Saturated Fat and Coronary Heart Disease, Part V: The “Science”

Before I begin, I'll simply point you to part one of the series and you'll find the links to all the other parts there.

So it's time to discuss the "science" behind the idea that saturated fat intake leads to heart disease. Let's begin with pure observational epidemiology and then move on to the more solid prospective studies. For the first part, I'll just point out that I've posted on it a number of times before (here's a search link for those who wish to scour). Here's a few I picked out.

Here's pretty much what it always looks like. Does it mean more saturated fat is necessarily better? No, but that's not the point. The point is to generally falsify the notion that it's independently bad for you.

CHD
CHD

There just doesn't seem to be any way to make a positive correlation; unless, of course, you cherry pick your data like Ancel Keys -- aka The Fraud -- did. The other part of the epidemiology is the supposed association between dropping rates of heart disease death and the decrease in saturated fat consumption.

Indeed, heart disease deaths have decreased as one can see from the graphs here and here. But why, and how about incidence? See, a decrease in deaths can be caused by a number of things and while incidence is fraught with bias and subjectivity (in diagnosis), I can't find anything to suggest that the incidence of heart disease has decreased at all. Dr. Stephan Guyenet, who was kind enough to correspond with me on this issue wrote in an email:

Keep in mind these are death rates, not incidence rates. CHD deaths have decreased considerably since the 50s-60s, but incidence hasn't changed much if at all. We're having heart attacks but not dying of them, due to better emergency services and treatments (refs in Colpo's book). They didn't graph the CHD line going back beyond 1950, but they did collect data on it and it dwindles to near zero around 1920 (graph available in Colpo's book; I reproduced it in that post on my blog).

The other thing to keep in mind is that the U.S. doesn't collect unbiased stats on CHD incidence that I know of. These data depend on diagnosis by a physician, which is highly subjective. The UK autopsy studies I cited in my post are less biased, and thus much more solid. I think they're worth mentioning, at least for comparison.

He's referring to Anthony Colpo's amazing book: The Great Cholesterol Con. And here's what the CDC says concerning the decline in deaths:

  • a decline in cigarette smoking among adults aged greater than or equal to 18 years from approximately 42% in 1965 to 25% in 1995 (13). Substantial public health efforts to reduce tobacco use began soon after recognition of the association between smoking and CVD and between smoking and cancer and the first Surgeon General's report on smoking and health published in 1964.
  • a decrease in mean blood pressure levels in the U.S. population (11,13,14).
  • an increase in the percentage of persons with hypertension who have the condition treated and controlled (11,13,14).
  • a decrease in mean blood cholesterol levels (12-14).
  • changes in the U.S. diet. Data based on surveys of food supply suggest that consumption of saturated fat and cholesterol has decreased since 1909 (15). Data from the National Health and Nutrition Examination surveys suggest that decreases in the percentage of calories from dietary fat and the levels of dietary cholesterol coincide with decreases in blood cholesterol levels (16).
  • improvements in medical care, including advances in diagnosing and treating heart disease and stroke, development of effective medications for treatment of hypertension and hypercholesterolemia, greater numbers of specialists and health-care providers focusing on CVD, an increase in emergency medical services for heart attack and stroke, and an increase in coronary-care units (13,17). These developments have contributed to lower case-fatality rates, lengthened survival times, and shorter hospital stays for persons with CVD (1,17).

A mixed bag (those numbers refer to the references at the link), so it's completely wrong headed to believe that a decrease in saturated fat consumption is a major factor, if any factor at all.

So let's move onto a study of studies. A summary, or "meta-analysis" is where they take a bunch of studies and essentially do a study on the studies. This is a good method because it tends to wash out outliers in either direction. It's a way to get tons more data, which makes statistical conclusions more valid (or less BS, perhaps). In this case, it's epidemiological, still, but this tends to give a bit more confidence.

