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
Lactose-free yogurt and kefir
Some fermented cheese
High in FODMAPs
Regular yogurt and kefir
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.