The Low-Carbohydrate Diet Myth

Increase calories 1970-2000A fundamental argument that is made at the beginning of many low-carbohydrate articles, books and websites is that the we has been following the expert medical advice for the past 20 years (or 30, 40 or 50 years) and following a low-fat diet.  Despite, this we are fatter than ever.  Many of these articles claimed that there is a conspiracy to hide the truth concerning fat and cholesterol.

However, USDA’s Economic Research Service data states that average daily calorie intake increased by 24.5 percent, or about 530 calories, between 1970 and 2000. Of that 24.5-percent increase, grains (mainly refined grain products) contributed 9.5 percentage points; added fats and oils, 9.0 percentage points; added sugars, 4.7 percentage points.[1]

The same publication shows the increase in different food groups from the 1950s.

Note that fats have 9 Cal/g whilst carbohydrates and protein have 4 Cal/g.

Item1950-19592000% change
Total Meats138.2195.241
Poultry20.566.5224
Fish10.915.239
Added Fats and Oils44.674.567
Total Calorific Sweeteners109.6152.439

USA Per Capita Annual Average (lbs)

BBC2 Documentary – The Men Who Made Us Fat

Robert Lustig BBC Robert Lustig is a pediatric endocrinologist at the University of California, San Francisco.  He is the author of Fat Chance: Beating the Odds against Sugar, Processed Food, Obesity, and Disease.[2]

He specialises in childhood obesity and studying the effects of sugar in the diet. He is the Director of the UCSF Weight Assessment for Teen and Child Health Program and also a member of the Obesity Task Force of the Endocrine Society. He was interviewed for the BBC2’s documentary The Men Who Made Us Fat.  Below are some by Robert Lustig excerpts from the documentary.[3]

This man, Ancel Keys, claimed he had the answer to heart disease. His theory had a decisive impact on what we would all eat. But it also had a devastating side effect – creating the conditions for obesity.
Keys’s theory was that fat alone caused heart disease …
In 1952 Keys did a sabbatical in England where he saw the epidemic of heart disease himself and correlated it with the enormously poor British diet of fish and chips, etc. – you know what I’m talking about!
. . . and decided that saturated fat had to be the culprit. And he actually said that back in the Fifties before he did any studies. And he spent the next fifty years attempting to prove himself right.
Keys won the battle. (John) Yudkin was thrown under the bus. And …Well, he was discredited by numerous societies basically saying that he did not have the data to make his claims about the importance of sugar.

Much of what a rather chubby Robert Lustig states is false.

  • Firstly, Keys research was not the starting point for nutritional and cholesterol research which had its foundations in the early years of the 20th century.
  • Keys early views on diet were formed in Italy and Spain, not in England.  He developed his ideas about diet and heart disease when he was invited to Naples. His studies showed dramatically lower rates of coronary heart disease in Italy and Spain.
  • He introduced the concept of the Mediterranean diet to America – a diet he described as mainly vegetarian.
  • Initially Keys did focus on fats in the diet (not saturated fats) as Lustig states above.
  • Keys conducted many trials and experiments both before and after he came to his initial conclusions regarding fat.
  • And John Yudkin was “discredited because he did not have the data”.  Well, where is the data?

Ancel Keys

Keys - Time Cover Jan 13 1961 Authors such as Uffe Ravnskov: (The Cholesterol Myths – 1991), Gary Taubes (Why We are Fat – 2011, Good Calories, Bad Calories -2007), Robert Lustig (Fat Chance: Beating the Odds against Sugar, Processed Food, Obesity, and Disease – 2013), John Yudkin (Pure, White and Deadly -1972) argue that cholesterol is not a health issue and concentrate on carbohydrates in the diet. One method of advocating their case is to ridicule the work of Ancel Keys.

Low-carbohydrate advocates claim he deliberately mislead generations of researchers, medical practitioners and the general public by manipulating data to fit his hypothesis and advocating a low fat, Mediterranean-style diet.

A brief biography of Ancel Keys can be found in Dialogs in Cardiovascular Medicine – Vol 13 No 3 that gives a different picture than the deceptive and manipulative researcher than he is portrayed by populist commentators.[4]

Below is a brief overview of his life.