Before showing what was found, it's appropriate I think to point out that epidemiological or observational studies ought to be used for one and only one thing: forming reasonable hypotheses -- hypotheses which you then go test with real, intervention, controlled studies where different groups get different things over hopefully a long period and you analyze the results.

Quoting Anthony Colpo, from his last newsletter:

After examining 28 prospective epidemiological studies, the researchers reported that:

"Intake of total fat was not significantly associated with CHD mortality..." (p. 175)

"Intake of total fat was also unrelated to CHD events..." (p. 175)

"Intake of TFA [trans fatty acids] was strongly associated with CHD mortality..." (p. 181)

"Intake of SFA [saturated fatty acids] was not significantly associated with CHD mortality...

Similarly SFA intake was not significantly associated CHD events..." (p. 181)

Their pooled analysis of data from randomized controlled clinical trials showed:

"...fatal CHD was not reduced by either the low-fat diets... or the high P/S diets [diets high in polyunsaturated fats and low in saturated fats] ...". (p. 188)

On page 193, they conclude:

"There is probably no direct relation between total fat intake and risk of CHD."

Here's the whole study (PDF).

Now let's move onto some independent prospective studies. In pure observational epidemiology, they simply "find" associations. The problem is that there's lots and lots of associations if you look -- and the more you look, the more you find -- and picking out stuff to check for associations is bias in and of itself. You could find dozens of them amongst people who get and die from heart disease. What if you found, for instance, that more left-handed people die from heart attacks than right handed people? How about toilet paper use, or cosmetics, or any number of other things? The truth is, you pick what you already think might be suspect. And the thing is, the general population seems to glom onto observational studies more than all else. They're simple to understand and easy for the sensational idiots in the press to make a scare story of.

Back in December Dr. Stephan Guyenet posted a review of his own concerning prospective studies. He says:

The diet-heart hypothesis is the idea that saturated fat, and in some versions cholesterol, raises blood cholesterol and contributes to the risk of having a heart attack. To test this hypothesis, scientists have been studying the relationship between saturated fat consumption and heart attack risk for more than half a century. To judge by the grave pronouncements of our most visible experts, you would think these studies had found an association between the two. It turns out, they haven't.

The fact is, the vast majority of high-quality observational studies have found no connection whatsoever between saturated fat consumption and heart attack risk. The scientific literature contains dozens of these studies, so let's narrow the field to prospective studies only, because they are considered the most reliable. In this study design, investigators find a group of initially healthy people, record information about them (in this case what they eat), and watch who gets sick over the years.

You can go over to his post to look at the actual studies, as well of a couple of review studies he points to drawing essentially the same conclusion he does:

Over 25 high-quality studies conducted, and only 4 support the diet-heart hypothesis. If this substance is truly so fearsome, why don't people who eat more of it have more heart attacks?

[...]

This is it, folks: the diet-heart hypothesis ends here. It's been kept afloat for decades by wishful thinking, puritan sensibilities and selective citation of the evidence. It's time to put it out of its misery.

Finally, there's something new that just hit the medical journals and has been blogged pretty extensively. In The American Journal of Clinical Nutrition:

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

Patty W Siri-Tarino, Qi Sun, Frank B Hu and Ronald M Krauss

ABSTRACT

Background: A reduction in dietary saturated fat has generally been thought to improve cardiovascular health.

Objective: The objective of this meta-analysis was to summarize the evidence related to the association of dietary saturated fat with risk of coronary heart disease (CHD), stroke, and cardiovascular disease (CVD; CHD inclusive of stroke) in prospective epidemiologic studies.

Design: Twenty-one studies identified by searching MEDLINE and EMBASE databases and secondary referencing qualified for inclusion in this study. A random-effects model was used to derive composite relative risk estimates for CHD, stroke, and CVD.

