Do high saturated fat diets lead to heart disease? | Peter Attia and Don Layman
Summary
TLDRThe transcript covers a discussion between two individuals reflecting on the research legacy of Ancel Keys at the University of Minnesota. They review Keys' famous seven countries study linking dietary saturated fat to heart disease, as well as his human starvation experiments. The discussion centers around analyzing and interpreting Keys' 1970s Minnesota Coronary Experiment which compared a high saturated fat diet to a high polyunsaturated fat diet in institutionalized patients. Though the polyunsaturated fat group had lower cholesterol, there was no difference in cardiac events after 5 years. They debate the meaning of these results in light of subsequent research questioning saturated fat's link to heart disease.
Takeaways
- ๐ Don wasn't an expert on lipids but remembered the Minnesota Coronary Experiment study
- ๐ง The evidence on saturated fat and heart disease has been mixed overall
- ๐ค The cholesterol and saturated fat hypotheses have weakened over time
- ๐ฎ A seminar speaker warned about trans fat dangers years before policies changed
- ๐คจ The Minnesota study found no difference in events despite cholesterol changes
- ๐ Ansel Keys had major influence on diet-heart disease ideas at Minnesota then
- ๏ฟฝToString The Minnesota study may have been too short to show diet effects
- ๐ค Don believes calories matter most for obesity, macros for lean healthy people
- ๐ Selective publishing and excuses maintained diet-heart hypotheses over time
- ๐คทโโ๏ธ Saturated fats don't seem problematic for weight-stable people
Q & A
What were the two things Ancel Keys was famous for when the narrator was at the University of Minnesota?
-Keys was famous for the seven country study, which promoted the idea that saturated fat in the diet causes heart disease, and for starvation experiments done in the 1940s or 1950s to study the effects of starvation on the human body.
What did the narrator start to realize about the diet-heart hypothesis as he conducted research early in his career?
-The narrator started to realize he didn't really believe the hypothesis that saturated fat and cholesterol cause heart disease, based on experiments he did involving fasting and malnutrition.
What happened after Fred Kummerow suggested at a Minnesota seminar that cooking oils and trans fats were dangerous?
-Kummerow was ridiculed at the seminar, but 20 years later trans fats were banned from foods as the most dangerous type of fat.
What were the two diets compared in the Minnesota Coronary Experiment conducted by Ancel Keys?
-One diet was high in saturated fat and one was high in polyunsaturated fat. The goal was to see if the diet lower in saturated fat would reduce risk of heart attacks and strokes.
What were the main results of the Minnesota Coronary Experiment?
-After 5 years there was no difference in cardiovascular events between the high saturated fat and high polyunsaturated fat groups, even though cholesterol levels were lower in the polyunsaturated group.
Why does the narrator think the Minnesota Coronary Experiment may have been underpowered?
-The narrator initially thought 5 years may not have been long enough to appreciate a difference in events between the diet groups if one existed.
What did further analysis of the Minnesota Coronary Experiment data show?
-Further analysis showed some subgroups actually had more coronary events on the high polyunsaturated fat diet.
What is Dr. Layman's view on the diet-heart hypothesis related to saturated fat?
-Dr. Layman believes the evidence on saturated fat and heart disease is mixed and the hypothesis has weakened over time as better studies are done.
What does Dr. Layman believe is most important if your goal is to be lean and healthy?
-If the goal is to be lean and healthy, Dr. Layman believes total calories are what matters most, not the breakdown of macros.
When might saturated fat quality start to matter more according to Dr. Layman?
-If someone is committed to being obese, Dr. Layman says saturated fat quality would become more important to consider.
Outlines
๐ Keys' Work and Influence at University of Minnesota
Paragraph 1 discusses Ancel Keys' reputation and influence at the University of Minnesota when the author was there. Keys was known for his seven countries study linking dietary fat to heart disease, and his starvation experiments. The author initially bought into Keys' hypotheses but over time through his own research realized he did not actually believe them. A seminar is recalled where Keys' colleague ridiculed a speaker warning about trans fats, which were later banned.
