What makes food processed and why is it unhealthy?

Question

You constantly hear about how processed food is bad for your health and should be avoided. But what is it and why is it so bad?

In: Biology

Answer 1

This is a hard ELI5 because it’s many questions folded into 1 question with 2 parts (and 1 of which is leading vs neutrally phrased).

Processed food is not inherently unhealthy. Anything that changes a raw ingredient, including physical manipulation, is processing.

So if you cut up a potato and boil it, you are processing the potato. Similarly, if you chop up tomatoes and vacuum seal them in cans, you are processing the tomatoes. If you take all the extra beef from a cow’s carcass, morselize them, and make them into beef patties, you are processing the beef. If you combine, milk, flour, eggs, sugar and bake a cake, you are processing all those ingredients and making a cake. None of these are inherently unhealthy.

Food scientists define the level of processing and what is “unhealthy” are the foods that fall into the “ultra-processed” category. It’s these foods that are the focus of the discussion.

Ultra-processed foods = industrial formulation of ingredients, with many processes, chemicals, and ingredients that would not be normally used in a home or restaurant kitchen and are far removed from the original fresh ingredients.

Go back to my cake example — milk, flour, eggs, sugar, cocoa, butter, etc. and I bake it in an oven at 350 F for 30 minutes. Even if I bake it on an industrial level, the cake is processed, but not ultra-processed. The ingredients themselves are processed as well (grains ground down into flour, milkfat churned into butter, sugar extracted from sugarcane), but they are not ultra-processed — they are directly sourced from an original fresh ingredient.

But if add hydrogenated oils instead of butter, sugar alcohols or substitutes instead of sugar, chocolate flavoring and caramel color instead of cocoa, preservatives, alternative milks (like nut milks with emulsifiers), alternative flours, etc., etc. the cake is now ultra-processed because all of the ingredients are now far removed from what would originally be used to make the cake. You cannot easily obtain any of these ingredients without the help from Dupont or 3M chemical factory.

And now because the ultra-processed cake is so far from the processed cake, it’s unhealthy because it’s just a simulation of the original cake. And the ingredients themselves may cause increased harm compared to the original ingredients. The hydrogenated oils increase risk of heart disease over butter, the sugar alcohols/substitutes may also increase the risk of metabolic disorders over regular sugar, flavorings/colorings/etc. could all be carcinogenic. vs just cocoa powder, etc. etc. etc.