Glutathione: The Master Antioxidant for a Healthier You

First discovered in 1888 by J. de Rey-Paihade, a French doctor, glutathione was found in high concentrations in most of the cells of the human body, especially in the liver. Glutathione is one of the most potent antioxidants in the body. It binds to fat-soluble toxins as well as heavy metals that make their way into the body. As such, it supports the liver and kidneys as they work to detoxify harmful compounds, both organic and inorganic. Glutathione also helps make proteins in the body and regulates the function of the immune system.

Your body naturally produces glutathione in your cells. The largest producer is the liver, which creates it from three amino acids: cysteine, glutamate, and glycine. That’s why glutathione is characterized as a tripeptide. Since glutathione serves to fight the free radicals that cause oxidative damage, we want our bodies to increase the concentration of glutathione in cells in response to oxidation. and one of the safest and most effective ways to raise resting levels of glutathione appears to be exercise. Just as lifting weights can grow your muscles and cardio can strengthen your heart, temporarily raising free radical levels through physical activity creates adaptations that increase glutathione activity throughout the body.

Recently Glutathione supplementation has been promoted by health influencers as a panacea cure all and ally in optimising health and elixir of youth. However, how valid are these claims regarding the benefits of Glutathione supplementation, what are the proven benefits and what is purely speculation and hype? How do you make sure you have enough in your body, and can you get enough form your body’s natural production and a good diet or is there a need and additional benefit from supplementation? With these questions in mind let's examine the effects of glutathione in various systems and conditions in the body and how the benefits and delivery of glutathione via supplementation.

Glutathione and the Liver

Since the liver is ground zero for glutathione production, it makes sense that glutathione levels are lower in people with a variety of liver disorders and diseases. Medical research has found that glutathione supplementation can help mitigate the effects of liver disease. A small 2017 clinical trial found that people with non-alcoholic fatty liver disease (NAFLD) had their liver function improve when given supplemental glutathione. This is good news, as NAFLD is associated with the development of insulin resistance (a root cause of type 2 diabetes), obesity, and high blood pressure. Glutathione also appears to restore some liver function in those with alcoholic liver disease.

Glutathione and the Immune System

When your glutathione stores are low, your body is less able to fight off viral infections. And glutathione also participates in the development of trained immunity, whereby your immune system gets better at defeating pathogens through exposure. A 2021 study showed that high concentrations of glutathione in plasma cells were associated with some immune cells’ ability to “remember” past infections and deal with new ones more effectively.

One way glutathione supports the immune system is by inducing a phenomenon called macrophage polarization, in which macrophages (the immune cells that consume pathogens; their name is Greek for “big eaters”) can adjust their programming based on environmental signals. A 2022 microbiology paper argued that glutathione deficiency could even be a risk factor in life-threatening cases of COVID-19.

Glutathione and the Brain

One of glutathione’s impressive list of feats is its ability to regulate brain metabolism. It turns out that when glutathione function is impaired, the brain loses more neurons — a process that’s associated with cognitive decline, Alzheimer’s, and increased risk of depression and anxiety. It’s also clear that insufficient glutathione may contribute to Parkinson’s disease.

Glutathione and Cell Death

Glutathione serves as a critical regulator of cellular function, orchestrating key processes such as cell growth, division, defense mechanisms, and self-destruction. One of its most vital roles is in signaling damaged or dysfunctional cells to undergo apoptosis, a highly controlled process of programmed cell death that prevents the accumulation of defective cells. This function is essential for maintaining tissue homeostasis, preventing excessive cell proliferation, and reducing the risk of diseases such as cancer.

In addition to apoptosis, glutathione is involved in another form of regulated cell death known as ferroptosis. This recently discovered pathway is driven by iron accumulation and an excess of reactive oxygen species (ROS), leading to the destruction of the cell’s mitochondria from within. By influencing both apoptosis and ferroptosis, glutathione plays a dual role in cellular health—helping eliminate harmful or mutated cells while also ensuring that necessary immune responses and tissue maintenance processes function optimally. This delicate balance is crucial in preventing chronic inflammation, neurodegenerative diseases, and cancer, as improper regulation of cell death can lead to uncontrolled cell growth or excessive tissue damage.

Glutathione and Type 2 Diabetes

There is a proven link between glutathione deficiency and the presence of type 2 diabetes. But it’s not entirely clear yet which one causes the other (or whether both are caused by an as-yet-unknown initial factor).