Results: During 5–23 y of follow-up of 347,747 subjects, 11,006 developed CHD or stroke. Intake of saturated fat was not associated with an increased risk of CHD, stroke, or CVD. The pooled relative risk estimates that compared extreme quantiles of saturated fat intake were 1.07 (95% CI: 0.96, 1.19; P = 0.22) for CHD, 0.81 (95% CI: 0.62, 1.05; P = 0.11) for stroke, and 1.00 (95% CI: 0.89, 1.11; P = 0.95) for CVD. Consideration of age, sex, and study quality did not change the results.

Conclusions: A meta-analysis of prospective epidemiologic studies showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD. More data are needed to elucidate whether CVD risks are likely to be influenced by the specific nutrients used to replace saturated fat.

Next I will speculate about what I think really contributes to heart disease.

1/20/2010: Stephan, this morning, posted on yet another paper by Krauss, just out. This one focusses on intervention studies.

In summary, although substitution of dietary polyunsaturated fat for saturated fat has been shown to lower CVD risk, there are few epidemiologic or clinical trial data to support a benefit of replacing saturated fat with carbohydrate. Furthermore, particularly given the differential effects of dietary saturated fats and carbohydrates on concentrations of larger and smaller LDL particles, respectively, dietary efforts to improve the increasing burden of CVD risk associated with atherogenic dyslipidemia should primarily emphasize the limitation of refined carbohydrate intakes and a reduction in excess adiposity.

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Comments

  1. Very good article! The truth is coming out more and more but there are still many skeptics and deniers and paid “experts” out there who try to maintain the status quo.

  2. Excellent way to get the ball rolling. I hope the answer to “why heart disease?” isn’t “reading too many primal/paleo blogs. Seriously, it’s good to go on the offensive when being defensive. Turn the tables on CW.

  3. I hope the more word gets out the more people will begin to question their paradigms about health. In the meantime, I’ll be over here chowing down on chili con carne, haha.

  4. Kateryna says:

    I just had supper: 4 eggs yolks fried in 4 tblsp of butter and 4 slices of bacon. I’m 60 and had a stroke when I was 46. Been eating properly now for about 5 years. Can’t seem to get my total cholesterol above 185, my HDL is usually around 65 and my LDL is usually around 95. Am I afraid of saturated fat? Never. It’s healing me. No meds, no health issues anymore, thanks to eating real, healthy meat and saturated fat.

    Wish the truth would just come out faster so that people don’t have to continue suffering and dying needlessly. Bloggers like you and many others are spreading the word and the truth will eventually win out.

    • “Can’t seem to get my total cholesterol above 185…”

      Classic. I do so wish people would just eat real food and stop worrying about cholesterol, in the sense of it being high, low or “normal.” We have no good idea of what normal is, since we don’t eat the highly inflammatory SAD upon which “normal” was established.

  5. When I increased my intake of saturated fat with a concurrent reduction in refined carbs and sugars, my HDL shot up, and my LDL went down.

    My LDL levels, and that of many other people, seem to actually be negatively correlated with saturated fat intake, as long as consumption of refined carbs and sugars is low.

    • Ned:

      Good. And me to. LDL dropped into the 60s and HDL into the 130s. But it doesn’t happen that way for all, and there are some out there a bit scared with TC levels in the 500s and 600s.

      I don’t know, and I have yet to see a great explanation by anyone. Genetics? Is the liver pumping out C to repair inflammatory damage from SAD for decades? I don’t know, and nobody’s going to look at it. Even worse, modern HGs are few and far between, now.

      You don’t learn anything from studying people on various iterations of the SAD, just shuffling macros around a bit, but fundamentally still the same shit.

      This is why Price and other need to be constantly put forth. There’s no other way, at this point.

