Tomatoes and IBS

Tomatoes, IBS, Gut Health and Immunity: What You Should Know (Beyond FODMAPs)

Lots of people suffering with symptoms of irritable bowel syndrome (IBS) often ask, are tomatoes and IBS compatible?  

On paper, at least from a low FODMAP diet standpoint, the short answer is usually yes.  

(Tomatoes in certain quantities are considered low in FODMAPs, aka small, poorly digested fermentable carbohydrates known to trigger IBS symptoms in ~75% of IBS cases.)

But in real life, I can tell you first-hand as a gut health dietitian in private practice, it’s a different story and anything goes!  

(I’ve witnessed more than just a few “anomalies” where tomatoes aren’t well tolerated by some of my clients who were dealing with IBS symptoms like diarrhea, bloating, nausea, and/or abdominal pain.)

So if you’re among the many who need something more customized than just a low FODMAP diet for managing IBS, and you suspect tomatoes could be triggering IBS symptoms, read on.  

In this article, we’ll unpack the top 7 reasons why and how tomatoes can potentially trigger IBS symptoms for some people.

But first, a quick disclaimer… 

Disclaimer:  This article was written for general educational purposes, not to replace 1-1 medical nutrition advice from your doctor and registered dietitian specializing in gut health.  Make sure to consult with your treatment team for customized advice tailored to your bio-individual needs.

When are tomatoes low FODMAP?

When are Tomatoes Low FODMAP (Pinterest)

Tomatoes, like many other foods, can be high or low in FODMAPs depending on the type and the quantity you’re eating at any given time.

For example, according to Monash University’s FODMAP App, up to HALF of a medium tomato is low in FODMAPs.  

Regular tomatoes

However, 2/3 or more of a medium tomato is high in fructose (a type of fermentable monosaccharide, the “M” in FODMAP).

Cherry tomatoes

When considering cherry tomatoes, up to 3 medium cherry tomatoes is low in FODMAPs, while 4+ cherry tomatoes contain more significant quantities fructose.  

  • This isn’t inherently bad.  But some people with IBS may have a fructose intolerance, which means eating large quantities of fructose could trigger IBS symptoms in those cases.

Tomato juice

4 ounces or less of 100% tomato juice is considered low in fructose, while an entire 8-ounce glass of tomato juice is high fructose (and thus high FODMAP).

Tomato sauces and salsas

Many types of tomato sauce and salsa are NOT low in FODMAPs, not because of the tomatoes but because of the garlic and onions.

(You can check out my favorite low FODMAP tomato sauce recipes and products on the market here!)

Given this information, let’s first dive deeper into the concept of “FODMAP stacking” – the first of 7 reasons tomatoes and IBS may not be compatible.

7 ways tomatoes may trigger IBS symptoms

FODMAP stacking:  too many tomatoes?

“FODMAP stacking” is a common mistake many people make on the low FODMAP diet.

It means you’re consuming large quantities of relatively low FODMAP foods that exceed the low FODMAP serving size, essentially turning them into high FODMAPs foods.

An example of FODMAP stacking with fresh tomatoes could be making a caprese salad using an entire medium tomato (versus the low FODMAP serving of 1/2 medium tomato or less) and eating the whole tomato in one sitting, thus over-consuming fructose.

A few other examples of FODMAP stacking with tomatoes could include snacking on 5 or 6 cherry tomatoes at one time, or drinking an entire 8-ounce glass of tomato juice at once.

TLDR:  Are you consuming too many tomatoes or too much tomato juice at once? If so, consider limiting the quantity to low FODMAP servings, and see if you stop reacting. 

Related article:  5 Side Effects of Eating Too Many Tomatoes

Residues in raw tomatoes 

The skins and seeds in fresh tomatoes are “residues” which don’t get easily digested or broken down by our digestive system.  

(Disclaimer:  like FODMAPs, residues in food aren’t inherently bad. In fact, if your gut were healthy, small amounts of residues in food would be a non-issue.)


The thing about IBS is that I often find many of my clients will get prematurely diagnosed with IBS before ruling out other possibilities.

For example, a certain percentage of people who work with me initially believe they have IBS-D (diarrhea-predominant IBS) dig deeper (after learning to advocate for themselves), only to find they actually have a medical condition like  inflammatory bowel disease (IBD) or diverticulitis.

IBD is a type of condition which causes an inflamed bowel, making it difficult to digest high-roughage, high-residue foods like raw tomatoes in certain cases.

Examples of different types of IBD may include:

  • Crohn’s disease
  • Colitis

Diverticulitis is a condition in which there are polyps in your colon which become inflamed, making it difficult to digest high-residue foods like tomatoes in some cases (much like IBD).

The symptoms of IBD and/or diverticulitis may appear similar and nearly identical to IBS symptoms on the surface-level, but these are entirely different medical conditions.

TLDR:  The residues and roughage in raw tomatoes may be difficult to digest if your IBS symptoms are caused by an underlying case of IBD or diverticulitis.  

