This came to light recently when I published an article about autolyzed yeast extract containing MSG, and I was contacted by the manufacturer of a popular veggie burger product who claimed that my article was incorrect, that their product didn't contain MSG, and that they used nothing but all-natural ingredients. I replied by reading their PR person the list of ingredients printed right on their own box (which included autolyzed yeast extract), then I showed them documentation supporting the fact that autolyzed yeast extract always contains MSG, and that autolyzed yeast extract is used for only one purpose in manufactured foods: as a chemical taste enhancer. It has no other purpose in the realm of food science.
At this point the spokesperson for this veggie burger manufacturer admitted that, yes, their product did contain free glutamic acid, which is another way of saying MSG, but that it was from an all-natural source, and that there are other foods like seaweed or tomatoes that have free glutamic acid. To this, I replied that, sure, tomatoes have a very small quantity of naturally occurring free glutamic acid, but that's different. What the veggie burger manufacturer is doing is using an MSG ingredient in a concentrated, refined form that greatly increases the potency and the potential toxicity of the ingredient. In my book, that's not natural.
Claiming MSG is natural because free glutamic acid appears in tomatoes is sort of like saying cocaine is natural because it's derived from ingredients found in the coca leaf. Of course, it's all a matter of potency -- you can take a natural plant like coca and drink coca leaf all day long in Peru without any of the dangerous or addictive effects of cocaine. And if you're hiking in the Andes, you'll be very glad you did drink coca leaf tea, because trying to keep up with the locals (who scramble up steep hillsides as easily as strolling down a paved sidewalk) is nearly impossible without some invigorating help from the local plants.
Coca leaf tea is not a hard drug, but when you take the active constituents of the coca tea and you refine them into a highly concentrated format, then you get cocaine. That's when it becomes a problem. The same thing is true with MSG. If you're eating seaweed, that's not a problem for your health; in fact seaweed is very good for you and it's now shown to actually prevent and even help treat cancer. But if you take MSG out of seaweed or you synthesize MSG and put it into a highly concentrated form, then it functions as a neurotoxin -- that's why it's called an excitotoxin by Dr. Russell Blaylock, who is perhaps the world's foremost authority on MSG and other excitotoxins such as aspartame.
Similarly, whole grain corn is a healthful, nutritious food. But when you refined that corn and extract the sugars to make high-fructose corn syrup, you now have a blatantly unnatural ingredient that contributes to obesity and type-II diabetes. Yet the corn associations insist that high-fructose corn syrup is "all natural" because it comes from a plant.
The point is that a food manufacturer can take anything that occurs somewhere in nature and refine it to increase the potency by a factor of 1000 times or more, and then claim that their product is "all natural." In other words, if cocaine were legal, they could put crack cocaine in their veggie burgers and call that all natural too. In fact, they can scrounge up just about anything found on the planet, whether it's heavy metals like mercury or arsenic, or refined sugars made from beets or corn, and they can put those in their foods and call it all natural.
Of course, it's all quite ridiculous. By that definition, anything derived from plants, animals or elements found on planet Earth could earn the "all natural" label. The key is in understanding that it's the process that's unnatural, not the source. When you chemically or structurally alter food ingredients into a form that no longer appears anywhere in nature, it's no longer natural, folks. Regardless of what the food manufacturers claim.
So don't believe food claims -- even from natural product manufacturers -- that state they are "all natural" unless you also verify what's on the ingredients label. And if it has yeast extract, or autolyzed yeast extract, or hydrolyzed vegetable protein or any of these other ingredients that actually harbor MSG, then it is, in my opinion, a deceptively positioned product, because it claims to be natural but in fact uses highly potent refined extracts that don't occur anywhere near that concentration in nature.
You'll see a much more detailed discussion of all this in my upcoming book, "Grocery Warning," due out shortly.