September 5, 2019
By Nkem Nwosa, MD
The foods we eat provide essential nutrients that are important for maintaining a healthy lifestyle. Globally, rising rates of chronic non-communicable diseases, overweight, and obesity have given rise to an increased interest in the nutritional quality of diets as a means of prevention.1
It is estimated that 39% of the world’s adult population is overweight and 13% has obesity; 71% of deaths worldwide are believed to be due to non-communicable diseases.
Traditionally, foods have been classified into food groups based on macronutrients and micronutrients. The NOVA system of food classification, which was originally proposed in 2010 by C. Monteiro and colleagues, classifies foods based on the extent and purpose of food processing.2 The view is that the degree of processing can change the nutrient profile of foods and therefore affect health benefits. Since the proposal of this new food classification system, there has been growing concern regarding ultra-processed foods.
Based on the NOVA classification, there are four categories of food.3-6
Group 1: Unprocessed Foods and Minimally Processed Foods
- Unprocessed Foods: Foods obtained directly from plants or animals (e.g., eggs, fish, seeds).
- Minimally Processed Foods: Foods that may be altered by the removal of inedible or unwanted parts. They may undergo processes such as drying, boiling, grinding, or freezing, but no salt, oils, fats, or other things are added to these foods (e.g., frozen vegetables and fruits, dried beef).
Group 2: Processed Culinary Ingredients
Substances extracted from unprocessed or minimally processed foods, or directly from nature (e.g., plant oils, honey, maple syrup, table sugar, butter).
Group 3: Processed Foods
Created by adding Group 2 foods to Group 1. For instance, adding salt, oil, or vinegar to increase preservation. Processes can include canning, bottling, pickling, or non-alcoholic fermentation (e.g., canned tuna, canned vegetables, fruits in syrup, salted nuts, smoked meat).
Group 4: Ultra-Processed Foods
Industrial formulations of food and drink products that typically have many ingredients. They contain food substances not commonly used in food preparation, such as hydrolyzed protein and hydrogenated oils. They usually involve several stages of industrial processing, and few to no whole foods are present. They can include colorants, emulsifiers, bulking agents, non-sugar sweeteners, and other additives.
Ultra-processed foods are characterized by being higher in added sugars, salts, and trans or saturated fats, and lower in fiber, proteins, and micronutrients.7 They are often designed to be ready to eat and highly palatable, to have a long shelf life, and to have a lower per-calorie cost when compared to processed foods.7
Examples of ultra-processed Group 4 foods:
- Hot dogs
- Fish sticks
- Chicken nuggets
- Reconstituted meat products
- Pre-prepared pizza or pasta
- Instant sauces/soup/noodles
- Breakfast cereals
- Energy bars
- Ice cream
- Packaged desserts
- Infant formula
- Carbonated drinks
Confusion may arise regarding the classification of certain foods like bread. For instance, bread may be classified in Group 1 if the ingredients only contain wheat flour, water, salt, and yeast. If ingredients such as emulsifiers are added, then bread would be classified as ultra-processed/Group 4, as is often the case with mass-produced breads. Plain yogurt would fall into Group 1; however, if there is added sugar or sweeteners in the yogurt then it would be classified as ultra-processed/Group 4.
Health Impact of Ultra-Processed Foods
Worldwide consumption of ultra-processed foods has increased over the decades. In the U.S., studies have shown that almost 60% of calories come from ultra-processed foods, which contribute 90% of total dietary added sugar.5,8 In Canada, calories consumed from ultra-processed products increased from 24% to 55% from 1938-2001.9 Similarly, in Brazil, consumption of ultra-processed foods increased from 18.7% in 1987 to 26.1% in 2003.9 In Mexico, the energy contribution of ultra-processed foods to household purchases increased from 10% to 23% from 1984-2016.10 A study looking at 19 European countries showed that ultra-processed foods contributed from 10-50% of total purchased dietary energy.11
Multiple studies have demonstrated health risks associated with increased consumption of ultra-processed foods.12-23 These include:
- Increased risk of overweight and obesity in adults.
- Increased risk of metabolic syndrome.
- Increased risk of cardiovascular, coronary, and cerebrovascular disease.
- Increased risk of cancer.
- Increased risk of depression.
- Increased risk of frailty in older adults.
- Increased abdominal obesity, total cholesterol levels, and LDL cholesterol levels in children.
- Increased association with food addiction in overweight children.
- Recently, a higher consumption (more than 4/5 daily servings) of ultra-processed food has also been associated with a greater risk of all-cause mortality.24,25
Additional concerns regarding ultra-processed foods require further investigation. These include the health effects of bio-active neo-contaminants that may be formed during the processing of food, such as acrylamide. Also, possible contamination from plastic packaging of ultra-processed foods with chemicals like Bisphenol A.17,24
Current government dietary guidelines in America recommend making healthier food and beverage choices. They also suggest limiting calories from added sugars, saturated fats, and salt. Specifically, less than 10% of calories per day should come from added sugars or saturated fats. Given the current evidence, it would appear that if the public is to meet those guidelines and lead a healthier lifestyle, increased consumption of whole foods and unprocessed or minimally processed foods should be encouraged. Consumption of ultra-processed food should be decreased.
