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Rethinking Potatoes: A Comprehensive Nutritional Analysis and Its Impact on Health

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11/15/2023
potatonewstoday.com

This article was written by Jorge Luis Alonso G.

This analysis, prepared by Stephen A. Fleming and Jenny R. Morris at Traverse Science in Illinois, provides a thorough evaluation of the nutritional value of potatoes and their impact on health, going beyond the narrow focus on the glycemic index.

By integrating data from epidemiological studies and clinical trials, the scientists provide a sophisticated perspective on how potatoes can contribute to a healthy diet, which can shape dietary recommendations and promote better public health.

Their research study and findings were published recently in a scientific article in the journal Advances in Nutrition: https://www.sciencedirect.com/science/article/pii/S2161831323013996?via%3Dihub

The article below is a summary of the scientists’ analysis.

Introduction

The long-standing debate about the role of potatoes in the diet has been influenced by their high glycemic index (GI) and a perceived link to an increased risk of type 2 diabetes (T2DM). Despite extensive research over the past twenty years, opinions remain divided. Some advocate potato consumption based on its nutritional benefits, while others point to a correlation between high potato intake and higher incidence of chronic diseases, often citing its prominence in energy-dense Western diets.

Research shows that the negative perception of potatoes may be due to an excessive focus on GI, misinterpretation of epidemiological data, and the unhealthy ways in which potatoes are often prepared in Western diets. The current consensus in the scientific community recognizes potatoes as a high-quality source of carbohydrates. They are considered comparable to other nutrient-dense staple foods, with clinical trials failing to support the negative effects proposed by some epidemiological studies.

This suggests that potatoes can be part of a healthy diet when consumed in moderation and prepared healthily.

Potatoes are a nutrient-rich vegetable

Potatoes, a sustainable and vital food for global food security, provide important nutrients such as fiber and potassium. Despite their high glycemic index, which has historically labeled them as a low-quality carbohydrate, they are now recognized as high quality, on par with legumes and sometimes superior to whole grains. Recent research contradicts earlier beliefs that potatoes have adverse health effects, although they are associated with a higher risk of T2DM and hypertension.

The negative perception of potatoes is often linked to their role in Western diets, where they’re typically consumed with energy-dense foods. However, in dietary patterns such as those in Japan and the Nordic countries, potatoes contribute to a nutrient-rich diet. When eaten with their skin and without high-calorie toppings, potatoes are classified as high-quality carbohydrates by the Carbohydrate Quality Indices (CQI) and Carbohydrate Food Quality Scores (CFQS).

Recent analyses have confirmed that potatoes score highly on carbohydrate quality metrics when baked or cooked, challenging the idea that they inherently contribute to a poor diet. It’s the additional foods that accompany potato dishes that often reduce their nutritional value. Therefore, the contribution of potatoes to diet quality is complex and context-dependent, highlighting the importance of detailed assessments in dietary recommendations and health studies.

Meta-analyses provide insights for specific populations but lack broad generalizability

Meta-analyses indicate that potatoes do not elevate the risk of mortality or stroke, while their link to cancer and hypertension remains unclear. Research consistently shows a correlation between high potato consumption and an increased risk of T2DM, but this is often based on data from similar cohorts across various countries.

Comparative studies suggest that in Eastern populations, where potato consumption and overall dietary intake differ, the risk of T2DM might be lower compared to Western populations with higher potato consumption.

The findings imply that the potential health risks associated with potato intake are possibly influenced more by overall dietary patterns and lifestyle choices rather than the consumption of potatoes alone.

Potato consumption in Western cohorts doesn’t reflect today’s diets

Research indicates that the health effects of potato consumption are related to both the amount consumed and demographic factors. Previous studies, which primarily involved middle-aged, overweight female health professionals in the U.S., may not accurately represent the general population, potentially limiting the relevance of their conclusions.