      • There is good and recent research out there. Particularly from Europe, where Big Pharma has a lot less influence on what gets published or not. Unfortunately, there are not enough of us to dig it up and blog about it. One example is this 2009 article on the prevalence of heart disease among the Greenland Inuit in the early 1960s, suggesting that it was around 63 times lower than in the US today:

        http://healthcorrelator.blogspot.com/2010/01/ischemic-heart-disease-among-greenland.html

        Some of those large increases in TC you mentioned are completely benign, as you know, as particle sizes change. Larger LDL particles carry more cholesterol, which is picked up by lab tests as an increase in cholesterol levels, when in fact the size of the particles is what increased, not the number. Large particles cannot penetrate the artery walls, so those folks are actually fine. (As far as I know.)

        Large TG increases are another story though. They are, I believe, often associated with metabolic abnormalities, such as insulin and/or leptin resistance. Even moderate insulin resistance can lead to severely altered lipid metabolism in some. So, if someone increases they sat. fat intake, on a low carb diet, and their TG levels go up instead of going down, they may have to make some adjustments to find their optimal level. Actually, they need to see a doctor who is not a pill dispenser and who is knowledgeable about this type of condition.

      • Excellent post there, Ned. Have you alerted Stephan to this study?

  6. So we’ve come to the conclusion that Saturated Fat is bad and it will KILL YOU… am I right? xD
    I think that’s how experts do it:
    No prove
    No causation
    Not even correlation

    But anyway Saturated fat is bad and that is it…

  7. Richard,

    I’m guessing you’re going to speculate that excessive intake of omega-6 and (for the insulin resistant) added sugars and grains are largely responsible for the high incidence of heart disease.

    Until recently I thought excessive sugar intake was the major artery-clogging factor. But after watching the October 15, 2009 presentation by Dr. Bill Lands, http://videocast.nih.gov/summary.asp?live=8108 I’m thinking considerable blame ought to be assigned to omega-6 fats.

    As Dr. Lands points out, the body only needs very small amounts of omega-3s and 6s in roughly equal amounts to satisfy its biochemical requirements. Exceeding those requirements by ten to twenty fold is like putting 200 to 400 hyperactive kids in a classroom with one teacher. The body simply does not have the resources to cope with that many highly reactive fat molecules. In contrast, saturated fats are more like well behaved adults who need no supervision. As long as the supportive nutrition is adequate, one can consume as much saturated fat as one wants without causing metabolic damage.

  8. Just based on my own experience, the worst possible food for me is grains. I get very sick every time.

    blogsthatmakemethink.blogspot.com

  9. Kimberly says:

    I am so glad to have finally found other people like me who don’t worry one iota about their fat intake; I just make sure that the fat I eat comes from real food. I don’t count fat grams and eat as much butter as I want, and eggs every morning. In my effort to cut out the omega 6’s I do try to use only meat & dairy from grass fed cows as their diet has everything to do with how much of these unwanted omegas we get. I also agree with Jm Purdy about the grains. I have had amazing results with all sorts of symptoms by cutting out the bread, pasta, etc and limiting my corn, potatoes. I have been doing hydra colon therapy for a year now, and it’s very interesting that all the unwanted fat or bad cholesterol in my diet goes out with any other waste; you can see it floating along the top of the tube as it goes through the machine. I guess it’s not accumulating in my arteries as I would be led to believe.

  10. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease Patty W Siri-Tarino, Qi Sun, Frank B Hu, and Ronald M Krauss
    In case anyone isn’t aware the full text of the Krauss meta analysis is online here thanks to Nutrition & Metabolism Society

  11. Anthony Colpo has a series of new articles in his website, some of them about heart disease, cholesterol and saturated fat. http://www.anthonycolpo.com

  12. Richard, I didn’t know where else to leave this link for you but I figured it would make you laugh/cringe/shout in frustration. I know I did! I use livestrong.com to log my calories and this was one of the articles that looped through after I signed in. They should know better. Anyway, enjoy and thank you for sharing so much valuable information with the rest of us!

    http://www.livestrong.com/article/30216-top-worst-foods-cholesterol/

    -Megan

  13. The health authorities are fully aware of the serious flaws and omissions in this meta-analysis. This study was funded by the National Dairy Council, dairy being the number one source of saturated fat in the U.S. and many other parts of the world. It was also conveniently published just before the USDA lowered the dietary recommendations of saturated fat for the first time in 20 years, from 10% to 7% of total calories.

