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An article at MayoClinic by an R.D. says:

Margarine usually tops butter when it comes to heart health. [...] So skip the stick and opt for soft or liquid margarine instead.

The American Heart Association says:

Recent studies on the potential cholesterol-raising effects of TFA have raised public concern about the use of margarine and whether other options, including butter, might be a better choice. Some stick margarines contribute more TFA than unhydrogenated oils or other fats.

Because butter is rich in both saturated fat and cholesterol, it's potentially a highly atherogenic food (a food that causes the arteries to be blocked). Most margarine is made from vegetable fat and provides no dietary cholesterol. The more liquid the margarine, i.e., tub or liquid forms, the less hydrogenated it is and the less TFA it contains.

And:

The best choice for your health is a liquid margarine.

Other research (summarized in this editorial from the British Medical Journal) says:

Calder says the findings argue against the "saturated fat bad, omega 6 PUFA good" dogma and suggest that the American Heart Association guidelines on omega-6 PUFAs may be misguided. They also "underscore the need to properly align dietary advice and recommendations with the scientific evidence base."

That quote refers to this study:

[C]linical benefits of the most abundant polyunsaturated fatty acid, omega 6 linoleic acid, have not been established. In this cohort, substituting dietary linoleic acid in place of saturated fats increased the rates of death from all causes, coronary heart disease, and cardiovascular disease.

I think these quotes establish two mutually exclusive claims:

  • Margarine (especially soft or liquid margarine that is low in TFA) is better for heart health than butter.
  • Death rate due to all causes, coronary heart disease, and cardiovascular disease increases when substituting liquid margarines in place of butter.

Which is true?

  • Both could be true if very few people use liquid margarine and the solid kinds are bad enough. I don't see how those are mutually exclusive. – William Grobman Sep 1 '13 at 20:13
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    @WilliamGrobman I paraphrased the second claim incorrectly. The substitute was of liquid margarines for butter. Margarines based on polyunsaturated fatty acid, omega 6 linoleic acid are liquid margarines. – user5582 Sep 1 '13 at 20:18
  • Up voted: Much clearer now and an interesting question. – William Grobman Sep 1 '13 at 22:39
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    @Sancho: there are always a few strange people – Henry Sep 4 '13 at 20:10
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    @Henry If you're serious, and think that a difference in taste renders useless the study that shows an increase in mortality, please provide evidence in an answer. – user5582 Sep 5 '13 at 18:35
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+50

In one 1997 review of 20 studies they compared the effect of margarine and butter on blood cholesterol levels.

Replacing butter with margarine with no trans fats reduced total and LDL cholesterol levels. Replacing butter with hard margarine high in trans fats also reduced total and LDL cholesterol levels, but for a lesser extent than non-trans fat margarine.

According to the study, theoretically, replacing butter with non-trans fat margarine could reduce the risk for coronary heart disease for 10%, but replacing with trans-fat margarine would have no effect.

The effect of saturated fats on the blood cholesterol levels may vary greatly from person to person.

Some researchers think that the study about a harmful effect of margarine (the second claim in the question) was not performed properly:

Australia’s National Heart Foundation has claimed a recent study published in the British Medical Journal is “misguided.”

Dr Robert Grenfell, National Cardiovascular Health Director at the Heart Foundation, said that the new research from the 1966-1973 study is “misguided” because it is not based on a healthy group of people...but a study in a small group of unhealthy middle aged men.

When this study began, Miracle margarine (used in the study) contained approximately 15 per cent trans fatty acids, ...the study was not objective because margarine no longer contains the trans fatty acids it did at the time of the trials.

In the answer to the article about the study published in February 2013, professor Jean Gutierrez also mentioned this issue with "miracle margarine."

If it is true that "miracle margarine" used in the study contained 15% trans fats, the conclusion that margarine is more harmful than butter is probably irrelevant, because soft (tub) margarines today may contains as low as 0.3% trans fats (0.3 g/100 g margarine).