In addition, these studies predate important dietary changes, particularly the reduction in trans fat consumption due to regulatory changes, which may mean that historical data doesn’t reflect current eating habits.

Despite the consistency in potato consumption over the years, it is theorized that advances in cooking methods may have made fried potatoes healthier today than in the past. Meta-analyses have linked one additional serving of potatoes to an increased risk of T2DM, but these findings are based on portion sizes larger than what most Americans typically consume. In fact, the most common daily intake is less than half a serving, and intakes of more than one serving per day are rare.

Emerging data suggest that eating less than 100 grams of potatoes per day may not increase the risk of T2DM and may even decrease it. This means that the amounts of potatoes typically consumed by the majority of people do not reach levels associated with increased health risks, in particular, T2DM.

Clinical trials: Comparisons matter

Clinical trials of potato consumption show that the health effects depend largely on the quality of the comparator carbohydrate. Potatoes appear less healthy when compared to higher-quality carbohydrates, but often appear beneficial or neutral when compared to lower-quality carbohydrates. Research shows that the effects of potatoes on glucose metabolism are similar to other refined grains and may even promote gut health and improve diet quality.

Comparisons with refined grains are mixed, generally showing neutral or sometimes beneficial effects. However, unlike nutrient-rich foods such as legumes, nuts, and whole grains, potatoes do not consistently produce optimal health outcomes, but neither do they show significant adverse effects. Despite acute studies highlighting a high GI, there’s no strong evidence from randomized clinical trials (RCTs) to suggest adverse long-term cardiometabolic effects. In fact, the increasing consumption of refined grains poses a greater health risk than potatoes, which have not seen a similar increase in consumption.

There is growing interest in the differential effects of different types of potatoes. Low GI varieties high in resistant starch may reduce postprandial insulin response. Colored potatoes, such as purple and yellow, show potential antioxidant benefits, although research into the different health effects of different potatoes is still in its early stages. The current body of evidence suggests that potatoes may not pose the health risks they are often thought to, especially when included as part of a balanced diet.

Intake of fried potatoes confused with total potato intake

Nutritional studies show inconsistencies in the classification of potatoes as a vegetable, leading to mixed results regarding their impact on health, particularly the risk of T2DM. How potatoes are prepared — fried, roasted or mashed — significantly influences their perceived health risks and distinguishes them from other vegetables. No consensus that fried potatoes alone contribute to health risks, as research on the effect of potato preparation on T2DM risk is limited.

Most dietary pattern studies do not specify the form of potatoes, and meta-analyses tend not to separate fried from unfried potatoes, which may exaggerate health risk assessments. This is more pronounced in Eastern populations, where potato consumption appears to be less risky, and misclassification in studies could inflate risk assessments.

Comprehensive analyses have not shown an increased risk of T2DM with potato consumption in Eastern populations, suggesting that preparation methods may influence risk perception. Future research should disaggregate potato forms, specifically between fried and unfried, to better understand the health effects of potatoes independent of their preparation and broader dietary context.

Conclusion

The prevailing view that potatoes should be excluded from diets because of their high glycemic index and association with Western eating habits is now being challenged by new research. Contrary to this view, potatoes have been identified as a quality carbohydrate. Current consumption patterns in Western diets are not typically associated with poor diet quality, and the negative health effects are often related to unusually high levels of consumption that are not common in the majority of the U.S. population.

Clinical evidence indicates that the health effects of potatoes are comparable to those of legumes and superior to those of refined grains. This indicates that potatoes can be considered a beneficial component of a nutritious and balanced diet.

As a result, public health guidelines are being updated to recognize the role of potatoes in improving dietary quality and promoting health.

Source: Fleming, S. A., & Morris, J. R. (2023). Perspective: Potatoes, quality carbohydrates, and dietary patterns. Advances in Nutrition.https://doi.org/10.1016/j.advnut.2023.10.010.
Corresponding author:
Stephen Fleming
engage@traversescience.com
Cover image: Credit Jorge Luis Alonso G.

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