Fermented Foods and the Low FODMAP Diet

In the past few years fermented foods have emerged as a hot topic in the area of gut and overall health. What exactly are they and what are their purported benefits? Should people with IBS or other gut health conditions include them in their diet?


Fermented foods are made when yeast and/or bacteria ferment the carbohydrate portion of a food to produce alcohol (as in wine or beer) or an acid (as in yogurt or sourdough bread). The process brings about changes in the taste and texture of the food and has been around for thousands of years as a way to preserve foods before the era of refrigeration. Today, commonly consumed fermented foods and beverages include yogurt, kefir, kombucha tea, tempeh, miso, kimchi and fermented cheeses.

As beautifully illustrated in this infographic from the International Scientific Association for Probiotics and Prebiotics (ISAPP), some of these foods still contain the live bacteria (yogurt, kefir, fresh kimchi, sauerkraut), whereas others don’t, as the live cultures are killed by further processing (baking or pasteurization as in sourdough bread, wine, beer and others).

Benefits of Fermented Foods

Whether they are a source of live bacteria or not, these foods have better digestibility, increased availability of certain vitamins/minerals and other important compounds, and reduced levels of anti-nutrients (such as phytates).

Most of the health benefits of eating fermented foods have been seen in epidemiological studies (where we can only observe an association between a behavior and a health outcome) and include reduced mortality and improved blood sugar control. There have been also a few controlled studies (where we can show a cause and effect) suggesting positive effects on blood pressure and total cholesterol.

The benefits of consuming fermented foods on gut health, however, have not been studied extensively and it is difficult to say whether people with chronic conditions – such as Irritable Bowel Syndrome (IBS) or Inflammatory Bowel Disease (IBD) would benefit from regular consumption of these foods. We need more research studies in this area!

Fermented Foods and FODMAPs

If you are currently following the low FODMAP diet, you should be aware that fermentation can either increase or decrease the FODMAP content of a food. I have previously talked about the effects of food processing on FODMAP levels, but here is a list of fermented foods that are either low or high in FODMAPs at standard serving sizes:

Low in FODMAPs

  • Sourdough bread

  • Lactose-free yogurt and kefir

  • Tempeh

  • Miso

  • Some fermented cheese

High in FODMAPs

  • Regular yogurt and kefir

  • Kombucha

  • Kimchi

  • Sauerkraut

  • Pickled vegetables and onions

Bottom line: if you are trying to alleviate symptoms of IBS with a low FODMAP diet, choose the low FODMAP foods until you have re-challenged the high FODMAP categories and have found out which ones trigger your symptoms. Try my Tempeh in Thai Coconut Sauce below. At that point you may find out that you can expand the variety of fermented foods you can eat.


Tempeh in Thai Coconut Sauce



8 oz tempeh

1 ¼ cup water

1 Tbsp low sodium soy sauce/tamari

½-inch piece fresh ginger, cut into slices

1 tsp curry powder

½ tsp paprika

2 tsp high-oleic sunflower  or avocado oil


1 cup coconut milk

1 tsp Thai curry powder

¼  tsp garam masala

⅛ tsp salt, or more to taste

Chopped cilantro,  to garnish 


1.     Cut the block of tempeh lengthwise, then into 16 triangles.

2.     Place tempeh in a large skillet with the water, soy sauce or tamari, ginger, curry powder and paprika. Bring to a boil, cover, lower the heat and simmer for about 20 minutes, until the water has evaporated. Set aside.

3.     In the meantime, place the coconut milk, curry powder, garam masala, and salt in a small saucepan. Bring to a boil, lower the heat and simmer while you are searing the tempeh (next step).

4.     Heat the oil in a skillet over medium-high heat and sear the tempeh, turning once, until golden brown. Stir in the coconut sauce, bring to a boil and reduce the heat, simmering until the sauce has thickened, 2-3 minutes.

5.     Serve over brown or red rice and garnish with cilantro.


4 servings

FODMAP Explained: “O” Stands For Oligosaccharides

Welcome back to my “FODMAP Explained” Series! This is a set of articles dedicated to explaining the acronym FODMAP and giving practical tips to avoid symptoms while including as wide a variety of foods as possible.