๐ Interpreting the Minnesota Coronary Experiment
Paragraph 2 examines the Minnesota Coronary Experiment study by Keys which compared high saturated fat to high polyunsaturated fat diets. Though the polyunsaturated group had much lower cholesterol, there was no difference in cardiac events. Keys did not publish the full data which was later released, showing higher events in some polyunsaturated fat subgroups. The author discusses potential reasons for the perplexing results and gets input from the guest who also cannot definitively interpret the data.
Mindmap
Keywords
๐กDietary Fat
๐กCholesterol Theory
๐กMinnesota Coronary Experiment
๐กCardiovascular Disease
๐กTotal Cholesterol
๐กCalories
๐กObesity
๐กPolyunsaturated Fat
๐กSaturated Fat
๐กTrans Fats
Highlights
Keys was famous for his seven country study and saturated fat-CVD hypothesis, as well as the starvation experiments in the 1940s/50s.
Learned that questioning established dogma is important - people bought into saturated fat and cholesterol theory aren't necessarily right.
In 1973, Ivan Frantz published the Minnesota Coronary Experiment comparing high saturated fat to high PUFA diets in institutionalized patients.
The diets differed only in fat type, not total calories or macros - but the PUFA group had 30mg/dL lower total cholesterol.
After 5 years there was no difference in cardiac events, despite lower cholesterol in PUFA group.
Frantz didn't publish the null results as they didn't match his hypothesis that lower saturated fat would reduce events.
Ramsden re-analyzed the data years later, showing no benefit of PUFA and potential harm in some subgroups.
The total cholesterol and saturated fat hypotheses have gotten weaker over time.
If calories are controlled, there's little evidence saturated fats are problematic.
For weight loss, calories are key - macro distribution is personal preference.
The Women's Health Initiative showed mixed results regarding saturated fats.
Those invested in the hypothesis try to explain away null findings rather than questioning it.
A correct scientific theory gets stronger over time, an incorrect one gets weaker.
Excess calories alongside excess saturated fat is likely problematic.
For leanness and health, calories are the priority.
Transcripts
let's go pick it up back in University
of Minnesota you've got the Legacy and
I'm guessing at the time you know Keys
is really famous for two things in the
mid-70s right I think by that point he's
probably already published his seven
country study and the the hypothesis now
is a very fat Centric view of you know
the the negative consequences of dietary
fat specifically dietary saturated fat
in the American diet especially as it
pertains to
ascvd and then I suspect the second
thing that he's probably still famous
for is the starvation experiments um
that were I'm guessing done in the 1950s
I mean these were done on conscientious
obur so they're probably in the 40s or
50s
right yeah I I can't exactly date that
but you're exactly right so those were I
mean we learned a lot
about starvation at that point for
obvious reasons we can't Dukes
experiments like that before but we
learned a lot about body composition and
how the body starve so were good but
certainly the Legacy was there and when
I got to Minnesota you know I sort of
bought into the cholesterol and the
saturated fat and total fat and you know
I I sort of okay this is what
everybody's teaching and you know that's
what I was forced to learn that's what
they were teaching uh and so I bought
into it but you know as I slowly started
doing experiments and early in my career
we did a lot of fasting type of
experiments with animals to look at
composition change and I did
malnutrition work in in Northern Africa
and I sort of got into all of that and I
I I started realizing you know I don't
really believe that and one seminar I
will always remember at Minnesota was
individual by their name of Fred Kumo
came to Minnesota and gave a seminar
about the dangers of cooking oils and
specifically trans fats and Blackburn in
France just ridiculed him B basically
said this is the craziest thing we've
ever heard all these plant oils are
great uh and basically you know 20 years
later we ban trans fats from Foods
literally as the most dangerous fat that
you can encounter so I I always remember
that just sort of thinking well you know
people who have bought into this Dogma
aren't necessarily right and we need to
keep questioning it speaking of FRS um
obviously in
1973 he completes a study the Min
Minnesota coronary
experiment um I I actually find this to
be one of the most difficult studies to
interpret not so much the one that he
published 16 years later by the way in
1989 but the one that Chris Ramden
republished just a couple of years ago
based on all of the data from France's
study Plus data he never
published this to me is one of the most
complicated stories and I I will tell
you I have posed this question to every
friend of mine who is more steeped in
nutrition than I am and um I still don't
have a great sense of how to explain
these results so I'll explain it for the
for the listener and the viewer and I'm
