MSG in food
What is MSG?
MSG stands for monosodium glutamate and is the sodium salt of an amino acid called L-glutamic acid. Glutamic acid is one of the most abundant amino acids found in nature and exists both as free glutamate and bound with other amino acids into protein. Glutamate is synthesised by the body and plays an essential role in human metabolism.
MSG is produced through fermentation processes using molasses from sugar cane or sugar beet, as well as starch hydrolysates from corn, tapioca and other sources. It is typically produced in crystalline form.
Why is MSG added to foods?
In the early 1900s, free glutamate was found to have a flavour enhancing effect when present in foods. MSG is commonly used in Asian cultures where it is recognised as having a unique taste called umami. Roughly translated, umami means 'savoury deliciousness'. Since being recognised as a flavour-enhancing compound, its use in Western cultures has become more commonplace.
How MSG enhances the flavour of foods is not yet fully understood. Many scientists believe that MSG stimulates glutamate receptors in the tongue to enhance meat-like flavours.
Which foods contain MSG?
Glutamate occurs naturally in virtually all foods, including meat, fish, poultry, breast milk and vegetables. In general, protein-rich foods - such as breast milk, and meat - contain large amounts of bound glutamate, whereas vegetables and fruits (especially peas, tomatoes, and potatoes), mushrooms and certain cheeses (eg. Parmesan) tend to contain high levels of free glutamate. It is the free glutamate in foods, such as cheese and tomato, which contributes to their flavour enhancing effects when used in cooking.
Foods, such as fermented and hydrolysed protein products (eg. soy sauce, vegemite), can also contain large amounts of free glutamate. Various processed and prepared foods, such as traditional seasonings, stocks, sauces, canned soups, can therefore contain significant levels of free glutamate, both from natural sources and from added MSG.
In addition, MSG may be added during food preparation by certain restaurants and other food outlets. The amount of MSG added can vary, but in addition to being added during preparation, MSG is sometimes also added at the time of serving to further season the dish. This can result in significant quantities of MSG being present in a single meal.
Is MSG safe?
The overwhelming evidence from a large number of scientific studies is that MSG is safe for the general population at the levels typically incorporated into various foods. This has been confirmed by a number of expert bodies.
While a small percentage of the population may experience a mild hypersensitivity-type reaction to large amounts of MSG when consumed in a single meal, there is no convincing scientific evidence that MSG is responsible for causing more serious adverse reactions such as the allergic reactions experienced by some people in response to peanuts, or the triggering of asthmatic attacks such as experienced by some asthmatics in response to sulphites.
How does MSG affect people?
Most people are unaffected by MSG but evidence indicates a few people may experience a mild hypersensitivity-type reaction when a large quantity of MSG is consumed in a single meal.
The types of symptoms experienced in response to large amounts of MSG may vary from person to person, but can include headache, numbness/tingling, flushing, muscle tightness, and generalised weakness. These reactions, while unpleasant, tend to be transient and do not produce any long-lasting effects, and are quite distinct from the more serious allergic reactions experienced by some people in response to certain foods, such as peanuts.
What proportion of the population is affected?
Some studies have estimated that the complex of symptoms described above may occur in about 1% of the population following a meal. However it is not clear what proportion of these can actually be attributed to MSG because the vast majority of reports are anecdotal and not linked to the actual MSG content of the food consumed. The actual percentage of the population affected is therefore likely to be less than 1%.
How can I tell if a food contains MSG?
When MSG (or other glutamates) is deliberately added as a flavour enhancer, it must be listed in the ingredientsof packaged foods. A manufacturer may either declare the presence of MSG specifically by name simply declaring it as 'flavour enhancer' with the food additive code number following in parentheses. Glutamates are identified by the food additive code numbers 621 to 625 inclusive, with MSG being identified as 621.
A number of other ingredients typically added to savoury foods may also be significant sources of MSG. These are listed as 'autolysed yeast extract', 'hydrolysed vegetable protein (HVP)', 'sodium caseinate' or 'natural flavourings'.
