From: Harvey Newstrom (mail@HarveyNewstrom.com)
Date: Wed May 07 2003 - 09:20:48 MDT
gts wrote,
>
> Harvey Newstrom wrote:
>
> > Point 2 goes on to say that "all fats raise HDL" as if this
> > were a good thing. I submit that this "ratio" isn't improved
> > unless LDLs are lowered at the same time.
>
> Why do you say this? Certainly it is better to see LDL drop while
> HDL rises,
> but I would not dismiss as meaningless an improvement in the
> ratio due only
> to a rise in HDL.
Good catch! To be more clear, I should have said "unless LDLs are lowered
or at least not raised." Where total cholesterol is measured without
distinguishing between HDL and LDL, we cannot infer anything good or bad
from the fact that total cholesterol is raised. Total cholesterol increases
does not tell us if HDL was raised without raising LDL, or if both were
raised proportionately, or if LDL was raised more. An increase in total
cholesterol may not be bad, but it may not be good either. I think both HDL
and LDL must be measured to know for sure.
> I would say that as long as total cholesterol does not rise significantly
> above ~200, any increase in HDL/LDL is a good thing even if LDL does not
> decline. Studies show that the risk of heart disease is inversely
> related to plasma HDL.
I agree with the first part. Raising HDL while keeping LDL the same does
improve the ratio. This is good. But I think the second part is
oversimplified. Raising HDL is not necessarily good by itself. If LDL is
not kept even, but increases as well, then the ratio is not improved. I
think this would be worse (or at least no improvement). LDLs tend to build
up on artery walls, while HDLs tend to remove this buildup. I am not sure
if increasing both the buildup and the cleanup equally is a net wash or
loses something in the inefficiency or requirement of extra repair work.
> A few days ago I posted an abstract here about the adverse effects on mood
> that occur when switching from a high-fat to a low-fat diet. I did not
> mention it at the time, but the statistics in that abstract show also a
> significant reduction in HDL from the low-fat diet, *without* a
> corresponding reduction in LDL or total cholesterol. Here is the relevant
> excerpt:
I agree with this. A low-fat diet that does not distinguish between good
fats and bad fats ends up lowering the good ones as well as the bad ones.
The results are a net wash at best, or poor nutrition usually.
In typical mail-list fashion, I only responded to the studies I had problems
with. I did not respond to this study to say that I agree with it. Low-fat
diets are old school before we learned to distinguish different fats.
People who avoided all fats, including good fats, and worse including
essential fatty acids, omegas and other helpful fats ended up becoming
deficient in these required fat nutrients.
> I remain convinced that extremely low-fat diets are unhealthy.
I totally agree. Besides there being several required fat nutrients, there
are a number of other fat-soluble nutrients that can only be digested and
processed in the presence of fats. Avoiding all fats is a simple recipe for
nutritional deficiency in all lipid-soluble nutrients and required fatty
acids.
I think the only place where we would disagree on fats is that I believe in
a certain ratio of fats which prefers essential fatty acids >
monounsaturated > polyunsaturated > saturated > hydrogenised. I am not sure
if you have no preference between different kinds of fats, or if you prefer
the reverse order than I do.
As far as all the studies you post, I tend to only jump on the ones I don't
like and ignore the ones that I think are OK. I apologize for the
inconsistency, but it seems to be a side-effect of e-mail lists.
My biggest problem with some older studies is that they don't distinguish
between different kinds of fats or different kinds of cholesterol. When
they lump them all together, we can't be sure what is being measured or what
the results were due to. One "high-fat" or "low-fat" diet could be all
saturated fats while another is all essential fatty acids. We can't combine
them or compare them or get any useful data. It leads us to no conclusion
as to whether we should increase or decrease "fats", or which kinds. I have
a similar objection to any measure of "total cholesterol" which doesn't
distinguish between HDL or LDL. (An unrelated but similar nitpick I have is
the measure of vitamin B12 which doesn't distinguish between usable B12 and
unusable analogs, especially in plants which have lots of analogs but no
usable B12.)
-- Harvey Newstrom, CISSP, IAM, GSEC, IBMCP <www.HarveyNewstrom.com> <www.Newstaff.com>
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