A few ways to dig deeper and do some “detective work” would be to:

  1. Keep a food-symptom journal.  (Do other high-residue foods with seeds and skins seem to trigger similar symptoms?  If so, maybe you’re onto something!)
  2. Try 100% tomato juice, which is naturally low in fiber and residues.  If you can tolerate tomato juice, but not raw tomatoes, you may be onto something!
  3. Consult your gastrointestinal doctor about running a colonoscopy to see if there’s any inflammation (or inflamed polyps) in your colon.

But if residues aren’t the issue, and even tomato juice bothers you, the histamine in tomatoes is something else to consider.

Histamine in tomatoes

Histamine is a type of naturally occurring compound occurring in high concentrations in certain types of foods.  It can also get produced in our body by certain histamine-producing foods (aka “histamine liberators”) like tomatoes, citrus, and lots of aged, fermented foods like sauerkraut and pickles. (1, 2, 3, 4)

Histamine is also a type of chemical mediator which gets released by certain types of white blood cells in response to threats, leading to inflammatory symptoms in our body when levels build up too high.

If you have a histamine intolerance, it means your gut isn’t producing enough of one or two enzymes called diamine oxidase (DAO) and/or histamine-N-methyltransferase which are collectively responsible for breaking down the histamine in foods and keeping the histamine from getting into your bloodstream through your gut wall.  (1)

So, certain foods that are high in histamines and/or certain food that trigger the release of histamine may leave you feeling sick 

Some common symptoms of histamine intolerance may include, but aren’t limited to any or all of the following: (1, 2, 3, 4)

  • Sweating
  • Burning in your mouth and throat
  • Hives and itching
  • Drop in blood pressure 
  • Tachycardia
  • Headache and dizziness
  • Nausea
  • Vomiting
  • Diarrhea
  • Bronchial obstruction

According to a 2021 study published by  Nutrients, about ~1 to 3% of people worldwide suffer from histamine intolerance. (1)

But about 58% of people with IBS appeared to experience IBS symptoms following consumption of certain high-histamine or histamine-producing foods, according to the Journal of Neurogastroenterology and Motility. (2).

(I’ve often seen histamine intolerance co-occur alongside small intestinal bacterial overgrowth / SIBO and Mast Cell Activation Syndrome (MCAS) as well as celiac disease, and disaccharide deficiencies like congenital sucrase isomaltase deficiency / CSID and acquired sucrase-isomaltase deficiency / ASID.)

TLDR:  If you notice that even low FODMAP, low sucrose and low maltose foods like tomatoes, strawberries and spinach seem to make you feel sick, and/or you’ve also noticed some of the above symptoms (like hives) alongside your IBS symptoms, consider asking your treatment team for help ruling out a histamine intolerance.

High acidity

I realize this list is getting quite long, but when it comes to adverse food reactions, I always prefer to leave no stone unturned (until you feel realigned, at least! ).

One last way that tomatoes and tomato juice can directly irritate IBS symptoms and other types of gut issues is because of their high acidity.  

Tomatoes, like citrus and spicy foods, are highly acidic and can be too much for some people, especially if you have an underlying case of gastritis, or you’re prone to symptoms of heartburn and reflux.

If you notice that spicy foods and maybe even alcohol leave you doubled over in pain or with a burning feeling in your esophagus, I’d guess it’s the acidity in tomatoes that could be bothering you.

Or you could try reducing the quantity at one time and see if this helps! (I recall once putting too much tomato sauce onto my zucchini noodle bolognese while I was still healing… and I never made that mistake again!)

TLDR:  Tomatoes are highly acidic, so if you’re sensitive to spicy foods and feel better on a bland diet, tomatoes may be more of a foe than a friend to you. 

Or, you could also try reducing the quantity of tomatoes you’re consuming at one time, and pair them with starchy foods to help buffer the acidity!  (This worked for me during the early stages of my healing journey, when I was sensitive to too much acidity in foods.)

Nightshade sensitivity

Tomatoes contain solanine, the “nightshade” chemical which is also found in potatoes, eggplant, peppers, and ashwagandha.

Some people with IBS may also have a chemical sensitivity to nightshades, especially if you’re prone to:

  • Diarrhea
  • Gastritis
  • Joint pain
  • Fibromyalgia
  • Migraines/headaches

TLDR:  If you notice that you also don’t feel well when you eat peppers, potatoes, eggplant and/or ashwagandha… it may be worth trying an elimination and reintroduction of nightshades to rule out a nightshade sensitivity!  (I’ve also seen a chemical sensitivity to solanine show up when I run the Mediator Release food sensitivity test in some of my clients.)

Tomato sensitivity

If you have a leaky gut, and you eat tomatoes often, you may actually have a food sensitivity to tomatoes themselves.

(If that’s the case, you may notice that eating large quantities of tomatoes in any form triggers symptoms of food sensitivity such as diarrhea, headaches, heartburn, autoimmune flares, joint pain, depression, fibromyalgia, fatigue, or many other potential reactions.)

