Category Archives: saturated fat

Fat consumption, Fat circulating in your blood, Heart Disease

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Another nail has been driven into the coffin of the diet-heart hypothesis. The Annals of Internal Medicine (the official journal for the American College of Physicians) just published a review article that considered three kinds of studies related to fat and heart disease. (1)

  1. Studies that evaluated the association between dietary consumption of different kinds of fat and cardiovascular disease (heart attack and stroke)
  2. Studies that evaluated the association between levels of different kinds of fat circulating in the blood and cardiovascular disease
  3. Studies that evaluated supplementation with various kinds of fat and cardiovascular disease.

Most importantly, the authors found no statistical association between consumption of saturated fat and cardiovascular disease. I have previously discussed another large meta-analysis published in 2010 with the same finding. (2)

I have discussed the unscientific demonization of saturated fat many times (3,4,5).

This is important because it again speaks against the dietary advice promulgated by the AHA and the USDA to reduce consumption of saturated fat. The low-fat advice has resulted in a proliferation of low-fat high-sugar and high-carbohydrate food products which arguably have contributed to the epidemics of obesity and diabetes in the US.

Similarly, recent studies have correlated dementia with high carbohydrate consumption. (6) If you reduce fat in the diet you must replace it with something else and unfortunately in the US that something else has been sugar and other refined carbohydrates.

Other statistically significant findings in the Annals of Internal Medicine study were an inverse relationship between circulating blood levels of the omega three fats found in seafood (EPA and DHA) and cardiovascular events. The authors pointed out that although higher blood levels of EPA and DHA were significantly associated with lower cardiovascular risk, supplementation with EPA and DHA have had mixed results  with many studies showing positive results but some showing no protective effects. My comments on the omega three supplement studies are

  1. supplementation with fish oil (omega three fats) will not benefit most individuals unless excess pro-inflammatory omega six fats (found in refined vegetable oils) are reduced/eliminated and that side of the equation has not been addressed in any of the published studies. In other words, the studies did not reduce omega 6 fats, they just supplemented with omega 3 fat. If an individual is consuming 30-60 grams of omega six fats per day, trying to balance that with 2-3 grams per day of fish oil will not achieve a healthy ratio.
  2. many of the fish oil (omega three) supplement studies used very low amounts of fish oil, well below the amounts used in the studies that demonstrated benefit.

I am not suggesting that everyone should take fish oil supplements. Instead, I support eating a whole foods paleolithic diet based on grass-fed meat, free range poultry, free range eggs, fresh wild seafood, fresh vegetables, fresh fruits and nuts.

Finally, the data on trans-fat consumption demonstrated statistically significant correlation with cardiovascular disease. The biochemistry and physiology of manufactured trans-fats demonstrate a disruptive role of these man-made fats and the elimination of these harmful fats from our food supply will likely provide great health benefits.

The authors comment on the complex relationship between fat consumption and circulating levels of specific fats in the blood as demonstrated by Forsythe et al. (6,7) I will discuss this in future posts. For now consider the paradox that high-fat carbohydrate restricted diets result in lower circulating levels of saturated fat compared to high carbohydrate diets. (6,7), Explanation: excess carbohydrates are immediately converted to fat and stored as saturated fat by humans.

1. Annals of Internal Medicine | Association of Dietary, Circulating, and Supplement Fatty Acids With Coronary Risk: A Systematic Review and Meta-analysis

2. Siri-Tarino PW, Sun Q, Hu FB, Krauss RM. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. Am J Clin Nutr. 2010; 91:535-46.
PubMed

3. https://practical-evolutionary-health.com/2014/02/16/can-goose-liver-grass-fed-meat-aged-hard-cheese-free-range-eggs-and-cod-liver-oil-prevent-a-heart-attack/

4. https://practical-evolutionary-health.com/2013/11/03/saturated-fat-vs-sugar/

5. https://practical-evolutionary-health.com/2013/11/01/saturated-fat-does-it-matter/

6. Relative intake of macronutrients impacts risk of mild cognitive impairment or dementia. Journal of Alzheimers Dis. 2012;32(2):329-39. doi: 10.3233/JAD-2012-120862.

