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Food Chemical Sensitivity: What It Is and How To Manage, According To a Dietitian

by Valerie Polley | Sep 15, 2025 | 0 comments

Have you ever eaten a perfectly normal meal, only to feel bloated, foggy, or unwell hours later, wondering if hidden "food chemicals" might be to blame? More and more people are asking this question as awareness around food chemical sensitivity grows. 

Unlike an allergy, which involves the immune system, food chemical sensitivity is a reaction to naturally occurring compounds (like amines, salicylates, and glutamates) or food additives (such as preservatives and food colorings). While these substances are harmless to most, they may trigger symptoms like headaches, gut problems, skin reactions, and fatigue in sensitive individuals.

 This article will explore what food sensitivity is, potential causes, testing options, and strategies for managing it with evidence-based diets.

Food Allergy vs. Food Sensitivity: What's The Difference?

First things first — what's the difference between a food allergy and a food sensitivity? A food allergy is an immune system reaction and is potentially life-threatening. Peanut allergies are a common food allergy.

 In contrast, a food sensitivity is a non-allergic reaction that typically gets worse the more you eat of a food you're sensitive to. A food sensitivity often involves chemicals like salicylates, amines, or certain food additives.

Symptoms of a food sensitivity include digestive issues, headaches, fatigue, skin issues, and even mood changes. However, it's essential to get properly diagnosed, as some food allergy symptoms overlap with food sensitivity symptoms.

Common Food Chemicals That Trigger Sensitivities

Some people experience digestive issues, skin flare-ups, or headaches after eating certain foods due to naturally occurring or added food chemicals. While reactions can vary from person to person, here are some of the most common culprits.

Amines

Compounds like histamine and tyramine are found in aged cheese, cured meats, and fermented foods. In sensitive individuals, they may dilate blood vessels and affect the nervous system, leading to headaches or migraines. 

Salicylates

Naturally occurring in fruits, vegetables, herbs, and spices, as well as present in medications like aspirin, salicylates can trigger symptoms such as hives, asthma, or gut discomfort in sensitive individuals. These reactions may occur due to an inability of the body to break them down.

Glutamates

Monosodium glutamate (MSG) and naturally occurring glutamates in foods like tomatoes and mushrooms are controversial. While research is mixed, some people report headaches, flushing, or digestive upset after consuming high amounts of glutamates.

Food Additives

Preservatives like sulfites, benzoates, and nitrates can worsen asthma symptoms, trigger rashes, or cause stomach upset in certain individuals. These reactions may stem from immune or inflammatory responses.

Because food chemical sensitivity is often highly individual, not everyone reacts to the same substances. A structured elimination diet, guided by a food sensitivity dietitian, is often the safest and most effective way to pinpoint specific triggers.

How Food Chemical Sensitivity Is Diagnosed

There is currently no single gold-standard laboratory test for diagnosing food chemical sensitivity. Instead, diagnosis often relies on a detailed symptom history, food and symptom diaries, and a structured elimination and reintroduction process. Working with a food sensitivity dietitian is essential, as they can help identify patterns, minimize unnecessary restrictions, and guide safe food challenges.

A medical evaluation is also vital to rule out other conditions that can mimic food chemical sensitivity symptoms, such as food allergies, celiac disease, irritable bowel syndrome (IBS), and inflammatory bowel disease (IBD).

Some food sensitivity tests are available, but they should be interpreted with caution:

  • KBMO Food Sensitivity Test: Measures IgG antibody responses to food. However, IgG presence often reflects exposure, not sensitivity, and may lead to false positive results. The American Academy of Allergy, Asthma, and Immunology does not recommend using IgG testing to diagnose food sensitivities.
  • MRT Food Sensitivity Testing (Mediator Release Testing): Measures changes in immune cell reactions when exposed to food and food chemicals. While it's marketed as being more comprehensive, its validity remains debated, and an expert panel recommends against its use to diagnose food sensitivities.
  • LEAP Food Sensitivity Testing: Based on MRT, this test is offered through trained practitioners, but faces the same limitations in scientific support as other food sensitivity tests.

The major drawback of these tests is a lack of consistent scientific validation, which increases the risk of false positives and overly restrictive diets. While testing may provide clues, the most reliable way to identify specific food triggers is a carefully structured elimination diet followed by reintroduction, ideally under the guidance of a dietitian specializing in food sensitivities.