The “O” in FODMAP stands for “Oligosaccharides”. These are short-chain carbohydrates (or sugars) – in Greek oligos means “a few” and saccharide means sugar – that can have 3 to 10 single sugar units. In contrast, polysaccharides are long-chain carbohydrates – poly means “many” – that have more than 10 sugar units.

Greek aside, what is important to remember is that we cannot digest these molecules as they are but need to break them down to their single sugar units (glucose, fructose or galactose). Humans, unfortunately, don’t have the enzymes that are able to accomplish that task, and these carbohydrates move through the GI tract undigested. When they reach the large intestine, they meet our good bacteria. And - you probably guessed it - they do have those enzymes that break down the bonds between sugar units and use them for energy (their fast food!). Whereas healthy people only have a bit of gas as part of this normal digestive process, people with IBS have a hypersensitive gut and this fermentation process leads to excess gas, bloating, abdominal pain and perhaps altered motility (constipation or diarrhea).

The two main Oligosaccharides

There are two main oligosaccharides in our diet: galacto-oligosaccharides (GOS) and fructo-oligosaccharides (FOS), or “fructans”. The foods that contain a high amount of these FODMAPs are avoided or limited during the elimination phase of the low FODMAP diet. Some examples are:

Galacto-oligosaccharides (GOS)

  • Nuts (cashews, pistachios, high amounts of other nuts)

  • Legumes (butter beans, red/green lentils, chickpeas)

  • Some vegetables (peas, butternut squash)

Fructo-oligosaccharides (FOS)

  • Grains and cereals (wheat bread and pasta, couscous, amaranth)

  • Some vegetables (garlic, onions, artichokes, Brussels sprouts)

  • Some fruits (dried fruit, persimmon, grapefruit)

  • Some beverages (strong black tea, chamomile tea, kombucha)

To complicate things, some foods have both GOS and FOS: black beans, cashews, barley and beets, just to name a few.

Bottom line: what can you eat?

If you have IBS and are trying to alleviate your symptoms, you shouldn’t avoid FOS and GOS altogether as they can have beneficial effects. They act as prebiotics, that is, they encourage the growth of good bacteria, and are rich in fiber and many nutrients. Here are a few tips:

  1. While on the elimination phase of the diet, avoid the foods that have the highest amounts of FOS and GOS (see some examples above and check out more on the Monash University low FODMAP Diet App).

  2. Have small amounts of some nuts (almonds, hazelnuts), seeds (chia seeds, sunflower seeds), and canned chickpeas or lentils (they are lower in FODMAP than their dried and boiled counterparts). Try my Silk Road Spiced Nuts recipe below.

  3. Choose gluten-free grains such as brown rice, millet, quinoa and corn tortillas.

  4. Eat small amounts of fruits (a ½ cup per meal or snack is a good rule of thumb) but no dried fruits.

  5. Eat mostly low FODMAP vegetables and load up on those that have only trace amounts or none at all (some examples are kale, carrots and red bell peppers).

  6. Drink weakly brewed black tea or herbal teas such as ginger and peppermint (these are all great to soothe a tummy ache).

 Most important of all, stay on the elimination phase of the low FODMAP diet as little as possible, until your symptoms have mostly subsided. Then move on to the re-challenge phase with the help of an expert dietitian who can guide you and help you find out which food you can safely re-introduce into your diet. At the end of this process, most people find they can reintroduce many of these foods and enjoy a more nutritious and varied diet.

spiced walnuts or pecans have oligos.jpg

Silk Road Spiced Nuts


2 Tablespoons lemon juice

1 Tablespoon avocado oil

¼ teaspoon sea salt

½ teaspoon ground cumin

½ teaspoon ground coriander

¼ teaspoon cayenne or paprika (optional)

1 cup walnuts, pecans, or almonds


1.     Preheat the oven to 350°F. Line a rimmed baking sheet with parchment paper.

2.     Put the lemon juice, oil, salt and spices in a small bowl and whisk to combine. Add the nuts, and toss until evenly coated. Spread the mixture evenly on the baking sheet.