You may also see tomatoes come back as moderately or severely reactive on a food sensitivity test.

(This can happen because when the gut is “leaky” or compromised, we may become sensitive to the foods we’re eating most often.  Read more about leaky gut and food sensitivities here!)

Does it mean you cut tomatoes out of your diet indefinitely?  No!

But you may want to look more into addressing and healing your leaky gut, or food sensitivities will continue to be an issue until they aren’t.

Hidden accomplices

Last, but not least, we need to consider the possibility that perhaps it isn’t the tomatoes themselves triggering your IBS symptoms.  

(How often are we eating straight plain tomatoes stand-alone, without anything alongside them?! Probably not often.)

That being said, the most common “heavy hitters” I see triggering IBS symptoms in foods consumed alongside tomatoes include, but aren’t limited to:

  • Garlic and/or onions (high FODMAP ingredients often found in hummus, dressings, salsas, tomato sauces, pico de gallo, guacamole, etc.)
  • Wheat (high in fructans, a type of FODMAP in “regular” pasta, bread, and crackers – all of which tend to pair well with tomatoes)
  • Cream or milk in tomato soups (high in lactose, a type of fermentable disaccharide – the “D” in FODMAP)

These are just a few top-of-mind examples to consider!  It might require a bit of detective work to look for any patterns in reactive foods you could be eating alongside tomatoes. 

TLDR:  Consider keeping an IBS food diary (food-symptom journal) and consult with a gut health dietitian as needed, for guidance in pinpointing the underlying food culprits of your IBS symptoms hiding alongside tomatoes.

Tomatoes and IBS: 7 things to consider (beyond FODMAPs)

Tomatoes and CSID

Are tomatoes low sucrose?

Yes!  Tomatoes are naturally low in sucrose, so they are generally well tolerated by most people with a sucrase-isomaltase deficiency – whether genetic (congenital) or secondary (acquired).

But if you notice tomatoes make you feel sick, consider looking into the above factors to help you gain clarity and insight into what else could be going on.

I also wanted to point out, many of the garlic-free, onion-free tomato sauces and salsas on the market contain carrots – a high sucrose veggie.

If you’re seeking a CSID-friendly marinara sauce, I invite you to check out my 7-Day CSID-Friendly Meal Plan + 21 Recipes here which includes a low sucrose, low maltose, garlic-free onion-free tomato sauce recipe.  😀

Sucrose Intolerance 7-Day Meal Plan + 21 Sucrose Intolerance Recipes - PDF

Recommended reading

Final thoughts

While tomatoes and IBS are generally compatible in most cases, there are a handful of exceptions worth considering. 

In my experience, the 5 most common reasons tomatoes could potentially trigger IBS symptoms on the surface-level are the following:

  1. FODMAP stacking:  aka eating too many servings of tomatoes at once, which leads to high fructose consumption.
  2. The residues in raw tomatoes: these are most often an issue in cases of IBD and/or diverticulitis, gastrointestinal medical conditions which can fly under the radar and often get mis-diagnosed as IBS.
  3. Histamine intolerance:  the high levels of histamine in tomatoes may trigger IBS symptoms and other unwanted symptoms if you have a histamine intolerance.
  4. High acidity:  the acidity in tomatoes can be too much for a sensitive stomach, especially if you’re prone to heartburn/reflux or gastritis.
  5. Nightshade sensitivity:  a chemical sensitivity to solanine, the “nightshade chemical” in tomatoes, peppers, eggplant, tomatoes, and ashwagandha.
  6. Tomato sensitivity:  a food sensitivity to tomatoes, which is typically caused by leaky gut, microbial imbalance, and/or nervous system hypersensitivity.
  7. Hidden accompaniments: in this case, it isn’t the tomatoes but rather the stuff you’re consuming alongside tomatoes that might be triggering unwanted symptoms. (Think: garlic, onions, regular bread/pasta/crackers, beans, milk/cream, and other “heavy hitters!”)

Keep in mind, more than one of the above factors may apply to you!  Figuring out your adverse food reactions is a huge undertaking, which goes far beyond the scope of what I can provide for you in a blog article.  

Lastly, it’s important to remember that while certain foods (like tomatoes and other counterparts) may trigger IBS symptoms, these foods aren’t the underlying root cause of your symptoms.

According to the Universal Law of Cause and Effect, everything has a cause… which means there’s a reason you aren’t tolerating certain foods.  

And in my experience, adverse food reactions stem from underlying imbalances in your gut lining, gut microbiome, other digestive organs (liver/gallbladder/pancreas), immune system, and/or nervous system.

Always listen to your body, and make sure you’re working with a qualified treatment team who is equipped to support and guide you on this journey.

Next steps

If you’d like to learn more, make sure to download my free gut health nutrition guide, where I reveal 5 common diet mistakes to avoid (and what to do instead) on your gut healing journey

Free Download - 5 Diet Mistakes to Avoid When Healing Your Gut - by Jenna Volpe RDN LD CLT

XX – Jenna

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