"Do Potatoes Increase the Risk of High Blood Pressure and Death?"
Potato intake and the incidence of hypertension.
Harvard researchers followed the diets and diseases
of more than 100,000 men and women for decades and found that
those who ate potatoes on most days—even just baked, boiled,
or mashed, not just French fries and potato chips—
appeared to be at higher risk of developing high blood pressure.
Okay, but what do people put on potatoes?
Salt, not to mention butter; so, maybe the potatoes are just
innocent bystanders. Maybe... but the researchers made attempts
to tease out the effects of salt and saturated fat,
and there still seemed to be a link between
potato consumption and high blood pressure.
Maybe potato eaters are just meat-and-potatoes people.
After all, these same Harvard researchers have found that
meat, including poultry alone appeared to be associated with
an increased risk of hypertension,
and the same with even a moderate amount of canned tuna.
So, in the potato study, they were careful to try to factor out
any effects from the consumption of all types of animal flesh.
Yet they still found an increased potato risk and got concerned
that the association of potato intake with hypertension
could be a critical public health problem.
We had assumed potatoes might actually
decrease high blood pressure
given their high potassium content,
but they found evidence of the opposite effect.
Two similar studies performed in Mediterranean Europe
did not find any association between potato consumption
and high blood pressure, though.
Perhaps this is because they don’t smother their potatoes
in butter and sour cream in that neck of the woods
and instead eat potatoes with other vegetables.
Now, the Harvard folks tried to control for the bad salty
and fatty dietary components associated with eating potatoes
in the West, just like these researchers tried to factor out
all the extra vegetables, but you can’t control for everything.
A primary reason we care about blood pressure is
because we care about the consequences.
In two studies done in Sweden, where they primarily eat
their potatoes boiled, no evidence was found that
potato consumption was associated with the risk of
major cardiovascular disease, and no relationship was found
between potato consumption and risk of premature death
found in Southern Italy either.
In the U.S., however, potato consumption was
associated with increased mortality:
a whopping 65 percent increased risk of dying from heart disease,
a 26 percent increased in fatal stroke risk,
a 50 percent increased risk of dying from cancer,
and increased risk of dying from all causes put together.
This all disappeared after adjustment for confounding factors.
In other words, it wasn’t the potatoes at all.
Potato eaters must just smoke or drink more,
or eat more saturated fat, or something.
Once you control for all these other factors,
the link between potatoes and death disappears.
This was confirmed in the NIH-AARP study,
the largest such study of diet and health in human history.
If you just separate out the potatoes, researchers find
that they are not associated with increased risk of death,
with the possible exception of French fries, which are
associated with an increased risk of dying from cancer.
Put all the studies together—20 in all—
and no significant association has been found
between potato consumption and mortality, though again
fried potatoes may be the exception.
Even just twice a week, fries may double one’s risk of
dying prematurely, independently of other factors;
but the consumption of unfried potatoes seemed to be neutral.
You know, it’s funny. I’ve done a bunch of videos on how
all plant foods are not created equal, talking about
healthy vs. unhealthy plant-based diets.
To this end, researchers created not just an overall
plant-based diet index—just scoring plant vs. animal foods—
but also a healthy plant- based diet index (hPDI)
and an unhealthy plant- based diet index (uPDI).
The healthy index puts a greater emphasis on whole plant foods,
whereas the unhealthy index scores how much low-quality
plant foods you’re eating, grouping potatoes
along with soda, and cake, and Wonder Bread.
Then, when you run the numbers, the more plant-based you eat
the longer you live, the lower your risk of cardiovascular disease.
In other words, more plant foods and less animal foods are
associated with a significantly lower risk of dying prematurely.
This benefit was limited, though, to those eating the
healthier plant food diets, but they were surprised that
those eating all that processed plant-based crap
didn’t live significantly shorter lives.
Now maybe, that’s just because they were eating fewer
animal products, and that’s really the primary determinant
of lifespan here, or maybe the lack of an association between
less healthy plant-based diets and mortality outcomes
is because potatoes were kind of coming to the rescue.
And indeed, higher intake of potatoes did appear protective;
so, given these conﬂicting ﬁndings, future studies may consider
just resigning fried potatoes to the unhealthy list.
Now, in terms of mortality, fried potatoes may not be as bad
as fried meat—fried chicken and fried fish—
but that’s not really saying much.
The French fry death data gave the industry trade group
Potatoes USA a bit of a chip on their shoulder,
reminding readers that observational studies can only prove
correlation, not causation, to which the authors replied,
“our data add to the pressing public health calls
to limit fried potato consumption.”
French fries may be so bad for you that it wouldn’t be ethical
to do an interventional study and randomize people to eat them.