What to Avoid When Taking Glutathione [Science Backed]

What to Avoid When Taking Glutathione [Science Backed]

Glutathione is a powerful antioxidant your body naturally makes, and it works to neutralize free radicals, support your immune system, and metabolize nutrients. Without it, the body may be left prey to oxidative stress, which is a key contributor to many chronic diseases and health issues, such as Alzheimer's, Parkinson's, liver disease, cancer, heart attack, stroke, and diabetes, according to a 2004 report in the Journal of Nutrition

Glutathione is made up of three amino acids: glutamate, cysteine, and glycine.

Amino acids are the building blocks of protein, so it makes sense that eating protein-rich foods can help your body produce more glutathione. A 2019 Nutrients study found that eating less protein may lower blood glutathione levels, contributing to a reduction in antioxidant effects. 

There are other factors, aside from protein intake, that can contribute to lower glutathione levels — and the common thread of all of these factors is oxidative stress. When we're exposed to oxidative stress, it increases free radicals and can deplete glutathione levels in the body — and lower glutathione can contribute to inflammation and a higher susceptibility to infection, per a 2021 study in Foods.

Here's everything you need to know about what to avoid when taking glutathione, and how to prevent lowering your levels of this important antioxidant. 

Key Foods to Avoid

Processed and Fried Foods

Processed and fried foods are rich in all the nutrients we aim to limit in our diet: unhealthy fats (like trans fats and certain saturated fats), sodium, and added sugar. Multiple bodies of research have confidently established the link between a diet high in ultra-processed foods and fried foods and inflammation. 

Regularly eating ultra-processed foods contributes to changes in the cells that cause oxidative stress, per a 2021 Nutrients study. Repeatedly heating cooking oils, which is how many fast food restaurants fry their foods, can cause trans fats to form. These trans fats are significantly associated with increased inflammation, per a 2021 Foods study

Because oxidative stress and inflammation reduce your glutathione levels, it's important to focus your diet on nutrient-dense whole foods. Specifically, foods rich in polyunsaturated fatty acids, fiber, and polyphenols may help regulate oxidative stress, according to the 2021 Foods study. Sources of polyunsaturated fats include fatty fish, seeds, and nuts, while fiber and polyphenols are found in fruits and vegetables.

High-Sugar Beverages

Sugary drinks, such as sodas and juices,  are one of the top sources of added sugar in our diet. Sipping on high-sugar beverages can cause your blood sugar to spike and then crash, which can contribute to insulin resistance over time. Insulin resistance is a precursor to type 2 diabetes, and people with type 2 diabetes have been shown to have lower glutathione levels, per a 2018 study in PLOS One.

Rather than hydrating with high-sugar drinks, turn to healthier options such as unsweetened tea, fruit-infused water, zero-sugar sparkling waters, or get used to plain ol' H2O. 

Harmful Habits to Eliminate

What to avoid when taking glutathione Image


We all know how harmful smoking is, but let's hone in on how it affects glutathione levels. A 2016 study in Free Radical Biology & Medicine found that smokers had lower blood levels of the antioxidant compared to non-smokers. However, the study also found that glutathione levels significantly increased three weeks after quitting smoking.

Excessive Alcohol Consumption

Imbibing one too many cocktails too often can hinder your glutathione levels. A 2022 study in Antioxidants found that chronic alcohol intake consistently reduces glutathione levels in the brain and blood and leads to increased oxidative stress. 

Limiting — or, even better, avoiding — alcohol can help keep your glutathione at a healthy level.

Medications and Supplement Interactions

There aren't any known drug interactions with glutathione supplements. However, it's always best practice to speak to your doctor before starting a new supplement — and that's especially important if you're on medications. 