7. Forsythe CE, Phinney SD, Feinman RD, Volk BM, Freidenreich D, Quann E, et al. Limited effect of dietary saturated fat on plasma saturated fat in the context of a low carbohydrate diet. Lipids. 2010; 45:947-62. PubMed

8. Forsythe CE, Phinney SD, Fernandez ML, Quann EE, Wood RJ, Bibus DM, et al. Comparison of low fat and low carbohydrate diets on circulating fatty acid composition and markers of inflammation. Lipids. 2008; 43:65-77. PubMed

Peace,

Bob Hansen MD

The Ornish Low Fat Vegetarian Diet, does it work?

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Dr. Dean Ornish has done wonderful research in the area of cardiovascular disease and lifestyle intervention. His study on comprehensive lifestyle intervention (1) is often quoted to support a low fat vegetarian diet as treatment for cardiovascular disease. But his “Intensive lifestyle changes for reversal of coronary heart disease” included several components that would be expected to improve health and decrease cardiovascular risk independent of a vegetarian diet as will be discussed below.

Let’s review what this study did.

48 patients with diagnosed moderate to severe coronary artery disease were randomized to one of two treatment groups, an “intensive lifestyle change” (ILC) group or a “usual-care” (UC) control group. 28 patients were allocated randomly to the ILC group and 20 were allocated to the UC group. Out of 48 patients starting the study only 35 completed the study,   20 out of 28 in the ILC group completed the study and 15 out of 20 in the UC group completed the study.

The intensive lifestyle change group followed this program:

  • 10% fat whole foods vegetarian diet
  • daily aerobic exercise
  • stress management training (training in and daily performance of meditation and/or yoga)
  • smoke cessation (they quit smoking)
  • group psychosocial support (3 hour group therapy sessions)

At the start of the study only one patient in the ILC group was smoking and she quit. We do not know how many smokers were in the UC group or how many quit. (I consider that a deficiency of this study. Because smoking is such a significant determinant of cardiovascular outcome, details of smoking at start and end of the study for both groups should have been reported)

At the end of five years the intensive lifestyle change group demonstrated an average 3.1% absolute reduction in the coronary artery blockage as measured by coronary arteriograms (or to put it another way, the diameter of the blocked coronary arteries increased by 3.1%). The usual care group (receiving cholesterol lowering statin drugs) showed an average 2.3% absolute increase in the coronary artery blockage (2.3% reduction in diameter). These are not huge changes or differences but they were measurable and statistically significant.

Twenty five total  “cardiac events” occurred in the 28 patients randomized to the intensive lifestyle change group over the five years and 45 cardiac events occurred in the 20 patients randomized to the “usual care” group (receiving cholesterol lowering statin drugs). But this was due to differences in the number of hospitalizations and angioplasties. There was no statistically significant difference in the number of deaths, heart attacks or coronary artery bypass surgeries.

By the end of the study 2 patients in the ILC group had died compared to 1 death in the usual care group but as mentioned above, this difference was not statistically significant.  We do not know how many deaths occurred in the 8 patients who dropped out of the treatment group or in the 5 patients who dropped out of the usual care group, nor do we know any of the other outcomes for the drop-out patients.

So there were no lives saved by the intensive lifestyle change program and no reduction in the number of heart attacks. In fact the ILC group had 2 deaths compared to 1 in the usual care group.

What does this all mean and why has the Ornish Diet attracted so much attention.?

First, I would suggest that the demonstrated benefits (reductions in the number of angioplasties and hospitalizations) are likely explained by the following parts of the lifestyle changes.

  1. stress reduction training and implementation (meditation and yoga)
  2. elimination of manufactured trans-fats from the diet
  3. elimination of unhealthy pro-inflammatory excess omega six fats (vegetable oils) from the diet
  4. elimination/reduction of processed carbohydrates and sugar.

Although the intensive lifestyle intervention included regular exercise the data show no significant difference in times per week or hours per week of exercise at the end of the study between the two groups.

The big difference was in stress management. The ILC group averaged practicing meditation and/or yoga 5 times per week (48 minutes per day) versus less that once per week (8 minutes per day) in the usual care group.

Stress reduction is a major issue in any disease and in particular in cardiovascular disease.

