What the evidence says · double-blind trials failed repeatedly
1 · Put the three doses side by side
Natural foods bring far more glutamate each day than the in a meal, which usually holds far less than the 5 g swallowed fasting in trials.The glutamate natural foods bring in each day (mostly locked in protein) is far more than the added to season a meal, and the MSG in a meal is usually far less than the 5 g swallowed on an empty stomach in the trials. The dose that might cause trouble has to meet empty stomach, large amount, and a minority hypersensitive constitution at once.
2 · Fasting dumps the whole dose on a short stretch of wall
On an empty stomach a swallow of water reaches the small intestine quickly, so the whole dose lands on a short stretch of gut wall at almost the same time.Trials used fasting plus a large dose to force a reaction out with maximum effort.
3 · In a meal the same grams make a very different peak
Food pads the stomach and emptying slows, other amino acids compete with glutamate for the same transporters, and absorption spreads over a long stretch.The researchers were not simulating a meal. They were building a condition far more extreme than eating.
4 · Even amplified, it still barely shows up
Blinded and fasting, people who believed they react to took 5 g and showed only inconsistent, unreproducible reactions, and no such reaction when MSG came with food.Geha 2000, a multicenter trial, enrolled 130 people who believed they react to and gave 5 g of MSG and placebo, blinded, on an empty stomach. With the large fasting dose a few more people reported symptoms than on placebo, though plenty also felt unwell on placebo; the same person often did not react the same way on retest, and no such reaction was seen when MSG came with food. If even an amplified condition forced out only inconsistent, unreproducible reactions, a real table is even less likely to be the cause.
Mechanism
MSG — a fasting peak is not a meal
Trials dump the whole dose on an empty stomach; a meal makes a different peak.