January 4, 2022 • 5 mins
Hands up who likes brussel sprouts? How are you with broccoli? I ask because we know that our genetic make-up goes some way to explaining whether you’ll be fine eating some foods, such as broccoli and brussel sprouts, that others find too bitter to nibble on.
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Episode Transcript
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(00:01):
So, hands up who likes brussel sprouts? How are you with broccoli? I ask because we know that our
genetic make-up goes some way to explaining whether you’ll be fine eating some foods,
such as broccoli and brussel sprouts, that others find too bitter to nibble on.
The understanding of this actually goes back nearly 100 years and it started with an accident.
(00:26):
It was in 1931 when the chemist, Arthur Fox, was at his lab bench, working with a chemical
called Phenylthiocarbamide, or PTC for short. It was in the form of a powder, and he was pouring
some of it into a bottle, when some of the powder accidentally blew into the air, creating a little
dust cloud around him. His colleague, Carl Noller, standing nearby complained, saying that the dust
(00:52):
tasted bitter, whereas Arthur, who was much closer to the chemical, couldn’t taste anything.
Apparently, it was not unusual for organic chemists to taste their compounds
and the two of them then went about tasting the powder, which you’ll be happy to know
isn’t poisonous or that would have been the end of that. They put some PTC crystals on their tongues
and found they really were different in terms of whether they could taste anything or not.
(01:17):
Carl said it tasted very bitter whereas Arthur thought it was tasteless.
Arthur got very interested in this and started asking his family, his mates,
and other colleagues to taste and was intrigued by what he found. Regardless of their age,
sex, or biogeographic ancestry, they fell into two main groups. Those who couldn’t taste anything
(01:42):
unless it was at very high concentrations and those who could taste bitterness.
For those who could taste bitterness, some people found it intensely bitter, whereas the others
just found it moderately so. The finding was published and drew the attention of geneticists,
including a chap called Albert Blakeslee, who did the first big study of PTC testing
(02:07):
in the 1930’s, and found that being a taster or not, was strongly genetic, so much so
that this led to PTC testing being used in paternity testing along with blood tests.
It’s now known that a good chunk of this ability to taste the bitterness of PTC is down to a single
(02:28):
gene known as TAS2R38, which was discovered in 2003. And whether you can taste PTC or not is down
to what form, or allele as it’s known in genetics, of the gene that you carry. The two most common
(02:49):
forms of the gene (there are a few much rarer ones) are the tasting form and the non-tasting
form. Each form of the gene codes for a particular taste receptor protein that sits on your tongue.
The two different forms of the gene results in two slightly different proteins that have
different shapes. The shape is important because it determines how strongly it can bind to PTC.
(03:17):
So, you inherit one copy of this gene from your mum and one from your dad, so depending on which
version you got from each, this will affect how you taste this bitterness or not. If both your mum
and your dad have given you the tightly binding version, you’ll taste strong bitterness from PTC.
(03:40):
If both parents have given you the version that doesn’t bind well to PTC you won’t taste much of
anything unless it’s at high concentration. If one parent gave you the strong binding version
and the other gave you the other version then you’ll taste the bitterness, just not as strongly.
So why is this interesting? Okay, so while you don’t find PTC in nature,
(04:05):
the ability to taste it does correlate with the ability to taste bitter substances that
ARE found in nature, such as in brussel sprouts, broccoli, and cabbage. So,
it generally correlates with whether you find these foods bitter or not.
In addition to this, it’s known that some of the bitter substances
(04:26):
that do occur in nature are toxins.
So, this ability to taste toxins may have been evolutionarily a good thing, to stop ourselves
from eating poisonous plants and getting sick or, worse, munching something that could kill us.
It’s important to say that we know all this this isn’t quite so simple. For example,
(04:50):
we know that scientists found that some people, with a non-taster version of the
gene, were able to taste a different bitter compound that the PTC tasters couldn’t taste.
We know humans have about 30 genes that are coding for receptors that are for bitter taste,
with each receptor being able to bind with several different molecules,
(05:12):
which means people can taste a wide variety of bitter substances.
We also know that what you’ve eaten or drunk, before PTC testing, can affect your
ability to taste PTC and that taste sensitivity can change over time,
so presumably that’s the same for foods as well.
