Category: News

January 8, 2018

Peer-Reviewed Publication
Fleishman-Hillard, Inc.

Denver, CO. – A report about high-quality carbohydrates and physical performance was recently released in the peer-reviewed journal Nutrition Today. The report focuses on commentary that took place during an expert panel. The results of the report suggest that balanced diets high in natural, carbohydrate-rich foods, including nutrient-dense potatoes, may be optimal for improving performance among elite endurance athletes. The report is aligned with numerous studies conducted over the past 40-50 years, which have suggested that carbohydrates are a primary macronutrient for sustaining and improving athletic performance.

The expert commentary, “High-Quality Carbohydrates and Physical Performance,” was authored by Mitch Kanter, PhD, and is a summation of a meeting of five sports nutrition researchers and practitioners. The meeting and this published commentary were funded by the Alliance for Potato Research & Education (APRE), as part of its ongoing research efforts to understand the role of potatoes in healthful lifestyles. Panelists discussed the existing research surrounding the nutritional needs for optimal physical performance and provided their collective perspectives on how dietary recommendations for athletes have evolved over the years. The expert panel included Janet Rankin, PhD, Virginia Tech; Katherine Beals, PhD, RD, CSSD, University of Utah; Bob Murray, PhD, respected researcher and lecturer in sports nutrition; and Lawrence Spriet, PhD, University of Guelph. The session was moderated by Mitch Kanter, PhD, chief science officer, FoodMinds.

To learn more about the role of potatoes in athletic performance, visit PotatoGoodness.com/Performance.

About Potatoes USA

Potatoes USA is the nation’s potato marketing and research organization. Based in Denver, Colorado, Potatoes USA represents more than 2,500 potato growers and handlers across the country. Potatoes USA was established in 1971 by a group of potato growers to promote the benefits of eating potatoes. Today, as the largest vegetable commodity board, Potatoes USA is proud to be recognized as an innovator in the produce industry and dedicated to positioning potatoes as a nutrition powerhouse.

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Journal

Nutrition Today

DOI

10.1097/NT.0000000000000238 

February 13, 2020

Daily potato intake leads to better diet quality compared to refined grains

Peer-Reviewed Publication
FoodMinds LLC

UNIVERSITY PARK, PA -Potatoes are often equated with refined grains due to their carbohydrate content. Yet, potatoes contain fiber, resistant starch, and key micronutrients that Americans need more of in their diet. A randomized crossover study that included 50 generally healthy adults directly compared the nutrient quality and impact on cardiometabolic risk factors of non-fried potatoes to refined grains. The study was conducted by researchers at Penn State and was recently published in the British Journal of Nutrition. Its findings demonstrate that potatoes can support a healthy diet; daily intake of one serving of non-fried potato did not affect markers of glycemia and was associated with better diet quality compared to refined grains.

“Clinical studies are important to contextualize observational findings,” say Penn State Researchers. “Some epidemiologic studies have suggested an association between potato intake and increased risk of cardiometabolic diseases. However, the context around how potatoes are eaten, such as their preparation method or other foods eaten alongside them, may be important factors in explaining why our clinical trial findings differ from those of observational studies.”

Participants were randomly assigned to eat either a refined grain side dish (e.g., pasta, rice, white bread) or a steamed/baked potato side dish of equal calories each day with a main meal for four weeks. After a two-week break, the same individuals ate the opposite side dish with a main meal for another four weeks. Aside from being required to consume either a potato or refined grain side dish, no other dietary restrictions were placed on participants. Several markers of cardiometabolic risk were measured including plasma glucose, serum insulin, cholesterol and other blood lipids, blood pressure, and participants’ reported diet quality.

While neither refined grains nor potatoes impacted cardiometabolic risk factors, participants’ potassium and fiber intake, total vegetable and starchy vegetable intake and Healthy Index Score – a sign of how well people are following the Dietary Guidelines for Americans were higher when they ate potatoes, compared to refined grains.

“Americans eat too many refined carbohydrates and not enough whole grains or starchy vegetables, according to the 2015-2020 Dietary Guidelines for Americans. Our study findings suggest that eating 1 serving of non-fried potatoes in place of refined grains can help individuals meet more dietary recommendations.”

