According to Terrain Theory, the main causes of disease are toxins/pollutants and nutrient deficiencies.
Here we see the many kinds of toxins that certain bacteria can secrete, which causes an immune response. Some toxins can be fatal.
The body occasionally removes these toxins as necessary. Toxins in our food, water and air, plus medications, vaccines (metals, adjuvants, aborted fetal tissue, animal tissue), smoking, pollution, pesticides, alcohol abuse, all add to a toxic inner terrain.
Nutrient dense diets with pasture raised animal fats, gelatin broths and organ meats help protect against toxic damage to cells.
Following Weston A. Price