Several studies have demonstrated that the daily practice of meditation  improves immune function, increases telomerase activity, reduces inflammatory markers, and reduces circulating stress hormones (cortisol and epinephrine) independent of dietary changes.
Meditation has also been observed to improve “endothelial function”, the ability of the cells that line arteries to respond to changes in demand. (2,3,4,5,6,7)

Here is a press release from the American Heart Association 13 November 2012. (8)

“African Americans with heart disease who practiced Transcendental Meditation regularly were 48 percent less likely to have a heart attack, stroke or die from all causes compared with African Americans who attended a health education class over more than five years, according to new research published in the American Heart Association journal Circulation: Cardiovascular Quality and Outcomes.

Those practicing meditation also lowered their blood pressure and reported less stress and anger. And the more regularly patients meditated, the greater their survival, said researchers who conducted the study at the Medical College of Wisconsin in Milwaukee.”

I believe the major benefit of the interventional program was from the stress reduction and the elimination of three major dietary sources of trouble (trans-fats, excess omega 6 fats from processed-refined vegetable oils, and refined carbohydrates-sugar)

I have already discussed in other posts the problems associated with excess omega 6 fats and refined carbohydrates-sugar relative to cardiovascular risk. (9,10,11)

There is little controversy that elimination/reduction in trans-fats produces benefit. (12,13,14)

All three of these changes were essential to the whole foods approach of the intervention group.

I have also discussed the lack of data to support the contention that saturated fat from animal sources of protein contributes to cardiovascular disease. (15, 16))

I remain a strong proponent of a whole foods diet that includes a variety and abundance of organic vegetables and fruits, nuts, pastured grass-fed meat, fresh wild seafood, free-range organic poultry and eggs from that kind of poultry.  This diet represents the foods we have evolved to eat, free from added sugar, hormones, antibiotics, pesticides. This dietary approach also produces a healthy balance of omega 6 to omega 3 fatty acid as well as a significant improvement in the ratio of potassium to sodium.

Stress reduction should be an essential part of our lives and data on this aspect of health will be discussed in future posts. References for this discussion appear below.

Peace,

BOB Hansen MD

REFERENCES:

1. JAMA Network | JAMA | Intensive Lifestyle Changes for Reversal of Coronary Heart Disease

2. Intensive meditation training, immune cell telomerase activity, and psychological mediators.

3. Can meditation slow rate of cellular aging? Cognitive stress, mindfulness, and telomeres.

4. A pilot study of yogic meditation for family dementia caregivers with depressive symptoms: effects on mental health, cognition, and telomerase activity.

5. Meditation Improves Endothelial Function in Metabolic Syndrome, American Psychosomatic Society (APS) 69th Annual Scientific Meeting: Abstract 1639. Presented March 10, 2011.

6. Alterations in brain and immune function produced by mindfulness meditation.

7. Adrenocortical activity during meditation.

8. Meditation may reduce death, heart attack and stroke in heart patients | American Heart Association

9. Polyunsaturated fat, Saturated fat and the AHA

10, Lose weight, control blood sugar, reduce inflammation

11. Sugar, a serious addiction

12. The negative effects of hydrogenated trans fats and what to do about them.

13. Trans fats in America: a review of their use… [J Am Diet Assoc. 2010] – PubMed – NCBI

14. FDA to Ban Trans Fats in Foods – US News and World Report

15. saturated fat | Practical Evolutionary Health

16. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease.

Intestinal Permeability, Food and Disease

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In medical school I learned some fundamental concepts about nutrition and digestion that turn out to be wrong. For example, we were taught that proteins in our diet are completely broken down into single amino acids in the gut, then absorbed through the wall of the intestine as individual amino acids. Turns out that not all proteins are completely digested in this manner and that fragments of proteins that are several amino acids long can be absorbed through the gut and enter our blood. Examples of such proteins include wheat gluten and bovine serum albumin (found in cows milk and whey protein) to name a few. The problem with absorbing such nutrients into our bloodstream is that these protein fragments are “foreign” and can be recognized by our immune systems as foreign, triggering an immune (inflammatory) response.

Some peptides (short chains of amino acids) in bovine serum albumin have structural similarity to peptides in human tissues. This foreign protein has been implicated in autoimmune diseases such as Multiple Sclerosis, Rheumatoid Arthritis and Type 1 Diabetes.

Other substances such as bacterial endotoxin similarly can be absorbed into the blood and cause trouble. Endotoxin, also called LPS or  Lipopolysaccharide, is a major component of the outer membranes of certain kinds of bacteria (gram negative bacteria such as E-coli) that live in the  Lumen of our gut. High levels of endotoxin circulating in the blood occur during septicemia and can result in death from septic shock. Lower levels of circulating endotoxin have been demonstrated to contribute to alcoholic and non-alcoholic liver disease, both of which can cause liver failure and death.

