New Scientist - USA (2021-02-27)

22 | New Scientist | 27 February 2021

D

URING my master’s

degree, I lived high up in

the mountains of rural

Ecuador, studying the practices

of traditional Andean medicine.

I was fascinated by beliefs of

culturally specific syndromes,

like susto, thought to be caused

by spiritual attack, resulting

in insomnia, depression and

anorexia, or mal de ojo, in which

a stare from another person

can cause severe fever, diarrhoea

and even death in children.

What always stood out when

I asked about the basis of these

ideas was that the explanations

seemed far-fetched to me but

common sense to them. That is

the thing about culture: to the

people enveloped in it, even beliefs

that defy explanation can seem

like unquestionable reality. Ours

is, unsurprisingly, no exception.

To illustrate this, let’s look at

the evidence supporting what

is arguably one of the West’s

culturally specific syndromes:

“Chinese restaurant syndrome”.

Coined in the US in the 1960s,

it describes a constellation of

symptoms such as numbness,

palpitations and nausea that are

thought to occur after consuming

the food additive monosodium

glutamate (MSG), often associated

with East Asian restaurants. This

belief is so pervasive that it has

been propagated in bestselling

books, espoused on blogs and

has even led many restaurants to

advertise food as “MSG free” to

avoid a backlash. So what could be

behind this worrying reaction?

Well, as I found when talking

to Andean communities, the

exact explanation for beliefs

can vary dramatically depending

on who you ask. Some cite the

fact that MSG doesn’t exist

in nature, others its synthetic

means of production, or even

its “unpronounceable” scientific

name. Still others cite the fact

that scientific trials clearly prove

its toxicity. However, perhaps

surprisingly, when we look at

the evidence, none of these

“facts” is really a fact.

While it is true to say that

since as early as 1969 studies have

reported startling symptoms such

as stunted skeletal development,

marked obesity and female

sterility associated with MSG,

it is crucial to consider the

design of these studies. You might

be forgiven for thinking that

scientists set up a clinical trial,

in which they fed unfortunate

volunteers MSG-laced food and

witnessed the terrible effects.

This wasn’t the case. These studies

actually involved doing things like

injecting enormous doses of the

compound into newborn lab mice.

Many harmless compounds found

in all sorts of foods, including

key nutrients, would probably

show similarly undesirable

outcomes in a similar set up.

If you take such poor-quality

studies out of the equation, and

focus on human clinical trials,

you are presented with a different

picture. One of the earliest was

carried out in the 1990s, on a

small group of people who self-

identified as experiencing MSG

sensitivity. They were fed randomly

assigned meals with varying levels

of MSG, including a placebo, and

then asked about their reactions.

Around 36 per cent of them did

indeed report these effects after

a meal containing a threshold of

about 2.5 grams of MSG. However,

around 30 per cent of them

had no reaction to any meal,

including placebo. A difference

of 30 per cent to 36 per cent can

still be statistically significant

with enough participants, but in

this study we are only comparing

18 people with 22.

How much MSG is there in a

typical serving of food containing

the compound? According to the

US Food and Drug Administration,

0.5 grams, meaning that to get the

results in the study, you would have

to eat five times the average serving

in one go. Even in countries like

Japan, where daily consumption

of MSG is among the highest on

the planet, the amount eaten daily

has been estimated at between

1.2 and 1.7 grams. I am game for

the experiment of eating two days’

worth of Japanese food in one

meal, but even for me that might

be hard to achieve.

What of concerns about the

“synthetic” nature of this food

additive? Well, in actuality, MSG

is naturally found in all sorts

of foods eaten in the West, like

cheese and tomatoes. In fact,

the glutamic acid, the alleged

problematic component, is even

produced by our own bodies.

The MSG in food additives

is made by fermenting plant

extracts like tapioca or sugar-cane

molasses using naturally

occurring bacteria, which makes

calling it “synthetic” a stretch.

So does Chinese restaurant

syndrome count as a culturally

bound syndrome? Well, although

the scientific consensus is pretty

resounding, it is also fair to say

that the studies to date are few

in number and, in some instances,

contradictory. Indeed, many food

intolerances once dismissed on

the basis of poor evidence are

now being taken more seriously.

So I, for one, can’t wait to learn

what new evidence turns up. ❚

This column appears

monthly. Up next week:

Chanda Prescod-Weinstein

“ This belief is so

pervasive it has

even led many

restaurants to

advertise their

food as ‘MSG free’ ”

The truth about MSG Monosodium glutamate is eaten without

problems in many countries, yet in the West there is a strange

cultural aversion to it. James Wong investigates what’s going on

#FactsMatter

What I’m reading

The largest pile

of seed catalogues

in the universe.

What I’m watching

I know I am late to the

party, but Schitt’s Creek

is my essential antidote

to troubled times.

What I’m working on

I have just released

an online houseplant

course, which is, to

be honest, a flimsy

justification for living

with 500 houseplants.

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 @botanygeek

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