Fermented Foods Are Not for Everyone: Who Should Be Careful Even With Yoghurt and Pickles, According to Research

From homemade yoghurt to dosa and pickles, fermented foods are a regular part of our diet. They can supply beneficial microbes and help keep the gut healthy, but that depends on how the food has been prepared. And these foods may not be equally suitable for everyone.

For most healthy people, fermented foods are safe when properly prepared and stored. But people with certain medical conditions, food intolerances or a weakened immune system may need to be careful about the type and amount they eat. Knowing these exceptions makes it easier to choose food more wisely.

Some fermented foods contain histamine and other biogenic amines, which can trigger symptoms in people sensitive to them. The amount varies depending on the food, the ingredients, the fermentation process and the storage conditions.

People with histamine intolerance may, after eating certain foods, experience symptoms such as headache, facial flushing, itching, a runny nose, digestive discomfort or palpitations.

According to a study published in the journal Nutrients, fermented foods that can contain high amounts of histamine include aged cheese, some fermented vegetables, fermented soy products and certain processed or fermented meats.

Reactions to histamine, however, vary widely from person to person, and having these symptoms does not mean everyone has histamine intolerance. Anyone who suspects such a link should consult a dietitian or a doctor.

Other ingredients in the food can also cause symptoms. Spices, vinegar, preservatives and other ingredients added during preparation can also create problems. It is therefore important to distinguish between a reaction to the fermentation process and an allergy or sensitivity to another ingredient. If symptoms recur after eating a particular food, medical advice should be taken before deciding which foods to avoid.

Yoghurt is a common fermented dairy food in our households. According to a report published in the Journal of Dairy Research, fermentation reduces the lactose content of milk to some extent, and many people with lactose intolerance can tolerate yoghurt better than ordinary milk.

That tolerance, however, differs from person to person. Even after eating yoghurt or other fermented dairy foods, some people may have bloating, gas, stomach pain or diarrhoea. Those who experience such symptoms can try small amounts or lactose-free alternatives, if suitable for them. They do not need to avoid all fermented foods, because alternatives such as fermented rice batter and some fermented vegetables contain no dairy ingredients.

People undergoing chemotherapy, those who have had an organ transplant and some people taking immunosuppressant medicines may be at higher risk of foodborne infection. Commercially produced fermented foods prepared in a controlled environment may be suitable for some of them, but unpasteurised products and homemade foods carry varying levels of risk.

People whose immune system is significantly weakened should ask their doctor which fermented foods are safe for them. They should avoid products that visibly have mould, have spoiled or have been stored incorrectly.

Salt is another important consideration. Fermented foods such as pickles and some fermented vegetables can contain a considerable amount of salt. Eating large amounts can make it difficult to control sodium intake. People with high blood pressure, heart failure or chronic kidney disease may need to limit salt depending on their condition and treatment plan. Fermentation alone does not mean a food is high in sodium; the amount depends on the method of preparation. Homemade pickles and fermented vegetables can sometimes be prepared with less salt, but caution is needed when reducing salt in fermentation because it can affect food safety.

The picture is also not the same for people with certain digestive problems. Fermented foods are promoted as a way to improve gut health, but they are not equally beneficial for everyone. In people with irritable bowel syndrome (IBS), certain fermented foods can increase bloating, gas or abdominal discomfort. Some products contain fermentable carbohydrates that can trigger symptoms in sensitive people.

Overall, the main message is that fermented foods cannot be described in one sentence as beneficial for everyone or harmful for everyone. Choosing the amount and type according to one's own health condition, intolerances and medical advice, opting for lower-sodium foods where needed and following a doctor's dietary guidance is the safer path.