Is Liquid Smoke Flavoring Carcinogenic?

"Is Liquid Smoke Flavoring Carcinogenic?"

We know smoke inhalation
isn't good for us,

what about smoke
ingestion?

Decades ago, smoke
flavorings were tested

to see if they caused DNA
mutations in bacteria,

and the test
was negative.

Even as more and more
smoke flavoring was added,

the DNA mutation rate
remained about the same.

But the fact that something
is not mutagenic in bacteria

has little predictive value
for its effect on human cells,

so a group at MIT tested
a hickory smoke flavoring

they just bought at the store against
two types of human white blood cells.

Unlike the bacteria,
the mutation rate shot up

as more and more liquid
smoke was added.

But there is little evidence
that mutagenic activity

in a particular human cell
line is more closely related

to human health risk than is
mutagenic activity in bacteria.

In other words, just
because liquid smoke

causes DNA mutations to human
cells in a petri dish,

doesn't mean that it does the
same thing within the human body.

Damaging DNA is just one of many
ways chemicals can be toxic to cells.

A decade later researchers
tested to see what effect

liquid smoke had on
overall cell viability.

If you drip water on
cells, nothing happens,

they keep powering away
at around 100% survival.

But drip on more and
more wood fire smoke

and you can start killing
some of the cells off.

Cigarette smoke
is more toxic,

but 3 out of 4 of the brands
of liquid smoke they bought

at the supermarket killed
off even more cells,

leading them to conclude that
the cytotoxic potential

of some commercial smoke
flavorings is greater

than that of liquid
cigarette smoke–

a finding they no doubt celebrated
given that the researchers

were paid employees of the
R.J. Reynolds Tobacco Company.

Unfortunately, they didn't name
names of the offending brands.

That's one of the reasons I was
so excited about this new study,

where they tested—and named 15
different brands of liquid smoke.

This maximum "response" they were measuring
was what was called p53 activation.

P53 is a protein we make,
illustrated here in pink and red,

that binds to our
DNA, shown in blue.

It activates our
DNA repair enzymes.

So a big P53 response might be
indicative of a lot of DNA damage,

and a few of the liquid smoke
flavorings activated P53

almost as much as a chemotherapy
drug like Etoposide

whose whole purpose is
to break DNA strands.

Other flavorings
didn't seem as bad,

though there was a hickory smoke
powder that ranked pretty high,

as did the fish sauce, though smoked
paprika didn't register at all.

The p53-activating property
in liquid smoke was eliminated

by standard baking
conditions (350°F for 1h),

so if we bake something with
liquid smoke for long enough

it should eliminate
this effect,

though just boiling, even for
an hour, or slow cooking

didn't appear to work.

They conclude, "If the DNA-damaging
activities of liquid smoke"

"were thought to be deleterious,
it might be possible to replace"

"liquid smoke with other,
safer, smoky substances."

Why do they say IF thought
to be deleterious?

That's because they're not
directly measuring DNA damage.

Remember, they're measuring
P53 activation,

and that's not
necessarily a bad thing.

P53 is considered "Guardian of
our Genome," guardian of our DNA.

It's considered a
tumor suppressor gene,

because it helps
repair our DNA.

So if something boosts the activity
of P53, is that good or bad?

It's like the
broccoli story.

Cruciferous vegetables dramatically
boost our liver's detoxifying enzymes.

Is this because our body
sees broccoli as toxic

and is trying to get
rid of it quicker?

Either way, the end result from
broccoli is good, lower cancer risk.

It's maybe a biological
phenomenon known as hormesis,

that which doesn't kill
us may make us stronger.

Like exercise is a
stress on the body,

but in the right amount can make
us healthier in the long run.

So, for example, teas and coffees
caused P53 activation as well,

but their consumption is associated
with lower cancer risk.

So it's hard to know what to make
of that smoke flavoring P53 data.

Due to the limitations
of the available tests

it's hard to calculate the genotoxic
potential of liquid smoke,

or any other food
for that matter.

A better approach may be to just analyze
liquid smoke for known carcinogens,

chemicals that we
know cause cancer.

This was first attempted
back in 1971.

One of the seven liquid
smoke flavors they tested

contained a polycyclic
aromatic hydrocarbon

known to be
cancer-causing,

but there's a bunch of similar
carcinogens that they didn't test for.

A later study, tested
across the board,

looking specifically at
5 different carcinogens

in retail liquid
smoke seasonings.

The recommended daily upper safety
limit for these carcinogens is 47.

Hickory smoke flavoring
only has 0.8 per teaspoon,

so you'd have to drink three bottles
a day to bump up against the limit.

And mesquite liquid
smoke, only 1.1.

It turns out that most of these
carcinogens in smoke are fat soluble,

and so when you make a water-based
solution, like liquid smoke,

you capture the smoke
flavor compounds

without capturing most of
the smoke cancer compounds.

The only time you need to really
worry is eating smoked foods,

foods directly exposed
to actual smoke.

For example, smoked
ham comes up to here,

and smoked turkey
breast up to here.

So one sandwich and we may
be half way to the limit.

But one serving of
barbecued chicken takes us...

over the top.

Less than a single drumstick
and we may nearly

double our daily allotment
of these carcinogens.

Nothing, however,
is as bad as fish.

Smoked herring? 140.

And we have to shrink down the graph
to fit the worst of the worst...

smoked salmon.

One bagel with lox could take
us 10 times over the limit.