3.     Bake for 10-15 minutes, until the nuts are aromatic and slightly browned. Let cool to room temperature, then use a metal spatula to loosen the mixture.

Chef’s note: as soon as you start to smell the aroma wafting from the oven, it’s time to remove the nuts. The will continue to cook as they cool.


8 servings, about 2 Tablespoons each


Store in an airtight container in the refrigerator for up to 5 days.


Adapted from The Longevity Kitchen, by Rebecca Katz


Is It the Gluten or the FODMAPs? – A Confusion, Explained

A common misconception about the low FODMAP diet is that it is a gluten-free diet. This is understandable as gluten-containing grains - wheat, barley, and rye - are greatly reduced or avoided during the elimination phase. For some people, these foods trigger common digestive symptoms (gas, bloating, abdominal pain, constipation or diarrhea). What is it in these foods that is responsible for the symptoms? Let’s dig in.

Gluten vs Fructans

Gluten is the main protein in wheat, barley and rye and needs to be avoided by people diagnosed with celiac disease. People with non-celiac gluten sensitivity (NCGS), a newly recognized condition that occurs when someone has a reaction from eating gluten but does not have celiac disease or a wheat allergy, also feel better when avoiding these grains and their products. These conditions are typically diagnosed by a gastroenterologist. Finally, people with a wheat allergy need to avoid all varieties of wheat (including spelt, kamut, einkorn, farro/emmer and triticale).

Fructans are a type of carbohydrate in gluten-containing grains, one of the FODMAPs (within the larger category of oligosaccharides, the “O” in FODMAP – more on this topic in a future article of my FODMAP Series). The common confusion comes from the fact that both gluten and fructans co-exist in wheat, barley and rye. The reason why these grains are reduced in the low FODMAP diet is that the fructans are poorly digested in people with IBS and may trigger symptoms. During the elimination phase, gluten-free grains like rice, quinoa, buckwheat and millet become a staple but small amounts of wheat can still be included. The main wheat-containing food allowed is true sourdough bread, as the fructans have been “digested” by the live cultures during a long process of fermentation, which reduces the fructan content of the bread. Soy sauce and even one small slice of regular wheat bread are usually tolerated and considered low FODMAP. In conclusion, the low FODMAP diet is not a gluten-free diet.

Not all gluten-free products are low FODMAP

During the elimination phase of the low FODMAP diet people rely on gluten-free grains and some gluten-free alternatives to bread, pasta, crackers and cookies assuming these are low in FODMAPs. It is important to point out that not all these packaged products are necessarily low in FODMAPs. When looking at a gluten-free product you need to become an expert label reader. Although the main flours used are low FODMAP (rice, tapioca, cassava), there are very often high FODMAP ingredients such as honey, agave, pear or apple juice (used as sweeteners), inulin or chicory (added to increase the fiber content) and others.

Take home message

Many people report feeling better on a gluten-free diet but don’t necessarily know why. Is it because they are sensitive to gluten, or the fructans? If you are one of them, I strongly encourage you to get a proper diagnosis first. If celiac disease or NCGS are diagnosed, then you will know that you need to avoid gluten-containing grains and their products. If you are found to have a wheat allergy, you will need to avoid all wheat products.

If you don’t have any of these conditions or continue to have symptoms on a gluten-free diet, the fructans (FODMAPs) may be to blame. Working with a dietitian to identify the source of the problem may help you liberalize your diet and find that you don’t need to unnecessarily avoid all gluten-containing grains and products. Interestingly, a recent study from Monash University (Biesiekierski et al, Gastroenterology 2013) found that only a small percentage of the subjects who had both IBS and NCGS were indeed sensitive to gluten (8%) but all felt better while eating a low FODMAP diet, suggesting that the FODMAPs had the greatest impact in their digestive symptoms.

FODMAP Explained: “F” stands for Fermentable

Welcome to my FODMAP Explained series! This is a set of articles dedicated to explaining the acronym FODMAP and giving practical tips to avoid symptoms while including as wide a variety of foods as possible.


