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Miso Side Effects

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Probiotics, essential nutrients, and both low in calories and carbs, miso has a lot of nutritional value that results in great health benefits overall. But most miso products are processed with high levels of salt, which makes them potentially dangerous when consumed in large amounts. 

Other than fermentation, the level of salts in miso products determines how healthy the product is. The uncertainty of consuming large amounts of salt in miso has both short and long term side effects. 

What are miso side effects? Typical side effects of miso are nausea, vomiting, diarrhea, stomach cramp, uterine contractions, and menorrhagia. However, the side effects occur only if miso is consumed above the daily recommendation amount. 

Despite miso being associated with isoflavones that may play a role in breast cancer, numerous animal research done in Japan shows that consuming large quantities of miso soup is associated with gastric cancer.

Salt contains sodium, so consuming a large amount increases the level of sodium ion concentration in the blood, which can result in hypertension. The sodium ions make the body retain water and causes an imbalance of blood concentration that results in high blood flow in the arteries.

Miso is produced from fermented soybeans, which makes it a soy product. Some people are sensitive to soy and results tend to trigger allergic reactions such as nausea, diarrhea, and vomiting.

The benefit of consuming miso on a daily basis includes a rich source of amino acid proteins. These micronutrients enhance the production of the hormone melatonin, which is considered to trigger tiredness and sleep.

Miso is processed from fermented soybeans and falls under the category of goitrogenic foods. These foods may cause issues with thyroid function and hyperthyroidism as the chemical isoflavones present in miso eliminates iodine levels that trigger impairment of thyroid function.

Most side effects of miso result from consuming large quantities, so look for healthier miso flavors to minimize exposure to salts. This article answers frequently asked questions about the side effects of miso and how the dangers can be avoided to maximize the benefits in your diet.

Does miso cause inflammation?

No, miso does not cause inflammation. On the contrary, miso helps the body to fight inflammation and boost gut health. 

Miso actually helps reduce inflammation. Fermented soybeans are rich in anti-inflammatory compounds such as isoflavonoids and phenolic acid. [1, 2]

These two compounds act as powerful antioxidants during the neutralization of free radicals, resulting in stomach inflammation. 

The isoflavones present in miso are broken down into anti-inflammatory agents along the guts. This not only helps in the prevention of inflammation, but also chronic diseases related to the heart. [3, 4]

Furthermore, miso contains fungal strains such as oryzae, which also help control inflammatory intestinal diseases. [5, 6]

Can miso paste make you sick?

Yes, miso paste can make you sick. Concerns are related to allergens, high salt concentration or consuming spoiled miso paste that causes food poisoning due to the growth of harmful bacteria. 

Therefore, checking for any signs suggesting the miso paste has gone bad before consuming is always advisable. Verify the expiration date and look for a change of color, taste, and smell indicating the miso is spoiled.

Majority of fresh miso paste is derived from soybeans, which can trigger allergic reactions like skin rashes, vomiting, and nausea in people who are intolerant to soy products.

Consuming a large amount of miso paste can cause hyperthyroidism by impairing thyroid functions since it depletes the iodine level.

For people at risk of hypertension, consuming a large amount of miso paste can cause high blood pressure since it will increase the sodium ions levels in the blood.

What happens if you have too much miso?

Miso is an easy condiment to be added to soup, salad dressing, and marinating meat. It adds flavor and nutrients to every dish.

However, most miso is prepared with excessive salt for flavor and fermentation purposes. Therefore, consuming too many miso products increases the level of salt intake in the body, which is associated with health disorders like heart diseases such as stroke and blood pressure. [7, 8, 9]

The science behind this revolves around the sodium ions affecting blood flow in the arterial vessels. Excess salts increase the concentration of sodium ions in the blood, and provokes the body to hold water leading to a high flow of blood in arteries as the vessels try to balance concentration in the blood triggering high blood pressure.

Moreover, miso belongs to the food category known as a goitrogen, resulting in thyroid impairments by depleting iodine. Therefore, consuming too much miso can cause hyperthyroidism, especially in people with thyroid issues.

Miso benefits and side effects

Miso has its pros and cons. Most disadvantages of miso come along once a person consumes large amounts. 

Made with fermented soybeans, here are health benefits of consuming moderate amounts of miso:

  • Improvement of the digestive system: The fermented miso is rich in probiotics that contain good bacteria to help gut health. These nutrients contain anti-inflammatory agents that break down radicals causing inflammation.
  • Boost immunity system: The presence of probiotics helps the body to fight against harmful bacteria and infections.
  • Helps in cardiovascular health: The presence of isoflavones compound in miso helps lower the level of cholesterol in the body, which causes “bad LDL” associated with health issues such as heart diseases.
  • Prevention of cancer: The isoflavones compound in miso helps boost the estrogen level in the body, which plays a key role in preventing breast cancer.
  • Improvement of reproduction health: The isoflavones compound is associated with easing the menopause symptoms, such as hot flushes for women in their post-menstrual stages. 

However, despite the above health benefits, consuming miso in large amounts above daily recommendations can have some adverse side effects such as:

  • High blood pressure: Increases salt intake and sodium levels in the blood. As a result, the imbalance of concentration raises the blood flow pressure. 
  • Cause hyperthyroidism: Being a goitrogen food, consuming a large amount of miso can deplete iodine level that causes thyroid impairments. 
  • Trigger allergic reactions: For people who are sensitive to soy products consuming miso paste can provoke allergic responses such as nausea, diarrhea, vomiting skin rashes, among others.
  • Triggers certain cancer: Consuming too much salt has recently been associated with increases in gut cancer.
Side effects of miso

Side Effects of Miso: Conclusion 

Miso is rich in nutrients essential to maintaining a healthy diet and proper body functioning. However, only consume moderate amounts to get the maximum benefits without experiencing adverse effects. 

Because consuming large amounts of miso can result in some harmful side effects. It is advised to consume a bowl of miso soup per day for health benefits, 1 tablespoon for every 1 to 1½ cups of water is a reasonable amount.

It is considered healthy fermented food, but the high salt content in miso creates concern for multiple side effects. Therefore, the best miso products to consume are the ones with vegetable flavors and fewer salts. 

People allergic to soy products and fermented foods should keep away from miso paste since it can trigger an adverse reactions including nausea, vomiting, diarrhea, stomach cramps, and many more when consumed large quantities. 

However, moderate amounts have been proven to boost gut health and fight inflammation

Check whether the product is spoiled or not since, like any other foods, miso causes food poisoning when it has gone bad. When not properly stored, miso may cause food borne illness due to the growth of harmful bacteria.

Above are listed benefits and side effect of consuming miso for you to consider. Always consult a medical professional for recommendation on the amount of miso to add to your diet.

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