Intestinal wall permeability is governed by many factors. There are regulatory proteins that open and close the gaps (tight junctions) between the cells that line the walls of our intestines, thereby allowing more and larger foreign substances to enter our blood. This mode of entry is referred to as “paracellular” since it does not involve the usual absorption mechanism through the walls of the cells that line the intestines.

Substances regularly consumed by Americans known to increase intestinal permeability include gluten (the sticky protein found in wheat, barely, rye, oats), alcohol, non-steroidal anti-inflammatory drugs  like ibuprofen (Motrin, Advil), naprosyn (Alleve), and aspirin.  Refined “vegetable oils” that are high in a specific Polyunsaturated fatty acid called linoleic acid (examples of these vegetable oils include corn oil, soy oil, cottonseed oil) have also been demonstrated to increase intestinal permeability.

Vegetable oils have also been found to enhance the liver inflammation and destruction caused by  alcohol which is at least in part mediated by absorption of endotoxin and ultimately also caused by oxidative stress.

The same applies to non-alcoholic liver fatty liver disease. (Progression of alcoholic and non-al… [Drug Metab Pharmacokinet. 2011] – PubMed – NCBI)

Interestingly, consumption of saturated fat (as found in beef tallow, coconut oil, butter and cocoa butter-the oil of dark chocolate) protects the liver from inflammation and destruction caused by alcohol, while polyunsaturated fat consumption (vegetable oils)  do the opposite. (References above and below)

There is growing evidence for a link between auto-immune disease and Alterations in intestinal permeability. Increased intestinal permeability (IP) has been observed in a substantial percentage of individuals with Type I diabetes. It is commonly observed in populations at high risk of developing Crohn’s disease and has been observed in patients who subsequently develop Crohn’s disease. Patients with ankylosing spondylitis have increased IP and although these patients are typically treated with NSAIDs which increase IP, the effects of NSAIDS have been isolated from a primary defect in IP which is shared by relatives without the disease.

“increased intestinal permeability is observed in association with several autoimmune diseases. It is observed prior to disease and appears to be involved in disease pathogenesis.”

A paleolithic diet avoids all sources of gluten (paleo is grain-free) and it also avoids refined “vegetable oils”. These food items present a double hit relative to inflammation. First, they increase IP which increases circulating levels of various “foreign” proteins and other foreign macromolecules which can stimulate the immune system. The second hit from these food items represents their direct inflammatory effects once absorbed into the body. I have previously discussed the  inflammatory response to excess omega six fats here.

An excellent review of the importance of the ratio of omega six fats found in “vegetable oil”  to omega three fats found in fish oil can also be found here ,  here   and  here.

The potential inflammatory response and anti-nutrient effects of cereal grains and in particular the gliadin portion of wheat gluten has been discussed and reviewed in multiple papers including:

Do dietary lectins cause disease?

Non-Celiac Gluten Sensitivity: The New Frontier of Gluten Related Disorders

BMC Medicine | Full text | Spectrum of gluten-related disorders: consensus on new nomenclature and classification

BMC Medicine | Abstract | Divergence of gut permeability and mucosal immune gene expression in two gluten-associated conditions: celiac disease and gluten sensitivity

Bioactive antinutritional peptides derived from cere… [Nahrung. 1999] – PubMed – NCBI

Antinutritive effects of wheat-germ agglutinin and… [Br J Nutr. 1993] – PubMed – NCBI

This discussion just scratches the surface of the effects of intestinal permeability and health. Future discussion will address how the micro-flora (bacteria and viruses that live in our GI system) affect intestinal permeability, our brains, our immune system and our health.

Avoiding foods that we have not evolved to eat will result in decreased inflammation and will often reduce the symptoms of auto-immune and other inflammatory diseases. Many present day diseases are considered by evolutionary biologists to represent a mismatch between our culture, food, and our evolutionary biochemistry. These diseases were likely rare or non-existent  before the advent of agriculture and the subsequent industrialization of society with highly processed foods.

Eat only pastured meat, free range poultry and eggs, wild seafood, fresh vegetables, fruit and nuts and you will avoid the problems discussed above as well as a host of other problems to be discussed in future posts.

