Cholesterol and Saturated Fat Myths Addressed Here

[Mihow]

Great thread. I have nothing to contribute but it was fun/interesting to read these posts so far.

 

[turbozed]

Large double-blind, controlled studies with human subjects, over long periods of time tend to be very expensive, and difficult to pull off. Thus, there always is some trade-off. But IMO it's irresponsible to ignore smaller studies if a trend between them is established, which is usually the object of a meta-analysis, to find trends in acquired data.

Yeah. It seems backasswards to include in the meta-analysis the studies with larger subjects and more compromised methodology. Wouldn't it make more sense to compile all the most controlled studies where the variables are known or more precise regardless of sample size?

 

[scottm]

I think what he is trying to say is most people don't recognize their limitations. If you don't have an advanced degree (Wikipedia PhD's don't count) or extensive education in a scientific field, evaluating a body of scientific literature is probably not going to be one of your strong suits. This is not necessarily a problem, as long as you realize this and act accordingly.

The problems arise when people fail to recognize weaknesses. The inherent weakness of a rubber band isn't a problem unless you fail to realize it and try to bungee jump with one. Liekwise, a lack of expertise in a field is only a problem if you don't realize it. I've seen people with great expertise in one area completely embarrass themselves (without even realizing it) by thinking their skills in X somehow gave them an ability to understand science.

I'm sure you are probably more familiar with many concepts than the average person. But this greater level of knowledge may have led you to believe you have a comprehensive understanding of the subject, and this, in due order, has led to believing you know more than the majority of the scientific community.

I must admit, it is rather difficult for me to understand, to imagine that I am an expert in a subject in which I have little or no training. Even as a phd candidate and doctor in training, I wouldn't ever claim to know more. What's odd is this type of behavior doesn't seem to happen much outside the sciences. You don't hear of people thinking they have expertise in building houses or car repair. It might be because when people try to play an expert in these areas, they run up against the sharp tip of reality more often.

Take home message: If you're not a professional--meaning you're not paid for your research and don't have a bunch of fancy letters after your name--acknowledge this fact and don't pretend you are. Consensus is your best bet.

That is a terribly narrow minded view point, and I actually feel sorry for you.
I never went to school to be a mechanic, but through teaching myself I can now take apart a complete motorcycle and put it back together in under 4 hours. I can also do a complete build of a turbo diesel motor in a weekend. Your analogies apply both ways here. Because more often than not your so called "professionals" cannot be trusted. The plethora of negative reviews available for "expert" car repairmen or house builders speaks for itself. Which is why I do all my own work in both of those fields. If consensus were truly the best bet everyone would be overpaying for mediocre work in return. The same applies in the fields of science as well, otherwise by your logic we would still be using mercury as a cure for syphilis, dispensing heroin as a cough suppresent, or performing lobotomies to cure depression and anxiety.

It's unfortunate that you do not have confidence in your fellow human being's intelligence and capacity for learning and reasoning. You may see it as arrogance but I feel even an undergrad bio chem classes coupled with my ability to reason and intelligence level gives me more than enough of a solid basis for making informed decisions about my health. If I were to listen to your so called community of experts I would be taking a prilosec followed by a breakfast of grains chased with orange juice and an adderall.

 

[Sinister]

Yeah. It seems backasswards to include in the meta-analysis the studies with larger subjects and more compromised methodology. Wouldn't it make more sense to compile all the most controlled studies where the variables are known or more precise regardless of sample size?

Well, to be fair, the criticism on that is that smaller sample sizes increase the likelihood that what could be occurring is anomalous as opposed to standard. Now, I'd like to think that researchers are more technically savvy than that, but the skepticism is definitely warranted. It's difficult to argue when someone simply makes the statement: "yes, but the sample sizes seem too small to form a conclusion"...even if a pattern is established, when matched versus population, it can be looked at as too minimal to be strongly considered. This is some of the hardest scrutiny the research in the specialized field of lipid metabolism has come to.