A 2018 study of just 24 people (16 with type 2 diabetes and 8 matched controls who did not have the disease) found that the people with type 2 diabetes had lower glutathione concentrations, suggesting that something about the disease might cause less tripeptide production. Additionally, it appears that there’s something about excess blood sugar that requires more glutathione, leaving less for other critical functions.

For someone with type 2 diabetes, the question of causality may be less important than finding out if glutathione supplementation can improve symptoms and mitigate progression. A 2021 controlled trial out of Denmark sought to answer that question, studying the effects of three weeks of oral glutathione supplementation in 20 obese males — 10 with type 2 diabetes, and 10 without. The 20 were randomized to receive either 1,000 mg GSH (a common form of glutathione present in the body) or a placebo.

The results were promising: the group receiving glutathione improved their whole-body insulin sensitivity, meaning that it became easier for them to move glucose from the bloodstream into the cells. And the glutathione had apparently been absorbed and sent to where it was needed; a muscle biopsy confirmed that GSH concentrations increased by 19% in skeletal muscles. These findings occurred in subjects both with and without type 2 diabetes, suggesting that oral glutathione could help prevent prediabetes from developing into full-blown diabetes.

Ways to Boost Glutathione Levels

For most people, the best way to boost glutathione levels is to eat foods that contain glutathione or its precursors.  A few of the nutrients that appear especially important to helping your body make and synthesize it effectively include:

Vitamin C: A group of researchers discovered that consumption of vitamin C supplements resulted in a rise in glutathione levels in the white blood cells of healthy adults. One particular study found that consuming 500mg of vitamin C daily led to a 47% hike in glutathione levels in red blood cells.

Selenium: One investigation analysed the impact of selenium supplementation on 45 adults suffering from chronic kidney disease. The participants got a daily dose of 200mcg of selenium for a period of three months. The results revealed a significant increase in the levels of glutathione peroxidase in all of the participants. Another study demonstrated that the consumption of selenium supplements led to an elevation in glutathione peroxidase levels among patients undergoing hemodialysis. Perhaps the best way to ensure an adequate supply of selenium is to eat 1–2 Brazil nuts per day.

Turmeric: Turmeric is a brightly colored herb with vast therapeutic and anti-inflammatory properties. Several animal and laboratory studies have demonstrated that turmeric and its extract, curcumin, have the potential to raise glutathione levels. Researchers believe that the curcumin found in turmeric can enhance the functioning of glutathione enzymes. For more on turmeric and curcumin, see our article here.

Food Sources of Glutathione

Some nutrients are essential, meaning that your body can’t manufacture them and you have to get them from food (vitamin C, for example). But glutathione isn’t like that; you can manufacture it in your liver and increase its production by creating appropriate amounts of oxidative stress through exercise.

But that doesn’t mean nutrition isn’t important here. You still need to consume the building blocks of glutathione. And many plant foods provide those building blocks, either in the form of amino acids, precursor molecules, or in some cases, glutathione itself. The following are some of the best food sources of glutathione and glutathione precursors.

1. Alliums

Onions and garlic were both found to increase concentrations of a few forms of glutathione in rats. Both alliums raised GSH levels in the animals’ livers and kidneys. This may be one of the many mechanisms by which onions and garlic can prevent cancer.

2. Avocados

Avocados contain glutathione, along with many other health-promoting compounds. A 2021 animal study compared avocado oil to a common hypertensive drug, prazosin, and found that, while both treatments decreased high blood pressure in hypertensive rats, only the avocado oil improved the mitochondrial function in the rats’ kidney cells. The avocado oil, the researchers found, improved the ability of glutathione to neutralise free radicals and thereby prevent the damage often caused by high blood pressure.

3. Asparagus

If you’ve ever eaten asparagus and then noticed a funny smell when you urinate, the culprits are sulphur-containing compounds that form when asparagusic acid breaks down. Sulphur is one of the main ingredients in glutamate, which as you may recall is one of the three amino acids that form glutathione. Sulphur is also critical for the synthesis of glutathione. For the highest concentrations of these beneficial compounds, choose brightly coloured green asparagus spears rather than pale or white ones.

Other plant-based foods that are high in sulphur, and that are associated with increased glutathione levels, include cruciferous vegetables like cauliflower, broccoli, broccoli sprouts, kale, brussels sprouts, and mustard greens.

4. Watermelon

Watermelon is rich in many compounds, among them lycopene and vitamin C. Both of these may lower biomarkers of oxidative stress and inflammation, partially through increased glutathione production.

