Does Eating Red Meat Increase Type 2 Diabetes Risk?
Mark’s Daily Apple
by Mark Sisson: How
Many Calories Does Muscle Really Burn? (and Why It’s Not About Calories
If you already
Primal, your email inboxes are most likely filling up with links
to the story. Concerned mothers clutching the local paper's "Health"
section are calling (or, if they're hip, texting). Smug vegetarian
Facebook friends are posting the story on your wall, sans commentary.
Yes, it's about that time again. It's another week, it's another
observational study by data-mining researchers hoping to establish
a solid link between red meat and some chronic, horrific illness.
So, what's killing us this time? Well, considering that they've
already done studies linking red
meat to colorectal
disease, and outright
2 diabetes is next.
Here's a link
to the full study (PDF).
Researchers drew on data from three large-scale dietary habit questionnaires
of medical professionals to explore how red and processed meat intakes
associated with the incidence of type 2 diabetes. The first set
was the Health Professionals Follow-Up Study, which comprised 37,083
male physicians followed for 20 years; the second was the Nurses'
Health Study I, which included 79,570 female nurses followed for
28 years; and the third was the Nurses' Health Study II, which followed
87,504 women for 14 years. These data were pooled with additional
data from 442,101 participants in existing studies, so it was a
big pile of numbers with which to work.
they found a link between processed meat intake and type
2 diabetes, with a smaller link between unprocessed red meat and
the illness. A daily 50 gram serving of processed red meat
was associated with a 51% greater risk of developing type 2 diabetes,
while a 100 gram serving of fresh red meat represented a 19% increased
risk. Unprocessed meat included "beef, lamb, or pork as main dish"
(roasts, steaks, chops), "hamburgers" (but I'm sure they got bunless
burgers, right?), and "beef, pork, or lamb as sandwich or mixed
dish" (served up on coconut
flour bread, no doubt). Processed meat meant "hot dogs," "bacon,"
"sausage, salami, bologna, and other processed red meats."
To give a complete
picture of the data, I'll briefly discuss what the "heavy meat eaters"
did when they weren't eating red meat. You tell me if you notice
any alarming trends that might have something to do with type 2
diabetes. Folks in the highest quintiles of meat intake were the
least active and the most sedentary. They exercised the least and
smoked the most tobacco. They drank more alcohol than any other
quintile. They guzzled more soda and other sweetened beverages.
In the high meat quintiles, folks ate 800 more calories per day
than folks in the low meat quintiles. They were much heavier, too
I'm sure). Trans
fat intake was higher in the high-meat quintiles, too, as was
intake (since these data included the years before trans fats were
taken out of fast food deep fryers, I'm thinking these guys enjoyed
a burger and French fry value meal on occasion). They ate the least
amount of fiber from grains, indicating they probably ate the most
refined grains, drank the most coffee, and ate the fewest fruits
and vegetables. In short, people who ate the most red and
meat were also the unhealthiest by both Primal and mainstream
standards. And if what they were doing was actually healthy
or neutral (like drink coffee
and avoid fiber
from grains), it wasn't by design. These people (all health professionals,
ironically) most likely didn't particularly care about their health.
There are also
variables that weren't even considered that could have impacted
the results. Added sugar, which many people heap into their coffee,
wasn't covered. They did cover the polyunsaturated fat:saturated
fat ratio, but those numbers only incorporated the fat content of
whole foods like nuts,
not whatever cooking
oils were used to fry up all that meat. So there are a couple
other significant confounders.
You know how
we're always making the point that people who eat the most meat,
except for us weirdo Primal types, are also the most likely to be
unhealthy in other areas, to eat fast food, to be sedentary, and
to smoke? Well, here's direct evidence that this actually is the
then there's the issue of relative versus absolute risk (for
a good primer on relative risk, check out Dr.
Eades' post on the subject). 51% greater risk sounds pretty
awful, right? I mean, that's over half. And when most people hear
a figure like that, they take notice. They don't really think about
what the number means in terms of absolute risk, but they immediately
link whatever risk factor is being highlighted to the big scary
percentage figure – and the damage is done. In reality, the
effect size is tiny. The absolute risk of getting diabetes was rather
small for a participant of the studies mined for their data –
about 7% over the course of the 14-28 year range. A 51% increase
in risk bumps that up to about 10.5%, not 58%, while a 20% increase
bumps risk up to around 8.4%, not 27%. I don't fault the researchers
for using statistics, because they're totally valid, but I worry
that the average person will see those big percentages and think
that represents absolute risk. And then they give up their meat.
the rest of the article
August 17, 2011
© 2011 Mark's Daily Apple
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