How Cholesterol and Fat Got a Bad Reputation

Heart disease prevention has been a major research topic since the 1950’s [1]. It’s a safe bet that at some point, you have been told dietary cholesterol and fat is bad. The good news is science has now proven dietary cholesterol isn’t bad. Unfortunately, it was also science telling us it was bad all those years ago. How did the science change so drastically? Patients, nutritionists and doctors alike have a tough time breaking old habits – especially when they were originally based on ‘scientific fact’.

This article will show you HOW and WHY we were misled when it came to nutrition and heart disase risk; particularly why the original ‘theory’ telling us cholesterol and fat was bad was simply bad science.

It Started With an Observation

The presence of cholesterol in atherosclerotic plaques is undeniable. In fact it was first observed in 1842 [1]. Even to this day, everyone agrees cholesterol is present in atherosclerotic plaques. The issue is some people say cholesterol causes the plaque formation. I’m here to tell you that other things cause the plaque formation, and cholesterol happens to be there too [2].  They looked at the gunk clogging the artery rather than the whole disease process, including clotting factors, vascular spasms, heart rhythm, viscosity of the blood, calcium deposition, inflammation and toxins [2].

diagram showing healthy artery versus artery with atherosclerotic plaque.

Figure 1: Initially, people looked at the yellow gunk and found cholesterol inside, and attributed atherosclerosis to cholesterol. In reality, there are many contributing factors and several components to this atherosclerotic plaque.

Rabbit Studies

Fig 3: Nikolai Anichkov

Fig 2: Ilya Mechnikov

Studies were conducted in St. Petersburg/Leningrad between 1909 and 1913 on rabbits. The scientists (Nikolay Anichkov and Ilya Mechnikov) aimed to prove that meat and excess cholesterol accelerated aging [3]. From the beginning, based on their methodology, they said their findings would not relate to humans.

They fed rabbits pure cholesterol dissolved in sunflower oil. The rabbits developed atherosclerotic plaques that resembled that of humans [3] and also inflammation and liver toxicity [4].

Remember, these authors said themselves these findings did not relate to humans. However, once people heard of this study, a surge in cholesterol and heart disease research came out. People immediately saw these findings and thought cholesterol caused atherosclerosis and heart disease.

There are many reasons these studies shouldn’t apply to humans:

  1. Rabbits usually don’t eat cholesterol (they’re herbivores) – their systems aren’t equipped to eat and metabolize cholesterol [3], [1], where as humans can eat and metabolize cholesterol

    Picture of a rabbit in grass

    Figure 4: Initial studies on cholesterol were based on rabbit studies. Although they shouldn't have been, these studies were a driving force behind human dietary recommendations.

  2. Cholesterol feeding in many other animals failed to produce atherosclerosis [3], [1]
  3. These animals were fed pure cholesterol, something we cannot obtain through diet. Cholesterol is always part of a whole food – along with other macro- and micro-nutrients

The rabbit study did prove the importance of thyroid health on cholesterol metabolism.

  • animal studies show if you block thyroid hormone – it induces atherosclerosis [3]
  • A follow-up study was done on rabbits: This time they fed them cholesterol with supplemental thyroid hormone and it was found they didn’t develop atherosclerosis [3]
  • By 1936 – it was well understood that hypothyroidism plays a big role into cholesterol metabolism, and subsequently heart disease [3]

Anitschkov never said dietary cholesterol in diet caused atherosclerosis in humans [3], in fact human studies have shown dietary cholesterol has a weak effect on serum (blood) cholesterol [1]. In 1950 John Gofman published work on lipoproteins that also clearly disproved the idea that dietary cholesterol causes heart disease but it never got public attention [3].

The Sugar Industry: Influence on Research and Bribery

Fig 5:The Sugar Research Foundation is now known as the Sugar Association.

As the low fat craze was getting some momentum, partly due to the aforementioned rabbit studies, there were debates as to the dietary sources of heart disease. Early arguments pinned fat against sugar and the sugar industry wanted to step in to promote fat as the dietary culprit in cardiovascular disease [2].

In 2016, JAMA (a research journal) published a report examining the Sugar Research Foundation (now called the Sugar Association) and their influences on research pertaining to cardiovascular disease dating back to the 1950’s. They looked at internal documents, historical reports and statements. The findings are quite telling.

In the early 1950’s the heads of the Sugar Research Fund (SFR) Henry Hass and John Hickson, identified a strategy to increase market share by getting American

s to eat lower fat diet. They spent $600 000 (equal to $5.3 million in 2016) to teach people that “sugar is what keeps every human being alive and with energy to face our daily problems” [2] [5]. Researchers such as John Yudkin had reported that sugar, not fat, caused heart disease [2], [6], and the SFR planned to embark on a major program to counter Yudkin and other ‘negative attitudes towards sugar’ [2].

The SRF reached out to prominent Harvard Researchers. Fredrick Stare (Chair of Harvard University School of Public Health Nutrition Department) was invited to join the Sugar  Advisory Panel, and he did [2].