Peace,

Bob Hansen MD

Addendum to lose weight, control blood sugar, decrease inflammation

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To those of you who have subscribed to my blog by e-mail, I must apologize that I hit the “publish button” by mistake before I completed the finished article. So if you would like to read the full article, please go to the website for the updated and completed version.

Thanks

Bob Hansen MD

Lose weight, control blood sugar, reduce inflammation

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The Duke University Lifestyle Medicine Clinic prescribes a nutritional program based upon a very simple concept, limit carbohydrate intake and multiple problems improve. This approach is so powerful in controlling blood sugar that diabetic patients must reduce their medication  before adopting the nutritional program in order to avoid very low blood sugars.

Compared to a low-fat diet weight loss approach, it is better or equal on every measurement studied. Here is what happens on the carbohydrate restricted program when compared to a low fat diet (American Heart Association diet). The carbohydrate restricted diet results in

  • Greater reduction in weight and body fat
  • Greater reduction in fasting blood sugar
  • Reduction in the amount of saturated fat circulating in the blood despite a higher intake than a low fat diet
  • Greater reduction in insulin with improved insulin sensitivity
  • Reduction in small LDL (low fat diets increase small LDL which is considered to be associated with more heart attacks and strokes)
  • Increase in HDL (low fat diets decrease HDL, decreased HDL is associated with increased risk of heart attack and stroke)
  • Greater reduction in Triglycerides
  • Reduction in the ApoB/ApoA-1 ratio (low fat diets do the opposite, and the opposite is considered to increase risk of heart attack and stroke).
  • Reduction in multiple markers of inflammation
  • Spontaneous reduction in caloric consumption without counting or restricting calories (people automatically eat less as a result of restricting carbohydrates, low-fat diets require counting and restricting calories in order to lose weight)
  • Increased consumption of non-starchy vegetables

All of these beneficial effects are accepted by the medical community as reducing cardiovascular risk .

The improved metabolic outcome can occur even without weight loss simply by substituting fat for carbohydrate.

“The key principle is that carbohydrate, directly or indirectly through the effect of insulin, controls the disposition of excess dietary nutrients. Dietary carbohydrate modulates lipolysis, lipoprotein assembly and processing and affects the relation between dietary intake of saturated fat intake and circulating levels.” see here

Yet despite these proven effects, the proponents of low-fat diets refer to the carbohydrate restriction approach as a “fad diet”. In his excellent discussion of this term, Richard Feinman points out that historically, a carbohydrate restriction approach is actually the longest standing and proven approach to the treatment of obesity compared to a low-fat diet which is a relative newcomer. He describes how a low-fat diet more closely meets the dictionary’s definition of a “fad”.

Multiple Studies have compared carbohydrate restriction to low fat diet approaches and the results are consistent. In addition to the advantages cited above, carbohydrate restricted approaches when compared to low-fat diets reveal that symptoms of  “negative affect and hunger improved to a greater degree” compared with those following a low fat diet”. (see here)

When one analyzes the carbohydrate restricted diet (CRD) approach employed by many centers, including the Duke Interventional Medicine Clinic, one finds great similarity to a paleolithic diet.

They both eliminate or dramatically reduce

  • sugar-sweetened foods and beverages,
  • grains, flour foods and cereal foods
  • legumes (paleo completely, CRD to a large extent)
  • processed-refined vegetable oils
  • dairy (paleo completely, CRD to a large extent)

Fruits under a CRD are limited to small amounts of berries initially and this is liberalized over time as weight loss is achieved and metabolic parameters are improved. This is consistent with a paleolithic approach that recognizes that fruits and vegetables grown today have been bred to provide much higher sugar and starch content compared to the pre-agricultural  fruits and vegetables that early hominids consumed for hundreds of thousands of years.

A carbohydrate restricted nutritional approach to treat obesity, diabetes, or metabolic syndrome appears to be a valid and arguably superior remedy to a growing problem in the developed world. Yet despite this strong and convincing scientific data, dietary fat-phobia has impaired the utilization of this proven therapeutic modality.

Peace,

Bob Hansen M.D.

Saturated Fat vs. Sugar

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Within one week of my post on saturated fat two discussions supporting my position have appeared in peer-reviewed journals. The first discussion can be found here.

Observations: Saturated fat is not the major issue | BMJ

The second can be found here.