Evidence-Based Diet Approaches

When it comes to food sensitivities, several structured dietary approaches exist. One of the most well-known is the RPAH Elimination Diet, which was developed in Australia.

The RPAH Elimination Diet (FAILSAFE Diet) is considered one of the best ways of identifying sensitivities to food chemicals. It involves the strict elimination of additives, salicylates, amines, and glutamates. This is followed by a careful, systematic reintroduction to pinpoint triggers. While it's effective for people struggling with chronic, unexplained symptoms like migraines, IBS, or rashes, this diet is extremely restrictive and should be supervised by a dietitian to prevent nutrient deficiencies and ensure accurate results.

Some people attempt DIY elimination diets, but these can be confusing, overly restrictive, and potentially harmful if followed long-term. Without professional guidance, it's easy to misinterpret symptoms, cut out entire food groups unnecessarily, or fail to reintroduce foods properly. 

Practical Management Strategies

There are several management strategies you may find helpful when addressing a food chemical sensitivity. Here are a few to consider:

  • Keep a detailed food and symptom journal: Track what you eat and any symptoms that arise to help identify potential food triggers.
  • Use trusted food lists: Use resources like food lists or guides to help with meal planning.
  • Focus on fresh, minimally processed foods: This reduces your exposure to additives and preservatives that may trigger reactions. However, it's important to note that many fresh foods still contain food chemicals.
  • Be mindful of portion sizes: Symptoms are often dose-dependent. You may be able to tolerate smaller portions of some trigger foods.
  • Work with a food sensitivity dietitian: This will help ensure your meals are balanced, nutritionally adequate, and tailored to your unique dietary sensitivities.
  • Gradually reintroduce foods: Prevents unnecessary broad avoidance and helps identify true triggers without compromising on dietary variety.

When To Seek Professional Help

See a doctor if you experience:

  • Severe or worsening symptoms
  • Unintended weight loss
  • Blood in your stool
  • Multiple food restrictions leading to nutritional gaps.

And remember, a food sensitivity dietitian can help you:

  • Interpret results from food sensitivity tests (e.g., KBMO, MRT, LEAP)
  • Guide you through structured elimination diets like the RPAH Elimination Diet
  • Help ensure your diet remains nutritionally balanced
  • Provide evidence-based support and practical advice for long-term management.

 Working with both a medical provider and a dietitian ensures your symptoms are appropriately evaluated and managed, reducing the risk of misdiagnosis or unnecessary dietary restrictions.

Final Thoughts

Food chemical sensitivity is real but complex, and not all symptoms point to a sensitivity. While many food sensitivity tests are available, a structured elimination diet followed by food challenges remains the gold standard for identifying food chemical sensitivities.

 Working with a food sensitivity dietitian ensures you can pinpoint problem foods without compromising nutrition or quality of life. With patience and professional guidance, symptoms can often be reduced and effectively managed.

Click here to get in touch with us at Blue Tree Nutrition.

Spend any amount of time on social media these days, and you'd think protein is the answer to all your health concerns. Protein coffee, protein cereal, protein deserts…even foods that never needed protein are getting a boost.

Protein absolutely plays an important role in overall health. But when it comes specifically to gut health, fiber is the real MVP.

Why Gut Health Depends on What Your Microbes Eat

Your gut is home to trillions of microorganisms collectively known as the gut microbiome. These microbes, which include bacteria, viruses, fungi, and more, influence everything from digestion and metabolism to inflammation and immune function. 

But microbes need fuel to survive.

Unlike human cells, your gut microbes thrive on dietary fiber—not protein—as their main source of energy. When you eat fiber, your gut microbes ferment it and produce compounds that actively support health.

However, when fiber intake is low, your gut microbes are forced to rely on other sources of fuel, including protein. And that shift can change which metabolic byproducts are produced in your gut. And spoiler alert—that's not always for the better.

What Happens When You Eat Fiber

Fiber is a type of carbohydrate that resists digestion in the small intestine. Instead of being absorbed, it travels to the colon intact. 

This is where the magic happens. Your gut microbes ferment fiber, producing a variety of different compounds. Some of the most important byproducts of fiber breakdown by your microbiome are short-chain fatty acids (SCFAs).

SCFAs are incredibly beneficial for overall health. Here are just some of their benefits:

  • Nourish colon cells
  • Strengthen the gut barrier
  • Reduce inflammation
  • Support regular bowel movements
  • Maintain a healthy gut pH
  • Protect against several diseases

In other words, fiber doesn't just help you poop—it actively supports the structure and function of your gut.

