Jump to content

Re-evaluating Saturated Fat

Recommended Posts

There's been a lot of activity and controversy on the roles of various FA when it comes to health, both in all-cause morbidity/mortality and CVD specifically. A recent consensus seems to have formed that SFA by itself is not deleterious to CV health, although it may be that some question as to whether the food that most often contains SFA might be deleterious (as in: the meat is bad, but not because of SFA). This controversy has been developing for quite some time, but now it seems they have gone back to old studies that claimed the SFA=Bad CV health, and actually completely upended the conclusions in those studies positing that the studies conclusions did not reflect their own data. Worse, the recommended n6 oils, while indeed lowering serum cholesterol, in fact nonetheless resulted in a sharp elevation of CVD. That is a huge issue. We are looking at the ironclad connection of more LDL cholesterol = more CVD being upended insofar as we have evidence of the lowering of cholesterol resulting in more CVD - SFA elevate cholesterol, but don't result in more CVD, n6 lower cholesterol and elevate CVD. Then there was a paper recently showing how supposedly n6 is vastly superior to monounsaturated oil (olive) from a CVD point of view, and I declare that we can officially start from scratch when it comes to the whole issue of FA. I am shocked that there is not more chatter on the boards about this - after all, one major macronutrient - Fat - is being completely upended and there is no clarity or consensus anymore (other than trans FA being bad, I suppose). Personally, my diet naturally happens to be SFA avoidant, and as I have always distrusted n6, I mostly consume monounsaturated FA from EVOO and almonds, with the next fraction being n3 (from daily tablespoon of flaxmeal), some long chain omega 3 from salmon/sardines twice a week and whatever n6 accumulates from almonds and various vegetable sources; finally trace amounts of SFA from almonds, salmon, F&V etc. I can't say that I feel much confidence in this profile of FA consumption based on science, given how unsettled everything is. Anyhow the recent developments (maybe Al P. has access to this?):



"New research of old data suggests that using vegetable oils high in linoleic acid failed to reduce heart disease and overall mortality even though the intervention reduced cholesterol levels. And researchers found that consuming vegetable oils might actually be worse for heart health than eating butter."

Link to comment
Share on other sites



Eat nuts and avocado rather than extracted oils... See this thread for a discussion of both the mortality reduction evidence for nuts, and a discussion of PUFA vs. SFA.


Regarding this reevaluation [1] of a PUFA vs. SFA study from the early 70s. It appears to me from the full text they used margarine for the PUFA, which likely contained trans-fats back then. If this is the case, it's not surprising that a diet higher in PUFA might be worse than one high in SFA.





[1] BMJ 2016; 353 doi: http://dx.doi.org/10.1136/bmj.i1246(Published 12 April 2016)


Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968-73)

Christopher E Ramsden, medical investigator1 2, Daisy Zamora, epidemiologist3, Sharon Majchrzak-Hong, research chemist1, Keturah R Faurot, epidemiologist2, Steven K Broste, retired statistician4, Robert P Frantz, professor of medicine5, John M Davis, professor of psychiatry3 6, Amit Ringel, guest researcher1, Chirayath M Suchindran, senior biostatistician7, Joseph R Hibbeln, senior clinical investigator1
Objective To examine the traditional diet-heart hypothesis through recovery and analysis of previously unpublished data from the Minnesota Coronary Experiment (MCE) and to put findings in the context of existing diet-heart randomized controlled trials through a systematic review and meta-analysis.
Design The MCE (1968-73) is a double blind randomized controlled trial designed to test whether replacement of saturated fat with vegetable oil rich in linoleic acid reduces coronary heart disease and death by lowering serum cholesterol. Recovered MCE unpublished documents and raw data were analyzed according to hypotheses prespecified by original investigators. Further, a systematic review and meta-analyses of randomized controlled trials that lowered serum cholesterol by providing vegetable oil rich in linoleic acid in place of saturated fat without confounding by concomitant interventions was conducted.
Setting One nursing home and six state mental hospitals in Minnesota, United States.
Participants Unpublished documents with completed analyses for the randomized cohort of 9423 women and men aged 20-97; longitudinal data on serum cholesterol for the 2355 participants exposed to the study diets for a year or more; 149 completed autopsy files.
Interventions Serum cholesterol lowering diet that replaced saturated fat with linoleic acid (from corn oil and corn oil polyunsaturated margarine). Control diet was high in saturated fat from animal fats, common margarines, and shortenings.
Main outcome measures Death from all causes; association between changes in serum cholesterol and death; and coronary atherosclerosis and myocardial infarcts detected at autopsy.
Results The intervention group had significant reduction in serum cholesterol compared with controls (mean change from baseline −13.8% v −1.0%; P<0.001). Kaplan Meier graphs showed no mortality benefit for the intervention group in the full randomized cohort or for any prespecified subgroup. There was a 22% higher risk of death for each 30 mg/dL (0.78 mmol/L) reduction in serum cholesterol in covariate adjusted Cox regression models (hazard ratio 1.22, 95% confidence interval 1.14 to 1.32; P<0.001). There was no evidence of benefit in the intervention group for coronary atherosclerosis or myocardial infarcts. Systematic review identified five randomized controlled trials for inclusion (n=10 808). In meta-analyses, these cholesterol lowering interventions showed no evidence of benefit on mortality from coronary heart disease (1.13, 0.83 to 1.54) or all cause mortality (1.07, 0.90 to 1.27).
Conclusions Available evidence from randomized controlled trials shows that replacement of saturated fat in the diet with linoleic acid effectively lowers serum cholesterol but does not support the hypothesis that this translates to a lower risk of death from coronary heart disease or all causes. Findings from the Minnesota Coronary Experiment add to growing evidence that incomplete publication has contributed to overestimation of the benefits of replacing saturated fat with vegetable oils rich in linoleic acid.
Link to comment
Share on other sites

