“Here in Anatevka we have traditions for everything… how to eat, how to sleep, even, how to wear clothes…You may ask, how did this tradition start? I’ll tell you – I don’t know. But it’s a tradition….”
-Tevye; Fiddler on the Roof
Ask most any cardiologist about saturated fat, cholesterol and heart disease and they will tell you it is SCIENCE, not tradition, which drives their decision making. But influences; political, financial, and even egotistical, can subtly bend the will and direction of the purest intellectual pursuit.
As another recently published study brings to light past transgressions and errors; we appropriately tack and adjust our course. However, we can only reach our destination by knowing where we are. And we can only know where we are, by seeing where we have been. A brief synopsis of the story involving fat, saturated fat, animal fat, polyunsaturated fat, vegetable oils, cholesterol, and cardiovascular disease over the last century is both intriguing and illuminating.
The figure below gives a brief timeline of some of the major events and highlights that accompany this topic from over the last century. However, a more detailed description provides a deeper understanding of why we flounder in our current dietary doldrums.
In the early 1900s a German chemist by the name of Wilhelm Normann developed an inexpensive way to turn normally liquid vegetable oils into semi-solid and solid products through the addition of hydrogen; a process known as hydrogenation. Enterprising businessmen William Procter and James Gamble watched the lightbulb illuminate; literally. The soap and candle making duo realized that the invention of the lightbulb was going to seriously impact their bougie business, so they looked to alternatives.
Because the meat-packing industry in Cincinnati, Ohio (then known as Porkopolis) controlled the lard and tallow needed for candles and soap, P&G had secured their own supply of raw materials and by 1905 owned eight cottonseed mills in Mississippi. With the help of another German chemist, E. C. Kayser, P&G was able to transform the liquid cottonseed oil into a solid that resembled lard.
Since hydrogenated cottonseed oil resembled lard, why not sell it as a food? Thus Crisco (CRYStalized Cottonseed Oil) was introduced to the American consumer in 1911. In 1924 The American Heart Association was formed. In 1948, thanks to the being the beneficiary of the P&G sponsored “Walking Man” radio contest, the AHA went national with a $1.75 million dollar windfall. A national fund raising campaign in 1949 netted another $2.7 million and the AHA never looked back.
Following World War II, Ancel Keys, who held PhDs in biology and physiology became interested in the rise of heart disease in the United States and the dearth of a similar phenomenon in post war Europe. He proposed the cholesterol hypothesis as the cause. This was the idea that saturated fat in the diet, mostly from animal sources, caused an increase in blood cholesterol levels. The increased cholesterol in the blood resulted in atherosclerosis. This was the suggested origin of cardiovascular disease (CVD) morbidity and mortality.
The die was cast and Keys vaulted to national and international acclaim. In 1961 he was on the cover of Time Magazine and appointed to the prestigious and influential AHA nutrition committee. Later that same year the AHA issued the first ever dietary recommendation to replace animal fats in the diet with plant based alternatives. The proposition was solidified when Keys published his Seven Countries Study in 1970; purportedly demonstrating beyond question the causal effect of animal (saturated) fat consumption, cholesterol and heart disease.
Such was the confidence in this conventional wisdom that the US Senate adopted the low fat (30% of total dietary energy) and low saturated fat (less than 10% of total dietary energy) proposal. These were published in the United States Senate Select Committee on Nutrition and Human Needs dietary guidelines and accepted as gospel by many-even to this day. Unfortunately, much of the data and conclusions were taken at face value, because as Senator McGovern remarked at the time, “Senators don’t have the luxury the research scientist does of waiting until every last shred of evidence is in.”
The process of hydrogenation which transformed the liquid plant oils into solids and semi-solids also created what are known as trans-fatty acids (TFAs). While TFAs occur naturally in very miniscule amounts, mostly in digestive system of ruminants, they do not normally comprise a significant portion of the diet. However with the push over the last half century to move away from animal fats and toward plant based alternatives, the diet contained increasingly more TFAs as a result of hydrogenated and partially hydrogenated vegetable oils.
They also contained more liquid vegetable and seed oils as the push for polyunsaturated fats (PUFAs) derived from vegetable sources to replace saturated animal fats continued to mount. Many of these oils were derived from sources such as corn, safflower, sunflower, etc. which are predominately omega-6 rich. Omega-6 PUFA tends to feed the inflammatory pathway while the omega-3 PUFA tends to counterbalance those effects via the body’s anti-inflammatory pathway. These omega-6 rich oils remain a staple in the production of processed and fried foods.
Studies from as early as the 1970s suggested potential detrimental health effects from the consumption of TFAs. However, it was not until the 1990s that these studies began to yield evidence that could not be ignored nor dismissed away. In 2002 the Institute of Medicine (IOM) published an analysis irrevocably linking TFA consumption and CVD. That same year P&G divested of the Crisco brand. At the time, Crisco commanded 24% of an annual $360 million dollar market. It took the federal government almost a decade and half to follow up on the IOM report and ban TFAs (although there are still loopholes).
