimulus for making new muscle proteins compared to protein.”

The demand for protein has risen dramatically to meet the increased demands from the rising global population and plant-based proteins could fill that gap.

“This study provides evidence that the quality of proteins from plants can support muscle,” says Oikawa. “I think you’ll see more work on plant-based protein sources being done.”


The research was funded by the Alliance for Potato Research & Education.



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