The Myth of the Diet-Heart Hypothesis: The Saturated Fat Fabrication

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Plain and simple: Cholesterol and saturated fat are not your enemies.

Low Fat

Low-Fat

I am a child of the late 70s and mid-80s.  I started college in the mid-80s and finished in the early 90s.  Medical school for me started in the mid-90s and ended right before the turn-of-the-century.  I was educated during a period that vilified saturated fat and cholesterol as being the end all be all of the heart diseases.  You could hardly pick up a health magazine during this period without reading an article on the adverse effects of saturated fat and cholesterol.  These two so-called villains were blamed from everything from heart disease to metabolic syndrome to strokes to obesity.  The problem with these claims is that there was scant to no evidence to back them up.

So how did we get there?  From the.  Following World War II to the 1980s, the nutrition and medical academia were dominated by a tiny group of men.  One of them was a man name Ancel Keys.   Dr. Keys performed a few epidemiological studies to back up his belief that cholesterol and saturated fat were the cause of heart disease.  The problem with his studies is that they interpreted causation from the trend data that was flawed.  He excluded countries that we provided potential evidence against his belief and included studies that helped his belief.  This bias was never truly revealed.  In fact, many organizations to include the American Heart Association accepted them as being factual.  They took his recommendations and thrust them on the American public and the American public even today still accepts saturated fat and cholesterol as being the major player in heart disease.

So why were they so worried about heart disease?  After World War II,  middle-aged men began dropping dead of heart attacks within the United States.  The medical community felt that we had defined what was causing these premature deaths.  We now know that this was likely due to smoking and trans fatty acids.  Sugar and process flower may have also played a part.  Along to the rescue came many of these epidemiologists to nutritionists who began sending up the alarm bells about fat and cholesterol.  Sure, Dr. Keyes was not the only one,  but he was the most influential player among the group during this period.  My goal is not to vilify man is dead and can no longer defend himself.    My goal is to clear the air, but then again, he spent most of his life vilifying the opponent instead of arguing the quality of his data, so I think the discussion is fair.  

Fat Free

Fat-Free

I do not want to sensationalize may impact a cardiovascular disease on citizens of United States. The fact is the cardiovascular disease is not only one of the top causes of death in the United States, but it also is one of the major costs in our medical expenditures.  Cardiovascular disease is one of the most misdiagnosed and mistreated conditions in medicine, and this is especially true in women who often present slightly different than men.  Medical professionals have learned a tremendous amount about what causes heart disease over the past two decades since I started practicing medicine, but we continue to focus in on nutritional principles that are outdated, and we poorly researched even 50 years ago, and the basis of which was based more opinion than fact.   

Heart Disease in the United States (According to the CDC):

  • About 610,000 people die of heart disease in the United States every year–that’s 1 in every four deaths[1].
  • Heart disease is the leading cause of death for both men and women and more than half of the deaths due to heart disease in 2009 were in men[1].
  • Coronary heart disease is the most common type of heart disease, killing over 370,000 people annually[1].
  • Every year about 735,000 Americans will have a heart attack. Of these, 525,000 are a first heart attack and 210,000 happen in people who have already had a heart attack[2].
  • Heart disease is the leading cause of death for people of most ethnicities in the United States[1].
  • The total cost of cardiovascular disease in 2008 was estimated at $300 billion.

You can quickly see why heart disease has such a huge impact is such a center of focus in the United States.  OYou can quickly see why public officials, scientists, and medical professions jumped to conclusions and rushed to judgment.   They felt a need to quickly find and implemented corrective actions to prevent what they perceived to be a national disaster.  As convincing as the data is, the problem is that you cannot determine causation from observational data. To establish causation with observational data, you need a 30 fold difference from one data point to another. In the situation of saturated fat, the data point difference is only 2 to 3 fold.  

fresh butter curls in dish

Fresh butter curls in a dish

If cholesterol is truly the cause and we have born all our resources to solve the problem, why does heart disease remains one of the primary killers of Americans?  We know what causes it and have implemented changes both resolve, but yet, the problem persists and appears to be growing. We have billion dollars medical industries designed around creating new cholesterol-lowering drugs and developing new stents to open arteries, but yet the number continues to grow. We have outlawed trans fatty acids in vilified saturated fat and yet we still heart disease continues to grow.  The problem is in my opinion that we are focusing our treatments on the wrong cause.  

So, let’s focus on what the true cause of heart disease is.  Heart disease is a process it occurs when blood vessels narrow and close off and can no longer supply oxygen and nutrients to the heart muscle. To understand the cause, we must understand the disease process.  We know that heart disease and type II diabetes run together. In fact, diabetes is considered a heart disease equivalent. We know that the precursor to type II diabetes is syndrome X or metabolic syndrome.  We can safely assume that disease processes and physiology of these three illnesses/Syndromes are similar.  This is basic logic, nd the problem is we have failed to use basic logic in the past.

Because of metabolic syndrome and type II diabetes his insulin resistance. Because events on resistance in most cases is truncal obesity.  As we age, we increase the amount of fat around our waistline and this predisposes us to type II diabetes. It also predisposes us to atherosclerotic coronary artery disease.  Elevated insulin levels increase total cholesterol, triglycerides, and LDL cholesterol. This is a symptom of the disease process and not the cause. The true cause of heart disease is the underlying insulin resistance the increases as metabolic syndrome develops and a coronary artery disease and diabetes type II.