(05:33):
But bearing all that in mind, we do know that genetics has a role to play in being able to
taste bitterness– and so that may be why you don’t fancy eating all those brussel sprouts at dinner.
So, hands up who likes brussel sprouts? How are you with broccoli? I ask because we know that our
genetic make-up goes some way to explaining whether you’ll be fine eating some foods,
such as broccoli and brussel sprouts, that others find too bitter to nibble on.
The understanding of this actually goes back nearly 100 years and it started with an accident.
(00:26):
It was in 1931 when the chemist, Arthur Fox, was at his lab bench, working with a chemical
called Phenylthiocarbamide, or PTC for short. It was in the form of a powder, and he was pouring
some of it into a bottle, when some of the powder accidentally blew into the air, creating a little
dust cloud around him. His colleague, Carl Noller, standing nearby complained, saying that the dust
(00:52):
tasted bitter, whereas Arthur, who was much closer to the chemical, couldn’t taste anything.
Apparently, it was not unusual for organic chemists to taste their compounds
and the two of them then went about tasting the powder, which you’ll be happy to know
isn’t poisonous or that would have been the end of that. They put some PTC crystals on their tongues
and found they really were different in terms of whether they could taste anything or not.
(01:17):
Carl said it tasted very bitter whereas Arthur thought it was tasteless.
Arthur got very interested in this and started asking his family, his mates,
and other colleagues to taste and was intrigued by what he found. Regardless of their age,
sex, or biogeographic ancestry, they fell into two main groups. Those who couldn’t taste anything
(01:42):
unless it was at very high concentrations and those who could taste bitterness.
For those who could taste bitterness, some people found it intensely bitter, whereas the others
just found it moderately so. The finding was published and drew the attention of geneticists,
including a chap called Albert Blakeslee, who did the first big study of PTC testing
(02:07):
in the 1930’s, and found that being a taster or not, was strongly genetic, so much so
that this led to PTC testing being used in paternity testing along with blood tests.
It’s now known that a good chunk of this ability to taste the bitterness of PTC is down to a single
(02:28):
gene known as TAS2R38, which was discovered in 2003. And whether you can taste PTC or not is down
to what form, or allele as it’s known in genetics, of the gene that you carry. The two most common
(02:49):
forms of the gene (there are a few much rarer ones) are the tasting form and the non-tasting
form. Each form of the gene codes for a particular taste receptor protein that sits on your tongue.
The two different forms of the gene results in two slightly different proteins that have
different shapes. The shape is important because it determines how strongly it can bind to PTC.
(03:17):
So, you inherit one copy of this gene from your mum and one from your dad, so depending on which
version you got from each, this will affect how you taste this bitterness or not. If both your mum
and your dad have given you the tightly binding version, you’ll taste strong bitterness from PTC.
(03:40):
If both parents have given you the version that doesn’t bind well to PTC you won’t taste much of
anything unless it’s at high concentration. If one parent gave you the strong binding version
and the other gave you the other version then you’ll taste the bitterness, just not as strongly.
So why is this interesting? Okay, so while you don’t find PTC in nature,
(04:05):
the ability to taste it does correlate with the ability to taste bitter substances that
ARE found in nature, such as in brussel sprouts, broccoli, and cabbage. So,
it generally correlates with whether you find these foods bitter or not.
In addition to this, it’s known that some of the bitter substances
(04:26):
that do occur in nature are toxins.
So, this ability to taste toxins may have been evolutionarily a good thing, to stop ourselves
from eating poisonous plants and getting sick or, worse, munching something that could kill us.
It’s important to say that we know all this this isn’t quite so simple. For example,
(04:50):
we know that scientists found that some people, with a non-taster version of the
gene, were able to taste a different bitter compound that the PTC tasters couldn’t taste.
We know humans have about 30 genes that are coding for receptors that are for bitter taste,
with each receptor being able to bind with several different molecules,
(05:12):
which means people can taste a wide variety of bitter substances.
We also know that what you’ve eaten or drunk, before PTC testing, can affect your
ability to taste PTC and that taste sensitivity can change over time,
so presumably that’s the same for foods as well.
(05:33):
But bearing all that in mind, we do know that genetics has a role to play in being able to
taste bitterness– and so that may be why you don’t fancy eating all those brussel sprouts at dinner.
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