Here's a wonderful piece which isn't directly about SFA, and is about sugar and disease in The Guardian. The article outlines some of the reasons (eg, Ancel Keyes' ego and the industry's genius-collections) that lead to the (perhaps unfair) demonization of SFA whilst simultaneously ignoring the harmful effects of sugar.


In 1972, a British scientist sounded the alarm that sugar – and not fat – was the greatest danger to our health. But his findings were ridiculed and his reputation ruined. How did the world’s top nutrition scientists get it so wrong for so long?



Link to comment
Share on other sites

Thanks, Dean - indeed, the only extracted oil I consume is EVOO - otherwise I take in 1.3 oz of raw almonds daily in addition to the 1tbsp of flaxmeal, and water packed wild caught salmon (and sardines). Re: your point about margarines - I'm not sure that TFA would have accounted for this for a very strong reason: the n6 group lowered cholesterol (according to the paper "significantly") - if there is one thing we know about TFA is that they drastically worsen serum lipid profiles with much elevated LDL. So it can't be that, it seems(?).

Link to comment
Share on other sites

Look at statins for the answer. They lower ldl and they lower inflammation. It has been known for decades that statins lower risk proportional to the DOSE and that the total cholesterol levels don't factor into it. Therefore, as the now famous Jupitor study showed, the main impact statins have is on the artery lining and reducing inflammation which in turn reduces cholesterol damaging the arteries.


Hence higher cholesterol levels vs inflamed arteries. The latter is the primary problem. And that appears to be what was happening in the old study. But as the NYtimes article pointed out old paradigms hang on because once established They sort of become coventional wisdom. That can be a good, but it also has a downside to it. Resistance which sometimes is not entirely rational.

Link to comment
Share on other sites



Re: using hydrogenated fats in the study,





"The MCE experimental serum cholesterol lowering diet was derived from the “BC” diet of the institutional arm of the National Diet-Heart Feasibility Study at Faribault Hospital.2 6 15 16 20 22 Liquid corn oil was used in place of the usual hospital cooking fats (including hydrogenated oils) and was also added to numerous food items (for example, salad dressings, filled beef (lean ground beef with added oil), filled milk, and filled cheeses). Soft corn oil polyunsaturated margarine was used in place of butter."




Dietary fats: a new look at old data challenges established wisdom.

Veerman JL.

BMJ. 2016 Apr 12;353:i1512. doi: 10.1136/bmj.i1512. No abstract available.

PMID: 27072816


Replacing saturated fat with polyunsaturated fat might not prolong life


It is widely accepted that diets rich in polyunsaturated fats protect against heart disease. Recently, the Global Burden of Disease team reported that each year insufficient intake of omega-6 polyunsaturated fats, the most common subgroup of polyunsaturated fats, results in over 700 000 deaths from coronary heart disease.1 Or does it? A linked study by Ramsden and colleagues (doi:10.1136/bmj.i1246) adds to the doubts around the health benefits of replacing saturated fat with polyunsaturated fats.2


This new study re-examines recovered data from a double blind randomised controlled trial that took place 45 years ago. The Minnesota Coronary Experiment (MCE) followed 9423 participants from state mental hospitals and a nursing home for 4.5 years. The trial tested whether replacement of saturated fat with vegetable oil rich in linoleic acid (an omega-6 polyunsaturated fat) reduces the risk of coronary heart disease and death through a reduction in serum cholesterol concentration.


