Lessons from Pottenger’s Cat Study

Dr Agnes Ryu

In the early 20th century, Francis Pottenger Jr., M.D. conducted a landmark 10-year study on the effects of processed foods on cat health and fertility. Known today as the Pottenger’s Cat Study, this research revealed troubling declines in cats fed cooked and processed foods compared to those fed raw, natural diets. Pottenger’s findings suggest vital lessons for human health and fertility as well.

Pottenger’s Study Methodology

From 1932 to 1942, Pottenger conducted his study at his medical clinic in California. He divided 900 cats into two groups – one fed raw meat and milk, the other fed cooked meat and pasteurized milk. The cats were studied across four generations. Pottenger evaluated the health of each cat, noting physical changes, fertility rates and how long the cats lived.

Declining Health Over Generations

By the third generation, the cats fed processed foods showed marked degeneration in health and fertility. They had higher rates of allergies, heart problems, vision loss, arthritis and other issues. Their bones became soft and pliable. Pregnancy rates plummeted and infant mortality rates rose. The cats had altered skull development and reduced immunity to disease.


Cats following a raw diet showed the following qualities  Cats following a heat-processed diet showed the following qualities
  • Gentle dispositions
  • Sound bone structure and density
  • Wide palates that were able to accommodate teeth
  • A lack of parasites and disease
  • Shiny fur
  • The absence of reproductive disorders
  • Superior overall health
  • Arthritis
  • Behavioural abnormalities
  • Sterility (lack of fertility)
  • Skin disorders
  • Allergies
  • Hypothyroidism
  • Skeletal deformities
  • Dental deterioration
  • Decrease in height
  • Poorly formed skulls
  • Inferior overall health

Physical Changes: Feminization of Males

One startling change Pottenger noted was altered gender-specific features in the cooked food cats. The male cats appeared feminized – they had narrow faces, sweet expressions and docile natures. The female cats became more masculine and aggressive. By the third generation, doctors examining the cats struggled to determine gender without inspecting genitals.

Pottenger saw similar feminization of men in his medical practice. He included photos in his study showing groups of male and female college students. Doctors could not reliably identify gender based on physical features alone – the students appeared remarkably similar.

Pottenger attributed this feminization to poor nutrition, specifically consumption of processed foods high in sugar and vegetable oils. The raw food cats maintained normal gender features across generations.

How Soon Did Cats Health Decline in Pottenger’s Cats Study?

The cats fed a diet of cooked and processed foods displayed remarkable generational decline in health and fertility. As early as the second generation, these cats showed physical degeneration including bone and organ issues. By the third generation, the cooked food cats suffered high rates of infertility, miscarriages and infant mortality. They were unable to sustain their population. The females underwent prolonged periods of heat with no pregnancy. They suffered miscarriages and had few surviving kittens. The male cats showed lower sperm counts and more difficulty impregnating females. This trend culminated in extinction by the fourth generation – none of these cats were able to reproduce after being fed processed foods over multiple generations.
In contrast, the cats fed raw foods continued to thrive and reproduce normally through four generations. They lived long, vibrant lives free of degenerative disease.

Relevance to Human Health

Pottenger’s research highlights the compounding generational impacts of diet on health due to epigenetics. His cats demonstrated how poor nutrition can steadily worsen over generations as gene expression is altered. This has profound relevance for humans, as our modern processed food diet diverges farther from ancestral eating patterns. The exploding epidemics of infertility, chronic diseases and developmental disorders suggest we are undergoing a generational decline in health much like Pottenger’s cats.

Political agendas pushing plant-based, ultra-processed “foods” and nutrient-deficient diets could further accelerate this decline. Epigenetics make clear the risks of straying too far from the diets our bodies evolved upon. If we wish to reverse generational health decline, we must re-embrace traditional diets rich in meat, fish, eggs, raw dairy and vegetables that nourished humans for millennia.

Agnes Ryu

Agnes Ryu

Dr. Ryu is a clinician and biochemist specializing in integrative medicine. Her clinical interests include fertility, hormones, metabolism, healthy ageing, menopause, and natural breast cancer care. As an integrative practitioner, Dr. Ryu aims to uncover the root causes of health issues and strives to empower patients with the knowledge and tools to take charge of their own health.

Shopping cart0
There are no products in the cart!