Does MSG cause you to retain fluid? The nutritional truth behind the myth

October 9, 2025 •

4 min read

Monosodium glutamate (MSG) contains only about one-third the sodium of table salt, yet many people fear its connection to water retention. So, does MSG cause you to retain fluid, or is the culprit a broader issue with high-sodium diets?

Quick Summary

Despite its reputation, MSG is less likely to cause fluid retention than table salt due to its significantly lower sodium content. Overall dietary sodium is the main contributor.

Key Points

Less Sodium Than Salt: MSG contains only one-third the amount of sodium found in table salt, making it less likely to be the primary cause of fluid retention.
Focus on Total Sodium: The true culprit for fluid retention is high overall dietary sodium intake, which is often prevalent in heavily processed foods.
MSG Is Safe: Regulatory bodies like the FDA and WHO consider MSG safe for human consumption at typical dietary levels.
Dosage Matters: While very high doses in animal studies have shown effects, these do not reflect the moderate amounts typically consumed by humans.
Enhance Flavor, Reduce Salt: Using MSG can be a tool to reduce overall sodium in cooking, as it can enhance the savory flavor of dishes with less salt.
Beyond MSG: When you experience bloating from processed foods, it's more likely a result of the high total sodium content from all ingredients, not just the MSG.

Understanding Fluid Retention

Fluid retention, also known as edema, is the body's accumulation of excess fluid within tissues. It is often caused by eating too much salt, which contains a high concentration of sodium. The kidneys manage the body’s sodium levels, and when too much is consumed, they struggle to excrete the excess. This imbalance signals the body to hold onto more water to dilute the sodium, leading to bloating and swelling. The common fear that MSG contributes to this stems from the fact that it is the sodium salt of glutamic acid. However, as we will explore, the amount of sodium in MSG and its typical consumption patterns paint a different picture.

The Truth About MSG's Sodium Content

One of the most persistent myths about MSG is that it is exceptionally high in sodium. The fact is, MSG contains only about 12.28% sodium by mass, which is approximately one-third the amount found in regular table salt (sodium chloride), which is about 39.34% sodium. This critical distinction is often overlooked when discussing MSG's health effects.

How MSG can reduce overall sodium

For those watching their sodium intake, MSG can actually be part of the solution rather than the problem. Because it provides a powerful umami flavor, food manufacturers and home cooks can use a smaller amount of MSG in combination with a reduced amount of salt to achieve the same or better savory taste. Research has shown that using MSG can help reduce the total sodium content in a recipe by 20 to 40 percent without compromising flavor. This is a valuable strategy for improving public health by helping people lower their sodium consumption without feeling deprived of taste.

Scientific Evidence on MSG and Fluid Balance

Multiple scientific and regulatory bodies, including the U.S. Food and Drug Administration (FDA) and the World Health Organization (WHO), have classified MSG as safe for consumption at customary levels. The idea that MSG causes an adverse reaction, sometimes called "Chinese Restaurant Syndrome," has been widely debunked through controlled studies. The perception of symptoms like headaches, flushing, and bloating has been inconsistent and largely attributed to anecdotal reports rather than reproducible scientific evidence.

Animal vs. Human studies

It is important to differentiate between studies conducted on animals and those involving humans, as well as the dosage levels used. Some animal studies, particularly those involving high-dose injections or long-term high oral consumption, have shown effects on blood pressure and kidney function. However, these studies use dosages that far exceed normal human dietary intake. For instance, a 2022 study on rats found that moderate to high doses of MSG could alter water balance and induce salt retention. In contrast, human studies on MSG intake at typical dietary levels have not established a clear link to significant health problems.

The context of processed foods

Fluid retention is often a symptom of consuming large amounts of heavily processed foods, many of which contain MSG as a flavor enhancer. However, these foods are also typically loaded with high amounts of regular table salt, sugar, and unhealthy fats. It is more likely that the high overall sodium content from all these ingredients, rather than the MSG specifically, is causing the fluid retention. Simply blaming the MSG ignores the larger nutritional context of the diet.

Practical Tips for Managing Sodium Intake

If you are concerned about fluid retention, focus on your overall sodium consumption rather than demonizing a single ingredient. Here are some actionable steps:

Read food labels: Check the sodium content on packaged foods, which are a major source of dietary sodium.
Use MSG as a salt replacement: As mentioned, MSG contains less sodium than table salt. Experiment with using it to replace some of the salt in your cooking to maintain flavor.
Cook at home: Cooking from scratch gives you full control over the amount of salt and flavor enhancers in your meals.
Embrace natural flavors: Incorporate herbs, spices, and naturally glutamate-rich ingredients like tomatoes and mushrooms to boost flavor without adding sodium.
Stay hydrated: Drinking plenty of water helps your kidneys function properly and flush out excess sodium.

MSG vs. Table Salt: A Comparison


Feature	Monosodium Glutamate (MSG)	Table Salt (Sodium Chloride)
Sodium Content	~12.3% by mass	~39.3% by mass
Flavor Profile	Umami (savory)	Salty
Typical Usage	Flavor enhancer, used in smaller quantities	Standard seasoning, used in larger quantities
Impact on Fluid	Minimal impact on fluid balance at typical doses	Major contributor to fluid retention when consumed in excess
Effect on Sodium Intake	Can help reduce overall sodium intake by enhancing flavor	Increases overall sodium intake directly
Regulatory Status	"Generally Recognized As Safe" (GRAS) by FDA	Safe, but excessive intake is a public health concern

Conclusion

While many people hold onto the belief that MSG causes fluid retention, the scientific evidence indicates this is a misconception. Fluid retention is primarily a result of high overall sodium intake, and MSG actually contains significantly less sodium than regular table salt. The broader issue often lies in the excessive consumption of processed foods, which are high in total sodium from various sources. For the vast majority of people, consuming MSG in typical amounts is perfectly safe and poses no risk of causing fluid retention. By understanding the real facts about sodium, we can make more informed dietary choices and focus on the overall nutritional quality of our meals.

For further reading on the safety of MSG, refer to the U.S. Food and Drug Administration's official page on the topic.

Frequently Asked Questions

While anecdotal reports of bloating exist, robust scientific evidence has not established a direct causal link between MSG and bloating at normal dietary levels. The high sodium content of many processed foods that also contain MSG is a more likely cause of bloating.

MSG contains approximately 12% sodium, which is about one-third the amount found in table salt, which contains around 39% sodium.

Excessive sodium intake is a major risk factor for high blood pressure, and MSG contributes some sodium to the diet. However, some studies suggest MSG can help reduce overall sodium in food without sacrificing flavor, potentially benefiting those managing their blood pressure.

Chinese Restaurant Syndrome is an outdated term used to describe a set of symptoms, including flushing and headaches, allegedly caused by MSG. Controlled studies have largely failed to find a consistent link, and the phenomenon is now largely discredited.

To reduce fluid retention, limit your intake of high-sodium processed foods, increase your water consumption, and use herbs and spices for flavor instead of relying heavily on salt.

The human body metabolizes the glutamate in MSG in the same way as the glutamate found naturally in foods like tomatoes, mushrooms, and cheese. The body does not distinguish between the sources.

Glutamate is naturally found in a wide variety of foods, including aged cheeses (like Parmesan), tomatoes, mushrooms, soy sauce, and protein-rich foods like meat, fish, and dairy.