A recent analysis of a study performed in the late 1960s and early 1970s, the Sydney Diet Heart Study, evaluated the effectiveness of replacing dietary saturated fat with omega-6 rich safflower oil. This inquiry found that the vegetable oil group had statistically significant higher rates of heart attack and death than those eating animal fats.
Another study which was not published at the time, the Minnesota Coronary Experiment performed from 1968 to 1973, also recently underwent a contemporary testing. The goal of this study was to determine whether replacing saturated fat with vegetable oil rich in omega-6 PUFAs reduced coronary heart disease and death by lowering serum cholesterol.
The vegetable oil group had significant reduction in their serum cholesterol. In other words, by replacing the saturated animal fat with polyunsaturated vegetable oil alternatives did lower the blood cholesterol levels. However, there was no survival advantage for those who dropped their cholesterol level through this dietary maneuver. In fact, those who consumed the omega-6 rich vegetable oil and lowered their cholesterol had a 22% higher risk of death for each 30 mg/dL (0.78 mmol/L) reduction in serum cholesterol. In other words, the more their cholesterol dropped, the higher their risk of death.
A further review of almost 11,000 patients revealed that lowering cholesterol by replacing saturated animal fat with PUFAs rich in omega-6 fatty acids like linoleic acid showed no evidence in reducing risk of death from CVD or any cause. The authors conclude that, “Available evidence from randomized controlled trials shows that replacement of saturated fat in the diet with linoleic acid effectively lowers serum cholesterol but does not support the hypothesis that this translates to a lower risk of death from coronary heart disease or all causes. Findings from the Minnesota Coronary Experiment add to growing evidence that incomplete publication has contributed to overestimation of the benefits of replacing saturated fat with vegetable oils rich in linoleic acid.”[i]
A contemporary of Keys, Professor John Yudkin who served as Chair of Physiology at Queen Elizabeth College in London and later as a Chair in Nutrition, had argued that refined carbohydrates like sucrose were the primary cause of such modern maladies as obesity, diabetes, cardiovascular disease and the like. Keys responded that “It is clear that Yudkin has no theoretical basis or experimental evidence to support his claim for a major influence of dietary sucrose in the etiology of CHD [coronary heart disease]; his claim that men who have CHD are excessive sugar eaters is nowhere confirmed but is disproved by many studies superior in methodology and/or magnitude to his own; and his “evidence” from population statistics and time trends will not bear up under the most elementary critical examination. But the propaganda keeps on reverberating… Unfortunately, Yudkin’s views appeal to some commercial interests with the result that this discredited propaganda is periodically rebroadcast to the general public of many countries.”[ii],[iii]
Science is the hand wielding the shears pruning the unnecessary, unwanted and undesired directions we may wander unguided. Tradition is a gift to humanity; it provides bearing as it anchors us. It is the rootstock gripping deep legacy. Confusing the two yields not petals of wisdom, but stinkweed.
[i] (Ramsden C. E., et al., 2016)
[ii] (Keys A. , Sucrose in the diet and coronary heart disease, 1971)
[iii] (Keys A. , Coronary heart disease — The global picture, 1975)
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Andrade, J., Mohamed, A., Frohlich, J., & Ignaszewski, A. ( 2009). Ancel Keys and the lipid hypothesis: From early breakthroughs to current management of dyslipidemia. BCMJ, 51(2): 66-72 .
Center for Science in the Public Interest. (2014). Artificial Trans Fat: A Timeline. Retrieved from CSPInet.org: http://cspinet.org/transfat/timeline.html
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Page, I. H., Allen, E. V., Chamberlain, F. L., Keys, A., Stamler, J., & Stare, F. J. (1961). Dietary fat and its relation to heart attacks and strokes: Report by the Central Committee for Medical and Community Program of the AHA. . Circulation, vol 23.
Ramsden, C. E., Zamora, D., Majchrzak-Hong, S., Faurot, K. R., Broste, S. K., Frantz, R. P., . . . Hibbeln, J. R. (2016). Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968-73). BMJ, 353:i1246 http://dx.doi.org/10.1136/bmj.i1246.
Ramsden, C., Zamora, D., & Leelarthaepin, B. (2013). Use of dietary linoleic acid for secondary prevention of coronary heart disease and death: evaluation of recovered data from the Sydney Diet Heart Study and updated meta-analysis. . BMJ , 346:e8707.
Ramsey, D., & Graham, T. (2012, April 26). How Vegetable Oils Replaced Animal Fats in the American Diet. Retrieved from The Atlantic: http://www.theatlantic.com/health/archive/2012/04/how-vegetable-oils-rep...
Teicholz, N. (2014, May 6). The Questionable Link Between Saturated Fat and Heart Disease. Retrieved from The Wall Street Journal.com: http://www.wsj.com/articles/SB10001424052702303678404579533760760481486
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