Toxic Taste: The Invisible Additive Fuelling Obesity, Autism & Inflammation: An Interview with Katherine Reid, PhD & Barbara Price

We recently connected with Katherine Reid, PhD, and science writer Barbara Demske, authors of Fat, Stressed, and Sick: MSG, Processed Food, and America’s Health Crisis. Katherine’s daughter’s health struggles sparked their deep dive into MSG and hidden glutamates in processed foods—substances linked to inflammation, obesity, autism, and more. Together, they reveal how these additives quietly harm our health and expose what the food industry doesn’t want you to know.

Prepare to rethink everything you thought you knew about processed food.

What inspired you to write Fat, Stressed, and Sick? Was there a personal story or event that sparked your investigation into MSG?

Katherine Reid: “Yes, my investigation into MSG and processed foods was deeply personal. As a biochemist and mother, I was alarmed when my young daughter began exhibiting severe behavioural and physical health issues—severe mood swings, rashes, and chronic inflammation—which led to an autism diagnosis, yet there was no clear medical explanation. After eliminating common allergens without success, I turned my scientific lens to her diet. When I removed processed foods containing MSG and other hidden excitotoxins, her symptoms dramatically improved.

“This experience forced me to confront a troubling gap in public awareness: while MSG is often dismissed as harmless (or narrowly framed as a concern only for those with ‘sensitivity’), the broader biochemical impact of processed foods on metabolism, neurology, and chronic disease is vastly underappreciated. My daughter’s drastically improved health propelled me to research the science behind these additives, their role in the obesity and autoimmune epidemics, and how industry practices have obscured their risks.

“What began as a mission to help my child evolved into a commitment to expose how the modern food system, fueled by MSG and other synthetic additives, is making America fat, stressed, and sick.”

Barbara Price

For readers who may not be familiar with glutamate, can you explain what it is and how it differs from MSG as a food additive?

Barbara Demske: “MSG (monosodium glutamate) and glutamate are the same thing. In simplest terms, it’s an amino acid, and it’s found everywhere in the body. Sometimes it’s part of protein, but often it exists all by itself as a free molecule. When added to food, glutamate tells our taste buds that the food is delicious and makes us crave more. That’s why MSG is so important to the food industry—people will buy unhealthy food in spite of themselves because it tastes so good.

“However, glutamate has multiple roles in the body, which makes enriching food with MSG problematic. As we explain in our book, Fat, Stressed, and Sick: MSG, Processed Food, and America’s Health Crisis, glutamate in processed food contributes to a suite of chronic inflammatory conditions, including obesity, diabetes, autism, addiction, depression, and cancer.”

Reid: “Glutamate is a naturally occurring amino acid that serves as one of the building blocks of protein. It’s found in whole foods like tomatoes, mushrooms, and breast milk, and it plays critical roles in the body, from supporting brain function to aiding metabolism.

“The problem isn’t glutamate itself, but load and how it’s delivered. In whole foods, the vast majority of glutamate is bound to other amino acids in proteins and released slowly during digestion. But MSG (monosodium glutamate), or processed free glutamate (PFGs), the food additive, is ‘free glutamate’—isolated, concentrated, and rapidly absorbed. This floods the body with up to 20 times the glutamate you’d get from a whole food source, overstimulating receptors in the brain and gut.

“Think of it like sugar: An apple contains natural sugars along with fibre and nutrients that slow absorption. But refined sugar, stripped of context, spikes blood glucose. Similarly, MSG or PFGs are refined glutamate. It’s engineered to bypass satiety signals, making processed foods hyper-palatable while potentially disrupting hormones, triggering inflammation, and contributing to conditions like obesity and neurological disorders.”

Many people associate MSG only with restaurant food, like Chinese takeout. What are some of the surprising places it’s hiding in our everyday diets?

Reid: “Most people are shocked to learn that MSG is in every aisle of the grocery store, far beyond takeout. Food manufacturers have become adept at disguising these additives under innocent-sounding names. Here’s where they lurk:

• ‘Healthy’ Packaged Foods: Flavoured rice cakes, protein bars, low-fat yogurt, and plant-based meat alternatives often contain hydrolyzed vegetable protein or ‘natural flavours’—sources of PFGs.
• Pantry Staples: Canned soups, bouillon cubes, salad dressings, and even some organic broths use yeast extract or autolyzed yeast (both MSG in disguise).
• Snack Foods: Potato chips, flavoured nuts, and crackers frequently list ‘spices’ or ‘seasonings’ as ingredients—umami-rich terms that often mask glutamate additives.
• Fast & Frozen Foods: From chicken nuggets to frozen pizzas, ‘textured protein’ or ‘carrageenan’ can deliver the same excitotoxic effect as traditional MSG.
• Infant Formula & Kids’ Foods: Shockingly, some pediatric nutrition products include PFGs to enhance palatability, despite growing evidence of their impact on developing brains.

