34 | New Scientist | 25 July 2020
delicious, but the reactions also produce the
compound acrylamide, which is a probable
human carcinogen. Cooking and processing
nutritional dark matter could produce
similar, but unknown, toxins, says Barabási.
Our metabolisms get to work on
nutrients, too, adding yet more complexity.
“Food compounds are often chemically
transformed by various enzymes in the
mouth, stomach and the intestine,” says
Wishart. “As a result, many of the dark
nutrients are biotransformed into a variety
of smaller, stranger metabolites that then
recirculate back into the blood and other
tissues. These biotransformed dark nutrients
are the ones that really have the more
significant health effects.”
There are also the myriad chemicals added
during food processing. What happens to
them when they encounter our metabolisms
and microbiomes is unknown.
And if just identifying the compounds in
food is a challenge, working out how they
interact with human biology is an even
bigger one. “Ultimately, we need to connect
all the food molecules to their molecular
effects in the human cell,” says Barabási.
That, too, requires laborious lab work.
Once again, new computational
techniques can do the heavy lifting. Over
at the USDA, for example, a team led by
Parnell is developing a way of using artificial
intelligence to predict how dietary dark
matter acts once we have eaten it.
Its system, called PhyteByte, cross-
references FooDB with another database
called ChEMBL. This is an inventory of
1.9 million compounds known to have
some sort of biological effect, maintainedby the European Bioinformatics Institute
near Cambridge, UK.
For a pilot project, the team wanted
to see whether the tool could figure out
which compounds in FooDB might activate
a protein that is involved in fat and glucose
metabolism, and therefore could be of
interest in treating diabetes.
When the AI was set loose to scour FooDB
for compounds that are also likely to interact
with the protein, it got 10 hits. Two of these
compounds were already known to act
on the protein. But the other eight weren’t,
including sesamin from sesame seeds, a
flavone called irigenin from lima beans and
compounds from tea, herbs and spices. It
will take time, says Parnell, but it should be
possible to eventually assess the biological
activity of all 70,000 compounds in FooDB.
Ultimately, says Barabási, the goal is to
build a complete picture of the interplay
between nutrients and human health. That is
a colossal undertaking that requires yet more
data on individuals’ genomes, microbiomes
and other factors, but it is the only way for
us to truly understand the complexities of
human nutrition and health. “So much to
do,” he says. “But we’re making progress.”
The Korean noodles are still in my kitchen
cupboard, and I don’t think I will be eating
them any time soon. I never kidded myself
that they were a health food. But I don’t want
to go over to the nutritional dark side. ❚MANOA/GET
TY
IMAGESGraham Lawton is a New
Scientist feature writerGarlic
crush
Researchers are hunting down
tens of thousands of untracked
“dark nutrients” in food
(see main story), but why do
we need to know about what
we eat in such fine detail?
To get an idea, let’s talk about
steak and garlic. Gut bacteria
break down a substance in red
meat to produce a compound
called trimethylamine (TMA).
This is then absorbed and
transported to the liver, which
converts it into trimethylamine
N-oxide (TMAO). High levels of
TMAO in the bloodstream are
linked to significantly higher
death rates from coronary
heart disease. But one of
garlic’s flavour molecules,
allicin, is known to inhibit TMA
production. This may be one
reason why the garlic-rich
Mediterranean diet protects
against heart attacks. Allicin
has also been reported to have
anticancer properties, while
another component of garlic,
luteolin, which isn’t in the
standard database of food
compounds produced by the
US Department of Agriculture,
also seems to protect against
cardiovascular disease.Raw garlic is
now known to
contain more than
2000 compounds,
some of which can
boost our health