They throw giant hissy fits about mercury &c being a cumulative poison.
Thus you know there is a cumulative poison, and the one to watch out for isn't mercury.
Is it BPA? Maybe pesticides? Iron? It's fructose.
Fructose causes long-term damage. The fat it produces is inflammatory. This in turn poisons your bloodstream and causes things like acne. And diabetes. And heart attacks.
Reminder, losing weight is a two-step process. First: go off all sugar. Break the addiction and get into a better metabolic frame of living. Even glucose is suspect; insulin is a distinctly suboptimal solution and it's best to use as little of it as you can get away with. Second, fasting. Go a full day - or 3 or 5 or 7 - without eating. Eat as much as you want on feast days. Intermittent fasting is hardly bad, but for real results try for at least 36 hours. If you get "hunger" pangs realize it's indigestion due to previously eating something you shouldn't have. Usually in the previous breakfast, but it can also be caused by lunches from years ago. This doesn't mean you can't eat something to settle your stomach, but understand the more you eat the more suboptimal that solution is. The upper path is additional starvation until you feel better.
Though I've found eating very very little - less than half the recommended minimum calories - is totally fine. It feels neat, like perpetual motion. However I'm pretty sure it's just nutritionists being on crack as per usual, combined with my excessively sedentary lifestyle.
Now you know why they love high-fructose corn syrup so much. Americans trusted their government to make the food safe, thus it is unsafe, and they're constantly working out how to make it less safe.