MSG does not have to be specifically declared for food purchased in restaurants and other food outlets but you can ask the staff. Some food outlets voluntarily provide advice on MSG absence in meals via menus or signage.
What should I do if I think I'm sensitive to MSG?
If you suspect that you might be reacting to MSG, you should confirm this through an appropriate clinical assessment. You should seek advice from your GP or an accredited practising dietitian who should be able to advise you on how to go about getting an assessment done. Specialist clinics in most States and Territories and in New Zealand undertake such assessments.
Remember, though, that foods are complex mixtures of ingredients. While you may suspect MSG, it may in fact be some other ingredient which is causing the problem, in which case you may be unnecessarily avoiding MSG-containing foods. Proper assessment should help to confirm this one way or the other.
If a suspected sensitivity to MSG is confirmed, the next step will be to obtain appropriate dietary advice to ensure that you are aware of all sources of MSG in foods - and which ones are best avoided.
What is FSANZ's advice to restaurants?
Consumers who may experience adverse reactions to MSG can be understandably cautious about eating in restaurants and other food outlets because they must rely on the staff to provide them with correct advice about the MSG content of food. If incorrect advice is provided, the consequences can be quite unpleasant for the affected person.
Food outlets should be aware of the public concerns in relation to MSG. They should also be in a position to provide accurate advice to their customers. The use of MSG should be reviewed, as reducing the amounts used may limit the occurrence of adverse reactions.
Clinical studies have shown that sensitive individuals may react to MSG in single doses greater than 3g. Therefore one way to limit the occurrence of these types of reactions may be to reduce the amount of MSG that is being added to food.
The concentration of MSG giving the best flavour enhancement is between 0.2 - 0.8% by weight of the food, therefore it may be possible to reduce the amount of MSG being added without compromising on the flavour or taste of the food. MSG used in excess of 0.8% tends to decrease the palatability of the food. The largest palatable dose for humans is about 60mg/kg body weight - for a 70kg individual, this equates to about 4.2g in a single meal.
In reviewing the amount of MSG that is added, it is important to take account of not only any crystalline MSG that is added but also other sources of MSG such as stocks, sauces (soy sauce, fish sauce), premixes, etc. These will all contribute to the MSG load of the meal.
In terms of providing advice to customers about the MSG content of foods, care should be taken to inform the customer of all potential sources of MSG. Consumers who are sensitive to MSG, not only need to know if crystalline MSG has been added, but also if MSG-containing ingredients (such as stocks and sauces) have been used.
Can restaurants make MSG-free claims?
MSG-free claims (also known as negative claims) are permitted under food law, provided they are not false, misleading or deceptive.
Many restaurant patrons who wish to avoid consuming foods that contain MSG may find such claims useful because it saves them from having to ask about the MSG content of foods when dining out. In certain circumstances, however, such claims also have the potential to be misleading and so restaurants and food outlets should take care when making such claims.
In determining if a negative claim is false, misleading or deceptive, consideration must be given not only to the technical accuracy of the claim but also to the overall impression created by the claim.
Vendors should consider how the claim would be interpreted in the context of that particular food. For example, if a claim is made that a soup contains 'no added MSG', consumers would expect that it contains no added MSG irrespective of whether the MSG was added directly to the soup or as part of another ingredient of the soup (eg. a stock). The claim would also mean that the soup should not contain any ingredients that contain MSG added at manufacture, such as flavouring premixes.
As MSG may occur naturally in some foods, vendors should make sure that consumers are aware of this fact. For example, a 'no MSG' representation on a tomato-based product would be false because tomatoes naturally contain MSG. Also, a claim of 'no added MSG' on the same product, while technically accurate, may be potentially misleading or deceptive because many consumers, unaware that MSG occurs naturally in tomatoes, could interpret the claim as being the same as 'no MSG'.