The study had several strengths, such as the randomized crossover design and isocaloric dietary substitution. All dishes were prepared in a healthy way with limited added fat or sodium. However, the researchers noted a few limitations: the need for larger sample sizes, a longer intervention time and controlled dietary intake rather than self-reported diets. “It is important to replicate our findings in other groups, such as those at higher risk of cardiometabolic disease. These findings apply to the generally healthy population.”

The article, “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,” is published in the British Journal of Nutrition (doi: 10.1017/S0007114520000252). Authors include Emily Johnston, Kristina Petersen and Penny Kris-Etherton of Penn State. Funding was provided by the Alliance for Potato Research and Education.

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Journal

British Journal Of Nutrition

DOI

10.1017/S0007114520000252 

June 21, 2021

New study finds that individuals with higher cardiometabolic risk may benefit from adding more dietary potassium, via potatoes, to a typical American diet

Peer-Reviewed Publication
FoodMinds LLC

A new study published in Nutrients investigated the effect of increased dietary potassium from a whole food source–baked/boiled potatoes and baked French fries–or a potassium supplement on blood pressure and other cardiovascular disease risk factors compared to a ‘typical American’ control diet (lower potassium intake) among 30 pre-hypertensive to hypertensive men and women. Results showed that including baked/boiled potato consumption as part of a typical American diet had the greatest benefit on reducing sodium retention, even more than the supplement, and resulted in a greater systolic blood pressure reduction compared to the control diet. Further, despite commonly held misbeliefs about French fries and their role in heart-healthy lifestyles, the authors observed that a 330-calorie serving of baked French fries, when eaten as part of a typical American diet, had no adverse effect on blood pressure or blood vessel function.

“While significant emphasis is often placed on reducing dietary sodium intakes to better control for blood pressure and cardiovascular disease risk, that’s only half of the story,” says Connie Weaver, PhD, the primary investigator. “Potassium plays just as an important role, and perhaps the ratio of potassium to sodium is most important in the context of the entire food matrix, as the potato meal resulted in a greater reduction of sodium retention than the potassium supplement alone.”

Evidence on the effect of increased dietary potassium on blood pressure from clinical trials is extremely limited, and this is one of the first known controlled feeding interventions investigating dietary potassium as the primary variable of interest.

“It’s important to establish clinical trials that follow observational research to establish a causal link between diet and health,” notes Weaver. “For example, in this clinical study baked French fries had a null effect on blood pressure, which counters observational findings, at least in the short term, and helps to prioritize the importance of focusing on a total diet approach for maintaining health versus one that overemphasizes avoidance of any single food or food group.”

Potatoes comprise roughly 20 percent of the vegetable intake in the American diet and help fill several nutrient gaps, including dietary fiber and potassium.1 Eating just one medium potato meets approximately 10 percent of an adult’s daily potassium needs. According to the 2020-2025 Dietary Guidelines for Americans, potassium is an essential nutrient of concern, indicating most Americans aren’t consuming enough. The mineral has been linked to improvements in cardiovascular and other metabolic health outcomes – including decreased blood pressure in those with hypertension. Overall, potatoes and French fries represent about 7 percent and 3 percent of potassium intake, respectively, in the United States.1

“Considering Americans fall significantly short in meeting daily potassium intakes, these findings show the importance of promoting, not restricting, whole food good-to-excellent sources of potassium in Americans’ diets, like potatoes,” Weaver said.

A Closer Look at the Study Methodology, Strengths and Limitations

Participants were randomly assigned to one of four 16-day dietary potassium interventions:

• Control diet including 2300 mg potassium/day (reflective of typical intake, considered to be ‘low potassium’)
• Control diet + 1000 mg of potassium from potatoes (baked, boiled, or pan-heated with no additional fat)
• Control diet + 1000 mg from baked French fries
• Control diet + 1000 mg from a potassium-gluconate supplement

Each diet was tailored to participants’ specific caloric needs while all other nutrients were kept constant. Blood pressure was measured across multiple visits of each phase, and participants also collected daily urine/stool samples to assess potassium and sodium excretion and retention.

