This is an open source response to http://www.hsph.harvard.edu/nutritionsource/fats-full-story which I decided to write for no apparent reason

gistfile1.txt

In your article "Fats and Cholesterol: Out with the Bad, In with the Good"
http://www.hsph.harvard.edu/nutritionsource/fats-full-story/#references there
is a citation to nine studies in this sentence:

"What really matters is the type of fat and the total calories in the diet.
(7-15) Bad fats, meaning trans and saturated fats, increase the risk for
certain diseases."

Your article focuses on reduction of "bad fats" including saturated fatty
acids.

I would like to quote you some text from those studies, with footnote number
included.

7. http://jama.jamanetwork.com/article.aspx?articleid=201882 Saturated fat is
not analyzed in any way in this study.

8 http://jama.jamanetwork.com/article.aspx?articleid=202340 "In In this study,
a low-fat dietary pattern intervention did not reduce the risk of colorectal
cancer in postmenopausal women during 8.1 years of follow-up"

9 http://www.ncbi.nlm.nih.gov/pubmed/16391215 " Weight loss was greatest among
women in either group who decreased their percentage of energy from fat" This
is the closest we get, and still this study has no mention of saturated fat.
The study also seems rickety and troublesome if you read the methods.

10 http://www.ncbi.nlm.nih.gov/pubmed/16467234 "Over a mean of 8.1 years, a
dietary intervention that reduced total fat intake and increased intakes of
vegetables, fruits, and grains did not significantly reduce the risk of CHD,
stroke, or CVD in postmenopausal women"

11 http://www.ncbi.nlm.nih.gov/pubmed/19364995 "Insufficient evidence (< or =2
criteria) of association is present for intake of supplementary ...  saturated
and polyunsaturated fatty acids; total fat; alpha-linolenic acid; meat; eggs;
and milk."

12 http://www.nejm.org/doi/full/10.1056/NEJMoa0804748#t=abstract I'm not sure
why this article is cited. Again, no mention of saturated fat. The only thing
we might be able to conclude is that replacing carbs with protein might have
faster weight loss results than with fat, but all three groups lost weight
(all  750 kcal caloric restricted diets, which, blegh, no one likes). Even more
troubling is that they mention "fat" with no reference to specific sources.

13
http://www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fjournal.pmed.1000252
The first study in the list to actually look at saturated fat. It is a meta
analysis, not a controlled study, but nonetheless actually suggests that
replacing sat. fat with polyunsaturated fat has a 19% reduction on
cardiovascular events. 

14 http://www.nejm.org/doi/full/10.1056/NEJMoa1014296 This study barely
mentions fat, and the mention is about low fat vs high fat dairy products. No
mention of saturated fat.

15 http://www.ncbi.nlm.nih.gov/pubmed/11687015 They found no evidence of effect
on interventions lasting less than two years. For over two year interventions,
"a small but potentially important reduction in cardiovascular risk". Again,
this study has no mention of saturated fat, and just mentions "fat".


Out of the nine studies you cite, only one has a direct connection with
saturated fat, and it's a meta analysis, not a directly controlled study. Here
are two studies to counterbalance the list:

http://ajcn.nutrition.org/content/early/2010/08/04/ajcn.2009.29146.abstract
"SFA intake was inversely associated with mortality from total stroke"

http://ajcn.nutrition.org/content/early/2010/01/13/ajcn.2009.27725.abstract "A
meta-analysis of prospective epidemiologic studies showed that there is no
significant evidence for concluding that dietary saturated fat is associated
with an increased risk of CHD or CVD"

It is of course important to note that these are both observational studies as
well. Observational studies can be very good basis for forming hypothesis, but
should not be used for evidence alone. If you also go back and read the study
in 13, they have an odd search process, including unpublished studies.

The point is that your article demonizes saturated fat and links to many
studies, but the evidence is purely observational and at times contradictory.
There is no conclusive evidence that saturated fat is harmful in a human diet
as far as we currently know. There is a growing population that embraces high
fat diets (excluding trans fat, which we all agree on) with no restrictions on
dietary saturated fat. The significance of this article is mainly that it has a
high ranking in Google results, so people are likely to find it when
researching diet. I urge the authors to reconsider their stance against
saturated fat based on the existing evidence.

I have no idea why I chose to spend a Sunday morning writing this. I'm going to
go eat some bacon now.