MSG and migraine

What the studies show

The main source is a systematic review of 13 human studies from 10 papers. It asked about headache, not migraine attacks specifically (Obayashi 2016).

Condition	MSG dose	Studies	Result
With food	1.5 to 3.15 g	6	No significant difference, with one exception: women in one study (6 with headache on the MSG day, 1 on the placebo day), with questionable blinding
Without food, in drinks or soup	1.25 to 12 g	7	4 showed a significant difference, 3 did not. One study of 99 men found no difference at any dose

The authors state that the human results are not consistent and that a causal link has not been proven. They attribute much of the inconsistency to poor blinding: above about 2% concentration in a drink, MSG’s taste can be detected, so participants may know what they received.

The review has a declared conflict of interest. The first author works for an MSG manufacturer, and the International Glutamate Technical Committee paid the publication fee.

Where sources differ

• A 2016 narrative review placed MSG dissolved in liquid among the strongest provocation findings for diet, alongside caffeine withdrawal (Martin 2016). This does not contradict the point above: both locate the signal in liquid. They weigh it differently.
• The US Food and Drug Administration considers added MSG generally recognised as safe. It has received reports of headache but says it could never confirm that MSG caused them, and that controlled tests of self-described sensitive people could not trigger reactions consistently. A FASEB report it cites identified mild, short-term symptoms in some sensitive people after 3 g or more without food. The FDA calls more than 3 g without food at one time unlikely.
• ICHD-3 has no separate code for MSG in its outline.
• Cross-sectional data. One study in the 2020 systematic review found chocolate and foods rich in MSG most commonly linked to migraine, but the review rated the overall evidence low (Hindiyeh 2020).
• The Migraine Trust says there is not enough evidence that MSG is likely to be a trigger for most people.

No mechanism is established in these sources.

How to check it in your diary

A diary is a weak test here, and you should know why before you start.

1. Record what you can see. In the US, added MSG must appear on the ingredient panel as monosodium glutamate. Foods that naturally contain free glutamate, and restaurant meals, may give you no figure at all, so a yes or unknown entry is honest.
2. Record the whole meal. A restaurant meal may also change alcohol, meal timing and sleep that night. Those need their own entries.
3. Note the form. The study signal was in drinks and soup taken without food, not in mixed meals.
4. Count meals with no attack.
5. Accept the limit. The studies needed blinding because expectation can affect results, and a diary cannot be blinded.

If your record points to MSG, discuss it with a clinician before restricting your diet. For the general method, see how to test a suspected trigger.