Almost any diet that contains mostly real food rather than artificial food-like substances will produce substantial improvements in health. Contents are hugely secondary to actually consuming real food.
Only when factories focus on making addictive instead of healthy food. You can ruin the food yourself in the same way. Different cultures do this differently, so you see much healthier fast food packages in some countries than others.
Since we have food production mostly figured out and we don't need any new production optimizations do we really need food production to remain the domain of free market?
Maybe governments should set up production of healthy convenient packaged food and give it away for free. Then gradually ban businesses from selling the worst products.
Technology advanced a ton since the last time it happened. And food making is no longer that lucrative. Other industries give more opportunities for corruption.
Besides, I don't advocate for nationalising entire food production. Just carving out small segment that by design operates at a loss because it acts altruistically not with market ruthlesness towards consumers.
It can be trusted as well/bad as for water, electricity, security…
It about quality food being vital for everybody, not about importance. A public “default food package“ could have a big impact for many families health. The private options can stay , regulated, as well as for water, electricity and safety.
Food isn’t all about macros, you need to get your micronutrients (minerals etc), which heavy processing partially removes. There’s also the rabbit hole of soil quality, where a plant can only contain the nutrients its soil has offered (copper, molybdenum, humic acid etc), where organic food tends to be better because soil health is actually looked at.