“The key takeaway? If a packaged food has a savoury, addictive quality or a long shelf life, there’s a good chance it contains PFGs—just not always labelled as ‘MSG.’ That’s why I teach readers to decode ingredient lists and prioritize whole, unprocessed foods whenever possible.”

Your book links MSG and glutamate exposure to a wide range of health conditions, including autism, depression, and obesity. Which of these findings surprised you the most during your research?

Reid: “The most startling connection, and the one that fundamentally shifted my perspective, was the emerging research linking excessive glutamate activity to neurodevelopmental conditions like autism.

“As a biochemist, I expected to see ties to metabolic disorders (obesity, diabetes) since MSG disrupts leptin signalling, essentially tricking the brain into overeating. The depression and anxiety links also made sense, given glutamate’s role as the brain’s primary excitatory neurotransmitter; an imbalance can overstimulate neural pathways.

“But the autism research was paradigm-shifting. Studies show that many children with autism have elevated glutamate levels in cerebrospinal fluid and impaired glutamate metabolism. Meanwhile, rodent studies demonstrate that early-life MSG exposure can trigger social deficits and repetitive behaviours resembling autism. This doesn’t mean MSG causes autism; genetics and environmental factors interact complexly, but it suggests glutamate dysregulation may be a previously overlooked piece of the puzzle.

“What haunts me is how little this is discussed. We’ve focused on sugar and fats in the obesity crisis, while ignoring how excitotoxins in ultra-processed foods—consumed even during pregnancy—might be altering neurodevelopment. That silence is what compelled me to write this book.”

Barbara Price x Katherine Reid, Phd “Fat Sick, and Stressed” book cover

What’s the connection between glutamate and inflammation in the body? Could you break that down for the average reader?

Demske: “As I mentioned earlier, glutamate has multiple roles in the body. For one thing, it’s a neurotransmitter and one of its jobs is setting off the body’s immune response. Normally, this is good—a healthy immune system keeps us safe from disease and allows the body to repair itself. The presence of too much glutamate, however, causes the body to overreact to stimuli that are inflammatory. The body then becomes chronically inflamed. That is the foundation of disease.”

Reid: “Think of glutamate in the body like a fire alarm. In small amounts, it’s essential; it helps your brain send signals and your immune system respond to threats. But when you flood your system with processed free glutamate, or PFGs (like MSG), it’s like pulling that alarm nonstop. The result? Chronic inflammation, linked to everything from joint pain to heart disease. Here’s how it works:

1. The Gut Connection:

“MSG and similar additives irritate the gut lining, making it ‘leaky.’ This allows toxins and undigested food particles to escape into the bloodstream, triggering an immune response—boom, inflammation.

2. The Brain-Immune Link:

“Glutamate overstimulates immune cells in the brain (microglia), which then pump out inflammatory chemicals. This is why people with autoimmune conditions often report symptom flares after eating MSG-heavy foods.

3. The Vicious Cycle:

“Inflammation disrupts your body’s ability to regulate glutamate naturally, creating a feedback loop. More processed foods → more glutamate → more inflammation → even less tolerance for whole foods.

“The scary part? This isn’t just a ‘sensitivity.’ Peer-reviewed studies show MSG directly increases markers like C-reactive protein (CRP), a key indicator of systemic inflammation. And since inflammation is the root of most chronic diseases, this isn’t just about headaches—it’s about long-term health sabotage.”

Barbara, as a science writer, how did you approach making this complex biochemical information accessible to the general public?

Demske: “Well, first of all, because so much information is available online, I’ve found that a lot of people already have a basic understanding of how food influences health. That said, the real meanings of technical terms people see online aren’t always obvious. That’s where I can help. I take concepts and make analogies with ideas that are familiar to everyone. I introduce jargon only if it is critical to the conversation, and then I flag it with a warning, something like ‘This is technical! Stay with me here!’ We don’t want readers to freak out when the going gets tough, but instead trust us to guide them through some pretty challenging information.

