Dr Francis Pottenger inadvertently became a nutritional pioneer when he observed that nutrient deficient diets have a long-term, cumulative effect on animals. This is a very real problem for humans in the Western developed world today. Processed and packaged food, less time spent cooking, the increase of sugar and the low-fat craze all combine to result in a very poor diet for many people. Widespread nutrient deficiencies are already manifesting and making us fat and sick, but how bad will this get over multiple generations?

Read on to find out how things turned our for our feline brothers and sisters…

Great discoveries in nutrition usually began with simple observations and this was certainly the case with Dr Francis Pottenger’s now famous “cat study.” This study observed the impact of inadequately prepared foods on the health of cats over multiple generations. Dr Pottenger identified the value of heat-labile elements: nutrients that are destroyed by heat and are only available in raw foods. He also highlighted that poor nutrition not only affects an individual (feline or human), but has cumulative intergenerational effect.

In Pottenger’s cats that were fed a poor diet, deep-seated nutrient deficiencies and a host of negative physical and mental health consequences emerged over two and three generations. This is representative of the situation in much of the developed world where human diets that are heavy in processed and nutrient-deplete foods are resulting in physically degeneration that is not only getting worse, but is harder to reverse over time.

Pottenger highlighted that poor nutrition has a cumulative intergenerational effect.

Background to Pottenger’s study

Dr Francis Pottenger came to his experiment accidentally. He began as a medical physician investigating the theory that Tuberculosis (TB) was the result of adrenal (stress gland) deficiency. Pottenger gave cats adrenalectomies (removed their adrenal glands) in the hope of identifying an appropriate dose of adrenal and other hormones that would help human patients with TB. Initially Pottenger fed his test subjects a diet of table scraps that were cooked because humans had consumed them. While these were generally healthy cats, Pottenger found that he wasn’t seeing the efficacy he had anticipated with the injections. As the number of cats at the Sanatorium increased Pottenger was forced to obtain raw scraps from a local butcher to feed a portion of his feline test-subjects. Pottenger noticed that the cats that were fed the raw-meat diet seemed to react far better to the treatment than those on the cooked diet. These observations prompted his curiosity and so he embarked upon his now influential cat study, which would lead him to the title of nutritional pioneer. His study was a controlled dietary experiment that would involve 900 cats over a period of ten years. He did two different controls one: the milk study and the meat study discussed below.

The Pottenger Milk Study

The first Pottenger study identified that processed, refined and denatured foods have a profoundly negative affect on an animal’s mental and physical health. All the cats in the study consumed diets that were one-third raw meat, organs, bones and cod liver oil and the remaining two thirds was used as a variable. Cats were split into four groups and were fed either: 1) raw milk; 2) pasteurised milk; 3) evaporated milk; or 4) sweetened condensed milk. Importantly, the first generation of cats were all in good health and were the offspring of very healthy parents. Pottenger cut the bodies of the deceased cats open to reveal the huge internal impacts of the diet.

A summary of the health impacts he noticed based on the type of milk.

  • Raw: Cats had good coordination, normal sexual interest, shiny fur, healthy uterus and healthy livers and intestines.
  • Pasteurised: cats became lethargic, had early arthritis, impaired coordination, reddish caste to gums, slight liver atrophy and distension of the uterus and intestines.
  • Evaporated: poor fur quality, purple vasomotor congestion of skin, bronze caste to musculature, failure of lungs, enlargement of heart, chronic passive congestion of liver, gaseous distension of small intestine
  • Sweetened condensed milk: cats were extremely anxious and timid, lacked any sexual interest, dental abscesses, fur extremely course, marked vasomotor skin disturbance, failure lungs to collapse, enlargement liver/spleen, chronic passive congestion, lack of intestinal tone, engorgement of uterus.

These huge effects took less than a generation to manifest and the physical impacts of processed, denatured and refined food were apparent after just a short time.

The Pottenger Meat study

This study highlighted the importance of nutrients and why consumption of at least some raw food is critical. Cats were divided into two groups. Both groups were fed a diet one-third raw milk and cod-liver oil, while the remaining two-third of the diet was 1) raw meat; or 2) cooked meat. It soon became apparent that the group fed cooked meat was becoming weak and deficient in certain nutrients that were destroyed in cooking. The first generation of cats to be subjected to the cooked meat diet showed signs of laziness and degenerative diseases. However, it was the second and third generation of cats to be fed this diet where the obvious health consequences lay. Second generation cats lack coordination, but by the third generation kittens were being born blind and with a host of allergies and susceptibility to parasites and infection. These kittens were much smaller than their raw meat counterparts and had misshapen, flattened heads and an incomplete zeugmatic arch. Many of these kittens did not even survive six months and those that did could not reproduce. By contrast the group that had been fed raw meat continued to thrive and did not show signs of any of the degenerative disorders of illnesses of the cooked meat group. Heat-liable nutrients obviously play a critical role in maintaining the long-term health and vitality of cats and no doubt other animals.


The first Pottenger study identified that processed, refined and denatured foods have a profoundly negative affect on an animal’s mental and physical health.

What does this teach us about human health? 

Pottenger’s experiments in many ways the cat experiments are a reflection of our society as we see younger generations getting sicker and sicker, plagued by allergies and sensitivities, behavioural disorders and depression. Although younger generations eat in a way similar to their parents, as a result of decades of nutrient deficiencies we are struggling to recover.

It took Pottenger’s sick cats almost four generations being fed a cat-healthy diet of raw meat and raw milk to recover to normal, healthy felines. It will likely take humans a similar amount of time, but we are still a long way from even starting the battle. Pottenger’s experiment emphasises the importance of a properly prepared, nutrient dense diet as the foundation for our own individual health and the health of future generations.

Final words on the Pottenger cat study 

The key lesson we learn from Pottenger’s cats is that we can impact how our genes are expressed. This can effect everything from our ability to detoxify, food sensitivies and our mental state. Eating a nutritious diet and avoiding toxicity is a critical way to try minimise the impact that potentially “bad” genetic inheritance can have. Sometimes that’s not always enough and conditions, particularly mental health conditions, can arise. If mental health is something you’re struggling with, then I recommend visiting Better Help and support in finding further, professional support.

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