5. Pomegranate

Pomegranates are another red fruit that can boost glutathione levels. A 2014 study fed pomegranate juice to 14 healthy volunteers for 15 days and found that their GSH levels had risen by almost 23% by the last day of the trial. And a 2017 study gave pomegranate juice or a placebo to 9 elite weightlifters right after a strenuous workout. Among many other positive effects, the pomegranate juice increased the antioxidant power of glutathione by about 7%.

6. Mushrooms

Some mushroom species are high in glutathione itself. One of them, Agaricus bisporus, or the common white button mushroom. A long-term study of over 15,000 participants found that the more mushrooms' people reported eating, the lower their chances of dying. So, whether it’s the glutathione or the full symphony of nutrients found in edible fungi, mushrooms can be a great addition to most diets.

Glutathione Deficiency

Because glutathione is so important across so many systems and functions, if you’re in good health, you’re probably not deficient. But it is possible to develop a deficiency, due to either aging, certain medical conditions, or a combination of the two. You can test for glutathione levels via a blood test. Optimal glutathione levels are between 177 and 323 μg/ml (micrograms per millilitre).

The tests can measure glutathione levels in both red blood cells and plasma. And another biomarker for glutathione levels is an enzyme called gamma glutamyltransferase, or GGT. When its high, glutathione is often low.

If you need to check your numbers, talk with your health care provider about which measure is more appropriate for you.

Do Glutathione Supplements Work?

Some studies show that supplementing with oral glutathione is effective for deficiency, while others show glutathione is poorly absorbed orally. While it may depend on the person and the condition, there’s some recent research suggesting that two forms of oral glutathione might be more bioavailable and therefore more effective in raising systemic glutathione levels.

The two forms of glutathione supplements that show the most promise are liposomal and sublingual. Liposomal glutathione supplements are prepackaged in a packet of fat cells, made to mimic the structure of our own cells. This can protect the glutathione from being broken down by digestive enzymes during the digestive process. Sublingual (under the tongue) glutathione gets absorbed into the mucous membranes of the mouth, which also increases transit time and bioavailability. Another option is intravenous glutathione supplementation, which may also be more effective in raising blood levels than oral intake.

A different supplement, N-acetylcysteine (NAC), is currently being studied as a supplement for glutathione support. Again, the research is not conclusive, and results differ from disease to disease. But it appears people who supplement with NAC in conjunction with cysteine and glycine may experience a boost in glutathione levels, especially among those who may not have adequate quantities of the amino acids or who need higher levels of glutathione.

Who May Want to Supplement with Glutathione?

As we’ve seen, glutathione does a lot of things. Two of its most urgent and therefore prioritized jobs are dealing with oxidative stress — basically, protecting cells from ROS and other free radicals and detoxifying heavy metals and other contaminants. When that job becomes overwhelming, your body may not be able to produce enough glutathione to take care of other, less immediate concerns. So if someone is dealing with lots of stress, which can also include malnutrition or exposure to environmental contaminants, they may need to supplement with glutathione just to keep up with demand.

For example, smokers and those with alcohol abuse problems tend to have decreased glutathione levels and may benefit from supplementation. And people with AIDS or cystic fibrosis may benefit from (or may need to take) glutathione supplements as well. The elderly may also experience decreased glutathione levels as their natural supplies of the amino acids glycine and cysteine diminish. And there’s some research showing that glutathione supplementation may aid in recovery from extended aerobic exercise, and so may become a helpful part of the regimen for endurance athletes.

A word of caution: for cancer patients undergoing chemotherapy, it’s important not to get too much, as glutathione can increase their resistance to chemo drugs.

How Much Glutathione Should You Take?

The recommended dose for adults who are choosing to supplement is generally going to be 500–1,000 mg/day of liposomal glutathione. For glycine, the standard dosage is 3 grams per day, and it’s considered safe up to 6 grams. And for NAC, a standard dose is 600–1,200 mg (that is, 0.6–1.2 grams). And it’s safe up to 3 grams, while 7 grams or more may be toxic.

Conclusion

Glutathione plays a fundamental role in maintaining optimal health, from detoxification and immune function to brain health and disease prevention. As one of the body's most powerful antioxidants, it protects against oxidative stress, supports liver function, and even regulates critical cellular processes like apoptosis and ferroptosis. Given its wide-ranging benefits, ensuring adequate glutathione levels through diet, lifestyle, and, when necessary, supplementation can be a crucial step toward long-term vitality. While supplementation may provide additional support for some individuals, focusing on natural ways to boost glutathione—such as consuming nutrient-rich foods, exercising, and managing stress—remains the most effective strategy for harnessing its full potential.