“The goal is to empower readers so that they don’t have to take our word for what we are saying—they can judge for themselves. Even with passages that seem as daunting as a short course in biochemistry (P.S. that’s the real title of a section of the book), I’ll summarize the whole argument at the end in simple terms, giving readers the gist of the takeaway. That way, we meet readers where they are, and readers decide how deep a dive they want to take.”

You discuss how glutamate is created during food processing, not just added. Why is this distinction important for consumers to understand?

Demske: “Most people believe MSG is something like salt, they sprinkle on food or it is added to big batches of food in industrial kitchens. That’s true, but in fact, most of the glutamate in processed food doesn’t come from manufacturers adding it to the recipe but is created during food processing itself—heating, mixing, fermentation, hydrolysis, extraction processes, etc. Because glutamate made this way is not technically ‘added’ to the food, it doesn’t have to be disclosed on food labels. That’s where the problem is: processed food has a lot of MSG in it, but you’d never know this from reading the ingredients label.”

Reid: “This distinction is critical because it reveals how ‘clean label’ tricks keep consumers in the dark. Many people carefully avoid ingredients like ‘monosodium glutamate’ (MSG) but unknowingly consume processed free glutamates (PFGs)—the same biologically active compound, just created through manufacturing rather than direct addition. In the Standard American Diet (SAD), 90 percent of our total free glutamate load comes from PFGs, with a whopping 10 grams of free glutamate being consumed every day.”

Here’s why it matters:

1. Hidden in “Natural” Ingredients:

• Foods labelled ‘no MSG added’ often contain hydrolyzed proteins, yeast extracts, or ‘natural flavours,’ all created through industrial processing (acid baths, enzymatic breakdown) that release free glutamate. The body reacts the same way, regardless of whether it came from a lab or a “natural” process.

2. The Umami Deception:

• Food scientists now use PFGs to mimic the savoury depth of slow-cooked, fermented, or aged foods, but in a fraction of the time. A ‘slow-roasted’ flavour in a bouillon cube? Likely PFGs from hydrolyzed soy. That ‘artisanal’ taste in mass-produced bread? Often yeast extract.

3. Regulatory Loopholes:

• Because PFGs aren’t technically ‘added MSG,’ they bypass labelling requirements in many countries. Consumers think they’re making safer choices, but their bodies don’t distinguish between glutamate created in a vat versus a shaker bottle.

How receptive has the medical or scientific community been to your findings, and have you faced any resistance or skepticism?

Reid: “The response has been polarizing, but that’s changing in the right direction. Early on, I faced dismissive attitudes from corners of the medical community that still operate on outdated notions like ‘MSG sensitivity is just a placebo,’ or ‘if the FDA says it’s safe, end of story.’

“But three key shifts are happening:

1. The Science Is Catching Up

• Cutting-edge research on the gut-brain axis, neuroinflammation, and excitotoxicity now validates what patients have reported for decades. Studies linking dietary glutamate to microglial activation (Journal of Neuroinflammation) or metabolic dysfunction (Nature Metabolism) are impossible to ignore.
• Many functional medicine doctors, neurologists, and nutritionists now actively use glutamate reduction protocols for conditions like migraines, autism, and autoimmune diseases.

2. Patient Outcomes Speak Loudest

• When physicians see patients with ‘mystery’ symptoms (fibromyalgia, brain fog, IBS) improve after removing PFGs, often after drugs failed, their skepticism turns to curiosity. I’ve collaborated with clinicians who’ve replicated these results in practice.

3. Industry Resistance Persists (But It’s Fragile)

• Big Food’s playbook mirrors Big Tobacco’s: ‘More research is needed,’ while funding studies that downplay risks. But their façade cracks as consumers demand clean labels. The EU’s stricter flavouring regulations prove that change is possible.

“The bottom line? Science marches forward. Ten years ago, doctors mocked gluten sensitivity; now it’s mainstream. PFGs are the next frontier.”

What practical steps can people take immediately if they want to reduce their exposure to harmful glutamates?

Reid: “There are a few.

1. Purge the Pantry (The Big Offenders)

Start by ditching the worst culprits, foods that rely on processed free glutamates (PFGs) for flavour:

• Savoury snacks: Chips, flavoured nuts, crackers with ‘seasonings’ or ‘natural flavours.’
• Instant/processed meals: Bouillon cubes, ramen, frozen dinners, canned soups.
• Condiments: Soy sauce (opt for coconut aminos), store-bought dressings, ‘umami’ sauces.
• Protein powders/fake meats: Hydrolyzed or textured plant proteins (check labels).

