[jacques_chester]

The most recent research still upholds that saturated fats, over and above their contribution to obesity, are a worse risk than polyunsaturated fats.

A meta-analysis of 8 randomised controlled trials with 13 thousand subjects showed that a 5% total energy substitution from saturated to polyunsaturated fats reduced risk of coronary heart disease by 10%.[1]

The point about substituting hydrogenated fats is good; but it's hardly an argument for switching back to saturated fat. It's an argument in favour of not eating unhealthy food in the first place.

But that's not how you sell books, is it?

[1] http://www.ncbi.nlm.nih.gov/pubmed/20351774/

[kareemm]

A meta analysis of 80 studies involving more than a half million people found no evidence of dangers from saturated fat, or benefits from other kinds of polyunsaturated fats (excluding trans fats, which were shown to be terrible)[1].

[1] http://well.blogs.nytimes.com/2014/03/17/study-questions-fat...

[jacques_chester]

That meta-analysis was not based on randomised controlled trials. It was largely based on observational and self-reporting studies, which are notoriously inaccurate.

Moreover, it was subject to numerous corrections due to sloppy work by the authors:

http://news.sciencemag.org/health/2014/03/scientists-fix-err...

[kareemm]

Thanks, hadn't seen this link. I'd like to see the specifics of what the errors are. Agree that observational and self-reporting are inaccurate, though unfortunately they're some of the best data we've got wrt nutrition.

Also, looks like there were some random trials in the meta analysis. From your link:

"These included trials in which participants were randomly assigned to different diets, as well as observational studies in which participants' intake of fatty acids was determined by asking them about their diet or by measuring the fatty acids circulating in the bloodstream."

[jacques_chester]

> Also, looks like there were some random trials in the meta analysis.

There were, but the statistical effect is drowned by the much larger pool of observational/self-reporting studies.

Observational studies are a useful place to find potential leads, but they are nowhere near as reliable as RCTs for many reasons. Observational studies can tell you that the fall in piracy is causing global warming. Short of a randomised controlled trial involving the introduction of pirates or non-pirates at random to 13,000 Earth-like planets, it's hard to know how strongly that relationship holds.

[kareemm]

I agree with you about observational studies when I wrote in the grandparent:

> Agree that observational and self-reporting are inaccurate, though unfortunately they're some of the best data we've got wrt nutrition.

[MDS100]

They are not the best data. It's just too widely used.

[raverbashing]

Good

What about only reducing saturated fats by 5% (replacing it with carbs, or something else?) and maintaining PUFA levels?

What about adding the PUFAs, maintaining SFAs and reducing caloric intake somewhere else?

Consumption of PUFAs have a known effect on cardiac health, so the result of this work is 1) not surprising 2) saying nothing about SFAs (what about diets with different levels of SFAs and no difference in PUFAs?)

[tim333]

The trouble with those sorts of studies is that they don't prove much - only that there's a weak correlation between thing A and thing B which is a good starting point for research but poor evidence for drawing conclusions from in itself. To follow up a scientist might say - ok lets look as people who eat basically nothing but saturated fat and people who eat basically none and see if one group drops dead quicker. This has been done, for example traditional eskimos live basically on saturated fat from the seal like stuff they eat and their health is fine. On the other hand some stuff like man made trans fats do kill you in a measurable manner - use them as your main diet and you'll drop some years earlier which is why they are being banned - eventually after many years of such evidence. The human body is pretty adaptable and can live OK on most foods that we have evolved with so switching from nuts to meat will probably not have a dramatic effect on life span as the body can deal ok with both on the whole.

[nitrogen]

What if there are other diseases beside heart disease that might be helped by consuming saturated fats?

[jacques_chester]

Then people with those diseases should follow the advice of their doctor and/or a registered dietitian. The rest of us live in middle-of-the-curve land, where vengeful sigmas kill more people from heart disease than almost everything else.

[ch4s3]

excellent point.