Dietary Fats and Health: Dietary Recommendations in the Context of Scientific Evidence

The first article was written by a cardiologist who teaches and practices at Croydon University Hospital in London. He states that advice to reduce saturated fat intake

“has led to the over-medication of millions of people with statins and has diverted our attention from the more egregious risk factor of atherogenic dyslipidaemia”

He states that recent studies “have not supported any significant association between saturated fat intake and risk of CVD”. He discusses sugar and highly refined carbohydrates as the culprit in causing atherogenic (artery plaque forming) dyslipidaemia (abnormal blood lipid profiles).

Here are comments by three Professors about Dr. Malhotra’s article:

David Haslam, Chair of Britain’s National Obesity Forum states the following.

“It’s extremely naive of the public and the medical profession to imagine that a calorie of bread, a calorie of meat and a calorie of alcohol are all dealt in the same way by the amazingly complex systems of the body. The assumption has been made that increased fat in the bloodstream is caused by increased saturated fat in the diet, whereas modern scientific evidence is proving that refined carbohydrates and sugar in particular are actually the culprits.”

Professor Robert Lustig (Pediatric Endocrinologist, UCSF) stated

“Food should confer wellness, not illness. And real food does just that, including saturated fat. But when saturated fat got mixed up with the high sugar added to processed food in the second half of the 20th century, it got a bad name. Which is worse, the saturated fat or the added sugar? The American Heart Association has weighed in – the sugar many times over. Plus added sugar causes all of the diseases associated with metabolic syndrome. Instead of lowering serum cholesterol with statins, which is dubious at best, how about serving up some real food?”

Timothy Noakes (Professor of Exercise and Sports Science, University of Cape Town) states

“Focusing on an elevated blood cholesterol concentration as the exclusive cause of coronary heart disease is unquestionably the worst medical error of our time. After reviewing all the scientific evidence I draw just one conclusion – Never prescribe a statin drug for a loved one.”

Here is the abstract summary of the second article cited above.

“Although early studies showed that saturated fat diets with very low levels of PUFAs increase serum cholesterol, whereas other studies showed high serum cholesterol increased the risk of coronary artery disease (CAD), the evidence of dietary saturated fats increasing CAD or causing premature death was weak. Over the years, data revealed that dietary saturated fatty acids (SFAs) are not associated with CAD and other adverse health effects or at worst are weakly associated in some analyses when other contributing factors may be overlooked. Several recent analyses indicate that SFAs, particularly in dairy products and coconut oil, can improve health. The evidence of ω6 polyunsaturated fatty acids (PUFAs) promoting inflammation and augmenting many diseases continues to grow, whereas ω3 PUFAs seem to counter these adverse effects. The replacement of saturated fats in the diet with carbohydrates, especially sugars, has resulted in increased obesity and its associated health complications. Well-established mechanisms have been proposed for the adverse health effects of some alternative or replacement nutrients, such as simple carbohydrates and PUFAs. The focus on dietary manipulation of serum cholesterol may be moot in view of numerous other factors that increase the risk of heart disease. The adverse health effects that have been associated with saturated fats in the past are most likely due to factors other than SFAs, which are discussed here. This review calls for a rational reevaluation of existing dietary recommendations that focus on minimizing dietary SFAs, for which mechanisms for adverse health effects are lacking.”

Of course both articles produced a stormy debate with letters to the editor from supporters and detractors, but thank God this debate has finally entered mainstream academic discussion.

These two authors have coincidentally introduced the topics of my next two blogs so please stay tuned for discussions of sugar/refined carbohydrates and coconut oil (filled with health promoting and infection fighting medium chain triglycerides)

Go in peace

Bob Hansen MD

Saturated fat, does it matter?

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Recommendations to reduce saturated fat consumption have pervaded our media since the AHA published its first dietary guidelines for the American public in 1961. The AMA at first opposed the recommendations but the AHA pushed on. The guidelines encouraged substitution of polyunsaturates for saturated fat. The guidelines were presented in a two page report with 1/2 page of references. A subsequent independent review of those references revealed that 1/2 of them did not support the recommendations, details, details.

My last blog looked at a meta-analysis of the major studies subsequently published on this topic and found that implementation of that recommendation does not reduce heart attacks or cardiac deaths and in fact there was a trend (not statistically significant) for worse outcomes associated with substituting PUFA (polyunsaturated fatty acids, primarily linoleic acid) for SFA (saturated fatty acids).

