Yeast Extract
<p>Since <a href="http://en.wikipedia.org/wiki/Glutamates" title="Glutamates" class="mw-redirect" >glutamates</a> are important <a href="http://en.wikipedia.org/wiki/Neurotransmitters" title="Neurotransmitters" class="mw-redirect" >neurotransmitters</a> in the human brain, playing a key element in learning and memory, there is ongoing study by <a href="http://en.wikipedia.org/wiki/Neurologists" title="Neurologists" class="mw-redirect" >neurologists</a> about possible side-effects of MSG in food but no conclusive studies drawing any connections.<sup id="cite_ref-twsNovK8d_27-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Monosodium_glutamate#cite_note-twsNovK8d-27" >[28]</a></sup></p>
<p>
Monosodium glutamate (MSG) is one of several forms of glutamic acid found in foods, in large part because glutamic acid, being an amino acid, is pervasive in nature. </p>
<p>
Glutamic acid and its salts can also be present in a wide variety of other additives, including <a href="http://en.wikipedia.org/wiki/Hydrolyzed_vegetable_protein" title="Hydrolyzed vegetable protein" class="mw-redirect" >hydrolyzed vegetable protein</a>, <a href="http://en.wikipedia.org/wiki/Autolyzed_yeast" title="Autolyzed yeast" class="mw-redirect" >autolyzed yeast</a>, <a href="http://en.wikipedia.org/wiki/Hydrolyzed_yeast" title="Hydrolyzed yeast" class="mw-redirect" >hydrolyzed yeast</a>, <a href="http://en.wikipedia.org/wiki/Yeast_extract" title="Yeast extract" >yeast extract</a>, <a href="http://en.wikipedia.org/wiki/Soy" title="Soy" class="mw-redirect" >soy</a> extracts, and protein isolate, which must be labeled with these common and usual names. Since 1998, MSG cannot be included in the term "spices and flavorings". </p>
<p>
The food additives <a href="http://en.wikipedia.org/wiki/Disodium_inosinate" title="Disodium inosinate" >disodium inosinate</a> and <a href="http://en.wikipedia.org/wiki/Disodium_guanylate" title="Disodium guanylate" >disodium guanylate</a>,
which are <a href="http://en.wikipedia.org/wiki/Ribonucleotides" title="Ribonucleotides" class="mw-redirect" >ribonucleotides</a>, are usually used in synergy with monosodium glutamate-containing ingredients. </p>
<p>
However, the term "natural flavor" is now used by the food industry when using glutamic acid (which is similar to MSG, lacking only the sodium ions)<sup class="Template-Fact" >[<i><a href="http://en.wikipedia.org/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed" >citation needed</a></i>]</sup>. </p>
<p>
Due to lack of FDA regulation, it is impossible to determine what percentage of "natural flavor" is actually glutamic acid<sup class="Template-Fact" >[<i><a href="http://en.wikipedia.org/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed" >citation needed</a></i>]</sup>.</p>
<p>
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. </p>
<p>
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.</p>