5 Downsides to Eating Fermented Vegetables

Fermented Vegetables

Fermented foods are popular due to the obsession with having a healthy gut microbiome. No wonder! The gut microbiome is the focus of a multitude of research into what role it plays in health and vitality. Why are the bacteria in your gut important? The trillions of tiny critters that dwell in your large intestinal tract help with nutrient absorption, weight control, and even play a role in immune health. Since the immune system influences almost every aspect of health, it is not hard to see why maintaining a healthy microbiome is vital for a healthy body.

The composition of your gut microbiome could even affect your personality and how you respond to stress too. An Oxford University study found that the makeup of a person’s gut microbiome correlates with personality traits such as introversion /extroversion and how neurotic a person is. Plus, other studies show that gut bacteria play a role in anxiety and depression.

How might gut bacteria influence your mood or mental state? It turns out that gut bacteria make almost 60 substances that play a role in the function of the central nervous system and mood. They also produce anti-inflammatory short-chain fatty acids, such as butyric acid. Research into depression finds that inflammation is a driving force behind this common mental health condition.

We do not yet know what the ideal composition of bacteria in the intestinal tract is most conducive to health. It appears that a more diverse population of bacteria is more healthful than a narrow range of gut species. One way to get a more diverse microbiome is to consume fermented foods, including fermented vegetables.

Fermented Vegetables Contain Probiotics

If you love crunchy sauerkraut, you are in luck! If it is fresh and unprocessed, sauerkraut contains a wealth of probiotic bacteria that can populate your gut once you eat it. But sauerkraut is only one type of fermented vegetable. You can ferment almost any vegetable at home and enjoy it as a source of probiotics. Some of the most popular options include cauliflower, broccoli, radishes, peppers, carrots, green beans, beets, and more. But are there disadvantages to eating fermented vegetables? It’s always smart to know the downsides and the upsides. You already know the upsides, so let’s look at some drawbacks of eating fermented vegetables.

Fermented Vegetables Could Aggravate Headaches

Do you suffer from headaches? Think twice before eating lots of fermented vegetables. During the fermentation process, bacteria produce chemicals called biogenic amines. Two of these are tyramine and histamine. Some people are sensitive to histamine and can develop a vascular headache when they are exposed to these chemicals from fermented foods or other sources. The take-home message? If you have a history of migraine headaches, lay off fermented vegetables and other fermented foods for a few weeks and see if your headaches decrease in frequency. Fermented foods have health benefits, but they aren’t for everyone.

You May Experience Bloating

Although probiotics can create a healthier digestive tract in the long run, you could experience temporary bloating and flatulence when you first add these foods to your diet. When you add probiotic bacteria to your gut, the bacteria produce peptides that kill harmful bacteria of the type that cause food poisoning. A by-product are gas-producing substances that trigger bloating.

In addition, fermented vegetables are high in fiber. Most people don’t consume enough fiber but adding too much fiber to your diet too fast can also cause bloating. It takes a few weeks for your intestinal tract to adapt to fermented vegetables, but you can avoid some of the side effects by adding only small amounts to your diet at a time. Plus, you don’t need a lot. Studies show that a few tablespoons of fermented vegetables per day is enough to offer health benefits.

May Pose a Risk for Infection in Some People

Probiotics are live bacteria. Although they are “friendly” to the gut of most healthy folks, people with a weakened immune system, including young children, the elderly, and people with certain medical conditions, could experience infections when they take in probiotics from food or supplements. This doesn’t apply to the average healthy person though, but it suggests approaching probiotics with caution at the extremes of age or in people who have a weakened immune system, take medications that suppress immunity, or have other health problems.


If you ferment your own vegetables at home, there is a minor risk of contaminating the vegetables during or after the fermentation process. This can happen if you don’t wash your hands, surfaces, or utensils well or allow the veggies you are fermenting to come into contact with contaminated food sources like raw meat.  Since fermenting vegetables produces lactic acid, and that lowers the pH, the risk is lower than would be expected since the low pH helps keep pathogenic bacteria in check. However, lactic acid may destroy pathogenic bacteria but not the toxins they produce, so they could still lead to illness.  Don’t ferment your own vegetables unless you know what you are doing. There is a slight risk of contamination that lead to food poisoning.

The Bottom Line

Fermented vegetables are a rich source of fiber, probiotics, vitamins, minerals, and phytonutrients but they have some potential downsides too. Keep these drawbacks in mind and be careful if you ferment your own vegetables at home. Also, talk to your physician and make sure that consuming fermented foods is right for you. If so, enjoy them in moderation, along with an overall healthy diet that contains fermented and unfermented fruits and vegetables.



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  • Biosci Biotechnol Biochem 1997 Sep;61(9):1582-4.Okamoto, A., et al. Tokyo University of Agriculture, Tokyo, Japan.
  • University of Oxford. “Gut Bacteria Linked to Personality”
  • Psychiatry Advisor. “A Closer Look at the Importance of Gut Mechanisms in Depression”
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  • com. “Foods Implicated in Migraines”


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