- Vandevijvere S1, Monteiro C, Krebs-Smith SM, et al. Monitoring and benchmarking population diet quality globally: a step-wise approach Obes Rev. 2013 Oct;14 Suppl 1:135-49.
- Monteiro CA, Levy RB, Claro RM, et al. A new classification of foods based on the extent and purpose of their processing. Cad Saude Publica. 2010 Nov;26(11):2039-49.
- Menegassi B, Almeida JB, Olimpio MYM, et al. The new food classification: theory, practice and difficulties. Cien Saude Colet. 2018 Dec;23(12):4165-4176.
Gibney MJ. Ultra-Processed Foods: Definitions and Policy Issues. Curr Dev Nutr. 2018 Sep 14;3(2):nzy077.
- Martínez Steele E, Baraldi LG, Louzada ML, et al, Ultra-processed foods and added sugars in the US diet: evidence from a nationally representative cross-sectional study. BMJ Open. 2016 Mar 9; 6(3):e009892.
- Monteiro CA, Cannon G, Levy RB, et al Ultra-processed foods: what they are and how to identify them. Public Health Nutr. 2019 Apr; 22(5):936-941.
- Gupta S, Hawk T, Aggarwal A, Drewnowski A. Characterizing Ultra-Processed Foods by Energy Density, Nutrient Density, and Cost.Front Nutr. 2019 May 28;6:70.
- Martínez Steele E, Raubenheimer D, Simpson SJ, et al. Ultra-processed foods, protein leverage and energy intake in the USA. Public Health Nutr. 2018 Jan;21(1):114-124.
- Monteiro CA, Moubarac JC, Cannon G,et al Ultra-processed products are becoming dominant in the global food system. Obes Rev. 2013 Nov;14 Suppl 2:21-8.
- Marrón-Ponce JA, Tolentino-Mayo L, Hernández-F M, Batis C. Trends in Ultra-Processed Food Purchases from 1984 to 2016 in Mexican Households. Nutrients. 2018 Dec 26;11(1).
- Monteiro CA, Moubarac JC, Levy RB, et al Household availability of ultra-processed foods and obesity in nineteen European countries. Public Health Nutr. 2018 Jan;21(1):18-26. doi: 10.1017/S1368980017001379. Epub 2017 Jul 17.
- Hall KD, Ayuketah A, et al. Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake. Cell Metab. 2019 Jul 2;30(1):226.
- Mendonça RD, Pimenta AM, et al. Ultra-processed food consumption and risk of overweight and obesity: the University of Navarra Follow-Up (SUN) cohort study. Am J Clin Nutr. 2016 Nov;104(5):1433-1440.
- Poti JM, Braga B, Qin B. Ultra-processed Food Intake and Obesity: What Really Matters for Health-Processing or Nutrient Content? Curr Obes Rep. 2017 Dec;6(4):420-431.
- Martínez Steele E, Juul F, Neri D, Rauber F, Monteiro CA. Dietary share of ultra-processed foods and metabolic syndrome in the US adult population. Prev Med. 2019 Aug;125:40-48.
- Srour B, Fezeu LK, et al. Ultra-processed food intake and risk of cardiovascular disease: prospective cohort study (NutriNet- Santé).BMJ. 2019 May 29;365:l1451.
- Fiolet T, Srour B, et al. Consumption of ultra-processed foods and cancer risk: results from NutriNet-Santé prospective cohort. BMJ. 2018 Feb 14;360.
- Adjibade M, Julia C, Allès B, et al. Prospective association between ultra-processed food consumption and incident depressive symptoms in the French NutriNet-Santé cohort. BMC Med. 2019 Apr 15;17(1):78.
- Gómez-Donoso C, Sánchez-Villegas A, et al. Ultra-processed food consumption and the incidence of depression in a Mediterranean cohort: the SUN Project. Eur J Nutr. 2019 May 4.
- Sandoval-Insausti H, Blanco-Rojo R, et al. Ultra-processed Food Consumption and Incident Frailty: A Prospective Cohort Study of Older Adults (P01-012-19).Curr Dev Nutr. 2019 Jun 13;3(Suppl 1).
- Costa CS, Rauber F, et al. Ultra-processed food consumption and its effects on anthropometric and glucose profile: A longitudinal study during childhood. Nutr Metab Cardiovasc Dis. 2019 Feb;29(2):177-184.
- Rauber F, Campagnolo PD, et al. Consumption of ultra-processed food products and its effects on children's lipid profiles: a longitudinal study. Nutr Metab Cardiovasc Dis. 2015 Jan;25(1):116-22.
- Filgueiras AR, Pires de Almeida VB, et al. Exploring the consumption of ultra-processed foods and its association with food addiction in overweight children. Appetite. 2019 Apr 1;135:137-145.
- Kim H, Hu EA, Rebholz CM. Ultra-processed food intake and mortality in the USA: results from the Third National Health and Nutrition Examination Survey (NHANES III, 1988-1994).Public Health Nutr. 2019 Jul;22(10):1777-1785.
- Rico-Campà A, Martínez-González MA, et al. Association between consumption of ultra-processed foods and all cause mortality: SUN prospective cohort study. BMJ. 2019 May 29;365:l1949.