The strengths of the study include a highly controlled diet, cross-over design, and excellent compliance. However, the researchers note a few limitations as well, including the study’s relatively small sample size, poor retention in study participation and relatively short study duration.

“All clinical studies are faced with limitations; however, despite those found in this study, the rigor of the study design is strong and unlike any other studies that have investigated the effect of a whole food – and potassium – on high blood pressure,” Weaver notes. “Through our carefully controlled balance study, we could determine the mechanism by which potatoes reduced blood pressure. Overall, we concluded that boiled or baked potatoes can help reduce systolic blood pressure – and baked French fries have no adverse effects on blood pressure and can be included as part of an overall healthy diet.”

The research manuscript, “Short-term randomized controlled trial of increased dietary potassium from potato or potassium gluconate: effect on blood pressure, microcirculation, and potassium and sodium retention in pre-hypertensive-to-hypertensive adults,” is published in Nutrients (doi: https://doi.org/10.3390/nu13051610). Authors include Michael Stone, Berdine Martin and Connie Weaver of Purdue University. Funding was provided by the Alliance for Potato Research and Education.

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Journal

Nutrients

DOI

10.3390/nu13051610 

May 10, 2022

Newly published perspective examines the shortcomings of the glycemic index as a measure of carbohydrate food quality

Peer-Reviewed Publication
The Alliance for Potato Research and Education (APRE)

Today, many people struggle to make healthy food and beverage choices in line with the Dietary Guidelines for Americans (DGA). In fact, the average American under-consumes nutrient-dense fruits, vegetables, whole grains, beans and dairy foods – and more than half of American adults have at least one diet-related chronic disease.¹ To improve overall diet quality, Jill Nicholls, PhD, asserts in a recently published perspective in Frontiers in Nutrition, people need tools that are relevant, reliable and applicable – and evidence suggests the glycemic index (GI) falls short on all of the above.

“The GI is increasingly used and interpreted as a measure of overall carbohydrate food quality, with some proponents advocating for its broader adoption as a public health tool. However, the GI model doesn’t address nutrient density or translate well to healthy dietary patterns, and its narrow focus on just one dimension of carbohydrate-containing foods may divert public attention away from approaches to improving health that are accessible, affordable, culturally appropriate and environmentally sustainable,” stated Nicholls, owner of Food Context, LLC. “At best, it’s an incomplete gauge of carbohydrate food quality. At worst, it may be counterproductive to achieving the dietary recommendations set forth in the DGA.”

Intended for People with Type 1 Diabetes – Not the General Public

Developed in the 1980s as a blood glucose management tool for people with type 1 diabetes, the GI is a comparative measure of glycemic impact. The GI measures the ability of the available carbohydrate in a food to increase blood glucose. It is determined by measuring blood glucose after consuming 50 grams of carbohydrate from a single test food and normalizing to a comparable portion of a control food, typically pure glucose or white bread.²

Carbohydrate-containing foods are quite varied and make important contributions to dietary patterns, yet the GI measures only glucose response. It does not account for overall nutrient content, and research has shown it may not be an accurate predictor of overall diet quality. And because low-GI foods are not necessarily high in essential nutrients, over-reliance on GI values may lead to food choices that are inconsistent with current dietary guidelines. Energy-dense choices such as ice cream and candy bars, for instance, can have low GI values, while nutrient-dense choices that support healthy dietary patterns can also be high-GI foods, including carrots, potatoes and grains.

An Unreliable and Highly Individualized Measure of Glycemic Response

“The reliability of the GI has been scrutinized since its introduction more than 40 years ago, including critiques about methodology and questions about the relationship between a food’s GI value and true post-meal glycemic response,” said Nicholls.

Because GI values are calculated based on foods consumed in isolation and analyzed under standard laboratory conditions, their real-world application may be limited. “Under the GI model, fat, protein and fiber are treated as entirely independent variables, but that assumption is at odds with current views about our understanding of how eating patterns influence health based on all food and beverage contributions,” Nicholls explained.

