Food Categories Notepad Diagram

If you have ever suspected that you might have a sensitivity to a certain food or ingredient, you’re not crazy.

In a previous post, I discussed the difference between a food allergy, a food intolerance and a food sensitivity, so if you’re confused about those terms, get acquainted by reviewing that post.

I titled this “7 Signs and Symptoms”, but in reality, there are actually seven areas of the body where we typically observe signs and symptoms —and we are learning about more every day.

Let’s start with a flow chart that illustrates the general cause and effect of a food sensitivity:

Chart - Cause and effects of food sensitivity

From the graphic, we see that although the underlying contributing factors may differ, the gut is ground zero in regards to where the cascade of damage is initiated. I’ll be dedicating a series of posts to the gut later on, but for now let’s focus on the last segment of the graphic: Distant signs and symptoms.

I mentioned in my earlier post that symptoms from food sensitivities may not show up for hours or even days and can look a lot like symptoms seen in other conditions. As you read through this list of seven areas where symptoms can occur, keep in mind that other medical reasons why you may be having symptoms should also be ruled out. I always recommend you also consult your physician.

The list below contains both symptoms that can be triggered by foods as well as conditions that can be aggravated by food sensitivities:

1. The Gastrointestinal Tract

  • Sores in the mouth
  • Indigestion
  • Heartburn
  • Bloating
  • Gas
  • Chronic nausea and/or vomiting
  • Chronic constipation or diarrhea
  • Leaky gut: Yes, it can be a contributing factor and an effect of food sensitivities.
  • Irritable Bowel Syndrome (IBS): A review published in 2018 remarked that over 80% patients with Irritable Bowel Syndrome report that their symptoms are triggered after ingesting certain foods. i

2. The Brain and Behavior

Distressed woman

Mental health can be profoundly impacted by sensitivities to food. For example, approximately 30% of people with schizophrenia have high levels of the antibody against gliadin–a major protein found in gluten, compared to people without schizophrenia. ii A small study published in 2019 in the Journal of Psychiatry & Neuroscience (Kelly 2019) observed that schizophrenic patients who had gluten removed from their diet for 5 weeks had improved psychiatric and gastrointestinal symptoms. Here are other areas of the brain and mental health shown to be affected by food sensitivities:

  • Headaches or Migraines
  • Insomnia
  • Dizziness
  • Depression
  • Anxiety
  • Schizophrenia
  • ADHD
  • Autism

3. The Skin

  • Acne
  • Psoriasis
  • Eczema
  • Rosacea
  • Unexplained rashes
  • Hair loss
  • Dark circles under or irritation around the eyes

4. The Respiratory System

  • Runny or stuffy nose
  • Ringing in ears
  • Itchy, watery eyes
  • Excessive phlegm
  • Frequent coughing or sore throat
  • Postnasal drip
  • Sneezing attacks
  • Recurring ear infections

In some instances, food sensitivities can be sneaky. Aside from the famous food triggers like gluten, dairy, shellfish and soy, some people can react to chemicals that naturally occur in or are added to foods. A study done with 119 patients with nasal polyps (Esmaeilzedeh 2017) found that almost 70% of them were sensitive to salicylates, a chemical naturally occurring in aspirin and a wide variety of fruits and vegetables and other foods.iii

5. Muscles and Joints

  • Weakness
  • Aches
  • Swelling and stiffness
  • Fibromyalgia

6. Endocrine System

The thyroid is well studied in the functional nutrition world for its relationship with food triggers, however food sensitivities can also affect other hormones and even impact premenstrual syndrome.

7. Autoimmunity

  • Celiac disease
  • Rheumatoid arthritis
  • Lupus
  • Scleroderma
  • Ulcerative Colitis
  • Multiple Sclerosis

When I meet with my patients I take the time to educate them about how food can be triggering their symptoms, -or in the case of autoimmunity, how certain foods can worsen their symptoms–and what that looks like in the body’s different pathways. If you’ve been following my posts, you’ll remember that the gold standard for testing food sensitivities is the elimination diet, which I explain more in this post.

I’ll be talking more about food sensitivities, mental health, leaky gut and the mechanisms behind some of these 7 areas in future posts.


iSoares RLS. Irritable Bowel Syndrome, Food Intolerance and Non-Celiac Gluten Sensitivity. A New Clinical Challenge. Arq Gastroenterol. 2018;55(4):417-422. doi:10.1590/S0004-2803.201800000-88

ii  Kelly DL, Demyanovich HK, Rodriguez KM, et al. Randomized controlled trial of a gluten-free diet in patients with schizophrenia positive for antigliadin antibodies (AGA IgG): a pilot feasibility study. J Psychiatry Neurosci. 2019;44(4):269-276. doi:10.1503/jpn.180174

iii Esmaeilzedeh H, Esmaeilzadeh E, Faramarzi M, Nabavi M, Farhadi M. Salicylate Food Intolerance and Aspirin Hypersensitivity in Nasal Polyposis. Iran J Immunol. 2017;14(1):81-88.