Next, the SRF paid Harvard researchers D. Mark Hegsted and Robert McGandy to do a literature review on dietary sources of heart disease. Initially, they agreed to pay Hegsted and McGandy $500 and $1000 respectively. However, correspondence between the researchers and SRF prove they couldn’t come to a favorable conclusion for the sugar industry. Finally, the researchers were paid $6500 (equal to $48 900 in 2016) [2] and they published what the sugar industry wanted to see. They concluded there was “no doubt that the only dietary intervention required to prevent CHD was to reduce dietary cholesterol and substitute polysaturated fats

for saturated fat in the American diet” [2], [7]. Furthermore, the paper didn’t disclose the Sugar Research Fund as a contributor or sponsor.

The JAMA article shows the sugar industry sponsored research programs between the 1950’s and 1970’s that successfully cast doubt on the hazards of sugar while promoting dietary fat and cholesterol as the causative factor behind

cardiovascular disease [2].

The full JAMA investigation into the sugar industry can be found here.


Ansel Keys and the 7 Nation Study

All while the sugar industry was doing their part to influence the research, Ansel Keys was doing his own research. He was the American scientist who some say led the United States (and

Figure 6: Ansel Keys

subsequently the rest of the world) into the low fat, high carb craze. He reported research poorly and had strong political ties which eventually shaped the Food Guides across the world.


Ansel Keys was one of the nutrition advisors for American soldiers during World War Two. After the war he noticed well-fed, wealthy American Business executives (in Europe) had high rates of heart disease and he hypothesized that the American Diet of high fat and high cholesterol foods lead to the heart disease. He then made a study to prove his hypothesis.

The 7 Nations Study

Published in 1957, this study looked at countries with contrasting dietary patterns – and reported that those with highest fat diets had highest cholesterol levels and highest heart attack death rates. To a lot of people, this notion makes sense, but in reality this shows a pattern but does not prove causation.

The Many Weaknesses of This Study.

First off, Keys published data for 7 countries when he had data available for 22 countries at the time. As you can see, in the figure here, his relationship is established when only 7 data points are used. However, if all data points were used, you will see the association isn’t as strong. Statistically this is very significant.

Figure 7: Chart from Uffe Ravnskov's the 'The Cholesterol Myths'. Showing the data Ansel Keys reported (on the left) versus the data he had available to him (on the right)


Next, Keys focused on fat, but neglected all the other possible risk factors for heart disease. He neglected to report on things like smoking, sugar intake and lack of exercise.

Even with the flaws, Ansel Key’s principles were embraced by the American Heart Association, who in 1961 officially recommended Americans lower their intake of saturated fat. Then in 1977 the US Federal government also embraced this message in its 1977 Dietary Goals where they limited cholesterol to only 300 mg a day, equal to less than two eggs worth of cholesterol. Click here to  see why Eggs are in fact okay.

To add insult to injury, in 1997, a retired Ansel Keys stated “Cholesterol in food has no effect on cholesterol in blood and we’ve known that all along”. He did later recant this statement.

We Need to Trust Our Sources

News Media

The news media also played a big part of spreading the word fat and cholesterol was bad. Research is often sensationalized without much thought about the quality of research and the complexities of nutrition and disease. Often times, reporters with no formal medical knowledge will report on medical issues and the general population is given inaccurate advice.

A prime example is the way time magazine took a full 180 degree turn from celebrating Ansel Keys and advising against cholesterol between the 1960’s to 1980’s to promoting cholesterol positively in the 2000s.  It’s important to remember, even from the 1960’s there was plenty of research refuting the claim cholesterol was bad, it’s just a matter of reporters cherry-picking their sources.


Research is published daily and nutrition is still a hot topic. Opposing research is published all the time, but it’s up to the reader to read and analyze the research and determine what research is applicable to them.

Many things need to be considered when we look at research:

  1. Is it applicable to humans?
  2. Is the research good quality?
  3. Were there any conflicts of interest between the researchers and the outcomes they report? (like the Harvard researchers mentioned above)

Between 1970 and 1992, 16 trials were conducted on humans looking at the effects of lowering cholesterol on heart disease. Eight showed lowering cholesterol were beneficial for health; 8 showed it was detrimental. Of those 16 research papers, 40 other articles referenced them but not a single one referred to the research that showed cholesterol lowering was dangerous. This is an example of misrepresentation of the data within the scientific community.

When someone says something is ‘scientifically proven’ we need to question the science and make sure we interpret it properly.


Hopefully you understand why dietary cholesterol and fat are not as bad as they were made out to be. Research was weak and vested interests prevailed in promoting the message cholesterol was bad.

The next part in this discussion is how to reintroduce cholesterol and fatty foods into your diet. This is where the discussion around quality of foods and sources of cholesterol and types of fat will be important. Visit a local Naturopath, doctor or Nutritionist to talk about this more.

For now, click here to read why Eggs (and the cholesterol they contain) may be healthy, whether you have heart disease or not.


Works Cited


About the Author

picture of me, johann de chickera, naturopathic doctor

I'm Johann de Chickera, a Naturopathic Doctor, practicing in Ontario, Canada. My clinical practice relies on keeping up with the most up-to-date research and continued education. This blog serves as a way to provide others with a compilation of everything I've learned along the way. Please click here if you're local and want to see me in practice.

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