Much of the research has demonstrated significant variability in both inter- and intra-individual glycemic responses to the same food. Thus, it remains unclear whether the GI is a property of foods or a characteristic of each unique individual consuming those foods. Emerging studies have found that glycemic responses are more similar within individuals than between them, and an array of factors in addition to meal composition can influence individual carbohydrate metabolism, including, meal timing, physical activity and sleep habits. ⁴

A Questionable Predictor of Health Outcomes

Research also indicates that the GI may not be the best carbohydrate food quality metric to assess diets and chronic disease prevention. In a landmark series of systematic reviews and meta-analyses, Reynolds et al. found that the association between the GI and risk of non-communicable diseases was low to very low compared to fiber or whole grains.⁵ Meanwhile, the dietary patterns emphasized in the DGA contain more whole grains and fiber-containing foods than Americans usually eat, along with higher amounts of fruits, vegetables, and dairy foods. These patterns are associated with lower risk for NCDs. Eating nutrient-dense whole foods as part of balanced meals during the day is an easy way to improve glycemic responses and improve diet quality without monitoring the GI of foods.

“The Mediterranean Diet is one example of a dietary pattern that has been associated with reduced disease risk; yet, not every food in a Mediterranean eating pattern is low GI,” Nicholls added. In addition, clinical trials have shown compelling evidence that high GI foods eaten within the context of high-quality dietary patterns can yield improvements in cardiovascular disease risk factors, and weight loss regimens may be less reliant on glycemic responses than expected.^6-7

“Evidence increasingly suggests that it’s the total diet that counts. Improving the overall quality of an individual’s dietary patterns can have beneficial effects on a variety of diet-related chronic disease, but the effect of any single food choice is mediated by the other foods and beverages eaten, physical activity and other lifestyle choices. While the GI may illuminate some narrow insights, it also keeps many of these relevant variables in the dark.”

The article, “Perspective: The Glycemic Index Falls Short as a Carbohydrate Food Quality Indicator to Improve Diet Quality,” is published in Frontiers in Nutrition (https://doi.org/10.3389/fnut.2022.896333). Funding was provided by the Alliance for Potato Research and Education.

References:

¹U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. 9^th Edition. December 2020. [Internet]. Available from: https://www.dietaryguidelines.gov/sites/default/files/2020-12/Dietary_Guidelines_for_Americans_2020-2025.pdf

²Wolever, T.M., Jenkins, D.J., Jenkins, A.L., & Josse, R.G. (1991). The glycemic index: methodology and clinical implications. The American journal of clinical nutrition, 54 5, 846-54

³Zazpe, I., Sánchez-Taínta, A., Santiago, S., De la Fuente-Arrillaga, C., Bes-Rastrollo, M., Martínez, J., & Martínez-González, M. (2014). Association between dietary carbohydrate intake quality and micronutrient intake adequacy in a Mediterranean cohort: The SUN (Seguimiento Universidad de Navarra) Project. British Journal of Nutrition, 111(11), 2000-2009. doi:10.1017/S0007114513004364

⁴Berry SE, Valdes AM, Drew DA, Asnicar F, Mazidi M, Wolf J, et al, Human postprandial responses to food and potential for precision nutrition. Nat Med. (2020) 26:964–73. doi: 10.1038/s41591-020-0934-0

⁵Reynolds A, Mann J, Cummings J, Winter N, Mete E, Te Morenga L. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. Lancet. (2019) 393:434–45. doi: 10.1016/S0140-6736(18)31809-9

⁶Sacks FM, Carey VJ, Anderson CAM, Miller ER III, Copeland T, Charleston J, et al. Effects of high vs. low glycemic index of dietary carbohydrate on cardiovascular disease risk factors and insulin sensitivity: the OmniCarb randomized clinical trial. J Am Med Assoc. (2014) 312:2531–41. doi: 10.1001/jama.2014.16658

⁷Gardner CD, Trepanowski JF, Del Gobbo LC, Hauser ME, Rigdon J, Ioannidis JPA, et al. Effect of low-fat vs. low-carbohydrate diet on 12-month weight loss in overweight adults and the association with genotype pattern or insulin secretion: the DIETFITS randomized clinical trial. J Am Med Assoc. (2018) 319:667–79. doi: 10.1001/jama.2018.0245

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DOI

10.3389/fnut.2022.896333 

March 7, 2022

No short-term, statistically significant difference between calorie-matched fries and almonds on key health metrics

