Processed foods are an important part of the US food supply and ensure that Americans have food to eat (food security) and food that meets nutritional guideline requirements (nutrition security), according to a controversial scientific statement issued by the American Society for Nutrition (ASN) and published in the June issue of the American Journal of Clinical Nutrition.
These foods can have a positive impact on health, but when consumed "inappropriately or at inordinately high proportions of a total diet, [they] are deleterious to health," Connie M. Weaver, PhD, distinguished professor and department head, nutrition science, Purdue University, in West Lafayette, Indiana, and colleagues admit.
The statement, which was first published online in April, has generated a flurry of critical blogs, Dr. Weaver told Medscape Medical News. Some critiqued the authors' ties to the food-processing industry. However, although some of the statement authors have links to food and beverage manufacturers, industry had no say in this statement, she pointed out.
Others have criticized the broad definitions of "processed" and "minimally processed" food from the International Food Information Council (IFIC), where multiple foods, from baby carrots to rotisserie chicken to cookies — with varying degrees of nutrition or processing — are lumped together.
A new "processed-food" classification system emphasizing nutrition is needed, the authors agree, but, unlike their critics, they feel that the degree of processing is irrelevant. "Some sort of nutrient-density [classification] makes more sense than trying to categorize by the extent of processing," Dr. Weaver said.
Obesity Society public affairs committee chair Adam Tsai, MD, from the University of Colorado, in Denver, argues that extent of processing does matter. "If you're fortunate enough to have a choice between something that's more processed and something that's less processed — whatever the definition is — you probably want to go for something that's less processed because, [for one reason], you don't want to eat added sugar," and according to the article, processed foods contribute over half of dietary calories but also contribute three-quarters of added sugars, an amount disproportionate to the amount of calories.
"Minimally Processed," "Processed," or "Restaurant Food"
According to the IFIC, "processed foods" encompass 4 categories: foods that are processed to preserve freshness (eg, canned salmon and frozen fruits and vegetables); foods combined with sweeteners, colors, spices, or preservatives (eg, rice, cake mix, salad dressing, and pasta sauce); "ready-to-eat" foods (eg, breakfast cereal, yogurt, rotisserie chicken, granola bars, cookies, crackers, and sodas); and prepared foods (eg, deli foods, frozen meals, and pizzas).
The IFIC further identifies a "minimally processed" food category, which includes washed and packaged fruits and vegetables, bagged salads, and ground nuts.
A study based on National Health and Nutrition Examination Survey (NHANES) data from adults and children over age 2, from 2003 to 2006, showed that of the processed food in the diet, 57% was more than minimally processed; 14% was minimally processed; and 29% was prepared food that was eaten in restaurants.
Processed foods can be enriched (which replaces nutrients lost in processing) or fortified (with nutrients not found in the original food), which can up the nutrition content.
According to the NHANES data and the 2010 Dietary Guidelines for Americans, "of the nutrients to encourage, processed foods contributed 55% of dietary fiber, 48% of calcium, 43% of potassium, 34% of vitamin D, 64% of iron, 65% of folate, and 46% of vitamin B12," the position statement notes.
On the other hand, these foods can be high in calories, fat, and sugar. "Of the constituents to limit, processed foods contributed 57% of energy [calories], 52% of saturated fat, 75% of added sugars, and 57% of sodium."
Potentially Harmful, yet Possibly Useful for Obese Patients
It may be necessary to process food to bring it from the field to the store shelf to the table to feed the population, but too much processing — specifically too much added sugar — is a problem, Dr. Tsai points out.
"That processed foods provide 57% of energy intake but 75% of added sugar [is a concern, since] there's a fairly strong association between added sugar in the American diet and obesity." The Food and Drug Administration, which proposed food labeling changes that would require food companies to list all added sugars, aims to draw attention to this content, he noted.
The statement is timely. "There's clearly been a movement in the United States, over the past 5 to 10 years — I call it the 'Michael Pollan movement' — of trying to eat more whole foods, more natural foods....One of my patients yesterday referred to it as 'eating clean,' " Dr. Tsai said.
On the other hand, although sugary processed foods with empty calories are unhealthy, people are more likely to lose weight if they have a more structured diet, such as in the Jenny Craig program, which uses packaged foods, he added. "Those are processed foods, but they are of fairly high nutritional quality; they're balanced. I do recommend them," he said.
An estimated 14% of Americans go hungry, while a significant number are obese and are getting too many calories but may still be missing certain nutrients, Dr. Weaver noted.
The ASN hopes to start a conversation with stakeholders — including nutritionists, policy makers, and food manufacturers — "to come up with new definitions [of processed foods] and a way to improve the food supply," she said.
In the meantime, she advises, "Don't equate processed food with junk food," pay attention to nutrient density, and look for processed foods that "start with whole foods...a fruit, a vegetable, or milk...[that] are likely to have quite a few nutrients vs [those that] start with sugar and maybe add some fat."
Dr. Weaver serves as an unpaid board member for the International Life Sciences Institute of North America and serves on a scientific advisory board for Pharmavite, and her university has received research grants from the Dairy Research Institute, Nestle, and Tate & Lyle. Disclosures for the coauthors are listed with the article.
Am J Clin Nutr. 2014;99:1525–42. Abstract
Medscape Medical News © 2014
Cite this: Processed Food Is Vital in US Diet, Nutrition Society States - Medscape - Aug 01, 2014.