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"Is Liquid Smoke Flavoring Carcinogenic?"

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We know smoke inhalation [br]isn't good for us,

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what about smoke [br]ingestion?

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Decades ago, smoke [br]flavorings were tested

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to see if they caused DNA [br]mutations in bacteria,

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and the test [br]was negative.

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Even as more and more [br]smoke flavoring was added,

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the DNA mutation rate [br]remained about the same.

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But the fact that something [br]is not mutagenic in bacteria

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has little predictive value [br]for its effect on human cells,

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so a group at MIT tested [br]a hickory smoke flavoring

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

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Unlike the bacteria, [br]the mutation rate shot up

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as more and more liquid [br]smoke was added.

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But there is little evidence [br]that mutagenic activity

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in a particular human cell [br]line is more closely related

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to human health risk than is [br]mutagenic activity in bacteria.

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In other words, just [br]because liquid smoke

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causes DNA mutations to human [br]cells in a petri dish,

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

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

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A decade later researchers [br]tested to see what effect

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liquid smoke had on [br]overall cell viability.

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If you drip water on [br]cells, nothing happens,

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they keep powering away [br]at around 100% survival.

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But drip on more and [br]more wood fire smoke

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and you can start killing [br]some of the cells off.

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Cigarette smoke [br]is more toxic,

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but 3 out of 4 of the brands [br]of liquid smoke they bought

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at the supermarket killed [br]off even more cells,

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leading them to conclude that [br]the cytotoxic potential

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of some commercial smoke [br]flavorings is greater

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than that of liquid [br]cigarette smoke–

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a finding they no doubt celebrated [br]given that the researchers

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were paid employees of the [br]R.J. Reynolds Tobacco Company.

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

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

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

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

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

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that binds to our [br]DNA, shown in blue.

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It activates our [br]DNA repair enzymes.

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

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and a few of the liquid smoke [br]flavorings activated P53

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almost as much as a chemotherapy [br]drug like Etoposide

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whose whole purpose is [br]to break DNA strands.

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Other flavorings [br]didn't seem as bad,

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

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

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The p53-activating property [br]in liquid smoke was eliminated

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

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so if we bake something with [br]liquid smoke for long enough

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it should eliminate [br]this effect,

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though just boiling, even for [br]an hour, or slow cooking

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didn't appear to work.

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

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"were thought to be deleterious, [br]it might be possible to replace"

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"liquid smoke with other, [br]safer, smoky substances."

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Why do they say IF thought [br]to be deleterious?

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

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Remember, they're measuring [br]P53 activation,

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and that's not [br]necessarily a bad thing.

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

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It's considered a [br]tumor suppressor gene,

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because it helps [br]repair our DNA.

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

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It's like the [br]broccoli story.

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Cruciferous vegetables dramatically [br]boost our liver's detoxifying enzymes.

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Is this because our body [br]sees broccoli as toxic

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and is trying to get [br]rid of it quicker?

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

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It's maybe a biological [br]phenomenon known as hormesis,

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that which doesn't kill [br]us may make us stronger.

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Like exercise is a [br]stress on the body,

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

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

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but their consumption is associated [br]with lower cancer risk.

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

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Due to the limitations [br]of the available tests

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

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or any other food [br]for that matter.

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

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chemicals that we [br]know cause cancer.

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This was first attempted [br]back in 1971.

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One of the seven liquid [br]smoke flavors they tested

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contained a polycyclic [br]aromatic hydrocarbon

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known to be [br]cancer-causing,

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

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A later study, tested [br]across the board,

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looking specifically at [br]5 different carcinogens

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in retail liquid [br]smoke seasonings.

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

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Hickory smoke flavoring [br]only has 0.8 per teaspoon,

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

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And mesquite liquid [br]smoke, only 1.1.

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

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

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you capture the smoke [br]flavor compounds

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without capturing most of [br]the smoke cancer compounds.

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

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foods directly exposed [br]to actual smoke.

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For example, smoked [br]ham comes up to here,

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and smoked turkey [br]breast up to here.

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

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But one serving of [br]barbecued chicken takes us...

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over the top.

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Less than a single drumstick [br]and we may nearly

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double our daily allotment [br]of these carcinogens.

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Nothing, however, [br]is as bad as fish.

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Smoked herring? 140.

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

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smoked salmon.

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