It's easy for some of us to sit back and say how a study should be constructed, or even how data review (meta-analysis) should be done, but there are just more factors to it. Always a catch. Meta-analysis runs into the notion that with a large enough pool of data, one could find almost any trend they're looking for by omitting data until that's all that's left. If we can't question the data, we then question who is relaying it, right? In an idealistic scenario, to be conclusive about this particular subject, we'd dream of a scenario where not only fat consumption is both controlled and monitored, but carbohydrates (and their sources) as well, given what we know about glucose to lipid conversion in the liver, the role of insulin in triglyceride formation, and the epidemiological data suggesting that cultures who consume copious amounts of fat, but little carbohydrates by-comparison, do have instances of atherosclerosis, but minimal occurrences of CHD. But who are you gonna pitch that to? It'd be an incredibly expensive and tedious task, just to answer a question which many people are pretty convinced they already know the answer to.

If I had the money personally, I'd pay for it. Then what? Then you'd have the argument that it's not a non-biased study, as it would be interpreted that I did it purely to solidify my own position on the subject (that is, unless I posted contrary results were they to be found). But even then, there'd be someone on either side to claim that, like the on-going argument of aspartame vs. sugar. It's some to the point where the data is almost irrelevant, people believe what they want regardless of it, and disqualify data as mere propaganda, and that's both ways.

This is the main reason I grew a distaste for looking at abstracts, the trend of showing an abstract, with a conclusion on it as evidence (not indicating that's all miaou was doing, as I duly recognize miaou's efforts are of far more quality than that). I've found the most interesting parts of papers are the discussion sections, where the researchers give their actual first-hand feedback on not just what they observed, but why they observed it, or if they don't know, what their impressions were. Sometimes it can take an understanding of mechanical function PLUS trends in data to make the most insightful inferences from the testing of a hypothesis.

About the subject at-hand, does type of fat ingested matter? Absolutely, we learned a lot about fat quality in recent years, especially considering the debacle with margerine. Does carbohydrate consumption matter? Coinciding health complications of diabetes suggest so. I believe they're all definitely relevant.

 

[miaou]

This is the latest review from Krauss' team (referenced in links already posted in this thread). This is a very thorough and well-written analysis of the understanding we have so far (at least according to this team) of saturated fats and CVD. The entire text merits being posted in this thread:

Saturated fatty acids and risk of coronary heart disease: modulation by replacement nutrients. (Nov 2010)

Effects of Saturated Fat on Plasma Lipids and Lipoproteins

In humans, saturated fat intake increases LDL cholesterol in comparison with all nutrients except trans fats [2

 

[miaou]

...continued

High Carbohydrate Intake Contributes to Dyslipidemia

Elevated triglycerides, reduced HDL cholesterol concentrations, and increased concentrations of small, dense LDL particles characterize the dyslipidemia that is part of a metabolic profile considered to be a major contributor to increased CVD risk. Both insulin resistance and high carbohydrate intakes have been shown to contribute to this dyslipidemia, and refined carbohydrates, in particular, can raise triglyceride and lower HDL cholesterol concentrations [23]. Of interest, reductions in dietary carbohydrate, even in the context of a diet high in saturated fat, have been associated with reduced concentrations of small, dense LDL [5].

The type of carbohydrate consumed can affect blood lipid profiles. Using the glycemic index (GI) as a classification system that rates dietary carbohydrates by their ability to increase postprandial blood glucose levels, the consumption of lower-GI foods has been associated with lower triglycerides and higher HDL cholesterol [24]. Substituting low-GI foods for high-GI foods may lower triglyceride concentrations by 15% to 25% [25]. There is also considerable evidence that high intake of added sugars [26], and fructose in particular [27], adversely affects all components of atherogenic dyslipidemia. Most recently, an evaluation of data from 6113 adults participating in the National Health and Nutrition Examination Survey (NHANES) showed a positive correlation between added sugars and dyslipidemia [28]; the minimization of sugars as a component of the American diet would be expected to improve these diet-induced abnormal lipid profiles.



