This is the “modern age,” supposedly, and yet human health, infrastructure, and relationships seem to be depreciating instead of getting better. Humans remain largely the same as they have for centuries, and yet they seem to be in worse health than those who lived a few decades ago. Everything is in extremity: obese vs emaciated, poor/rich, religious/atheist, and so on. What has changed is the ecosystem: the food, the culture and values, etc.
Why is man-made product usually bad for you? It does not occur in nature and so something from nature does not necessarily know how to deal with it. It doesn’t have the tool-set.
For example, take trans-fat. Your body has these things called enzymes, which help break down food, in this analogy, enzymes will be scissors and the fats will be boxes.
Plant fats ( poly and monounsaturated fats) = Paper box = Easy to break down
Animal fats (Saturated) = cardboard box = More difficult
Trans-fat (man-made, hydrogenated oils) = Titanium box = no breaking that with scissors, your body just stores it somewhere leading to all sorts of problems.