Please note that we are talking hard endpoints here, death and heart attack. So much of the literature that consumes this issue only looks at the effect on so called risk factors. When you actually look at the clinical outcomes (death, heart attack, stroke)  there is no benefit demonstrated when saturated fats are reduced.

In 1966 the makers of Mazola Corn Oil and Mazola Margarine sponsored publication of Your Heart Has Nine Lives, a book advocating the substitution of vegetable oils for butter and other “artery clogging” saturated fats.

The history of this campaign to demonize SFA and glorify PUFA is well described in Gary Taubes Good Calories, Bad Calories, as well as in Mary Enig’s essay The Oiling of America. I would encourage you to read both.  The latter is available on line as is Gary Taubes’ famous essay What if its all a big fat lie?

http://www.westonaprice.org/know-your-fats/the-oiling-of-america

In 2010 a highly respected lipid research group published what should have been a wake-up call study for the medical profession.

Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease.

The data included 5 to 23 years follow up on 347,747 subjects. 11,006 developed coronary heart disease or stroke. Intake of saturated fat was not associated with an increased risk of coronary heart disease (CHD), stroke, or  cardiovascular disease (CVD =CHD plus stroke).

“there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD.”

To be clear, association (statistical correlation) does not prove or disprove causation, but if such a large amount of data from prospective studies shows no statistically significant correlation, than a causative theory should be rejected until and unless randomized controlled clinical trials suggest otherwise.

This study should have created a tsunami in the media and in the medical community but it hardly caused a ripple in the pond. Michael Eades explains why in an excellent post here.

http://www.proteinpower.com/drmike/lipid-hypothesis/eat-less-move-die-anyway/

The editors of the journal published a scathing rebuke of the authors but could not find anything wrong with the data and conclusions except that the data refuted their belief system. Busy physicians tend to read the editorials and place more credence in an editorial than in a study that questions or refutes a major thesis.

Lets look at some other studies that considered hard clinical endpoints.

Low-fat dietary pattern and risk of cardiovascular disease: the Women’s Health Initiative Randomized Controlled Dietary Modification Trial.

The objective of this study was:

“To test the hypothesis that a dietary intervention, intended to be low in fat and high in vegetables, fruits, and grains to reduce cancer, would reduce CVD risk.”

This study was a randomized controlled trial of 48,835 postmenopausal women aged 50-79 years of diverse backgrounds and ethnicity.

“RESULTS: By year 6, mean fat intake decreased by 8.2% of energy intake in the intervention vs the comparison group, with small decreases in saturated (2.9%), monounsaturated (3.3%), and polyunsaturated (1.5%) fat; increases occurred in intakes of vegetables/fruits (1.1 servings/d) and grains (0.5 serving/d).”

Did this decrease heart attacks or strokes? NO

“The diet had no significant effects on incidence of CHD (hazard ratio [HR], 0.97; 95% confidence interval [CI], 0.90-1.06), stroke (HR, 1.02; 95% CI, 0.90-1.15), or CVD (HR, 0.98; 95% CI, 0.92-1.05).”

Now lets look at a study where women were followed after a heart attack to see if reducing saturated fat helped.

Dietary fats, carbohydrate, and progression of coronary atherosclerosis in postmenopausal women. Am J Clin Nutr. 2004 Nov;80(5):1175-84.

In this study quantitative coronary angiography was performed at baseline and after mean follow up of 3.1 years. 2243 coronary artery segments in 235 women were studied.

Here is what they found.

  • a higher saturated fat intake was associated with a smaller decline in mean minimal coronary diameter (P = 0.001) and less progression of coronary stenosis (P = 0.002) during follow-up
  • Carbohydrate intake was positively associated with atherosclerotic progression (P = 0.001), particularly when the glycemic index was high
  • Polyunsaturated fat intake was positively associated with progression (of coronary atherosclerosis) when replacing other fats (P = 0.04) but not when replacing carbohydrate or protein
  • Monounsaturated and total fat intakes were not associated with progression. (extra virgin olive oil and macadamia nuts are rich in monounsaturated fat)

The P values cited demonstrate unequivocal statistical significance for all of these associations.

