From: Harvey Newstrom (mail@HarveyNewstrom.com)
Date: Thu May 01 2003 - 15:09:36 MDT
Brian Atkins wrote,
> I'm still a bit unclear on your take. Obviously we both believe that
> some of the articles on that site are bogus. However, as far as I can
> tell, the author of the specific article I wanted an opinion on didn't
> write any of those. In fact she appears to have fairly strong non-kooky
> credentials from my layman perspective (PhD in Nutrition Science, lab
> chemistry experience, published over a dozen papers, etc.). And again
> from my layman position the article itself looks like it makes some
> interesting points. If it indeed is incorrect information you should be
> able to easily shoot it down
Fair enough!
Here is my take on the paper. There is a shorter summary at the end. This
paper seems weak on science and logic, but does not present any totally
wacky theories. It seems to miss the mark in various areas and doesn't
provide strong proof either way. It is more of a opinion piece rather than
evidence, despite the attempted use of numerous footnotes.
> I brought up the page for discussion after you specifically asked to
> know if there was anyone out there advising that eating saturated fats
> is useful. I intend to do my part to keep at least this small part of
> the list on topic.
This paper totally fails to address this question about saturated fats. It
lumps all fats together, and merely argues that (some) "fats" are required.
It rambles around the mulberry bush and never directly addresses the value
of saturated versus unsaturated fats. It seems to be a rambling collection
of unrelated studies, most of which fail to prove anything, but few of which
actually support any point the author is making.
The introduction lumps all "fats" together. It doesn't distinguish between
saturated and unsaturated fats. It argues all the reasons why "fats" are
needed in the diet. Basically, the argument that "fat" is needed is
consistent with the theory that saturated fats are bad and unsaturated fats
are good. This introduction makes the logical flaw of lumping dissimilar
categories together and then applying any evaluation of one item to all the
others. Just because some "fats" are good doesn't mean all "fats" are good.
The basic outline of the paper in the introduction is confused and flawed
and illogical. It doesn't distinguish its position from the position it
attacks. The way it has worded its claims applies to both sides. It seems
to have evolved from an older paper where there was no distinction between
good fat or bad fat, good cholesterol or bad cholesterol. Thus, the
arguments for or against "fats" doesn't address whether saturated fats and
unsaturated fats are equally required.
The discussion of Pritikin doesn't really give any facts or evidence against
it. Pritikin was originally just low fat, and then later added vegetable
oils, so it contained unsaturated fats but not saturated fats. There is no
explanation why this diet was bad. The paper implies that the addition of
vegetable oils proved the low fat diet wrong, but instead it merely
clarified that saturated fats are bad and unsaturated fats are good. No
evidence against the modified diet was presented either. In fact, the main
point seems to be that Dr. Pritikin may of saved himself from heart disease,
but died of cancer instead. It presented the history in a negative tone,
but didn't really give any evidence or facts about what was wrong with it.
The section on "evidence" gives a history of the rise of heart disease, but
doesn't really given any evidence of what causes it. It claims that butter
consumption reduced during this time, but doesn't really address the
question whether fat consumption when up or down. It assumes total fat
consumption went down in the American diet proportional with butter
consumption, and that the modern American diet is less fatty than 60 years
previous. This is both unproven and unlikely. This is not very strong
evidence for the decline of fat in the diet, nor is there any evidence of a
cause and effect in any case. Furthermore, most of the studies being
"refuted" in this article are from the 1950's.
The representation of the Framingham Heart Study does not match what I find
on the Framingham Heart Study webpage
<http://www.nhlbi.nih.gov/about/framingham/>. The study did not divide
people into high-fat and low-fat groups, it had a single large group of
people. It did not focus primarily on diet or fat, but measured all
different factors in a person's life. High fat versus low fat is not
mentioned in the list of study findings at
<http://www.nhlbi.nih.gov/about/framingham/timeline.htm>. Cigarette
smoking, serum cholesterol, physical activity, blood pressure, menopause,
psychosocial factors, enlarged ventricles, and other factors are reported,
but I don't see anything about diet. This was not primarily a diet study,
nor did it compare high-fat with low-fat groups. I don't see how this
relates to the "lipid hypothesis", how it was supposedly refuted in this
article, and what difference it would make if it were.
I can't really evaluate most of the studies cited, because it doesn't give
any details about them or their methodology. However, all the studies are
ones that were supposed to prove the low-fat hypothesis and failed to do so.
There were no studies that actually showed that saturated fats were
required. This seems scant evidence that all studies showing unsaturated
fat to be superior to saturated fats were all flawed. It also provides
absolutely no evidence that saturated fats are required in the diet.
The dates of these studies also bothers me. They were 1983, 1983, 1982,
1983, 1984, 1985. We no a lot more about fats today than we did 20 years
ago. These studies may have been flawed since they reduced all fats and
didn't distinguish between different types. But a lack of proof from
studies 20 years ago does not refute modern studies performed today. I
think modern studies clearly do show some fats to be better or at least
different than other fats. A lack of proof of this fact from 20 years ago
is not conclusive or convincing.
