Potato Grower

June 2019

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30 POTATO GROWER | JUNE 2019 Potatoes' true nutritional value, and how the industry can leverage the facts The Good Guys Diggin' In Diggin' In CONSUMER HEALTH | ByJulie Miller Jones Fat = Bad. Carbs = Good. Vice versa. For 50 years fat was demonized, but now it's carbs—despite worldwide recommendations that 45 to 65 percent of calories in a person's diet should come from carbs. However, some say "fat did not make you fat; carbs did." Keto and Paleo diets shun all carbs including bread or potatoes. Others have tried to define "quality carbohydrates." This article will further explore each of these issues. The Carbohydrate-Fat Debate & Obesity The dietary carbohydrate-to-fat ratio has been debated since Sir William Banting issued his Essay on Corpulence, which extolled low-carbohydrate diets (LCDs) for weight loss. LCDs' popularity has waxed and waned, but each "new" LCD has a name—and gimmick, such as "addictive bread"—and recommends carbohydrate intakes under 30 percent of calories; some recommend under 10 percent (e.g., the ketogenic diet). Publications alleging carbs have caused the obesity epidemic and diseases such as diabetes have penetrated the public psyche. In fact, 25 percent of survey respondents believed carbs cause excess weight and prevent weight loss. Authors who correlate obesity increases with increases in percent of carbs fuel the debate. Associations never prove causation, but this one no longer applies after the year 2000. While carbs such as potatoes and wheat are blamed for obesity's epidemic rise, their consumption is decreasing. Low-Fat vs. Low-Carb Diets Studies comparing low-fat diets (LFDs) and LCDs show the following: • LCD produced greater weight loss than LFD initially but not after 12 months. Very low-carb ketogenic diets resulted in only 2 pounds more weight loss after a year. (For certain medical conditions VLCKD may show promise, but more studies are needed.) • Only 20 percent of well-controlled studies favored LCD over LFD for measures of body fat. • LCDs ranked in the bottom tier of diets ranked by the U.S. News and World Report in 2019. Mediterranean and DASH Diets ranked highest. These recommend 45 to 65 percents of calories be ingested as carbs, not omitting food groups, promoting balance and having good compliance—a major factor for diet successful in promoting overall health. • Among 15,000 adults, those eating the recommended 50 percent of calories from carbs two to four years longer than those consuming LCD or ketogenic diets. What Predicts Carb Quality? Glycemic index (GI) and glycemic load (GL) have been proposed to define carbohydrate quality, but this has been disputed for several reasons: • Published or labeled GI values don't accurately predict blood glucose due to the existence of factors such as variety, ripeness, food structure, cooking, size of meal and meal frequency, among others. • Even with strict protocols, GI values can vary by 20 to 40 points for one person eating the same food on different days. With only 15 points between categories, the high variability can result in goods being miscategorized. • GI values may not reflect the response when foods are eaten in a meal. Mashed potatoes have a high GI. However, when eaten with salad and chicken breast, the meal GI is lower than calculated from table values. • Studies of health benefits of GI/GL give mixed results. Those showing benefits often contain more recommended and fewer indulgent foods. Thus, the associations may not be due to GI, but food choice. • Adverse impacts of high GI intake are more likely with carb intakes higher than recommended. Carbs, Nutrients & Health Carb quality may not be accurately defined by GI/GL; rather, it should be determined by its role in the diet for achieving health and nutrient contribution. Potatoes, especially when boiled, may promote lower calorie intake because they have the highest satiety index of any food tested. Mashed potatoes as a side (while having a lower satiety index than boiled potatoes) resulted in the ingestion of 30 to 40 percent fewer calories than a variety of other carbohydrate sides. Potatoes are a significant source of nutrients, including those USDA lists as "nutrients of concern." Over 95 percent of the population fails to ingest these nutrients in adequate amounts. One small skin-on potato provides 20 percent of the potassium requirement critical for maintaining blood pressure. Potatoes head USDA's list of high-potassium foods. They also supply fiber, magnesium and vitamin C, nutrients that are under-consumed by many. Despite claims to the contrary, intake of potatoes has not proven to be associated with increased of risks of obesity, type 2

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