Ancel Keys[5] was one of the most famous public health researchers of the twentieth century. He was born in 1904, died in 2004.  Peripatetic for the first third of his life, his outstanding research followed appointment age 36 to the Laboratory of Physiological Hygiene, at the University of Minnesota’s Minneapolis Football stadium.  Born in Colorado, a refugee from the San Francisco earthquake aged 2, he studied chemistry at Berkeley, economics, and political science, earned a master’s degree in zoology, a PhD in oceanography and biology, won a fellowship in physiology to Copenhagen, and did a second PhD in physiology in Cambridge, England, becoming interested in high-altitude physiology.  Offered a permanent post in Cambridge,  he went to study biochemistry at Harvard, and then to the Mayo Foundation, Rochester, Minnesota researching human biochemistry and physiology, before accepting the Minneapolis post in the same university.[6]

He pioneered several modern techniques in health and biology including detailed comparisons of whole populations to determine the effects of different lifestyle factors on health.  He demonstrated experimentally that traits heretofore considered irrevocable and constitutional, such as body type, blood fat levels (cholesterol), blood pressure, heart rate, and responses to stress, were, in fact, largely modifiable by simple changes in the composition and quantity of diet and physical activity.[7]

His wife, Margaret, was a biochemist and an integral part of his work, She lived 97 years.

A Very Brief History of Cholesterol

In 1913, a 28 year old pathologist, Nikolay Anitschkow (or Anichkov), working at the Military Medical Academy in St. Petersburg, showed that by feeding rabbits cholesterol dissolved in sunflower oil induced vascular lesions closely resembling those of human atherosclerosis, both grossly and microscopically.  Controls fed only the sunflower oil showed no lesions.[8]

In 1946, Steiner and Kendall, showed that by inhibiting the thyroid function in dogs and then feeding them cholesterol does increase blood cholesterol and does induce lesions.  Under normal conditions, rats and dogs are efficient at converting excess cholesterol to bile acids. By the 1950s, a number of important advances had been made including the discovery of the mechanism for cholesterol transportation in the blood (via lipoproteins) and the mechanism for cholesterol to enter the artery wall from the blood.

Dr John Gofman was a leading pioneer researcher in the field of lipoproteins who was familiar with Anitschkow’s work.  His work showed that both cholesterol and low-density lipoproteins were both indicators of coronary heart disease risk.  This work and other evidence convinced Gofman that blood cholesterol, and the dietary determinants of blood cholesterol, was centrally important in atherosclerosis. His wife, Dr. Helen F. Gofman co-authored a low-fat, low-cholesterol diet book[9] that was published in 1951 – prior to Keys’s paper.  John Gofman wrote the preface for the book.

In 1951, Keys was working at Oxford when the Food and Agriculture Organization asked him to chair their first conference on nutrition in Rome. He states, “the conferees talked only about nutritional deficiencies”. When he asked about the new epidemic of coronary heart disease, Gino Bergami, Professor of Physiology at the University of Naples, said “coronary heart disease was no problem in Naples”. Later, Keys and his wife Margaret visited Naples.  Margaret measured serum cholesterol concentrations and found them to be very low except among members of the Rotary Club.  Heart attacks were rare except amongst the rich whose diet included daily servings of meat.  He obtained similar results in studies in Madrid. In Minnesota, he performed a series of experiments that lasted for 8 years with the results published in 1965. According to Keys:

The major villains in the diet that are responsible for raising the concentration of cholesterol in the blood serum are saturated fatty acids in the fat of meat and dairy products. Preformed cholesterol in the diet also tends to raise blood cholesterol concentrations slightly if the diet otherwise is extremely low in cholesterol. Mark Hegsled at Harvard University confirmed our Minnesota findings in similar experiments. Saturated fatty acids and preformed cholesterol are commonly found in the same foods. The good Mediterranean diet is low in both saturated fat and cholesterol.[10]

Atherosclerosis: A Problem in Newer Public Health – Six Countries Study

Newby Fat Calories Graph
Atherosclerosis: a problem in newer public health[11] was presented in New York in 1953. He stated that the present high rate of death from degenerative heart disease is not inevitable by showing comparisons with other countries. Keys does state in this paper that “the high reliability with groups and the low reliability with individuals apply to all of the measurements so far studied: total cholesterol, cholesterol/phospholipids ratio, . . . .”.

In the BBC documentary, Robert Lustig claims Keys made his claims regarding saturated fat in the diet as a hypothesis and that he spent the rest of his life trying to justify it. Firstly, at this stage of his research, Keys implicated fat (% calories from fat) as an indicator of heart disease – not saturated fat as Lustig states. Secondly, this paper does refer to his previous surveys and the works of others.  He was not relying on only the statistics of the 6 selected countries to make his conclusions.

J Yerushalmy and H Hillboe criticised the paper Atherosclerosis: A Problem in Newer Public Health in the publication Fat In The Diet and Mortality From Heart Disease[12], claiming that Keys only choose 6 countries that supported his hypothesis instead of using the World Health Organisation data from the 22 countries that was available.  They state Keys did not give reasons for his selection.  This is clearly incorrect.  If you read Keys’ paper, Keys did give the reasons for choices.