Peer-Reviewed Publication
The Alliance for Potato Research and Education (APRE)

White potatoes — especially French fries — are often described in nutrition research literature and dietary guidance statements as having associations with obesogenic diets and as increasing chronic disease risk based on observational research findings. However, there is limited evidence from randomized controlled trials (RCTs) testing cause-and-effect relationships. Now, an RCT published in the American Journal of Clinical Nutrition demonstrates that adding a 300-calorie serving of French fries to one’s typical diet every day for a month does not result in differential weight gain or other biomarker changes associated with impaired blood sugar regulation compared to adding an isocaloric daily serving of almonds, generally considered a healthy snack option.

“In our School of Public Health at Indiana University-Bloomington and in my own work, we adhere to a slogan: ‘It’s About Knowing.’ Because conjecture is good, but knowing is better,” says David Allison, PhD, the study’s principal investigator. “The way we come to know is through rigorous, randomized controlled trials. Based on our RCT findings, there is no statistically significant evidence of differential effects between consuming a typical 300-calorie serving of French fries daily and a 300-calorie serving of almonds daily when it comes to weight gain or markers of type 2 diabetes risk, at least in the short term.”

Changes in body composition (i.e., body fat mass), body weight, fasting glucose and fasting insulin levels at the end of the one-month trial were comparable across the French fry and almond intervention groups and were not clinically significant. As expected, given the difference in carbohydrate content between the French fries and almonds, acute peak blood glucose and insulin levels were higher after consuming the French fries. However, these levels were not elevated beyond a normal range, and this difference did not have an apparent impact on any other glucoregulatory biomarkers.

“Our results show two food items identified previously for opposite associations with health outcomes had no differences in effects on the health outcomes we measured,” notes study co-author Daniel Smith, PhD. “Nutrition recommendations that focus primarily on single foods in isolation may be missing the mark. A more effective approach to dietary guidance is likely one that takes total diet, lifestyle and individual needs and risk factors into account.”

Study Design, Strengths, and Limitations

A group of 180 adult men and women were randomized to one of three treatment groups for 30 days, with 165 completing the study. The three arms included an additional 300 kilocalories/day from one of the three food items (below) and participants were asked to add the specific food item into their “normal daily diet.”

• Almonds: approximately 1/3 of a cup of almonds, roasted and salted
• Standard French fries: approximately the size of a medium serving
• French fries with herb/spice mix: approximately the size of a medium serving, prepared with oregano, basil, garlic, onion and rosemary

Instructions were provided regarding storage and preparation methods of food items for all participants. Participants were simply asked to incorporate the specific food item into their normal daily diet. They were not instructed to compensate for these added calories in any way.

Body composition (body fat mass), body weight, blood sugar, insulin and hemoglobin A1c were measured at baseline and at study completion. A subset of five participants also completed post-meal evaluations to assess short-term blood sugar response.

The study’s strengths include its randomized controlled trial design, considered the gold standard in identifying causal relationships, as well as the standardization of the study foods’ preparation, presentation and convenience. Its limitations include the fact that it was a free-living study, limiting researchers’ control over the participants’ diets; however, such a study design also allows for real-world data collection. It also excluded participants with type 2 diabetes, limiting the application of the findings to individuals without the disease. Additionally, the study did not include an analysis of energy (calorie) intake, nor were satiety data collected, making it unclear exactly how the varied snack intakes affected calorie intake overall.

The research article, “French-fried potatoes consumption and energy balance: a randomized controlled trial,” is published in The American Journal of Clinical Nutrition (https://doi.org/10.1093/ajcn/nqac045). Authors include David Allison, PhD, Indiana University and Daniel Smith, PhD, University of Alabama at Birmingham. Funding was provided by the Alliance for Potato Research and Education; however, APRE had no influence on the study design, conduct, execution or data analysis after approving the initial proposal for funding.

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Journal

American Journal of Clinical Nutrition

DOI

10.1093/ajcn/nqac045 

Method of Research

Randomized controlled/clinical trial

Subject of Research

People

Article Title

French-fried potatoes consumption and energy balance: a randomized controlled trial

Article Publication Date

18-Feb-2022