My conclusion:

The second claim (liquid margarine more harmful than butter) in the question may be false because a margarine high in trans fats was used. This does not automatically mean that the first claim (butter more harmful than liquid margarine) is true, because neither the harmful effects of saturated fats (in butter) neither beneficial effects of polyunsaturated fats (in margarine) have been firmly proven until now (most, but not all, studies show substitution of polyunsaturated fats in place of saturated fats can help to prevent coronary heart disease, though). Additionally, there seems to be no other studies that would compare the harmful or beneficial effects of butter and margarine on health.

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    So they didn't actually witness a 10% reduction in coronary heart disease risk? – user5582 Sep 6 '13 at 14:37
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    The review you point to is 15 years old. And it focuses on cholesterol. It does not focus at actual mortality or other health effects. – Chad Sep 6 '13 at 21:21
  • Yes, the study checked for blood lipids only; the risk of heart disease is only an estimation. I've searched through Google scholar, pubmed and Google and did not find one single study about the effect of both butter and margarine on the (measured) heart disease or mortality. – Jan Sep 10 '13 at 13:16
  • ...except of the study from bmj quoted in a question above. – Jan Sep 10 '13 at 13:35
  • I edited my answer: I questioned the relevance of the study about the harmful effects of margarine. – Jan Sep 10 '13 at 15:10
-3

The Harvard School of Public Health recommends: "Switch from butter to soft tub margarine. Choose a product that has zero grams of trans fat, and scan the ingredient list to make sure it does not contain partially hydrogenated oils. Even better, use a liquid plant oil whenever possible; refrigerated extra virgin olive oil makes a great spread for toast." http://www.hsph.harvard.edu/nutritionsource/fats-and-cholesterol/

Here's the full story. http://www.hsph.harvard.edu/nutritionsource/fats-full-story/

Basically, trans fats, or partially hydrogenated oils, are the worst fats because they raise bad cholesterol (LDL) and lower good cholesterol (HDL). That's pretty much what stick margarine is. "The Nurses’ Health Study found that women who ate 4 teaspoons of stick margarine a day had a 50 percent greater risk of heart disease than women who ate margarine only rarely."

Monounsaturated fats and polyunsaturated omega-3 fatty acids are the best fats, because they raise HDL and lower LDL. A large recent study found that "Among persons at high cardiovascular risk, a Mediterranean diet supplemented with extra-virgin olive oil or nuts reduced the incidence of major cardiovascular events." http://www.nejm.org/doi/full/10.1056/NEJMoa1200303

In between, you have saturated fats like butter, which raise both LDL and HDL (but not as much), and polyunsaturated omega-6 fatty acids. The latter is basically what's in corn oil, which is used to fry fast food. When it's heated, it creates trans fats, which are especially bad.

Margarine is an emulsion of oil and water, and depending on the fat content and the amount of partially hydrogenated oil, or trans fat, it can be better or worse than butter. That's why the Mayo Clinic, the Harvard School of Public Health, and also the Cleveland Clinic recommend the softer trans fat-free margarine over butter.

  • To paraphrase your answer, "HSPH recommends soft tub margarine with zero trans fats", "4 teaspoons of stick margarine per day is worse than eating margarine rarely", "extra virgin olive oil or nuts reduces the incidence of cardiovascular events", and then some background about what margarine is. – user5582 Sep 7 '13 at 0:09
  • If I've missed something, please correct me, but it seems you don't answer the question. The quotes in my question claim: "The best choice for your health is a liquid margarine", and "When transfat-free liquid margarine is used in place of butter, all cause mortality increases". It is that contradiction that I would like sorted out. – user5582 Sep 7 '13 at 0:11
  • The best choice for your health is extra-virgin olive oil, but if you have to choose between margarine and butter, the experts recommend the softest margarine. Now, you have one study that found a contradiction. I'd let the experts sort it out. The study notes that "the trans fatty acid content of participants’ diets was not recorded," but speculates that "the intervention group would be expected to substantially reduce consumption of trans fatty acids compared with the control group." So reducing trans fats also increased mortality? That's very hard to believe. – Max Sep 7 '13 at 5:44
  • @Chad, did you stop reading at the first half of the first sentence? The experts say soft margarine is better, and the study acknowledges this. The study has some contradictions that are very hard to swallow, so I'd let the experts sort it out, and see if their advice changes. – Max Sep 8 '13 at 0:42
  • @Max I apologize for criticizing your answer. – Chad Sep 8 '13 at 4:05

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