Viruses,parasites and bacteria destroy cell and tissues by direct action and indirectly eliciting inflammation.Allergy and insulin resistance worsen and maintain inflammation.Blood glucose (BG) does this directly (?) and provoking unwanted reflexes.Lipids,mainly cholesterol sustain vascular diseases (or only mark damages?).Hypertension signals and contributes to vascular diseases.I prefer to think to a unique final way of damaging: the immune mechanisms of damage.Immune cells and antibodies are predisposed to destroy molecules or structures that are born outside the human body and are demolished in all tissues.These events develop also in the respiratory activity.Absorptive function is so important that is preserved by transferring these immune molecules or structures in all body tissues for elimination.Intestinal mucosa retains the killing function to limit the outside aggression.Killing invading viruses or bacteria marks the start of convalescence.