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Unpublished Data Review: The Minnesota Coronary Experiment (1968-73)

Discussion in 'Diabetes Discussions' started by Biggles2, Dec 30, 2017.

  1. Biggles2

    Biggles2 · Well-Known Member

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    This journal article below, published in BMJ in 2016, is well worth a read. The authors had previously recovered and reviewed unpublished data from the Sydney Diet Heart Study. In this paper, they review recovered unpublished data from the Minnesota Coronary Experiment. A snippet from their article is included below:
    Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968-73)
    “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.”​
    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4836695/?report=printable

    And a link to newspaper review of the above BMJ article in the Washington Post:
    https://www.washingtonpost.com/news...never-fully-published/?utm_term=.af0e53e71957
     
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  2. Guzzler

    Guzzler Type 2 · Master

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    I have only scanned the article in the first link but it is very interesting indeed. Will read in full tomorrow as one name in particular caught my attention, that of Ancel Keys, who, if I remember correctly, said at one point (not here) that cholesterol was not shown as a contributory factor in diet/heart mortality.
     
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  3. Kentoldlady1

    Kentoldlady1 Type 2 · Well-Known Member

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    He said that? Don't you just love the way that inconvenient truth is left out of studies. We are dying because of this practice.

    I am low carb but would drop it in a heart beat if conflicting but truthful evidence shows it to be detrimental. But I have no financial interest in any food. The temptation to not tell the truth must be overwhelming if you reputation and wealth depend on supporting one world view.
     
  4. bulkbiker

    bulkbiker Type 2 · Oracle

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    I think you may be thinking of when Keys said that dietary cholesterol does not raise cholesterol in the body. I don't think he ever said what you think he said... if he did then he undermined the whole dietary/heart hypothesis which he based the rest of his career on.
     
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  5. Guzzler

    Guzzler Type 2 · Master

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    That was it, BB. I know he was unconvinced. Wish I had a better memory.
     
  6. Tannith

    Tannith · Well-Known Member

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    The article says not that saturated fat is good for you, but that trying to lower cholesterol by substituting a worse fat, omega 6 is not a good idea because omega 6 causes the bad cholesterol to oxidise, making the bad cholesterol worse for you than it originally would have been.
     
  7. Tannith

    Tannith · Well-Known Member

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  8. Guzzler

    Guzzler Type 2 · Master

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    Polyunsaturates are highly oxidative and have high levels of omega 6s.
     
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  9. LittleGreyCat

    LittleGreyCat Type 2 · Well-Known Member

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    I'm working through the main link, and commenting as I go. Already this is getting very long. Beware ramble.

    I've looked at Linoleic acid and since Linoleic Acid is seen to be a good thing and an essential fatty acid I am not sure about the description of Omega 6 you give implying that it is bad. Happy that too much corn oil is potentially bad.

    LA is present in nuts and seeds (and their oils) but is also present in butter and beef. I am assuming that one aim of the trial is to source the LA from vegetable sources instead of from beef and dairy.

    All this is a little strange, anyway, because we suspect that LCHF can lower cholesterol and that most cholesterol is manufactured by the body from carbohydrates.

    I think the main point of the study is that using corn oil (which happens to be a source of Omega 6) as a major part of the diet may reduce the level of cholesterol in your blood but it doesn't improve your cardiovascular health. In fact, rather the opposite. This is possibly specific to corn oil, not Omega 6 in general.

    The control diet was not only heavy in animal fat, but in margarines and shortenings. The latter two items are not necessarily part of an LCHF diet. Shortenings especially can have all sorts of bad stuff, as the term covers any fat that is solid at room temperature, including all sorts of vegetable oils that have been chemically treated. That is, hydrogenated oils. Amazing what you learn.

    https://en.wikipedia.org/wiki/Shortening

    "Soon after arriving, Kayser made a business deal with Procter & Gamble, and presented the company with two processes to hydrogenate cottonseed oil, with the intent of creating a raw material for soap.[2] Since the product looked like lard, Procter & Gamble instead began selling it as a vegetable fat for cooking purposes in June 1911, calling it "Crisco", a modification of the phrase "crystallized cottonseed oil"."

    So it appears that modern shortening was originally intended to be soap.

    Anyway, it looks as though replacing some rather dodgy looking fat sources with Linoleic Acid didn't have the expected improvements in life expectancy. Noting that corn oil was used.

    Rather more scarily:
    "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). "

    Which seems to say that lowering the cholesterol level (using their chosen strategy) actually reduced life expectancy. This does seem to tie in with some more modern findings.

    Further:
    "Our recovery and 2013 publication of previously unpublished data from the Sydney Diet Heart Study (SDHS, 1966-73) belatedly showed that replacement of saturated fat with vegetable oil rich in linoleic acid significantly increased the risks of death from coronary heart disease and all causes, despite lowering serum cholesterol".

    Ouch!