Pro Tip: If an ingredient list includes hydrolyzed ___, yeast extract, or ‘spices’ (without detail), assume it contains PFGs.

2. Shop the Perimeter

Build meals around whole, single-ingredient foods:

• Fresh/frozen veggies (avoid pre-seasoned blends).
• Pasture-raised meats (processed meats like sausages often contain PFGs).
• Wild-caught fish (not ‘flavoured’ or pre-marinated).
• Organic eggs, plain dairy (if tolerated).

3. DIY Flavour Boosts

Swap PFG-laden ‘flavour enhancers’ with glutamate-safe alternatives:

• Herbs/spices: Fresh basil, turmeric, garlic (real, not powder with additives).
• Fermented foods: Traditional miso, tamari (non-hydrolyzed), sauerkraut.
• Homemade broth: Simmer bones + veggies (avoid store-bought—even ‘organic’ versions often use yeast extract).

4. Restaurant Survival Tips

• Ask how food is seasoned: Request no MSG, ‘seasoning blends,’ or pre-marinated meats.
• Avoid signature sauces: These are often PFG hotspots.
• Stick to simple dishes: Grilled proteins + steamed veggies (no mystery glazes).

5. Test & Observe

• Try a two-week PFG detox: Many report improved sleep, fewer headaches, and reduced joint pain.
• Reintroduce carefully: Note if symptoms return with foods like Parmesan cheese or bread.

“Remember: You don’t have to be perfect. Even reducing PFGs by 80 percent can yield dramatic benefits.”

How does the standard American diet compare globally in terms of glutamate exposure and associated health outcomes?

Reid: “The Standard American Diet (SAD) is a perfect storm of processed free glutamates (PFGs)—far exceeding most global dietary patterns in both quantity and health consequences. Here’s how it breaks down:

1. PFG Consumption: America vs. the World

• Ultra-processed foods dominate: 60 percent of the average American’s calories come from PFG-loaded foods (snacks, fast food, frozen meals), compared to:
Japan: Despite high natural glutamate intake (e.g., kombu, miso), traditional diets emphasize whole-food umami, not industrial PFGs.
Mediterranean countries: Focus on fresh produce, olive oil, and unprocessed proteins—minimal hidden glutamate additives.
Developing nations: Less reliance on packaged foods means lower PFG exposure (though rising with Westernization).
• Labelling loopholes: The U.S. permits vague terms like ‘natural flavours’ and ‘yeast extract,’ while the EU requires stricter disclosure of glutamate-containing additives.

2. Health Outcomes: A Stark Contrast

• Obesity & metabolic disorders: The U.S. leads in obesity rates (~42%), while countries with whole-food diets (e.g., France, South Korea) show lower prevalence, despite comparable calorie intake. PFGs’ role in leptin resistance may explain this.
• Neurological & inflammatory diseases: Autoimmunity, dementia, and ADHD rates are higher in the U.S. than in regions with minimally processed diets. Research links PFGs to neuroinflammation and blood-brain barrier disruption.
• Gut health: America’s skyrocketing IBS and ‘leaky gut’ cases align with PFGs’ ability to trigger intestinal permeability—a phenomenon less common in traditional diets.

3. The Globalization Trap

• Western fast food’s export: As countries adopt processed foods (e.g., China’s rising MSG-heavy snack market), their disease profiles shift toward U.S. patterns—including childhood obesity and diabetes.
• Traditional diets eroding: Japan’s rising metabolic syndrome rates correlate with increased processed food consumption, even as they retain some protective practices (e.g., fermented whole foods).

Key Takeaways:

• It’s not glutamate itself—it’s the amount coming from processing. Cultures consuming natural umami (e.g., Italian tomatoes, Japanese bonito) don’t face the same risks as Americans gulping PFG-laden chips and soups.
• The SAD is a lab experiment. No ancestral diet included hydrolyzed proteins or autolyzed yeast—these are modern, industrialized triggers.
• Action step: Eat like the Mediterranean or Okinawans—prioritize whole foods, using whole herbs and spices for flavours, and home cooking to avoid PFGs.
• The U.S. doesn’t just have a sugar problem—it has a stealth glutamate problem.

“Other countries savour flavour; we engineer addiction.”

Katherine Reid, PhD

What role do food industry regulations—or the lack thereof—play in the continued use of glutamate in processed foods?