Strom and Jensen - Norway Mortality 1927 - 1948The Scandinavian countries were excluded because of the effects of the World War II.  The consumption of meat and eggs dropped during the war and so did the level of heart disease.[13] However, two areas of Finland were included later in the Seven Countries Study. The WHO data shows France as having little heart disease even though it has a high fat consumption, giving rise to the French Paradox myth.  According to a paper in the Dialogues of Medicine – Vol 13 No 3 2008,[14] the French paradox is indeed a myth.

The clear conclusion, driven by the facts as summarized by Pierre Ducimetière, is that the rates of CHD are not so low in France, animal fat intake is not so high, and the diet-heart concept is not so unique that the existence of a “French paradox” can be sustained, except for satisfying cultural fantasy or for wine enthusiasm and marketing. Thus, the real paradox is why the French paradox continues to exist as a concept, when it should be replaced by the less mystifying view, namely, “the more Mediterranean, the better”.

Spain was excluded even though these figures supported the conclusions of the paper.

Mexico did not have a death certificate system in place.

Yerushalmy and Hilleboe examined the data from all of the 22 countries in the WHO Epidemiological and Vital Statistics 1951-1953 publication.  The results were published in their paper Fat in the diet and mortality from heart disease.

Note that Keys’ paper was presented in January 1953.  Yerushalmy and Hilleboe used WHO data from the years 1951-1953.  Yerushalmy and Hillboe - Correlation Table Even if data from all the 22 countries are included, it still shows:

  • positive correlations between heart disease and total calories consumed, fat consumption, animal fat consumption, animal protein consumption
  • negative correlations with heart disease and carbohydrate consumption, vegetable protein consumption, vegetable fat consumption.

Hillboe later co-authored a paper Risk Factors in Ischemic Heart Disease in Vol 53 No 3 American Journal of Public Health showing that “high cholesterol was the greatest risk factor of any single variable in ischemic heart disease”.

In the conclusion, Keys states that there is sufficient evidence to “warrant a large extension of this type of epidemiological research”.  His views were refined with later studies.

Critics commonly mistake the Six Countries Study with the later Seven Countries Study published in 1970.


View Atherosclerosis: A Problem in Newer Public Health – Ancel Keys

View Fat In The Diet and Mortality From Heart Disease – J Yerushalmy and H Hillboe

View Rank Correlation Coefficients from Yerushalmy and Hillboe’s paper


Seven Countries Study

Ancel Keys and colleagues posed the hypothesis that differences among populations in the frequency of heart attacks and stroke would occur as a result of physical characteristics and lifestyle and diet. Surveys were carried out between 1958 – 1970 in populations of men aged 40-59, in sixteen areas of seven countries. Follow-up surveys were continued until the 1990s. Most of the areas were stable and rural and had wide contrasts in habitual diet.

Women were excluded because cardiac disease was less common and because of the invasiveness of physical examinations. The Seven Countries Study was the first to explore associations among diet, risk, and disease in contrasting populations.  Central chemical analysis of foods consumed among randomly selected families in each area, plus diet-recall measures in all the men, allowed an effective test of the dietary hypothesis. The study was unique for its time, in standardization of measurements of diet, risk factors, and disease; training its survey teams; and central, blindfold coding and analysis of data.

The study areas were:

  • one area is in the United States
  • two areas in Finland
  • one area in the Netherlands
  • three areas in Italy
  • five areas in the former Yugoslavia (two in Croatia, and three in Serbia)
  • two areas in Greece (Crete, Corfu)
  • two areas in Japan

A graph from the study shows the relationship between coronary deaths and saturated fats in the diet.[15] Note the difference between East Finland (E) and West Finland (W).

 Diet Calories from Saturated Fats

B: Belgrade, Yugoslavia; C: Crevalcore, Italy; D: Dalmatia, Yugoslavia; E: East Finland; G: Corfu, Greece; J: Ushibuka, Japan; K: Crete, Greece; M: Montegiorgio, Italy; N: Zutphen, Netherlands; R: Rome, Italy; S: Slavonia, Yugoslavia; T: Tanushimaru, Japan; U: USA; V: Velika Krsna, Yugoslavia; W: West Finland; Z: Zrenjanin, Yugoslavia

A common criticism that is prevalent on the internet is that Crete (K) had the lowest rate of heart disease of heart disease even though they consume more saturated fat than Corfu (G). The graph does show Crete (K) having a very low death rate from heart disease.  What is not mentioned is that only 2 populations in Japan and the area in Corfu had a lower proportion of calories from saturated fats.  Compared with the other populations, Crete and Corfu both had a very low intake of saturated fats.