curious to your thoughts so the
experiment was done um in basically
institutionalized patients so again
maybe not a study that could be done
easily again today for ethical reasons
but had the advantage of being so well
controlled you you basically had
patients that were randomized into two
groups their total energy was identical
their total split of macronutrients was
identical the only thing that differed
was that in one group it was high
saturated fat and in the other group it
was high polyunsaturated fat the
hypothesis being tested was is saturated
fat intake leading to increased major
adverse cardiac events heart attacks and
strokes the experiment that completed in
I think it ran I I can't remember
exactly I think it ran about five years
in 1973 showed no difference there was
no difference in cardiac events despite
the fact that the group that was on the
higher polyunsaturated fat group did
indeed have much lower cholesterol
levels now this was this predated the
subf fractionation so they weren't
measuring LDL and HDL they were just
measuring total cholesterol and at the
time there was some correlation between
cardiovascular disease and total
cholesterol levels at the extremes that
was certainly
true again because I didn't think we'd
be talking about this I don't have the
numbers all in my mind but we'll link to
it all but directionally I believe that
the higher Pua group relative to the
saturated fat group was about 30
milligrams per deiler lower in total
cholesterol and based on everything we
know today we would assume that much of
that was in LDL cholesterol indeed being
lower and non-hdl cholesterol and yet
there was no difference in events and of
course it's become a very famous and
unfortunate story in nutrition research
and that France chose not to publish it
because he didn't like the results it
didn't match his hypothesis which was
that the group on Lower saturated fat
would have fewer events Ramden went and
published all of these data plus a whole
bunch of subdata as I said just a few
years ago I believe in the British
medical journal and I actually found
something that
was that threw a wrench in my initial
hypothesis my initial view of the
Minnesota Corner experiment was it
probably wasn't a long enough
intervention it might be that 5 years
was not long enough to appreciate a
difference and so it was underpowered or
Too Short in a duration to see a benefit
if there was a
benefit but in Ramon's analysis you
actually saw the opposite because he now
looked at some subgroups and you
actually saw a higher incidents of
coronary events in some of the people
that were consuming the high
polyunsaturated fat diet and I can't
remember what the dominant oil was I'm
blanking on it I don't remember if it
was canola or safflower I think it was
safflower so how much of that do you
remember Don from your time there and
can you can you shed any light on this
or do you have any thoughts on you know
how to interpret that experiment well
first of all I am definitely not a lipid
expert so
um I you know I sort of remember the
study but I can't put any more numbers
to it than you did I actually did some
research with Ivan France and Penny
Chris Etherton when I was at Minnesota
so I you know I sort of was in the loop
at the time but that's been a couple of
years ago um yeah I think if one really
looks at the literature on saturated fat
and is fair about all of those studies
you find a very mixed bag the women's
health initiative and all of those kinds
of things uh and unfortunately the
people who believe the hypothesis have
either delayed publishing it or said
well it couldn't have been wrong and
tried to you know it could have been
wrong and they tried to find all kinds
of excuses as opposed to just believing
it U you know there's an old theory in
science that you know if the theory is
correct it'll get stronger over time and
if it's not it gets weaker and I think
one would have to
realize that a the cholesterol Theory
the total cholesterol theory has
definitely gotten weaker and the
saturated fat hasn't held up very well
um you know we still believe it but your
comment a little bit ago it's first and
foremost calories if you put excess
saturated fat on top of too many
calories that's probably a problem but
if you're at or below your calorie needs
I don't see any data that suggests it is
so you know my sort of joke or comment
all the time is that if you're committed
to being obese you probably ought to pay
attention to the quality of your fats
but if your goal if your goal is to be
lean and healthy calories is what you're
paying attention to and the macro
distribution is sort of your personal
[Music]
preference
Browse More Related Video
Americans Are Still Tricked by The Biggest Fib in Food History.
Why eating saturated fat won't kill you, but vegetable oil might.
Fats - Types Of Fats - What Is Saturated Fat - What Is Unsaturated Fat - Omega 3's And Omega 6"s
Is The Keto Diet Healthy? (Saturated Fats) | Jason Fung
Is Cardiovascular Disease Really Linked to a High-fat Diet?
What If You Ate 4 EGGS A Day With The YOLKS For 30 Days?
5.0 / 5 (0 votes)