Reid: “How the Food Industry Exploits Weak Regulations to Keep Glutamates Hidden:

1. “Generally Recognized as Safe” (GRAS) Loophole

• MSG was grandfathered into the GRAS list in the 1970s without modern safety reviews. Companies can self-certify new glutamate-based additives (e.g., yeast extract) as GRAS without FDA approval, citing industry-funded studies.
• Example: A 2018 USA Today investigation found that >99 percent of GRAS applications were submitted by food manufacturers or their paid consultants.

2. Labelling Deception

• FDA rules allow vague terms like ‘natural flavours,’ ‘hydrolyzed protein,’ and ‘yeast extract’—all of which contain free glutamate—without disclosing MSG.
• Double standard: The EU requires glutamate-containing additives to be labelled as E621-E625; the U.S. permits obfuscation.

3. Industry-Funded Science

• A 2021 analysis in Public Health Nutrition found that studies sponsored by flavour manufacturers were 22x more likely to declare MSG “safe” than independent research.
• Tactic: Fund short-term trials, ignoring chronic effects (e.g., migraines, metabolic disruption).

4. Exploiting Cultural Bias

• By framing MSG concerns as ‘anti-Asian’ (since MSG is associated with Chinese food), the industry diverts attention from PFGs in American processed foods (e.g., Chick-fil-A’s ‘yeast extract’ in chicken sandwiches).

5. Lobbying Power

• The International Glutamate Technical Committee (IGTC), funded by Ajinomoto (MSG’s largest producer), spends millions lobbying against stricter labelling, as revealed in 2022 FEC filings.”

What do you hope this book changes about the way people eat, shop, and think about food labels?

Reid: “I want to spark a food label revolution.

“My goal isn’t just to inform—it’s to transform how people interact with their food, from the grocery aisle to the dinner table. Here’s the shift I’m fighting for:

1. From Blind Trust to ‘Label Forensics’

• Stop falling for ‘clean label’ tricks. Words like ‘natural flavours’ or ‘protein isolate’ shouldn’t disguise excitotoxins. I want readers to scrutinize ingredients like a detective because corporations count on our complacency.

2. From Convenience Addiction to Empowered Cooking

• Ultra-processed foods aren’t ‘easy’—they’re engineered captivity. I share simple, glutamate-free swaps (e.g., homemade bone broth vs. bouillon cubes) to prove healthy eating doesn’t require hours in the kitchen.

3. From ‘Diet Culture’ to Biological Awareness

• Obesity isn’t a willpower failure; it’s a biochemical hack. By exposing how PFGs manipulate hunger hormones (leptin/ghrelin), I reframe weight struggles as a fight against predatory food design.

4. From Anecdotes to Consumer Power

• Collective action changes industries. If millions reject hidden glutamates, companies will reformulate (like they did with trans fats).

The Bigger Vision: I want this book to do for processed foods what Silent Spring did for pesticides: expose a systemic threat hiding in plain sight, and give people the tools to fight back.

“You shouldn’t need a biochemistry degree to eat safely. This book is a rebellion against the food industry’s gaslighting—and a roadmap to reclaim your health.”

Demske: “My hope is that this book gives others hope, in particular, hope to families coping with seemingly intractable health problems. If changing the way you eat, by rejecting processed food and instead choosing a diet rich in fresh, organic whole foods—green leafy vegetables, beans, fruits, lean meats and fish—can help manage the devastating symptoms of chronic disease (or even prevent those diseases from occurring at all)—why wouldn’t you eat that way? Not to mention, fresh whole foods are truly delicious. It’s just a matter of looking at food differently.”

Finally, what’s next for you both? Do you plan to continue researching or writing in this area, and if so, what can readers look forward to?

Reid: “My desire is to continue to raise awareness and build our community through a variety of outreach platforms, such as creating a documentary exposing how Big Food manipulates science—think Sugar Coated meets The Social Dilemma, for PFGs. And being a guest with Jon Stewart because of his support in the autism awareness space has been a passion of mine.”

Demske: “Breaking news: turns out, my next project is a novel! I love explaining science and am now writing a novel that is one part romance, one part historical fiction, one part climate science. The story draws from the time I lived in the rural mountain community of Lake Tahoe. It’s fun to see how a group of fictional characters can form their own ecosystem, with all the complex relationships you’d expect when you throw together mismatched lovers, scientists (of course), a murderer or two, lovable dogs, and children. The storytelling rules, but readers shouldn’t be surprised that they learn a little climate science along the way.”