The Different Types of Fiber (And Why They All Matter)

You might be surprised to learn that not all fiber works the same way. Soluble fiber, which dissolves in water to form a gel-like substance, slows digestion, helps regulate blood sugar, lowers cholesterol, and, in some cases, acts as fuel for your good gut microbes. The fiber that can act as fuel for your gut microbes is called prebiotic fiber, and you can think of it as fertilizer for your gut microbiome. 

In contrast, insoluble fiber does not dissolve in water, but adds bulk to stool, helping promote gut regularity and speeding up the transit of waste through your digestive tract.

Both types of fiber are needed for a healthy gut, but soluble fiber is typically "gentler" on digestion and can be especially helpful for people with IBS.

What Happens When Protein Reaches the Colon

Protein is essential for muscle repair, immune function, and hormone regulation, and most of it is digested and absorbed in the small intestine. However, when large amounts of protein (especially protein from animal products) reach the colon, your gut microbes break it down through fermentation. Unlike fiber fermentation, protein fermentation produces compounds that can negatively affect gut health.

Byproducts of protein fermentation can include ammonia, hydrogen sulfide, phenols, and indoles. In large amounts, these compounds have been linked to gut barrier irritation, increased inflammation, unfavorable changes in gut microbiome composition, and a potential increase in colorectal disease risk.

This doesn't mean protein is harmful, but it highlights that a high-animal-protein, low-fiber diet shifts microbial activity toward less beneficial metabolic pathways. In other words? The extremely popular carnivore diet is not a good choice for gut health. Overall, it's best to focus on plant-based sources of protein, which studies show can improve gut microbiome composition. 

Why Fiber Matters More Than Protein for Gut Health

From a gut health perspective, fiber has several advantages over protein:

  • Feeds beneficial microbes
  • Produces anti-inflammatory compounds
  • Supports stool consistency and transit
  • Improves microbial diversity

Most people meet or exceed the recommended protein intake, but fall dramatically short on fiber intake (some studies suggest that as many of 95% of people in the United States don't reach the recommended fiber intake).

The National Academy of Medicine recommends that women aim for around 25 grams of fiber per day, while men should target about 38 grams per day.

Simple Ways to Increase Fiber Intake

Increasing your fiber intake doesn't require a complete diet overhaul. Small, consistent changes tend to work best, especially if you have a sensitive digestive system.

Instead of removing foods from your diet, focus on adding fiber where you can or switching to higher fiber options:

  • Toss canned beans or chickpeas into salads
  • Add chia or ground flax seeds to your yogurt
  • Include at least one plant food at every meal
  • Switch to whole wheat or fiber-enriched pasta
  • Choose rolled oats instead of sugary breakfast cereals
  • Cook and cool starchy foods like potatoes, rice, and pasta before eating to naturally increase resistant starch (a type of prebiotic) content

To avoid digestive problems, increase your fiber intake slowly by 2-3 grams per day, and ensure you're drinking plenty of fluids to keep things moving smoothly. To increase the diversity of fiber you're providing to your microbes, aim to eat 30 different plant foods (which include fruits, vegetables, legumes, nuts, seeds, herbs, and spices) per week.

The Bottom Line

Protein is essential for overall health, but when it comes to gut health, fiber plays the starring role. It feeds your beneficial gut microbes, strengthens the gut linking, and produces anti-inflammatory compounds that help keep your digestive system running smoothly. Meanwhile, diets high in protein but low in fiber may encourage metabolic byproducts linked with less favorable gut outcomes.

If your priority is improving gut health, the evidence consistently points in one direction. Eat more fiber, and your gut microbes will thank you. If you're struggling with increasing your fiber intake, a dietitian can help. Click here to get in touch with us at Blue Tree Nutrition and learn about how we can support your journey to better gut health.

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Hello, I am

Valerie

My name is Valerie Polley. I am a Indianapolis-based registered dietitian and owner of Blue Tree Nutrition. I consult with clients both local and far away.
I have a bachelor’s degree in nutrition from Purdue University and I have been practicing for 20 years.
I thoroughly enjoy helping clients through their gut health journey. I see a range of GI issues including, but not limited to celiac disease, IBS and SIBO. I also specialize in the FODMAP elimination diet.

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