The studies that refute the lipid hypothesis were similarly old and flawed.
They measured "cholesterol" without distinguishing between good (HDL)
cholesterol and bad (LDL) cholesterol. Cholesterol is not a direct
predictor of heart attack anyway. Even if these studies are flawed, this
doesn't address the question of saturated fats in the diet. All of these
studies discussed by this article seem to be a little off base. None of
them directly study saturated fat versus unsaturated fat. These studies
also "failed" to prove cholesterol caused heart attacks, or that dietary
cholesterol causes serum cholesterol. But these don't directly address the
question of whether dietary saturated fats are required or not.
Although none of the studies seemed to distinguish between different types
of fats, the paper goes on to discuss saturated, monounsaturated, and
polyunsaturated fats. None of the previously-mentioned studies support or
discount this discussion, as they all seem to be on orthogonal topics. The
discussion of the chemical classification of fats seems accurate, but
sloppily worded in places.
The problems with too much polyunsaturated oils seem like they would apply
to any oil. Excessive consumption of these fats causes obesity-related
symptoms such as cancer, heart disease, immune system depression, liver
damage, etc. It also discusses how oils can become oxidized and oxidized
oils are bad for you. However, it does not show that other oils don't have
the exact same problems. The paper then discusses the imbalance of too much
omega-6 and too little omega-3, but fails to show how saturated fats would
help this balance.
The section that actually gets into the benefits of saturated fats is very
short compared to the other rambling rants that don't get to the point.
This section seems to only describe the benefits of saturated fatty acids in
the body. Most of these uses inside the body provide no clue as to whether
saturated fat needs to be incorporated in the diet, or if the body is
incapable of manufacturing its own saturated fat. The second point does
assert that 50% of dietary fat should be saturated, but it is unclear why.
They study cited is about the effects of vitamin E on bone health, and not
details about why this dietary need is given. Besides this minor
references, all of the points are about the need for saturated fat in the
tissues, which is not disputed. Even vegetarian animals such as cows
produce a lot of saturated fat. This paper certainly provides no evidence
that humans have lost the ability to produce their own saturated fat like
other animals such that it needs to be incorporated into the diet.
The section on cholesterol is similar. It shows all the vital roles
cholesterol plays internally. it does not show that cholesterol is a
required nutrient which cannot be created by our bodies.
In summary:
1. This paper refutes a "low-fat" diet without distinguishing between good
and bad fats.
2. This paper uses mostly very old references and few modern sources.
3. This paper shows a few studies that failed to prove high fat was bad, and
acted like this was evidence for the reverse.
4. This paper showed no studies that high fat was good.
5. This paper showed saturated fats were required internally, and then just
assumed that they must be required in the diet if they are found in the
body.
7. This paper showed bad effects of too much or oxidized unsaturated fats,
but failed to show that saturated fats did not suffer from these same
negative effects.
8. The paper showed no evidence of good effects from eating saturated fats,
and no comparison studies that measured saturated fat in the diet at all.
9. The section on benefits of saturated fat only addressed fatty acids.
10. The paper frequently got off on unrelated tangents, like proving dietary
cholesterol might not cause cholesterol, or meat contains more B-vitamins
than vegetables, all of which are orthogonal to the discussion of saturated
fats.
11. The paper cited a decline in butter use and assumed that this indicated
a decline in total fat intake.
12. The paper had a lot of logical fallacies. It combined dissimilar
categories of items and used evidence about one to apply to another. It had
sections labeled with one topic which then proceeded to discuss a different
point. It took a lack of evidence of one theory to indicate support for
another. It made unsupported assertions laced with references supporting
minor unrelated points.
There was little to refute in this paper. Most of its logic was flawed and
its evidence orthogonal to what it was presenting. It mostly boiled down to
the argument that its theory hasn't been proven wrong and therefore must be
right. I saw only a few minor implied statements that eating saturated fat
would be good.
At best, this paper might be a hold-over from an earlier period when all
fats were lumped together and all cholesterol was thought to be bad. This
paper does a poor job of asserting the correct position that not all fats
are bad and not all cholesterol is bad. It does not address diet as much as
internal chemistry. It also appears to me that the chemistry section
discussing different types of fats was tacked on to an earlier paper that
didn't make this distinction. Although all the right definitions were
included in one section, these distinctions were ignored in the discussion,
evidence and persuasive sections. By mixing good fats with bad fats, and
good cholesterol with bad cholesterol, this paper neither supports nor
refutes the question of whether "fats" are "good" or "bad".
-- Harvey Newstrom, CISSP, IAM, GSEC, IBMCP <www.HarveyNewstrom.com> <www.Newstaff.com>
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