Lifestyle Recommendations for Enhanced Glutathione Levels

What to avoid when taking glutathione Image

Adopting a Balanced Diet

We know that a healthy balanced diet can help reduce chronic oxidative stress — and that, in turn, can help you achieve optimal glutathione naturally. So what does a balanced diet look like? An eating plan that focuses on healthy fats, lean protein, and antioxidant-rich plant foods is a great place to start. 

The 2021 Foods study found that foods high in polyunsaturated fatty acids, fiber, and polyphenols may help regulate oxidative stress. The 2019 Nutrients study found that lean protein sources, cruciferous vegetables, polyphenol-rich fruits and vegetables, herbs and spices, green tea, and omega-3-rich foods (such as salmon) can improve glutathione levels.

The Benefits of Exercise and Stress Management

When you're constantly stressed, your entire body feels the brunt of it. In fact, stress and anxiety disorders have been associated with reduced levels of glutathione and, increased oxidative damage, per a 2020 report in Neuroscience & Biobehavioral Reviews. That's exactly why managing your stress levels is so important for keeping your glutathione levels up.

Exercise is a great way to manage stress because it releases endorphins (the feel-good chemicals in your brain) and lowers levels of stress-related hormones. 

The Role of Amino Acids in Glutathione Production

Importance of L-Cysteine and Glycine

Glutathione is made up of the amino acids glutamate, cysteine, and glycine. However, cysteine and glycine are especially important when it comes to glutathione synthesis.

Cysteine is a sulfur amino acid, so consuming foods rich in sulfur and sulfur amino acids may support glutathione synthesis, per the 2019 Nutrients study.

Foods rich in cysteine and glycine include:

  • Beef

  • Chicken

  • Dairy

  • Fish

  • Cruciferous vegetables

  • Alliums (onions, garlic, and shallots) 

Precautions and Side Effects

Possible Side Effects of Glutathione Supplementation

There aren't any side effects of getting glutathione from food, but taking oral glutathione supplements is associated with a few potential risks. One small 2017 study in Clinical, Cosmetic and Investigational Dermatology found that glutathione supplementation was linked to rashes and tiredness. 

And  inhaled glutathione was shown to cause breathing problems in people with mild asthma, per a 1996 study in the American Journal of Respiratory and Critical Care Medicine.

Special Precautions for Pregnant and Nursing Individuals

As of now, we don't have enough data to confirm the safety of glutathione supplementation for people who are pregnant or nursing. So if you're pregnant, planning to get pregnant, or breastfeeding, avoid glutathione supplements, and always speak to your doctor before starting any supplement.


Glutathione is a potent antioxidant that plays a crucial role in neutralizing free radicals, protecting cells from oxidative stress, and supporting your immune response and your overall health.

That's why knowing what to avoid when taking glutathione is critical. Smoking, drinking too much alcohol, and eating and unhealthy diet can all lower your levels of this important antioxidant. On the flip side, eating a nutrient-dense diet, managing your stress levels, quitting smoking, and drinking less alcohol can all help you maintain optimal glutathione levels (and enjoy other health benefits).

While there's some evidence that suggests taking glutathione supplements can increase your levels of glutathione, the research is inconclusive. Always consult your healthcare provider before starting any new dietary supplement regimen. 


  1. https://www.sciencedirect.com/science/article/pii/S0022316623026639?via%3Dihub

  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6770193/#:~:text=Since%20the%20precursors%20and%20foundation,to%20draw%20to%20synthesize%20glutathione.

  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8391153/

  4. https://pubmed.ncbi.nlm.nih.gov/34399404/

  5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8535577/

  6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5991679/

  7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4761461/#:~:text=Plasma%20levels%20of%20GSH%20measured,1.0%20%CE%BCM)%20%5B5%5D.

  8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9311529/

  9. https://www.sciencedirect.com/journal/neuroscience-and-biobehavioral-reviews

  10. https://www.dovepress.com/clinical-cosmetic-and-investigational-dermatology-journal

  11. https://www.atsjournals.org/doi/10.1164/ajrccm.156.2.9611001

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