By Stephanie Vilendrer

When was the last time you drank a diet soda, ate a frozen pizza, or opened a can of tomato soup? If it wasn’t organic, you almost certainly consumed either monosodium glutamate (MSG) or aspartame.
Despite the fact that these two common food additives have been unregulated in the U.S. for over two decades, evidence shows that they are addictive and harmful for your health. MSG and aspartame may be to blame for issues ranging from anxiety and depression to headaches and seizures.
Think that “diet” marketed foods are healthy? Ironically, you are likely sabotaging your weight loss efforts if you are consuming these products. Foods containing aspartame or MSG pose a serious health risk, so it’s important to know which foods to avoid to better protect your health.
Aspartate and glutamate (the main components of MSG) are naturally-occurring amino acids that are essential for neurotransmission, the firing of nerve cells. However, in high enough doses, these amino acids can have detrimental effects on the brain by over-stimulating neural cells and causing cellular damage and even death. This is why aspartate and glutamate are “neurotoxins.”
An initial study conducted by neuroscientist Dr. Hayaski found that when glutamate was injected into the brain of dog, it would fall down and convulse wildly. Consuming excessive amounts of either amino acid has been linked to neurological disorders, memory loss, behavioral and emotional issues, depression, anxiety, blindness, seizures, headaches, muscle cramps or numbness, impaired mental development and even infertility.
The brain has mechanisms to protect itself from the damaging effects of neurotoxins, but they aren’t always effective. Glial cells that surround neurons closely regulate the amount of aspartate and glutamate present in the fluid space that surrounds neurons. This is accomplished by amino acid transport across the blood-brain barrier, which separates the brain from toxic substances that circulate in the bloodstream. Amino acids compete for transport across the barrier, which helps to control the amount of any single amino acid in the brain’s tissues.
When consuming meat, for example, the amino acids are presented in chains of 80 to 300 different components, and so the concentration of glutamate or aspartate is held in check by other competing amino acids. However, in foods that are exceptionally high in glutamate or aspartate, or that lack the presence of other amino acids (such as in diet sodas), protection conferred by the blood-brain barrier is lost. Additionally, the barrier may break down with age and some parts of the brain have no protection at all.
Consuming too much glutamate (like in foods that contain MSG) or aspartate results in cell damage and death and produces a wide variety of health consequences.
MSG is the monomeric salt of glutamate and used widely as a flavor enhancer or to mask “off-tastes” in processed foods. Gross, right? In 1908, a Japanese researcher named Dr. Ikeda made a profitable discovery when he isolated glutamate from Kombu seaweed. Probably unaware of its neurotoxic effects, he quickly founded a company to mass-produce the flavor enhancer, and soon MSG was widely present in Japanese restaurants and home cooking. By 1933, over ten million pounds were being used per year.
MSG found its way into the Western hemisphere during World War I when American soldiers found that Japanese rations were far more palatable than their own fare. Eager to make profits off this new finding, U.S. food producers were soon adding MSG to processed foods without questioning its possible effects on human health. Walk down any conventional supermarket aisle today, and you will find glutamate hidden in the vast majority of food products that line the shelves.
Aspartame is used in artificial sweeteners (Nutrasweet and Equal) and is composed of 50 percent phenylalanine, 40 percent aspartic acid (both amino acids), and 10 percent methanol. Aspartic acid is converted into glutamate and glutamine by the body, so consumption of aspartame shares many of the same consequences as consumption of MSG.
Yet in addition to the harmful effects of glutamate, phenylalanine and methanol also pose health risks. High amounts of phenylalanine in the brain leaves little room for other amino acids that perform important functions. For example, too much phenylalanine causes a drop in tryptophan, which is necessary to produce serotonin. Without this critical hormone, your sleep, body temperature, and appetite control are compromised.
Methanol is also highly toxic. In the body, it is transformed into formate, which is either excreted or converted into formaldehyde—a carcinogen and even lethal chemical.
Have you ever drank a diet Coke that was sitting out in the sun? Heat speeds up the process of methanol conversion, so you could be drinking formaldehyde directly if your diet soda exceeds 86 degrees! The concentration of methanol in artificially-sweetened products probably isn’t high enough to cause serious immediate damage, but exposure over the long-term could be dangerous. Symptoms due to methanol toxicity include seizures, headaches, shooting pains, leg numbness or cramps, vertigo, tinnitus, anxiety, depression, slurred speech, or memory loss.

Are you eating only “diet” foods to lose weight? Despite that aspartame-containing foods are marketed as healthy diet foods, their consumption could actually contribute to weight gain. Eating aspartame increases cravings for carbohydrates, and the formaldehyde that is formed from methanol is stored in fatty adipose tissue—especially in the thighs and hips—to protect the body from its toxic effects.
These effects are not reserved for artificially-sweetened foods; glutamate in MSG may promote weight gain as well. A five-year-long epidemiological study of over 10,000 Chinese adults found a positive correlation between MSG consumption and body weight. Those individuals who ate the most MSG were about 30 percent more likely to be obese than those who ate the least.
It is thought that glutamate may promote weight gain by impairing insulin signaling—a key hormone that controls appetite and metabolism. Eating and drinking “diet” is neither the easy nor the correct answer for weight loss.

Unfortunately, glutamate-containing foods go under many names: monosodium glutamate (MSG), glutamic acid, soy protein isolate, soy sauce, whey protein isolate, hydrolyzed vegetable protein, carrageenan, natural or artificial flavoring and seasonings. These ingredients contain especially high levels of glutamate, and they should be minimized in your diet or eliminated completely.
Be wary of anything processed, especially canned soups and sauces, chips, snack mixes, frozen meals and pizzas, dips (salsa, queso) and fast food items. Not only will you cut down your exposure to excitotoxins by avoiding MSG, but you will also avoid eating the low-quality and poor-tasting ingredients that MSG is meant to mask.
As mentioned, aspartame is the main ingredient in Nutrasweet and Equal, and you will find it in most diet beverages and sugar-free foods. I recommend avoiding all sodas and processed juices as they are unhealthy, anyway.

However, if you just can’t kick that diet Coke habit (excitotoxins are addictive), try transitioning into drinking natural sodas made with honey or real sugar. I enjoy Kombucha (a bubbly, sweet fermented tea available at Cub and Whole Foods) or combining orange juice with sparkling water and stevia, a healthy sweetener. The bottom line is to avoid processed foods whenever possible. If you can’t read the label, don’t buy it!