Is the glutamate in your food bad for your heart?
Probably a little, yes. In 108,932 French adults, every extra 200 mg a day of food additive glutamate, the MSG added to packaged foods, was tied to about 5% higher risk of coronary heart disease (hazard ratio 1.05). Glutamate that occurs naturally in food was tied to higher risk too.
Glutamate is an amino acid, one of the building blocks of protein. Your body makes it, and it shows up naturally in foods like cheese, tomatoes, mushrooms, and meat. Food companies also add a concentrated form to boost savory flavor. On an ingredient label it appears as monosodium glutamate, or as the E numbers E620 through E625.
Whether that added glutamate harms the heart has been argued for decades. Lab work has shown glutamate helps regulate how the heart beats at normal doses, which raises the question of what happens at high ones. Until now, no study had separated the glutamate people eat as an additive from the glutamate already sitting in whole foods.
What the data show about glutamate and heart disease
Researchers tracked participants in the French NutriNet-Santé cohort from 2009 to 2023. Over a median of 7.92 years, 2,397 people developed cardiovascular disease, 1,113 had a cerebrovascular event such as a stroke, and 1,284 developed coronary heart disease, meaning blocked or narrowed heart arteries.
Food additive glutamate came out linked to coronary heart disease at about 5% higher risk for each extra 200 mg per day, very likely somewhere between 1% and 9% higher (95% confidence interval 1.01 to 1.09). There is about a 2 in 100 chance a link that size showed up by luck.
Naturally occurring glutamic acid tracked with about 13% higher coronary heart disease risk per extra 3,000 mg a day (hazard ratio 1.13), very likely between 3% and 25% higher. Total glutamate from both sources tracked with about 15% higher risk (hazard ratio 1.15), very likely between 5% and 26% higher. Both had under a 1 in 100 chance of being coincidence.
For cardiovascular disease overall the same pattern held but weaker: roughly 3% higher risk for additive glutamate, 9% for natural glutamic acid, and 10% for total glutamate. The additive figure for overall cardiovascular disease was not statistically clear, with about a 7 in 100 chance of coincidence. For stroke and other cerebrovascular events, there was no link at all.
Dr. Kumar’s Take
The interesting result here is not the MSG. It is that naturally occurring glutamate showed a larger association than the additive did. That cuts against the popular story, where MSG is the villain and natural food is safe. Glutamate is glutamate once it reaches your bloodstream, and this study is consistent with that.
The effect sizes are small. A 5% shift in relative risk per 200 mg a day is not the kind of number that should change how you eat tomorrow. What makes it worth reading is the measurement quality. Most nutrition studies ask you what you ate last year with a checklist. This one used repeated 24-hour food records, an average of 21 per person and as many as 84, plus the actual brands people bought, plus lab testing of real food samples to figure out how much additive glutamate was really in them. That is unusually careful exposure data for a study this size.
It is still observational. People who eat a lot of additive glutamate tend to eat a lot of processed food, and processed food comes with salt, refined starch, and everything else. The authors say plainly that leftover confounding cannot be ruled out and that one observational study cannot prove cause.
How confident should we be in this?
The design is a strong version of a limited method. A prospective cohort follows healthy people forward and waits for disease to appear, which avoids the memory problems of asking sick people what they used to eat. Over 108,932 participants and nearly eight years, that produced enough heart events to detect small effects.
The limits are real. The group was 79.3% female with a mean age of 42.4 years, and volunteers who sign up to log their meals online are not a random slice of the population. Diet was self-reported, and no one was assigned to eat more or less glutamate. The linked risks were also linear and modest, so this is a signal to study further, not a verdict.
Practical Takeaways
- Do not single out MSG on a label as the thing to avoid, since naturally occurring glutamate showed a stronger link to coronary heart disease in this study than the additive did.
- If you want to lower additive glutamate, the practical move is eating fewer heavily processed savory products such as instant noodles, bouillon cubes, chips, and packaged sauces, which is worth doing for many reasons beyond glutamate.
- Do not remove cheese, tomatoes, or mushrooms from your diet over this, because an observational link of this size is not a reason to drop foods with well-established benefits.
- If you already have heart disease or several risk factors, spend your effort on blood pressure, cholesterol, and smoking, where the evidence is far stronger than anything here.
Related Studies and Research
- Ultra-processed foods linked to 47% higher heart disease risk
- Does replacing saturated fat with linoleic acid reduce heart disease risk?
- A plant-based diet lowered heart disease risk over 20 years
- Ultra-processed foods linked to weaker attention and higher dementia risk
FAQs
Is MSG actually dangerous, or is that a myth?
The idea that MSG causes headaches and flushing came from anecdotal reports in the 1960s and has not held up well in controlled testing. This study is a different question. It is not about immediate symptoms after a meal, it is about heart artery disease over years. The link it found was small and statistical, not a warning that a serving of MSG will hurt you. And because natural glutamate showed the same or a larger association, the finding does not support treating MSG as uniquely harmful.
Which foods have the most glutamate?
The study did not rank individual foods, but glutamate is well known to concentrate in aged and savory items. Naturally, it is high in parmesan and other aged cheeses, tomatoes, mushrooms, soy sauce, fish sauce, and cured meats. As an additive it turns up in savory processed products, listed as monosodium glutamate or as E620 to E625. Because the study used brand-level data and lab assays, it could tell those two sources apart, which is why the separate estimates exist.
Why did glutamate affect heart arteries but not stroke?
Coronary heart disease and stroke share risk factors but are not the same illness. Coronary disease is mostly about plaque building up in the arteries feeding the heart muscle. Stroke includes clots and bleeds in the brain, driven more strongly by blood pressure and irregular heart rhythm. The authors point to lab work showing glutamate helps regulate heart rhythm and function, which is a heart-specific mechanism. The stroke result was flat, with all the statistical tests showing nothing close to a signal.
Bottom Line
In 108,932 French adults followed for a median of nearly eight years, higher glutamate intake tracked with higher coronary heart disease risk from every source measured: about 5% per 200 mg a day of added MSG, about 13% per 3,000 mg a day of naturally occurring glutamic acid, and about 15% for total glutamate. Stroke showed no link. The associations are small, the study is observational, and the authors say causality cannot be established. The useful message is not to hunt for MSG on labels, it is that the savory processed foods carrying most of it are worth eating less of anyway.
