Newsletter｜加工食品为何会对青少年的营养摄入产生负面影响？

Processed food is characterised as ready-to-eat or ready-to-heat products manufactured mostly from multiple ingredients usually combined with additives, or ‘industrial formulations’, by which flavour, sugar, fats or chemical preservatives are added. This can include confectionery, fried snacks, processed meats, cakes and biscuits.

A 2020 study concluded that processed foods are prevalent in diets worldwide, and that the consumption of these foods offers no beneficial outcomes. In fact, of the 43 studies reviewed, 39 of them found at least one adverse health outcome when processed foods were consumed.

Highly processed food – which is made from substances derived from foods and additives – is generally not good for us. Studies have shown that food additives can alter our gut bacteria, and cause inflammation in our bodies, which is linked to higher risk of heart disease.

Also, research shows that people have a tendency to overeat ultra-processed food. Studies have shown that people who eat ultra-processed foods consume more calories overall and gain more weight, and have higher risk of developing heart disease.

The history of food processing began with a number of preservation and cooking techniques that are still used today, though on a much larger and more efficient scale. From prehistoric societies, to some of the earliest ancient empires, such as ancient Greece, India, China and Peru, up to the Middle Ages, these techniques were developed, refined and spread around the world across many different cuisines.

Two important processes were popularized in the 1800’s; pasteurization and canning. These processes became vital to the history of food processing, making foods safer and much more accessible.

Pasteurization, developed by and named for French microbiologist Louis Pasteur, was researched in the 1860’s. This process was particularly important for juices and especially milk, which is very susceptible to bacterial growth.

Pasteurization kills microbes by applying heat, without affecting the nutritional quality or taste of the food. Without this process, this history of food processing would not have advanced much farther. Long-term food storage and transport throughout the world would have been extremely limited.

New processes as well as new ingredients and new appliances contributed to the history of food processing in the 20th century. Spray drying, evaporation, freeze drying and the use of preservatives made it easier to package different types of foods and keep them on the shelf. 

Artificial sweeteners and colors helped to make these preserved foods more palatable. The home oven, microwave, blender and other appliances provided an easy way to quickly prepare these meals. Factories and mass production techniques made it possible to quickly produce and package foods. These developments paved the way for globally popular foods like frozen dinners, instant noodle cups, baking mixes, and more.

Though processed foods were fast and affordable, concerns began to rise about their nutritional value in the late 20th and early 21st century. Many preservation processes reduce the vitamin and mineral content of otherwise healthy foods. 

Added fat, sugar and oil increases calorie content without increasing nutritional value. Concerns about preservatives and their long-term health effects began to rise. The toll of disposable plastic packaging also began to rise. Though food processing made many foods easier to buy and prepare, there were trade-offs that had, so far, not been addressed.

Within both the United Kingdom and the United States, it is estimated that 65.4% and 66.2% of the daily caloric intake of school-aged children, respectively, is comprised of ultra-processed foods.

This growing consumption has been mirrored by a parallel rise in both childhood and adult obesity, thereby indicating that the consumption of ultra-processed foods may be a lead driver in the increased prevalence of obesity and diet-related diseases. More specifically, recent clinical trials have found that the consumption of ultra-processed foods increases the risk of obesity, type 2 diabetes, cardiovascular disease, cancer, and mortality in adults.

“In modern society the food environment is dominated by the ready availability of relatively cheap and accessible ultra-processed foods that are constantly marketed,” said Mark Lawrence, a public health and nutrition professor at Deakin University in Geelong, Australia and author of an editorial accompanying the studies.