So intake of carbohydrate and polyunsaturated fat was positively associated with progression of coronary atherosclerosis. Conversely, saturated fat intake was associated with less progression of coronary stenosis.  Again, I must point out that association does not prove or disprove causation. Nevertheless, there have been no prospective studies that demonstrate an association between saturated fat consumption and cardiovascular events (real clinical endpoints). Here we have data that show a negative association with saturated fat but positive association with carbohydrate and polyunsaturated fat consumption.

The logic has always been that substituting PUFA for SFA reduces cholesterol levels (short term studies) and therefore it should reduce heart attacks and strokes. But if you search the medical literature you find that the overwhelming body of data shows no reduction in hard clinical outcomes by reducing saturated fat, in fact just the opposite is true as in the two Ramsden studies cited in my previous post.

Uffe Ravnskov has pointed out that the proponents of the dietary  saturated fat-cholesterol theory often times misrepresent the data from published studies and cite those studies in support of the theory when in fact the data actually refute the theory. (as was the case for the AHA’s first dietary recommendations demonizing saturated fat in 1961) Uffe’s letters to the editor have been a nuisance to the proponents of that theory for decades.

An exhaustive review of the literature by Ravnskov was published in 1996. The summary deserves a complete quotation here.

J Clin Epidemiol. 1998 Jun;51(6):443-60.

The questionable role of saturated and polyunsaturated fatty acids in cardiovascular disease.

Source

uffe.ravnskov@swipnet.se

Abstract

A fat diet, rich in saturated fatty acids (SFA) and low in polyunsaturated fatty acids (PUFA), is said to be an important cause of atherosclerosis and cardiovascular diseases (CVD). The evidence for this hypothesis was sought by reviewing studies of the direct link between dietary fats and atherosclerotic vascular disease in human beings. The review included ecological, dynamic population, cross-sectional, cohort, and case-control studies, as well as controlled, randomized trials of the effect of fat reduction alone. The positive ecological correlations between national intakes of total fat (TF) and SFA and cardiovascular mortality found in earlier studies were absent or negative in the larger, more recent studies. Secular trends of national fat consumption and mortality from coronary heart disease (CHD) in 18-35 countries (four studies) during different time periods diverged from each other as often as they coincided. In cross-sectional studies of CHD and atherosclerosis, one group of studies (Bantu people vs. Caucasians) were supportive; six groups of studies (West Indians vs. Americans, Japanese, and Japanese migrants vs. Americans, Yemenite Jews vs. Yemenite migrants; Seminole and Pima Indians vs. Americans, Seven Countries) gave partly supportive, partly contradictive results; in seven groups of studies (Navajo Indians vs. Americans; pure vegetarians vs. lacto-ovo-vegetarians and non-vegetarians, Masai people vs. Americans, Asiatic Indians vs. non-Indians, north vs. south Indians, Indian migrants vs. British residents, Geographic Study of Atherosclerosis) the findings were contradictory. Among 21 cohort studies of CHD including 28 cohorts, CHD patients had eaten significantly more SFA in three cohorts and significantly less in one cohort than had CHD-free individuals; in 22 cohorts no significant difference was noted. In three cohorts, CHD patients had eaten significantly more PUFA, in 24 cohorts no significant difference was noted. In three of four cohort studies of atherosclerosis, the vascular changes were unassociated with SFA or PUFA; in one study they were inversely related to TF. No significant differences in fat intake were noted in six case-control studies of CVD patients and CVD-free controls; and neither total or CHD mortality were lowered in a meta-analysis of nine controlled, randomized dietary trials with substantial reductions of dietary fats, in six trials combined with addition of PUFA. The harmful effect of dietary SFA and the protective effect of dietary PUFA on atherosclerosis and CVD are questioned.

That was published in 1998, since then the evidence remains as Uffe described it 15 years ago. More studies show no relationship between saturated fat consumption and cardiovascular death, heart attack, or stroke.

Finally, multiple autopsy studies around the world have been conducted to investigate an association between diet and atherosclerosis. None of these studies have demonstrated a positive association between degree of atherosclerosis and saturated fat intake.

Yet the AHA continues to recommend lower levels of saturated fat consumption while showing little concern for the problem of sugar and refined carbohydrates.

In my next post I will discuss why sugar and refined carbohydrates are major players in the physiology of atherosclerosis. Future posts will address the China Study, Forks Over Knives, the Ornish Diet and related topics. Additionally I will discuss why an egg a day keeps the doctor away.

Go in peace.

Bob Hansen MD.