Complex environmental illnesses are often dismissed by doctors and friends as being "all in your head" because their symptoms are invisible and difficult to test for. This parallels the historical misdiagnosis of "hysteria" to label real but poorly understood medical conditions.

The ability to "smell" an illness, like an ear infection or Parkinson's, is not about detecting a universal "sick" odor. It is about recognizing a change from an individual's unique baseline body scent. This skill, once used by doctors, highlights the importance of familiarity in using scent for diagnostic purposes.

Despite their high theoretical sensitivity, standard PCR stool tests for parasites frequently fail to detect active infections in symptomatic patients. Old-school microscopy, where a sample is manually examined under a slide, has proven to be a more reliable diagnostic tool in practice.

The rise in consumer cleaning products and spick-and-span households reduces our exposure to diverse microbes. According to the hygiene hypothesis, this lack of immune system training can make our bodies less robust and more prone to overreacting to benign substances like food proteins, thus fostering allergies.

A physician strongly advises against consuming any raw fish (sushi) or rare meat, citing a much higher risk of parasitic infection than the public realizes. These infections are a leading global cause of iron deficiency anemia and can lead to severe liver damage.

Animals actively treat their own illnesses. Chimpanzees consume specific bitter plants to fight intestinal parasites, while urban birds weave nicotine-filled cigarette butts into their nests as a fumigant. This behavior reveals a sophisticated, evolved understanding of their environment for medicinal purposes.

Chronic issues like fatigue, moodiness, and brain fog are frequently dismissed as inevitable side effects of getting older. However, these are often direct symptoms of underlying environmental health problems, such as mold exposure or parasites, that can be addressed.

A physician was forced to add "environment" as a third pillar of health after a patient, who perfectly managed her diet and exercise, remained ill due to significant environmental exposures. This challenges the conventional two-pillar model of health.

When a public health intervention successfully prevents a crisis, the lack of a negative outcome makes the initial action seem like an unnecessary overreaction. This paradox makes it difficult to justify and maintain funding for preventative measures whose success is invisible.