"How Well Does Cooking Destroy the Cyanide in Flaxseeds?"
Sweden's dietary guidelines are pioneering in many ways;
for example, encouraging people to decrease their climate impact
by choosing more plant-based foods, which tend to produce greatly
fewer greenhouse gas emissions. But I was surprised by this page
on the official Swedish National Food Agency website,
which translates to cyanogenic glycosides and hydrogen cyanide,
encouraging people to stay away from ground flaxseed
for fear of cyanide toxicity, as in the ground flax seeds
I encourage everyone to eat every day.
You can see why this was the first question I got
when I spoke in Stockholm.
Was the Swedish government on to something?
Had I just been duped by Big Flax-funded researchers
who claimed you could eat pounds of ground flaxseeds a day without worrying,
more than 150 tablespoons a day? First, some background.
As many as one in five plants that we eat produce cyanide.
In fact, if you look at the major food crops in the world,
more than half are cyanogenic, meaning cyanide producing.
See, unlike toxic elements like lead, mercury, arsenic that can't be broken
down into anything, cyanide is an organic molecule:
one carbon atom attached to one nitrogen atom.
In this state it can definitely be toxic,
but broken down or complexed to something else and it loses its toxicity.
And we have an enzyme in our body that does just that,
a cyanide detoxifying enzyme.
And that's just one of five main ways our body can detoxify cyanide.
It does require protein to do it though, and so that's why you can read about
chronic cyanide toxicity among malnourished populations in Africa
trying to live off of improperly processed cassava root.
But as long as we're getting adequate protein in our diet,
our body can detoxify the normal amounts of cyanide we eat every day.
Now there is a rare, congenital genetic condition called Leber's disease,
where you're born without the ability to detoxify cyanide.
And indeed, yeah, you could go blind drinking apple cider or something,
but otherwise our bodies evolved to be cyanide-detoxifying machines,
but obviously there's a limit.
For example, a case of cyanide poisoning after bitter almond ingestion.
Not regular almonds, which produce about 40 times less cyanide,
but bitter almonds, which you can't even buy—they're used in flavor manufacturing—
but if you did, eating 50 of them could kill you,
or even just a handful for a small child.
This suggests that eating 2,000 regular almonds at one sitting
could also be bad news.
You can't buy bitter almonds, but you can buy apricots,
and apricot kernels, which are the seeds inside the stone, actually have
pretty toxic levels, and have indeed been implicated in cases
of severe cyanide poisoning, all linked to the
"Laetrile: cult of cyanide, Promoting poison for profit"
that I talked about previously.
So I'm totally sympathetic to regulators wanting to take a precautionary approach.
But are flaxseeds like bitter almonds, where just a few ounces could kill you,
or more like regular almonds where regular dietary intake
wouldn't even come close?
Although the fact that flaxseeds can produce cyanide sounds like
it would be a significant health concern,
it is not for several reasons, says flax industry-funded scientists.
First, the adult human body has the ability to detoxify
up to 100 mg of cyanide per day. That's where they come up with
their "pounds of flaxseeds a day are safe" number.
And if you wanted to eat more than
those totally unrealistic 150 tablespoons a day,
you could just eat them in baked goods since cooking destroys the cyanide.
And eating 7 or 8 tablespoons of raw doesn't even bump
urinary thiocyanate levels, which is an indicator of cyanide exposure,
so it doesn't even look like your body is even exposed to it.
Thus, the toxicity of flaxseed from cyanogenic glycosides
is not, evidently, a realistic health threat.
OK, let's unpack that.
The cooking part is mostly true. Yes, bake muffins with even
like a quarter cup of ground flax each for 15 to 18 minutes
at about 450 degrees Fahrenheit and the cyanide-forming compounds are gone.
Looks like the same thing happens with baked bread.
But bake ground flax seeds on their own, and even an hour at 350
only wipes out 20%, though baking them whole wipes out 80%.
And what, baking in bread or muffins wipes out 100%?
How does that make any sense?
It's the moisture.
It's heat plus water that wipes out the cyanide.
Boiling for just five minutes can wipe it out, like when making
hot cereal or something.
And so, yes, it's true in most cases
that cooking eliminates the cyanide compounds
because it typically starts out in a batter as an egg substitute,
or baking crackers, or the dough starts out moist.
And so, yes, in those cases the cyanide is gone upon cooking.
But you can't just spread ground flaxseeds on a baking sheet
because they dry out so fast that only a minority of the cyanide is lost.
But, look, why does it matter if your body
doesn't even seem to notice 7 or 8 tablespoons of raw?
But that's not true.
Urinary thiocyanate excretion doubled at that level,
though that's just a sign your body is actively detoxifying it.
And if we can detoxify a kilo worth of flax a day, what's the problem?
Well, look, even if the adult human body has the ability to detoxify
up to 100 mg of cyanide a day, first of all, look, kids eat flax too.
Second of all, a kilo has more than the 100 you said we could detoxify,
about 50% more.
And I'm not interested in how much we can detoxify "up to."
For safety you're interested in the worst-case scenario,
not the best-case scenario.
Would someone please just give people different doses of flaxseeds
and just measure how much cyanide ends up in their blood?
But that's never been done until now, which we'll cover next.