As expected, the diet enriched with linoleic acid lowered serum cholesterol concentration. But it did not reduce mortality: in fact participants in the intervention group had a higher mortality than controls. The pooled results of the MCE and four similar trials failed to find any reduction in mortality from coronary heart disease.3 4 5 6


These unexpected results proved difficult to stomach for researchers at the time. The trial ended in 1973, but it took until 1989 for the results to be published.7 The authors reported no differences between the treatment and control groups for cardiovascular events, cardiovascular deaths, or total mortality, but immediately added that “a favorable trend for all these end-points occurred in some younger age groups.” In contrast, Ramsden and colleagues now suggest the possibility of increased risk of death in older adults among the participants given more linoleic acid.2 The findings of the two teams of authors do not differ fundamentally, but their interpretation does.


In the past decade, old certainties regarding dietary fats have been questioned, and some have been abandoned. Last year, US dietary guidelines removed dietary cholesterol and total fat as risk factors worth worrying about.8 With these new findings,2 9 the recommendation to consume less than 10% of calories per day from saturated fats will be under increased scrutiny.10


How did researchers come to believe so firmly in the “diet-heart hypothesis,” which holds that eating foods high in cholesterol and saturated fat leads to heart disease? In the first half of the 20th century, experiments with rabbits and international comparative studies led to the belief that diets low in fat were good for heart health. In the 1950s and 1960s it became clear that not all fats were equal. Experiments showed that saturated fat increased and polyunsaturated fat decreased plasma cholesterol concentrations. Higher concentrations were associated with a greater risk of heart disease. It followed that polyunsaturated fats were good and saturated fat was bad for the heart. Effects on serum concentrations of low density lipoprotein and high density lipoprotein cholesterol were paramount in decisions on dietary guidelines.8 11 But if blood cholesterol values are not a reliable indicator of risk of cardiovascular disease, then a careful review of the evidence that underpins dietary recommendations is warranted. Ideally, recommendations should be based on clinical outcomes, not surrogates such as cholesterol concentration.11


Unfortunately, clinical outcomes do not point uniformly in the same direction in all studies. Ramsden and colleagues’ analysis reports no clinical benefits of replacing saturated fat with linoleic acid. This is supported by recent observational findings that saturated fat is not associated with mortality.9


In a systematic review and meta-analysis of prospective cohort studies, however, dietary intake of linoleic acid was inversely associated with risk of coronary heart disease in a dose-response manner.12 Furthermore, a Cochrane systematic review and meta-analysis of randomised controlled trials found a small but potentially important reduction in cardiovascular risk associated with reduced consumption of saturated fat.13 That review, however, included studies that replaced saturated fat with carbohydrate, monounsaturated fat and/or protein, not specifically linoleic acid.


The randomised controlled trial design is stronger than the longitudinal observational design, but such trials on this topic were rare, relatively small, and conducted among “captive audiences” such as residents of a nursing home and mental hospitals in the MCE or outpatients at a coronary care clinic in the Sydney Diet Heart Study.3 Generalisability beyond these settings is arguable.


The greatest risks with cohort studies is confounding, and here it is tempting to speculate that the strong belief that polyunsaturated fats are good for health might have led to a self fulfilling prophesy, whereby more health conscious participants consume more polyunsaturated fats and residual confounding14 by other healthy lifestyle choices produces better health and longer survival.


It is also possible that different omega-6 fatty acids have different effects. Further research is likely to specify more precisely the types of fat under study and what they replace in the diet and to focus on clinical outcomes.


The benefits of choosing polyunsaturated fat over saturated fat seem a little less certain than we thought. While we wait for further clarification, we should continue to eat (and to advise others to eat) more fish, fruits, vegetables, and whole grains. We should avoid salt, sugar, industrial trans fats, and avoid over eating.

Link to comment
Share on other sites

Yes Al,


I saw that same line in the full text. It's unclear to me whether the "Soft corn oil polyunsaturated margarine" from the late 60's / early 70's which they used in place of butter in the high-PUFA group would have contained partially hydrogenated trans-fats. I figured it probably would, but I expressed it as "likely" rather than definitive. Are you suggesting that it did or it didn't?



Link to comment
Share on other sites


This topic is now archived and is closed to further replies.

  • Create New...