24 | New Scientist | 22 February 2020
F
OOD fads come and go.
One minute, kale smoothies
are the elixir to everything
that ails you, the next it is ultra-
low-carb lard and offal. But what
if the real solution was far more
traditional? Meet the latest
trend: the “ancestral diet”.
Proponents of the diet say
research shows that people have
genetic adaptations – such as
lactose tolerance – to what would
have been their traditional diets.
Therefore, a personalised diet,
based on what our families ate
in centuries past, could be the
secret to good health.
All modern health conditions,
they say, can be attributed to the
mismatch between our current
diets and our genes. For example,
it is claimed that Asia has gone
from one of the lowest rates of
chronic disease to the highest
in just one generation, due to
increasingly Westernised diets.
So the recipe for a long and
healthy life is simple: we just need
to look at historical cookbooks for
what our genetic ancestors ate
500 years ago. Definitions vary, but
the general idea is that Europeans
should eat a wheat-based diet with
plenty of dairy, whereas Asians
should have a rice-based diet, rich
in vegetables and tiny amounts
of protein like fish sauce.
As an ethnobotanist, I am
fascinated by traditional diets,
but I must admit I would find
this advice hard to follow. Being
half-Bornean and half-Welsh, my
ancestral diet is rather harder to
pinpoint. Following this advice
would mean a diet that blends,
I guess, rice and wheat as a primary
energy source, with probably an
awful lot of millet and sago palm.
Protein and fats would probably
come from a significant dairy and
beef component, but also bush
meat like pangolins and bats –
which my Malaysian family atejust two generations ago – and if
we go back another century or two
in Borneo, possibly a bit of human
as well. This may sound facetious,
but it can be the reality of trying
to apply these principles.
Putting aside the questionable
ethics of eating pangolins or
people, nutritionally these diets
also aren’t a great idea. Although
these are extreme examples, the
diets of people in 16th-century
Wales probably aren’t to be envied
either. My family were likely to
have lived lives of abject poverty
characterised by frequent periods
of famine. Oh, and that advice
of just looking at old cookbooksdoesn’t help much when you
discover they were essentially
all written for the 16th-century’s
super rich. It would be like basing
a typical 21st-century diet on a
menu found on a private jet.
Another problematic aspect of
this advice is that it is predicated
on the modern assumption that
the lack of obesity and diet-related
degenerative diseases of the past
automatically means we were
once much healthier. By almost
any objective measure, we weren’t.
It is true there is now a higher
age-adjusted mortality from
cardiovascular disease in much
of Asia, but the same period has
also seen some of the greatest
reductions in malnutrition
on Earth in the region. In 1961,
East Asia had the lowest per
capita calorie availability of
anywhere on the planet, which
has subsequently rocketed more
than three-fold in a few shortdecades, resulting in an 80 per
cent reduction in nutrient
deficiencies. I can’t help but
think that my ancestors would
take a slightly higher risk of heart
disease over lifelong nutrient
deficiency any day.
Another problematic pillar on
which this movement rests is the
idea that humans have perfectly
adapted to their traditional food
sources. Although there is good
evidence that certain populations,
such as the Maasai in Kenya and
Tanzania, have evolved the ability
to better digest lactose because
of the selective pressure of a long
history of dairy consumption,
this is far from a universal rule.
Research into the plaque
build-up on teeth has
demonstrated, for example, that
the dairy-rich diet of Mongolia can
be traced back at least 3000 years
despite 95 per cent of Mongolians
still being lactose intolerant.
Traditional diets actually tend to
reflect the availability of certain
food types, far more than they do
their value to human nutrition.
For me, the trickiest thing
about this nutritional approach is
that it requires that people can be
neatly labelled in boxes and
assigned an “ideal” way of eating
on that basis. The idea that you
can generalise the “typical” diet
of a single country, let alone an
entire incredibly diverse continent
like Europe or Asia, to a small
set of prescriptive rules
inevitably means one falls back
on unhelpful stereotypes.
While the research into genetic
adaptations to diet is to me
endlessly fascinating, translating
this into a simple set of dietary
rules is fraught with difficulty.
Not least because, as most of us
are really genetic mishmashes,
like me, it seems that the
exceptions might just be
more common than the rules. ❚This column appears
monthly. Up next week:
Chanda Prescod-Weinstein“ Putting aside the
ethics of eating
pangolins or people,
nutritionally these
diets also aren’t
a great idea”Eat like your ancestors? There is a new diet trend in town –
eat what your family ate 500 years ago. Following the diet,
however, is more difficult than it sounds, writes James Wong#FactsMatter
What I’m reading
My Twitter feed, a bunch
of journals and stacks
of scripts.What I’m watching
An awful lot of
in-flight movies.What I’m working on
A new BBC wildlife
comedy show for Radio 4
and a TV series on global
farming.James’s week
James Wong is a botanist and
science writer, with a particular
interest in food crops,
conservation and the
environment. Trained at the
Royal Botanic Gardens, Kew, he
shares his tiny London flat with
more than 500 houseplants.
You can follow him on Twitter
and Instagram @botanygeekViews Columnist