Effects of Saturated Fat on Coronary Heart Disease

Animal Studies

Assessment of the effects of dietary saturated fat on atherosclerosis has been studied in various animal models [9

 

[miaou]

...continued

Observational and Prospective Epidemiologic Studies

Although early epidemiologic studies linking saturated fat with blood cholesterol and blood cholesterol with CHD were important in defining a conceptual model of etiology for CVD [33, 34], they were a simplification of the complex relationship of nutrients to disease outcomes. These studies were based on aggregated data and did not adjust for potential confounders (eg, trans fatty acids, polyunsaturated fatty acids, and high-GI carbohydrates), some of which have only more recently come to be known as relevant in modulating CVD risk.

Prospective cohort studies are designed to enable the evaluation of potential baseline disease determinants with future disease outcomes by following a cohort of study participants over a period of time. Large, prospective epidemiologic studies have the advantage of being able to adjust for co-variates, so that the effects of a specific nutrient can be assessed. However, caveats to such studies include the reliance on nutritional assessment methods with varying accuracy and the assumption that diets remain similar over the long term.

Our recent meta-analysis summarized data related to saturated fat and CVD from 21 prospective epidemiologic studies that included 347,747 men and women [35

 

[Sinister]

Good stuff^.

 

[turbozed]

Great review summary there miaou. I like how they put everything into the context of the biochemical mechanisms involved.

One interesting point I did fish out of it was this one:

Of note, some studies have suggested that saturated fat may increase LDL cholesterol only if the polyunsaturated fat intake falls below a threshold level; specifically, the availability of linoleic acid may determine the cholesterolemic effects of other fatty acids [16]

If this turns out to be true, then this adds a bit of nuance to their conclusion that blood lipid levels would be improved by replacing saturated fats with polyunsaturated fats.

For people that have not reached that threshold amount of polyunsaturated fat intake, their markers would definitely improve. However, for people that already have satisfactory polyunsaturated fat intake, saturated fat would have no negative effects.

This changes things significantly. Saturated wouldn't be bad per se but only bad in certain situations. There would be no reason to avoid them whatsoever if you made sure your PUFA intake was satisfactory. This second scenario clearly refutes the original lipid hypothesis that posited that saturated fats caused CHD. I'm really curious as to what exactly that threshold level is though. Hopefully, someone's studying that right now.

 

[miaou]

^ Good observation. This is the study referenced in that bit. It doesn't refer to PUFAs in general, it refers to linoleic acid in particular. I don't have time to go over it now.



EDIT:

This second scenario clearly refutes the original lipid hypothesis that posited that saturated fats caused CHD.

Given the fact that replacing saturated fats for carbs will have zero of a positive effect, it seems fairly certain that "saturated fats cause CVD" cannot be anywhere near an accurate description here. We obviously don't have a complete understanding of it, but it seems quite possible that there is a dynamic interplay of many different factors, with saturated fats, polyunsaturated fats, dietary cholesterol, and maybe down to specific fatty acids, somehow interrelating at once.

 

[mtruitt76]

I think what he is trying to say is most people don't recognize their limitations. If you don't have an advanced degree (Wikipedia PhD's don't count) or extensive education in a scientific field, evaluating a body of scientific literature is probably not going to be one of your strong suits. This is not necessarily a problem, as long as you realize this and act accordingly.

The problems arise when people fail to recognize weaknesses. The inherent weakness of a rubber band isn't a problem unless you fail to realize it and try to bungee jump with one. Liekwise, a lack of expertise in a field is only a problem if you don't realize it. I've seen people with great expertise in one area completely embarrass themselves (without even realizing it) by thinking their skills in X somehow gave them an ability to understand science.

I'm sure you are probably more familiar with many concepts than the average person. But this greater level of knowledge may have led you to believe you have a comprehensive understanding of the subject, and this, in due order, has led to believing you know more than the majority of the scientific community.

