Surprising glutamate judgement


Chinese food often contain MSG

Yes, I am surprised by the European Food Safety Authority’s (EFSA’s) 2017 verdict on glutamate. As it happens I was involved in an assessment of glutamate in the mid 2000’s. At the highest government level in New South Wales (Australia) illness was claimed after consuming a Chinese meal containing glutamate. This led to a heated debate in the Parliament. Of course, being responsible for food safety in the state, we got ordered to investigate. And so we did read the available literature and reviewed testimonial websites.

Our conclusions didn’t please the politicians much. Although we found plenty of websites with testimonial evidence of even near death experiences after consuming meals with glutamate, no clear evidence of ill effects could be ascertained from the scientific literature. Naturally, the Glutamate Association, an industry funded organisation, on their website attempted to balance negative opinions by claiming that glutamate was the most natural substance you could find.

Glutamic acid is a naturally occurring amino acid

It is true that glutamic acid is a naturally occurring substance in some foods. Glutamic acid is a non-essential amino acid, a building block of proteins, naturally produced in humans and occurring in free form in tomatoes, soy sauce, cheeses (Parmesan in particular) and some other foods. Glutamic acid and its different salts, commonly referred to as glutamates, are also authorised food additives in many countries. They are added to a wide range of foods to enhance their flavour by giving them a “savoury” or “meaty” taste. The most commonly known salt is monosodium glutamate or MSG.

Glutamic acid is the most abundant free amino acid in the brain and functions as an excitatory or stimulating neurotransmitter. It also serves as an important potential energy source. When the glucose concentration in the brain is low, the brain mobilises glutamate. So it is actually quite useful.

Toxicity of glutamic acid/glutamate

Previous evaluations of glutamic acid/glutamates have in the main found little evidence of consistent toxic effects. There is some evidence that experimental ingestion of large amounts (≥3g) of glutamate salts in the absence of food may provoke some symptoms in humans that, although unpleasant, are neither persistent nor serious. However, there is little evidence that those effects occur in the presence of food, the real life situation.


JECFA meeting to discuss food safety

Thus, at its meeting in February 1987, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) stated that glutamate salts were of low toxicity and did not constitute a health hazard as a result of their natural presence in food or use as flavouring agents. Meeting in May 1990, the European Union Standing Committee for Food also judged that the natural occurrence of glutamate in food and its use as a food additive did not present a hazard to health. In its 2003 review, Food Standards Australia New Zealand (FSANZ) concluded that there is no convincing evidence that MSG is a significant factor in causing systemic reactions resulting in severe illness or mortality.

The previous opinions were again supported by JECFA when, in its latest evaluation in 2004, it maintained the previously established ‘not specified’ group Acceptable Daily Intake (ADI) for glutamic acid and its salts. Equally, the Select Committee on GRAS Substances (SCOGS) of the US Food and Drug Administration in 2015 confirmed that glutamic acid and its salts posed no reasonable hazard when used at current levels and practices.

Surprising change of view

In the EU the addition of glutamates is generally permitted up to a maximum level of 10 g/kg of food. In salt substitutes, seasonings and condiments, there is no numerical maximum permitted level for glutamates, but they must be used in line with good manufacturing practices.

This might change after EFSA re-assessed the safety of glutamates used as food additives and derived a group Acceptable Daily Intake (ADI) of 30 mg/kg body weight (bw) for six glutamate salt additives. This safe level of intake was based on the highest dose at which scientists observed no adverse effects in animal toxicity studies.

EFSA also concluded that estimated dietary exposure to glutamic acid and glutamates may exceed not only the safe level, but also doses associated with adverse effects in humans for some population groups. On this basis, EFSA’s experts recommended reviewing the maximum permitted levels for these food additives.

So what’s behind the change of mind

Many animal studies of the effects of glutamate have included too few animals or shown conflicting results. Thus, EFSA in reviewing the scientific literature found no consistently reported adverse effects in available short-term, subchronic, chronic, reproductive, developmental, genotoxicity and carcinogenicity studies.

So far so good.


Delayed swimming development

However, dietary neurodevelopmental toxicity was identified in several mouse and rat studies, some of limited quality. One study was adequate showing delayed early swimming development, diminished rearing frequency in the open field, altered active avoidance acquisition and prolonged passive avoidance retention caused by MSG.

Not so good.

Peculiar as the effects might sound, this study was used to set a dose of 3,200 mg MSG/kg bw per day as safe based on the absence of neurobehaviour effects which occurred at higher doses (a NOAEL – or no-observed-adverse-effect-level).

Toxicologist normally use an uncertainty factor of 100 when translating results from animal studies to humans giving the 30 mg/kg bw per day calculated as glutamic acid as an acceptable intake after rounding.

The study on which EFSA based its recommendations is not new as it was published in 1979 and available to all previous reviews cited above. It can only be assumed that EFSA considered also human findings where glutamate has been associated with the MSG symptom complex (> 42.9 mg/kg bw per day), headache (85.8 mg/kg bw per day), blood pressure increase (150 mg/kg bw per day) and also insulin increase (> 143 mg/kg bw per day).

None of these findings were robust enough on which to base calculation of an ADI. But the selected animal study allowed calculation of an ADI that would be protective for any of the reported human findings.

Are we safe now?

Good question and unfortunately the answer is no looking at the provided exposure assessments.

When EFSA’s scientists (including my good friend Davide Arcella) combined food consumption data with glutamate additive levels in food they found that exposure may exceed the proposed ADI for individuals of all population groups whose diet is high in foods containing these additives, as well as for toddlers and children with medium exposure. Exposure may also exceed doses associated with some adverse effects in humans (e.g. headache) for highly exposed infants, children and adolescents.

EFSA’s experts also considered other dietary sources of glutamate besides food additives (including natural presence and addition as nutrient). They found that exposure estimates largely exceed, in several population groups with medium to high exposure, both the proposed ADI and levels associated with some adverse effects in humans.

What do we do?


Headache part of the MSG symptom complex

For years, consumer concerns about adverse effects of glutamate have been dismissed, but now when EFSA has confirmed possible health effects what should we do to limit the potential impact?

If taken seriously, the proposed ADI might trigger a rush by food manufacturers to remove glutamate additives where possible, but don’t hold your breath.

If agreed by other Government authorities, we might see new maximum use levels proposed and also a reduction of the number of food categories in which these additives are permitted. This might happen first in Europe, but countries outside Europe might await a recommendation from JECFA.

Finally, as a consumer you might find some reassurance in the fact that only 1-2 per cent of the population is considered to be extra susceptible to the adverse effects of high levels of glutamates.

We will see how the world reacts. EFSA has sometimes been criticised for being too lenient (see BPA and glyphosate). This time they have gone the opposite way.