Health Letter, November 2021
By Azza AbuDagga, Ph.D.
In recent decades, our food system has changed markedly. One such key change is the advent of highly processed industrialized (ultraprocessed) food formulations, such as sweet or savory packaged snacks, sugar-sweetened beverages, candy, industrial bread, industrial breakfast cereal, ready-to-heat and -eat pasta dishes, pizza, and sausages as well as other reconstituted meat products.
These foods are made primarily with ingredients that contain little to no whole foods and are generally high in added sugar, trans fat (partially hydrogenated oils), sodium and refined starch and low in fiber, protein, minerals and vitamins. Importantly, ultraprocessed foods include food substances that are not used in kitchens (such as high-fructose corn syrup and hydrolyzed proteins) or additives that make them palatable or more appealing (such as flavors, colors, emulsifiers, sweeteners and thickeners as well as bulking, carbonating, foaming, gelling and glazing agents).
A new study that was led by researchers from Tufts University demonstrated a troubling trend of increased consumption of ultraprocessed foods by U.S. children and adolescents (hereafter referred to as youths). The study was published in the August 10, 2021, issue of the Journal of the American Medical Association (JAMA).
Harmful effects of ultraprocessed foods
Nutritional health experts have recommended avoiding highly processed industrial food formulations because of accumulating evidence about their risks.
For example, a recent small controlled clinical trial that assigned weight-stable adults to ultraprocessed and unprocessed foods for 14 days each in a random order found higher energy intake and weight gain among subjects during their ultraprocessed-diet periods than their unprocessed-diet periods. Notably, the subjects were instructed to eat as little or as much they could, but their presented meals were matched in terms of calories and key elements including carbohydrates, fat, protein, sugar, sodium and fiber. This matching process ensured that the differences in energy intake and weight were due to the amount of ultraprocessed foods in their diets.
Epidemiological studies have found significant associations between consumption of ultraprocessed foods and adverse health outcomes after adjustment for total calorie intake and food quality. Other studies demonstrated strong associations between consumption of ultraprocessed foods and hypertension, cardiovascular disease, type 2 diabetes, cancer and risk of death.
The new JAMA study
The study researchers examined data from the National Health and Nutrition Examination Survey (NHANES), which is a standardized periodic survey by the Centers for Disease Control and Prevention. They selected information from the last twenty years of available survey data (from 1999 through 2018) that pertained to approximately 33,800 U.S. youths between 2 and 19 years of age. This sample was representative of noninstitutionalized youths in all 50 states and Washington, D.C. The mean age of the participants was 11 years, and 49% of them were girls.
These data entailed a 24-hour dietary recall of the food and beverage intake of the youth participants. Trained interviewers collected these data from the participating older children and teens directly and from parents or caregivers (proxies) of younger participants.
The researchers identified both commercially prepared foods and beverages and ingredients of handmade foods and beverages consumed by the participants and classified them as either ultraprocessed or not ultraprocessed using the NOVA food classification system. Developed by researchers at the University of Sao Paulo, Brazil, the NOVA system is the current gold standard for classifying foods according to the extent of their processing.
According to the study researchers, the estimated percentage of total consumed calories from ultraprocessed foods among the youths significantly increased from 61% in 1999 to 67% in 2018. Particularly, the estimated percentage of consumed energy from ready-to-heat and -eat mixed dishes significantly increased from 2% to 11% during the study period.
In contrast, the estimated consumed calories from healthful unprocessed or minimally processed foods (such as grains, fish, meat, milk and eggs) among the youths decreased from 29% to 24% during the study period.
The remaining estimated percentage of consumed calories came from moderately processed foods (which include foods containing consumer-added flavor enhancers such as sugar, honey, maple syrup and butter) and processed foods (which include canned fish, meat, fruits or vegetables as well as cheese).
The increasing estimated consumption of ultraprocessed foods among the youths during the study period was consistent among all age groups and boys and girls. It also occurred across all levels of parental education, suggesting that the problem is pervasive in the diets of all U.S. youths.
In terms of race and ethnicity, the estimated consumption of ultraprocessed foods increased from 62% to 73% among non-Hispanic Black youths and from 56% to 64% among Mexican American youths during the study period. These estimated increases among non-Hispanic Black and Mexican American youths were significantly greater than the increase among non-Hispanic White youths during the study period (from 63% to 69%).
Using data from 2017 to 2018, the study researchers revealed that the nutritional profile of ultraprocessed foods consumed by U.S. youths was poor. Specifically, ultraprocessed foods contained a substantially higher percentage of calories from carbohydrates and added sugars and a lower levels of protein and fiber than non-ultraprocessed foods.
The good news is the estimated percentage of calories consumed by youths from sugar-sweetened beverages significantly dropped from 11% to 5% and significantly decreased for processed fats or oils, condiments and sauces from 7% to 4% during the study period. The former decrease may be due to increased awareness about the risks of sugar-sweetened beverages.
Because the new JAMA study predates the COVID-19 pandemic, it will be interesting to see from future studies, including those using updated NHANES data, how the pandemic and its related stay-at-home orders have affected U.S. youths’ eating habits.
Nonetheless, the dietary consumption pattens of ultraprocessed foods among youths documented in the new JAMA study are concerning and have significant public health implications because children’s dietary patterns tend to persist into adulthood.
Hopefully these findings will prompt policy makers to introduce and enforce regulations to improve the ability of consumers, especially youths and their parents, to recognize and avoid ultraprocessed foods. At a minimum, the findings should prompt policies that require school foods to be based on whole or minimally processed foods.
At the consumer level, it is important to read nutrition fact labels of all packaged foods and to maximize the purchase of products that contain no additives or artificial colors or flavors as well as no nonculinary ingredients. It also is never too late for all of us to improve our dietary habits by avoiding ultraprocessed foods and relying on nutrient-dense unprocessed foods and beverages that contain little or no added sugars, saturated fat or sodium as recommended by the Dietary Guidelines for Americans, 2020–2025.