Editing Human nutrition (section)

=== 18th century until today: food processing and nutrition ===
{{Main|Food processing}}
{{more citations needed|section|date=February 2019}}
Since the [[Industrial Revolution]] in the 18th and 19th century, the [[food industry|food processing industry]] has invented many [[technology|technologies]] that both help keep foods fresh longer and alter the fresh state of food as they appear in nature. [[Cooling]] and [[Frozen food|freezing]] are primary technologies used to maintain freshness, whereas many more technologies have been invented to allow foods to last longer without becoming spoiled. These latter technologies include [[pasteurisation]], [[autoclavation]], [[drying]], [[salting (food)|salting]], and separation of various components, all of which appearing to alter the original nutritional contents of food. Pasteurisation and autoclavation (heating techniques) have no doubt improved the safety of many common foods, preventing epidemics of bacterial infection.

Modern separation techniques such as [[Gristmill|milling]], [[centrifugation]], and [[Expeller pressing|pressing]] have enabled concentration of particular components of food, yielding flour, oils, juices, and so on, and even separate fatty acids, amino acids, vitamins, and minerals. Inevitably, such large-scale concentration changes the nutritional content of food, saving certain nutrients while removing others. Heating techniques may also reduce the content of many heat-labile nutrients such as certain vitamins and phytochemicals, and possibly other yet-to-be-discovered substances.<ref>{{cite journal | last=Morris | first=Audrey | author2=Audia Barnett | author3=Olive-Jean Burrows | title=Effect of Processing on Nutrient Content of Foods | journal=Cajanus | volume=37 | issue=3 | pages=160–64 | year=2004 | url=http://www.paho.org/English/CFNI/cfni-caj37No304-art-3.pdf | archive-url=https://web.archive.org/web/20070604213903/http://www.paho.org/English/CFNI/cfni-caj37No304-art-3.pdf | archive-date=2007-06-04 | url-status=live | access-date=26 October 2006}}</ref>

Because of reduced nutritional value, processed foods are often enriched or [[fortified food|fortified]] with some of the most critical nutrients (usually certain vitamins) that were lost during processing. Nonetheless, processed foods tend to have an inferior nutritional profile compared to whole, fresh foods, regarding content of both sugar and high GI starches, [[potassium]]/[[sodium]], vitamins, fiber, and of intact, unoxidized (essential) fatty acids. In addition, processed foods often contain potentially harmful substances such as oxidized fats and trans fatty acids.

A dramatic example of the effect of food processing on a population's health is the history of epidemics of [[beri-beri]] in people subsisting on polished rice. Removing the outer layer of rice by polishing it removes with it the essential vitamin [[thiamine]], causing beri-beri. Another example is the development of [[scurvy]] among infants in the late 19th century in the United States. It turned out that the vast majority of those affected were being fed milk that had been heat-treated (as suggested by [[Louis Pasteur|Pasteur]]) to control bacterial disease. Pasteurisation was effective against bacteria, but it destroyed the vitamin C.