I must admit, it is rather difficult for me to understand, to imagine that I am an expert in a subject in which I have little or no training. Even as a phd candidate and doctor in training, I wouldn't ever claim to know more. What's odd is this type of behavior doesn't seem to happen much outside the sciences. You don't hear of people thinking they have expertise in building houses or car repair. It might be because when people try to play an expert in these areas, they run up against the sharp tip of reality more often.

Take home message: If you're not a professional--meaning you're not paid for your research and don't have a bunch of fancy letters after your name--acknowledge this fact and don't pretend you are. Consensus is your best bet.

Excellent post, excellent advice, and I am sure very few people are going to agree with you sentiments. Your post has the unfortunate quality of offering a reasonable and rational coarse of action.

This is the internet age, however, and people generally tend to believe that they can gather enough information in their spare time and posses a sufficient degree of understanding that their conclusions are more valid than those of the general scientific community.

 

[Sinister]

Way to not pay any attention to what's actually happening.

 

[turbozed]

Given the fact that replacing saturated fats for carbs will have zero of a positive effect, it seems fairly certain that "saturated fats cause CVD" cannot be anywhere near an accurate description here. We obviously don't have a complete understanding of it, but it seems quite possible that there is a dynamic interplay of many different factors, with saturated fats, polyunsaturated fats, dietary cholesterol, and maybe down to specific fatty acids, somehow interrelating at once.

As with any complex system where multiple variables (both known and unknown) interact, anything so simplistic as the original formulation of the lipid hypothesis just seems intuitively wrong.

Of course, the connection was an important first inquiry. It's unfortunate that government stepped in and diet guidelines were set so hastily and that the idea has persisted so stubbornly. Less time and resources would've been spent trying to defend it which could've been spent trying to refine it and flesh it out more (as it seems that we are doing now many decades later).

Thanks for providing all those studies and rescuing this thread. This conversation was falling into the vague realm of scientific methodology versus sociological phenomena and less about the thread topic.

 

[turbozed]

Excellent post, excellent advice, and I am sure very few people are going to agree with you sentiments. Your post has the unfortunate quality of offering a reasonable and rational coarse of action.

This is the internet age, however, and people generally tend to believe that they can gather enough information in their spare time and posses a sufficient degree of understanding that their conclusions are more valid than those of the general scientific community.

This must be some weird bizarro world you guys live in where you derive a sense of intellectual superiority by consciously making the choice to be ignorant and letting others do the thinking for you. Congrats on turning a negative into a positive I suppose.

 

[Sinister]

Of course, the connection was an important first inquiry. It's unfortunate that government stepped in and diet guidelines were set so hastily and that the idea has persisted so stubbornly. Less time and resources would've been spent trying to defend it which could've been spent trying to refine it and flesh it out more (as it seems that we are doing now many decades later).

Nice McGovern Committee reference.

 

[miaou]

As with any complex system where multiple variables (both known and unknown) interact, anything so simplistic as the original formulation of the lipid hypothesis just seems intuitively wrong.

Of course, the connection was an important first inquiry. It's unfortunate that government stepped in and diet guidelines were set so hastily and that the idea has persisted so stubbornly. Less time and resources would've been spent trying to defend it which could've been spent trying to refine it and flesh it out more (as it seems that we are doing now many decades later).

Thanks for providing all those studies and rescuing this thread. This conversation was falling into the vague realm of scientific methodology versus sociological phenomena and less about the thread topic.

I agree.

Let me sum a few of my thoughts here:

a) saturated fat/dietary cholesterol does not appear to be the root of all evil
b) replacing saturated fats with carbs appears to be an ineffective strategy for CV health purposes
c) replacing all fats in general with carbs (a la low-fat/high-carb) is definitely ineffective and possibly detrimental for CV health purposes
d) saturated fat/dietary cholesterol not being the root of all evil doesn't mean they can have no detrimental effects on CV health depending on the rest of the circumstances. It seems that, at this point, they may not be warranted a completely blank check.