I want to clarify one point that I’ve made. I am not saying that cholesterol in high LDL do not increase your risk of heart disease.  I am trying to illustrate is it’s not as clear is the American Heart Association and many nutritionists or dietitians want you to believe. The evidence against saturated fat is far from definitive.  Many of the definitive studies including the lauded Framingham study have been now proven to less definitive.  The American Heart Association continues to push reduced saturated fats despite many other professional organizations taking a step backward to perform more research.   

The research (it is anything but clear): 

  1. Saturated fats may not be the cause of atherosclerotic coronary artery disease.    Many scientific experts and physicians believe that this is already been decided and that there’s no reason to rehash this discussion.  In 2009, a meta-analysis of released which through the community into disarray[3].  Review of the causes and prevention of cardiovascular diseases had been accepted to be caused by atherosclerosis caused by elevated levels of saturated fat.  This meta-analysis indicated that there was no reliable link between saturated fat and coronary vascular disease.  With unprocessed foods, we should determine guilt based upon evidence.  In the case of saturated fats, they were condemned and vilified without any reliable evidence.  This was done based on models without any evidence of mortality or morbidity. the most important thing about this study is that it found no tie between saturated fats and increase in coronary vascular disease.  In 2010, this result was confirmed by a meta-analysis of prior studies[4],[5].   
  2.  Polyunsaturated fats or PUFAs may reduce coronary vascular events.   A Cochran meta-analysis review, from 2010, revealed that shifting a greater population of your fatty acid consumption from saturated fatty acids to polyunsaturated fatty acids may reduce your rate of coronary vascular events[6].  The results of this study are not surprising today because we have long known that people who eat salmon and tuna tend to less coronary events.  
  3. No change in all-cause mortality.  A 2015 Cochrane review looked at data from prior studies that included trials of 59,000 participants.  The scientific review found no statistically significant effects of reducing saturated fat on the following outcomes: all-cause mortality, cardiovascular mortality, fatal myocardial infarctions, non-fatal myocardial infarctions, stroke, coronary heart disease mortality, coronary heart disease events. These results were confirmed in 2016 by another analysis of 89,000 patients[7].  
  4. A nail in the coffin of the hypothesis?  A very large epidemiologic study was performed to look at the links to heart disease[8].  In this study, high carbohydrate intake was associated with higher risk of total mortality, whereas total fat and individual types of fat were related to lower total mortality. Total fat and types of fat were not associated with cardiovascular disease, myocardial infarction, or cardiovascular disease mortality, whereas saturated fat had an inverse association with stroke. Global dietary guidelines should be reconsidered in light of these findings.  I think the biggest point to make about this study is that it was not funded by a drug or food manufacturer. 

The bottom line: The current evidence does not seem to support the prior beliefs and saturated fats cause heart disease.  I am not saying that you should start splurging on saturated fats, but what I am saying is that the evidence is not clear and it definitely does not support a strict diet low in fat and high in misery.  I suggest that you tailor your diet to your own tastes and enjoy your food.  More research is needed but at this time there is significant evidence to suggest that you deny yourself saturated fat.

References

[1]
“CDC,” Heart Disease Facts, 07-Apr-2018. [Online]. Available: https://www.cdc.gov/heartdisease/facts.htm. [Accessed: 07-Apr-2018]
[2]
“Correction.,” Circulation, vol. 131, no. 24, p. e535, Jun. 2015. [PubMed]
[3]
S. Berger, G. Raman, R. Vishwanathan, P. Jacques, and E. Johnson, “Dietary cholesterol and cardiovascular disease: a systematic review and meta-analysis.,” Am J Clin Nutr, vol. 102, no. 2, pp. 276–94, Aug. 2015. [PubMed]
[4]
P. Siri-Tarino, Q. Sun, F. Hu, and R. Krauss, “Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease.,” Am J Clin Nutr, vol. 91, no. 3, pp. 535–46, Mar. 2010. [PubMed]
[5]
R. Chowdhury et al., “Association of dietary, circulating, and supplement fatty acids with coronary risk: a systematic review and meta-analysis.,” Ann Intern Med, vol. 160, no. 6, pp. 398–406, Mar. 2014. [PubMed]
[6]
D. Mozaffarian, R. Micha, and S. Wallace, “Effects on Coronary Heart Disease of Increasing Polyunsaturated Fat in Place of Saturated Fat: A Systematic Review and Meta-Analysis of Randomized Controlled Trials,” P, vol. 7, no. 3, p. e1000252, Mar. 2010 [Online]. Available: 10.1371/journal.pmed.1000252″ target=”_blank” rel=”noopener noreferrer”>http://dx.doi.org/10.1371/journal.pmed.1000252
[7]
Z. Harcombe, J. Baker, and B. Davies, “Evidence from prospective cohort studies does not support current dietary fat guidelines: a systematic review and meta-analysis.,” Br J Sports Med, vol. 51, no. 24, pp. 1743–1749, Dec. 2017. [PubMed]
[8]
M. Dehghan et al., “Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study.,” Lancet, vol. 390, no. 10107, pp. 2050–2062, Nov. 2017. [PubMed]
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About the Author

ChuckH
I am a family physician who has served in the US Army. In 2016, I found myself overweight, out of shape, and unhealthy, so I made a change to improve my health. This blog is the chronology of my path to better health and what I have learned along the way.

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