    If you look up the benefits of corn oil (which seems to come from the people selling it):
    https://www.prevention.com/food/food-remedies/corn-oil-lowers-cholesterol-more-olive-oil
    "
    With countless studies touting its benefits, it's no surprise that olive oil gets all the glory. But now a new study suggests that's not entirely fair: Turns out that corn oil might actually be better at lowering cholesterol than olive oil.

    Researchers studied the effects of both oils on 54 healthy men and women. For 21 days, participants were either given four daily tablespoons of corn oil or four tablespoons of olive oil. The results? Corn oil was shown to reduce LDL cholesterol (the bad kind) by almost 11%, while olive oil only lowered it 3.5%. Study participants experienced an 8.2% decrease in total cholesterol with corn oil, compared to just a 1.8% decrease with olive oil.
    "

    Now further down the article, and:
    "The higher risk of death associated with decreased serum cholesterol seems to be driven by the subgroup aged ≥65. Among participants who were older than 65 at baseline, a 30 mg/dL decrease in serum cholesterol was associated with 35% higher risk of death (hazard ratio 1.35, 95% confidence interval 1.18 to 1.54), whereas among people aged under 65 at baseline there was no relation between the change in serum cholesterol and death (1.01, 0.88 to 1.16)."

    Oof! And likewise woot!:woot:

    If this is true beyond the context of this study then lowering cholesterol seems to make little or no difference unless you are over 65 when it makes a very large difference.

    I finally reached the end, where there was a lot of gentle stepping to avoid upsetting people, but there does seem to be no improvement in cardiovascular health by consuming large amounts of corn oil to force cholesterol levels down.

    There also seems to be no evidence that use of significant quantities of Linoleic Acid in general is beneficial.

    One thing is that Ancel Keys was very good at predicting the effect of Linoleic Acid on cholesterol levels. Not, perhaps, as good at predicting the benefits.

    All in all it is an interesting excursion into the results of not publishing all the information of unique studies and assuming benefits of certain dietary approaches which are not proven.

    Largely irrelevant to me from a dietary point of view as I have no intention of taking large amounts of corn oil in my diet. Corn Oil 59% LA, Olive Oil 10% LA so I'll stick with the Extra Virgin, thanks.
     
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  10. Guzzler

    Guzzler Type 2 · Master

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    Phew! So glad I browned the beef in lard for New Years lunch!
     
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  11. LittleGreyCat

    LittleGreyCat Type 2 · Well-Known Member

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    Yeah.

    Just realised what has been nagging me about corn oil.
    One of the abominations in food in the USA is High Fructose Corn Syrup.

    Also just noted that Conjugated Linoleic Acid (good stuff) is at a higher concentration in grass fed beef than in grain fed.
     
  12. Crystalwand

    Crystalwand Type 1 · Well-Known Member

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    Thanks for all that so pleased, you read most of it and explained so that I understand, thanks again
     
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  13. Guzzler

    Guzzler Type 2 · Master

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    Have you heard Lustig's opinion on HFCS? He is less than enamoured. I recently got rid of all seed oils and made a reaquaintance with cooking in lard and suet, the difference in taste, smell and cleaning up is surprising.
     
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  14. LittleGreyCat

    LittleGreyCat Type 2 · Well-Known Member

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    Good point.

    I still cook with Olive Oil but that is probably a hangover from the time when it was considered to be healthier than lard. I do sometimes cook in butter, though.
     
  15. Guzzler

    Guzzler Type 2 · Master

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    Scrambled eggs cooked in butter with squares of dry cured bacon... I'm hungry now!

    I no longer cook with olive oil but keep the cold pressed stuff for salad dressing as long as I mix it with a good balsamic, not a great lover of the taste of OO by itself. I have half of a bottle of cold pressed rapeseed oil that I can't bear to throw away and have seen little info on. It was an expense I could ill afford.
     
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  16. LittleGreyCat

    LittleGreyCat Type 2 · Well-Known Member

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    Stop it!
    You are making me hungry now and I need to stop eating as much after the holidays.
     
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  17. ickihun

    ickihun Type 2 · Master

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  18. bulkbiker

    bulkbiker Type 2 · Oracle

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    and better for you too..
     
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  19. Tannith

    Tannith · Well-Known Member

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    I wouldn't bother to choose between two bad fats - polyunsaturated which is mostly highly oxidative or saturated which increases cholesterol. Why not eat only (or mainly) monounsaturated?
     
  20. Guzzler

    Guzzler Type 2 · Master

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    If we are talking dietary cholesterol then that accounts for just 15% of the bodys total, the other 85% is made by the body itself. Cholesterol is vital to life. Inflammatory oils on the other hand are not beneficial and coupled with a high carb diet are most injurious.

    If one is troubled by the levels of cholesterol then one may like to ask this question, how were the guidelines for cholesterol levels in UK set at <5 for the general population and <4 for those with Diabetes?
     
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