The unintended consequences of food additives can be unpredictable. Like pesticides many diminish health and well-being and can even be incapacitating. They are only in food so they are easier to protect against.
Some block absorption of nutrients. Some are carcinogenic. Some cause allergies. Some cause uncomfortable sensations like palpitations which lead to panic reactions. Some disrupt hormones which interferes with mood and intellectual activity.
Oestrogen analogues (for example in plastic absorbed from packaging or coated cooking utensils) disturb the hormonal system and foetal sexual maturation and lead to a range of illnesses and mood swings.
Some metals that leach out of cooking utensils disrupt neural transmission, hormones and energy systems affecting health and mood.
Glutamates like MSG and related excito-toxins act like speed. They make life exciting and food delicious but drive neurons to death through exhaustion, which in the long run leads to loss of brain mass and intellectual capacity.
Many food additives don't seem to produce adverse reactions and are possibly safe.
preservatives
We used to begin to decay hours after death. Now after a lifetime of eating preservatives it can take weeks.
Preservatives inhibit biological activity. Depending on the way they do this they slow down or disrupt physiological processes. They embalm the living.
In my experience most people who eliminate preservatives from their diet eventually after a few months or years find them noticeable and unpleasant.
water
Countries that added fluoride together with toxic metals from the waste products of industrial processes to tap water have had no more reduction in tooth decay than those that don't. They have unsurprisingly experienced significantly more health problems (including tooth damage and delayed eruption) as the toxic metals are biologically active and in significant dosages.
Water sitting in copper water pipes especially in long lengths heated by the sun can bring dangerous levels of copper into the kitchen. Copper and other heavy metals leach into water the longer it sits in copper pipes. This is enhanced by the chemicals added during fluoridation. Running water through the pipes before using it internally or on the skin reduces the possibilities of harm.i