    Below is a section from the statement released by the European Heart Network in regards to their opinion of this meta-analysis, titled “European Heart Network position piece: Impact of saturated fat on cardiovascular disease obscured by over‐adjustment in recent meta‐analysis”

    “However, the meta‐analysis (and an accompanying opinion piece by the same authors (4)) is compromised by a number of serious flaws and omissions. These are enumerated and discussed in detail in an editorial from Jeremiah Stamler (5). The most serious of these flaws is an over‐adjustment for serum cholesterol levels. The meta‐analysis involves data from 16 studies that evaluate the impact of saturated fat intake on CHD incidence or mortality, and 8 studies that evaluate the impact of saturated fat intake on stroke incidence or mortality. The authors state that ‘wherever possible, risk estimates from the most fully adjusted models were used in the estimation of the pooled [relative risks]’. It is well‐established that saturated fat intake is associated with increased level of serum cholesterol (6), and that serum cholesterol levels are associated with CHD and CVD (7). Therefore, serum cholesterol levels lie on the causal chain between saturated fat intake and CHD and CVD, and to adjust for serum cholesterol levels in a meta‐analysis will obscure the impact of saturated fat intake on these health outcomes. Yet 7 of the 16 studies included in the meta‐analysis of CHD events, and 4 of the 8 studies included in the meta‐analysis of stroke events were adjusted for serum cholesterol levels. These studies accounted for nearly half of all CHD and CVD events included in the meta‐analyses. Adjustment for serum cholesterol levels will inevitably bias the results of the meta‐analyses towards finding no association between dietary saturated fat intake and cardiovascular disease, but the authors do not mention this limitation in their article. As Jeremiah Stamler asserts in his editorial, what was actually found by the meta‐analysis was ‘a statistically non‐significant relation of SFA [saturated fat] to CHD… independent of other dietary lipids, serum lipids, and other covariates’ (5). A more appropriate and informative analysis would have included non‐adjusted associations between saturated fat and cardiovascular disease. An examination of the forest plots provided in the article shows that those cohort studies that did not adjust for serum cholesterol levels were more likely to find a positive association between saturated fat intake and cardiovascular disease, suggesting that a meta‐analysis of unadjusted data would likely produce positive results. “

    References 5-7
    (5) Stamler J. Diet‐heart: a problematic revisit. American Journal of Clinical Nutrition, 2010; 91: 497‐499.
    (6) Clarke R, Frost C, Collins R, Appleby P, Peto R. Dietary lipids and blood cholesterol: quantitative meta‐analysis of metabolic ward studies. BMJ, 1997; 314: 112.
    (7) Prospective Studies Collaboration. Blood cholesterol and vascular mortality by age, sex, and blood pressure: a meta‐analysis of individual data from 61 prospective studies with 55,000 vascular deaths. The Lancet, 2007; 370: 1829‐1839.

    The full statement from the European Heart Network can be found here:

    Below is a published study showing reversal of severe heart disease backed up with angiogram evidence.
    http://www.heartattackproof.com/resolving_cade.htm

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  6. [...] why advise any limitation of "saturated fat?" Haven't you guys gotten the memo? The saturated fat hysteria is DOA. Done. Finished. Dead and Buried. To continue to hold otherwise is ignorant at best, dishonest and [...]

  7. [...] Saturated Fat and Coronary Heart Disease [...]

  8. [...] Well, so now we have something to balance out the other recent meta-study by Ronald Krauss that concluded: "A meta-analysis of prospective epidemiologic studies showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD. More data are needed to elucidate whether CVD risks are likely to be influenced by the specific nutrients used to replace saturated fat." Here's a recent post that deals with that and bunch of other studies. [...]