straight from wikipedia:
Health concerns
Main article: 
Glutamic acid (flavor)#Research into health effects
MSG as a food ingredient has been the subject of health studies. A
report from the Federation of American Societies for Experimental
Biology (FASEB) compiled in 1995 on behalf of the 
United States Food and Drug Administration (FDA) concluded that MSG was safe for most people when "eaten at customary levels". However, it also said that, based on 
anecdotal reports, some people may have an MSG intolerance which causes "MSG symptom complex" and/or a worsening of 
asthmatic symptoms.
[11]
Subsequent research found that while large doses of MSG given without
food may elicit more symptoms than a placebo in individuals who believe
that they react adversely to MSG, the frequency of the responses was
low and the responses reported were inconsistent, not reproducible, and
were not observed when MSG was given with food.
[12] While many people believe that MSG is the cause of these symptoms, a 
statistical association
has not been demonstrated under controlled conditions, even in studies
with people who were convinced that they were sensitive to it.
[12][13][14][15] Adequately controlling for experimental bias includes a 
placebo-controlled double-blinded experimental design and the application in capsules because of the strong and unique after-taste of glutamates.
[13]
[
edit] United States
Monosodium glutamate is one of several forms of glutamic acid found
in foods, in large part because glutamic acid is pervasive in nature,
being an amino acid. Glutamic acid and its salts can also be present in
a wide variety of other additives, including 
hydrolyzed vegetable proteins, 
autolyzed yeast, 
hydrolyzed yeast, 
yeast extract, 
soy extracts, and protein isolate, any one of which may appear as "spices" or "natural flavorings". The food additives 
disodium inosinate and 
disodium guanylate
are usually used along with monosodium glutamate-containing
ingredients, and provide a likely indicator of the presence of
monosodium glutamate in a product. For this reason, the FDA considers
labels such as "No MSG" or "No Added MSG" to be misleading if the food
contains ingredients that are sources of free glutamate, such as
hydrolyzed protein.
In 1993, the FDA proposed adding the phrase "(contains glutamate)"
to the common or usual names of certain protein hydrolysates that
contain substantial amounts of glutamate.
In the 2004 version of his book, 
On Food and Cooking, food scientist 
Harold McGee
states that "[after many studies], toxicologists have concluded that
MSG is a harmless ingredient for most people, even in large amounts".
[
edit] Asia
The INTERMAP Cooperative Research Group conducted a study of 752
healthy Chinese (48.7% women), age 40–59 years, randomly sampled from
three rural villages in north and south China and determined that MSG
intake may be positively correlated to an increased BMI (
Body Mass Index).
[16]
[
edit] Australia and New Zealand
Standard 1.2.4 of the Australia and 
New Zealand
Food Standards Code requires the presence of MSG as a food additive to
be labeled. The label must bear the food additive class name (e.g. 
flavour enhancer), followed by either the name of the food additive, 
MSG, or its 
International Numbering System (INS) number, 
621.
i would say there are better things to worry about