The first letter of the acronym FODMAP goes to the very core of the why some foods trigger the uncomfortable, painful symptoms of Irritable Bowel Syndrome (IBS): Fermentable. This refers to food particles that are poorly absorbed or cannot be absorbed at all in the small intestine, continue to travel down the gastrointestinal (GI) tract and reach the large intestine (or colon). There, our friendly gut bacteria feast on the them (they are their fast food!), and produce gases and other by-products (short-chain fatty acids, SCFA) as a result of their fermentation. This is a good thing but, in people with IBS, the gas production may lead to bloating, pain and changes in motility (diarrhea or constipation).

Why it’s important to include fermentable fibers

It’s a good idea to keep feeding our friendly gut bacteria as their presence has several health benefits:

  • They are like an army defending us from the harmful (disease-causing) bacteria – the higher the number, the less space there will be for the bad bacteria to find a place to reside.

  • The by-products of their fermentation confer health benefits: SCFA have been shown to help protect us from colon cancer.

  • They can produce vitamins (several B vitamins including vitamin B12, as well as vitamin K) and even amino acids.

  • They may have several more health benefits that currently being studied. For example, they may help us improve our immune system and fight obesity.

Not all fermentable fibers are FODMAPs.

What distinguishes FODMAPs from other fermentable fibers is the speed at which they are fermented. Those that are rapidly fermentable may lead to symptoms, whereas those that are slowly fermentable produce gas at a more steady rate, and are more gentle on the GI tract. What makes FODMAPs rapidly fermentable is their chemical structure: they are shorter chains of sugars than the slowly fermentable fibers, which are made of long chains of sugars.

Bottom line: what can you eat?

If you have IBS and are trying to alleviate your symptoms, here are some useful tips:

1.     Choose foods rich in slowly fermentable fibers to avoid diminishing the number of friendly bacteria in your gut (if we don’t feed them, they die). These include vegetables, fruits, whole grains, legumes and nuts. See examples in my article Prebiotics: How to Keep Your Friendly Bacteria Happy on a Low FODMAP Diet. Try my Easy Overnight Oats recipe (below) to start your day with some good-for-your-gut fiber.

2.     Be careful about having too many of these foods in the same meal or snack, as a high dose at one sitting may lead to symptoms. To start, keep it to two or three servings (check the Monash University FODMAP Diet App for appropriate portion sizes).

3.     Avoid or limit foods rich in rapidly fermentable fibers such as  garlic/onions or artichokes; wheat, rye and barley and their products (cereals, pasta, bread). Other foods that can be fermented by the bacteria as they are poorly absorbed are shorter sugars such as monosaccharides (the “M” in FODMAP) and disaccharides (the “D” in FODMAP) and sugar alcohols or polyols (the “P” in FODMAP) - more on these in the next issues of the FODMAP Explained series.

4.     As IBS is a very individualized condition, not everyone reacts the same way to fermentable foods. You may want to consult with a dietitian specialized in FODMAPs to find out which ones trigger your own symptoms.


Easy Overnight Oats


1 cup rolled oats

1 tablespoon plus 1 teaspoon chia seeds

2 cups unsweetened almond milk

1/2 teaspoon cinnamon (optional)

Topping, per serving:

½ cup fresh or frozen blueberries or raspberries, or fresh sliced strawberries


1.     Put the oats, chia seeds and cinnamon (if using) in a glass container or large jar with an airtight lid. Add the almond milk and stir to combine.

2.     Close with the lid and refrigerate overnight or up to 4 days.

3.     When ready to serve, portion out one serving into a bowl, and top with the fruit.

Variation: add 1 tablespoon unsweetened cocoa powder and a few drops of stevia to step one for “cocoa-flavored” morning oats. Top with either one of the fruit choices above (raspberries are especially good) or 2 tablespoons chopped almonds.

Chef’s tip: if you have mason jars, you can divide the oat mixture in 4 jars and top them with the fruit, then close the jar. Every morning you have one serving ready to grab and go. This works especially well if using frozen berries, as they will defrost overnight.


4 servings


Store in an airtight container in the refrigerator for up to 4 days.