Note: the source of the quote for anyone curious to read more:
Humans probably have wildly different nutrition needs depending on how physically active they are, how hot it is in their part of the globe, which foods are available in their area, their gut microbiome, etc.
Nutritional Science seems based on the idea that relatively minor tweaks to diet can influence health outcomes. After several decades of failing to find what those tweaks might be, it always seems strange to me that people don't seem to consider that they might just not exist, and that the human body is fine with whatever food it gets, within some broad range.
The metabolism of vitamin C in particular is pretty well understood, and no magical benefits of getting huge doses has ever been proven to have any of the claimed positive effects (despite many prominent supporters' efforts, including Mr Pauling).
If you don't eat meat, it will be hard to get iron and B12 and carnitine and some other things. It will also be harder to get enough calories.
Or for example I usually avoid sausage and fat meat as it is heavy on the stomach and weight. But the last days I have been in the mountains, walking over ice and snow. Fat meat was excellent, because with the cold, I burned lots of energy.
Also might have something to do with how many tens of millennia some peoples' isolated ancestors spent surviving on relatively limited local items available or cultivated, compared to what is now considered mainstream.
In my case I lowered my metabolism considerably so I could thrive in Texas without air conditioning in the summer. When everyone else was complaining about the heat this week, all I could do is remind them "it's not even summer yet".
Definitely was not as much progress during the first decade.
I think what you mean is they are not meaningful to guide health decisions as they are too broad and can be further subdivided into more specific categories.
Since we don’t actually know anything about nutrition, it’s impossible to know whether the new engineered food products are unhealthy.
"We don't understand how the body metabolizes what it ingests, and what is healthy and what isn't! Every theory is wrong and has been overthrown! Therefore it's impossible to say whether eating this arsenic pill will be bad for you!"
My impression is that there is pretty solid evidence that eating highly processed foods correlates with worse health outcomes.
That is the conclusion of the Nutrition piece as well. But, crucially, it's important to recognize that we don't really know why that is, and we don't know many of the particulars. To take just two examples:
- Even our distant hominid ancestors had discovered fire and were using it to heat food, so it seems very unlikely that eating raw food would be significantly better for us than eating cooked food (by evolutionary arguments)
- Cutting food is often not even considered processing, and yet it's something which has a clear negative effect on our teeth at the very least (and is a much much more recent innovation than cooking)
So yeah, don't eat a Mars bar or a Chicken McNugget if you can at all help it - and gods help you if you like Spam. But beyond the worst of these foods, the story is actually quite unclear.
Edit: the specific quote about the exact point you're making:
> One of the trial new messages being tested by the nutrition establishment is “avoid processed food,” which has the big advantage (for their future credibility) that no one is likely to adopt it. Cooking has become an unacceptable hassle.[9]
> [9] Disclosure: I do avoid processed food, and most of what I eat I cook from scratch. This is not advice.
Not to mention, there are processed staples eaten all over the world for hundreds or thousands of years without leading to widespread obesity or addiction - bread and beer being some of the oldest such examples.
Many veggies can be delicious with just some heat + salt; though adding a few spices certainly helps.
I'd much rather eat a perfectly cooked skirt steak with home made chimichuri and a side of veggies than a domino's pizza.
This is one of the problems of this idea of processed foods - many things which don't actually seem to be a significant problem are in fact highly processed, we just don't tend to think of them like that.
Not everything that is processed is poisonous, and most “fresh” food today is full of chemicals or lacking in nutrients, so most food you would eat is not that healthy.