As for the trolls, don't feed them.

...unless it's refined carbs, you can feed them those.

 

[Erik Hart]

This must be some weird bizarro world you guys live in where you derive a sense of intellectual superiority by consciously making the choice to be ignorant and letting others do the thinking for you. Congrats on turning a negative into a positive I suppose.

Listening to those who know much more than you is not being ignorant. The surest sign of ignorance is those who act like they know everything.

 

[XTrainer]

Pardon me if someone already said this, I'm just skimming through, don't have a lot of time here.

Anyway, just a couple things I wanted to throw out there...

Some types of saturated fat (such as palmitic acid) can increase LDL. Absolutely, and I don't think anyone would argue with this. But this is a far cry from saturated fat=high LDL=CVD=don't eat saturated fat.

When we start to talk about the dangerous subtypes of LDL, and the conditions that create them, carbohydrates get implicated as much or more than saturated fat. I'm not just talking in terms of of systemic inflammation or other factors that apart from lipid profiles (not to dismiss the importance of those other factors) that contribute to CVD risk. Excess carbohydrate consumption causes the liver to produce palmitic acid, which is a precursor to VLDL formation. In other words, high carbohydrate intake increases the LDL sub-type we should probably be most concerned about.

Now, I'm NOT vilifying carbs here. I eat them, and I think they have their place in an athlete's diet (though I've never tried keto, so who am I to talk?)

I'm just pointing out a few ways in which the "saturated fat is bad" argument is overly simplistic, even if we narrow our focus to lipid profiles alone...and lipid profiles, especially in the general sense (not looking at LDL sub-types), are only part of what we need to be considering when it comes to CVD risk.

 

[turbozed]

Listening to those who know much more than you is not being ignorant. The surest sign of ignorance is those who act like they know everything.

This is rhetoric.

On any subject worth talking about, you can find experts that agree with a theory and those that don't. Presuming to know which expert is correct on any subject requires making a judgment which you're incapable of making. Yet you side anyway with establishment. This is not a logical or scientific approach, it's a sniveling social approach of wanting to be in the majority (on a subject that you don't even have knowledge of). How stupid is that?

This is what I've seen from you in this thread:
1) You didn't know anything about the origins or history of the "lipid theory," and thus you failed to clarify to others exactly what you were disagreeing about (actually this was mostly in the egg yolk thread).

2) You don't bother to state what the consensus view is regarding the state of the science, yet you defend it some vague notion of it anyway

3) Your long-winded replies all boil down to "it's good to listen to experts" and "nobody can know everything" Well no shit. Nobody disagrees with that. Anything more to add about the topic?

4) You go an extra illogical step further to say that we're ignorant for even attempting to increase our knowledge on the subject, implying that scientific inquiry is something only available to the chosen few with titles after their names.

5) You revel in your own imposed ignorance and whacked-out sociological (and anti-science) view of how science should be conducted, somehow turning your abstention from trying to learn into an intellectual virtue.

 

[turbozed]

I agree.

Let me sum a few of my thoughts here:

a) saturated fat/dietary cholesterol does not appear to be the root of all evil
b) replacing saturated fats with carbs appears to be an ineffective strategy for CV health purposes
c) replacing all fats in general with carbs (a la low-fat/high-carb) is definitely ineffective and possibly detrimental for CV health purposes
d) saturated fat/dietary cholesterol not being the root of all evil doesn't mean they can have no detrimental effects on CV health depending on the rest of the circumstances. It seems that, at this point, they may not be warranted a completely blank check.

These are the rough conclusions that I came to after becoming interested in nutrition too. The discussion here really clarified my thinking though.

The problem with the picture you paint is the nuance involved. Most people want simple recommendations and the most complex they'll accept is "don't eat that, eat this." I think there's even a book with that title.