According to Harry Blackburn, one of the collaborators in the study:

The Seven Countries Study provided evidence confirming the original hypotheses, that elevated mean blood cholesterol levels and intake of saturated fatty acids is a major and apparently necessary factor in the population burden of atherosclerotic diseases. Populations with saturated acid intake less than 10 percent of daily energy have little coronary heart disease or thrombotic stroke despite widely varying total fat intake or usual levels of blood pressure or high rates of tobacco use. Multivariate analysis of population rates and risk factors reveal that diet and smoking “explain” most of the differences in population rates and that the “standard” CVD risk factors operate universally within populations.
The main implications of the Seven Countries Study are that the mass burden and epidemic of atherosclerotic diseases has cultural origins, is preventable, can change rapidly, and is strongly influenced by the fatty composition of the habitual diet. The study implies the universal susceptibility of humans to CVD but that the frequency of susceptible phenotypes is greatly reduced in favorable environments. It suggests there may be other and important protective elements in the diet and lifestyles of Crete and Japan.[16]

Cholesterol Recommendations

  • Dr Bill Roberts (previous long-time editor of the medical journal Cardiology)
  • Dr Bill Castelli (director of the Framingham Heart Study)
  • Dr Caldwell Esselstyn  (surgeon at the Cleveland Clinic)

have stated that they have never seen a heart disease fatality when cholesterol levels are below 150 mg/dL (3.9 mmol/L).[17]

Dr John McDougall recommends the same guidelines and recommends oat bran, garlic, vitamin C, vitamin E and niacin if there there is difficulty in reaching this level.[18]

He also states that HDL “Good” Cholesterol is Not Worth Your Attention because HDL cholesterol will fall as total and LDL cholesterol falls.[19]

Footnotes

  1. U S Department of Agriculture (2002) Agriculture Fact Book 2001-2002.
  2. Lustig, R. (2013) Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease. New York: Penguin Group.
  3. Boulding, C. (2012) The Men Who Made Us Fat.
  4. Tunstall-Pedoe, H. (2008) The French Paradox : Fact or Fiction? Dialogues in Cardiovascular Medicine. 13 (3), 159–179.
  5. Bernard Safran (1961) Diet and Health. TIME Magazine LXXVII (3).
  6. Tunstall-Pedoe, H. & Evans, A. (2008) Summaries of Ten Seminal Papers: Coronary heart disease in seven countries. American Heart Association Monograph No. 29 – A. Keys, ed. Dialogues in Cardiovascular Medicine. 13 (3), 217.
  7. University of Minnesota (2012) Keys, Ancel « Heart Attack Prevention [online]. Available from: http://www.epi.umn.edu/cvdepi/bio-sketch/keys-ancel/ (Accessed 26 September 2017).
  8. Steinberg, D. (2007) The Cholesterol Wars: The Skeptics vs. the Preponderance of Evidence. San Diego, CA: Academic Press.
  9. Dobbin, E. V. et al. (1951) The Low-Fat, Low-Cholesterol Diet. Doubleday, Garden City, NY.
  10. Keys, A. (1995) Mediterranean diet and public health : personal reflections. American Journal of Clinical Nutrition. 61 (6), 1321S–1323S.
  11. Keys, A. (1953) Atherosclerosis: a problem in newer public health. Journal of Mt Sinai Hospital. July-Aug; 20 (2), 118–139.
  12. Yerushalmy, J. & Hilleboe, H. E. (1957) Fat in the Diet and Mortality from Heart Disease. New York State Journal of Medicine. 57 (14), 2343–2354.
  13. Strom, A. & Jensen, R. A. (1951) Mortality from Circulatory Diseases in Norway 1940-1945. The Lancet. 1 (6647), 126–129.
  14. Tunstall-Pedoe, H. (2008) The French Paradox : Fact or Fiction? Dialogues in Cardiovascular Medicine. 13 (3), 159–179.
  15. Steinberg, D. (2007) The Cholesterol Wars:  The Skeptics vs. the Preponderance of Evidence. San Diego, CA: Academic Press.
  16. Blackburn, H. (2012) Seven Countries Study « Heart Attack Prevention [online]. Available from: http://www.epi.umn.edu/cvdepi/study-synopsis/seven-countries-study/ (Accessed 26 September 2017).
  17. Campbell, T. C. & Campbell, T. M. (2006) The China Study. Dallas USA: BenBella Books.
  18. McDougall, J. (2002) Cholesterol - When and How to Treat [online]. Available from: http://www.nealhendrickson.com/mcdougall/020900pucholesterol.htm (Accessed 21 November 2015).
  19. McDougall, J. (2004) HDL ‘Good’ Cholesterol is Not Worth Your Attention [online]. Available from: https://www.drmcdougall.com/misc/2004nl/apr/040400pufav5.htm (Accessed 21 November 2015).

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