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Research Category: Healthy Dietary Patterns

Contributions of White Vegetables to Nutrient Intake: NHANES 2009–2010

Vegetables, especially white potatoes, provide significant levels of key nutrients of concern, such as potassium and dietary fiber. Per capita availability (PCA) data for vegetables—often used as a proxy for vegetable consumption—show that vegetable consumption, including consumption of white potatoes, declined in the past decade. Using dietary data for participants in the NHANES 2009–2010, we examined total vegetable, white potato, and French-fried potato consumption among all age-gender groups as well as mean energy, potassium, and dietary fiber intakes. Mean total energy intake for the US population (≥2 y old) was 2080 kcal/d, with white potatoes and French-fried potatoes providing ∼4% and ∼2% of total energy, respectively. Individuals who consumed white potatoes had significantly higher total vegetable and potassium intakes than did nonconsumers. In addition, the proportion of potassium and dietary fiber contributed by white potatoes was higher than the proportion that they contributed to total energy. Among white potato consumers aged 14–18 y, white potatoes provided ∼23% of dietary fiber and ∼20% of potassium but only ∼11% of total energy in the diet. The nutrient-dense white potato may be an effective way to increase total vegetable consumption and potassium and dietary fiber intake.

In Nutrition, Can We “See” What Is Good for Us?

The selection of foods to eat is a complex interplay of vision, taste, smell, and texture. In addition to micro- and macronutrients, plant-based foods also contain several classes of phytochemicals. In many cases, the phytochemicals account for the various colors of foods. Although aesthetically pleasing, the color of foods may mislead consumers as to their phytochemical content, which is particularly true with regard to polyphenols. Polyphenols are a broad class of compounds with antioxidant and other health benefits. Human vision is limited to a small window (390–765 nm) of the electromagnetic spectrum. Many important phytochemicals (e.g., vitamin C) have no absorbance in this range. Therefore, the human eye cannot directly judge the vitamin C content of foods. Being able to see in the ultraviolet range allows bees to locate the pollen-rich region of flowers, whereas pit vipers locate their prey by being able to “see” them in the infrared range. Assessing the impact of phytochemicals on human health depends on several factors. Colorless phytochemicals in unprocessed foods may be lost during the cooking process because no visual guide exists to ensure their retention. The molecular structures of phytochemicals influence the extent to which they are altered by cooking processes and the methods by which they are absorbed from the gastrointestinal tract. Extensive metabolism by phase I/II enzymes and by the gut microbiome may also create compounds that the eye is never allowed to appreciate.

White Vegetables: A Forgotten Source of Nutrients: Purdue Roundtable Executive Summary

Purdue University convened a scientific roundtable, “White Vegetables: A Forgotten Source of Nutrients,” in Chicago, IL, June 18–19, 2012, to bring together experts to address the contributions of white vegetables, including potatoes, as sources of key nutrients and other microconstituents within a dietary pattern supporting health and wellness. This paper summarizes the meeting and supplement papers, including discussion among participants. The group of researchers identified areas of ambiguity regarding classification of vegetables for research and dietary guidance, future research needs, and the imperative to draw on that research to enhance evidence-based dietary guidance about white vegetables, including potatoes. U.S. dietary guidance encourages consumption of a variety of fruits and vegetables, including at least 1 serving of a dark green and 1 orange vegetable daily. However, no such recommendation exists for white vegetables, such as potatoes, cauliflowers, turnips, onions, parsnips, mushrooms, corn, and kohlrabi. Vegetable subgrouping approaches need to be considered in the context of nutrients of concern and low fruits and vegetable consumption. This Roundtable and supplement provide a substantial body of evidence to demonstrate how the inclusion of white vegetables, such as potatoes, can increase shortfall nutrients, notably fiber, potassium, and magnesium, as well as help increase overall vegetable consumption among children, teens, and adults in the United States. In so doing, these increases can help consumers to effectively and economically meet the recommended 2010 Dietary Guidelines for Americans vegetable servings and improve nutrient intake for all age and sex categories. Although inclusion of many types of vegetables in the diet improves nutritional adequacy, a priority public health message is to increase vegetable consumption. Potatoes appear to be a pathway to increased vegetable consumption, thereby helping to meet the recommended 2010 Dietary Guidelines for Americans servings for vegetables provided the forms served limit the amount of added salt and fat. Potatoes, in all forms, when consumed in MyPlate serving sizes, can be part of health-promoting dietary patterns. More research is needed to determine the health contributions of white vegetables as a source of nutrients and bioactive constituents and their bioavailability beyond the isolated components.

Fundamentals of Glycogen Metabolism for Coaches and Athletes

The ability of athletes to train day after day depends in large part on adequate restoration of muscle glycogen stores, a process that requires the consumption of sufficient dietary carbohydrates and ample time. Providing effective guidance to athletes and others wishing to enhance training adaptations and improve performance requires an understanding of the normal variations in muscle glycogen content in response to training and diet; the time required for adequate restoration of glycogen stores; the influence of the amount, type, and timing of carbohydrate intake on glycogen resynthesis; and the impact of other nutrients on glycogenesis. This review highlights the practical implications of the latest research related to glycogen metabolism in physically active individuals to help sports dietitians, coaches, personal trainers, and other sports health professionals gain a fundamental understanding of glycogen metabolism, as well as related practical applications for enhancing training adaptations and preparing for competition.