8 Foods Containing the Highest Quantity of Glutathione

Did you know that your body produces antioxidants to combat excess free radicals, protect your cells and tissues from damage, and slow down aging?

Glutathione is a powerful antioxidant produced by cells in the body. Surprisingly, its concentrations in most cells are high [1]. It has the same concentration as potassium, cholesterol and glucose inside the cells! High levels of glutathione in the cells underlie its importance in body metabolism.

What is glutathione?

Glutathione is a protein made up of three amino acids: cysteine, glutamine, and glycine. It is critical in protecting cellular macromolecules from reactive oxygen and nitrogen species. While it combats free radicals, it directly deals with mercury and persistent organic pollutants (POPs). Both POPs and mercury cause oxidative stress.

Oxidative stress is an imbalance between the production of free radicals and antioxidant defences [2]. Reactive oxygen species (ROS) refer to the following [3]:

Superoxide radicals
Hydrogen peroxide
Hydroxyl radicals
Oxygen

These ROS are generated as by-products of metabolism in biological systems. Biological processes such as cell death, immunity, and protein metabolism depend on appropriate amounts of ROS in the cells. ROS levels must be low since any increase can damage cellular structures such as nucleic acids, lipids, and proteins [4]. When present at appropriate levels, ROS has many beneficial roles. They are responsible for synthesising cellular structures for fighting infections.

White blood cells called phagocytes produce and store free radicals. Once pathogens are present, phagocytes release free radicals to help destroy pathogenic microorganisms [5].

A large body of evidence [6] shows that oxidative stress can lead to the progression of several chronic conditions, such as cardiovascular disease, atherosclerosis, metabolic disorders, diabetes, and cancer.

What are the roles of glutathione in the body?

Glutathione plays several roles in the body. Here are some of its functions that keep you healthy:

It acts as a cofactor for different antioxidant enzymes. Cofactors are helper molecules that speed up biochemical reactions and transformations.
Vitamins C and E regeneration
When the liver metabolises chemical toxins, glutathione neutralises the free radicals formed during the metabolism of the chemical toxins.
It helps in the excretion of products of liver metabolism.
Excretion of mercury out of the brain and cell
Regulation of cell death and cell proliferation
Essential to the function of the mitochondria and maintenance of mtDNA or mitochondrial DNA

What are the diseases associated with the depletion of glutathione?

Research studies show that when glutathione is depleted, this is associated with loss of function and the development of several diseases. Depletion of glutathione occurs when there is a progressive loss of function of the mitochondria due to damage to mtDNA. In animal studies, the ability of organisms to protect their mtDNA is positively linked with longevity [7].

Here are some of the diseases associated with the depletion of glutathione [8]:

Chronic age-related diseases (glaucoma, hearing impairment, macular degeneration, and cataracts)
Cystic fibrosis
Liver disease
Ageing process itself
Cardiovascular diseases (cholesterol oxidation, myocardial infarction, hypertension)
Immune diseases (autoimmune disease, HIV)
Pulmonary diseases (acute respiratory distress syndrome, asthma, and COPD)
Neurodegenerative diseases (Friedrich’s ataxia, amyotrophic lateral sclerosis, Huntington’s disease, Parkinson’s, and Alzheimer’s disease)

How can I increase levels of intracellular glutathione?

The good news is that you can raise intracellular glutathione levels by eating the right food!

Almonds

Almonds are often called nuts. However, they are teardrop seeds in shape and are fruits of the almond tree. Almond is a tree native to Iran and other countries in the Mediterranean regions. Historically, the cultivation of almond trees dates back to as early as 3000 BC.

Edible parts of almonds are called drupes, seeds of the almond fruit. The fruit has an outer shell and layers of an unedible hull.

Almonds are excellent sources of vitamin E, fibre, biotin, monounsaturated fats, magnesium, phosphorus, calcium, and trace minerals such as copper, phytonutrients, plant sterols, flavonoids and phenolic acids.

There is growing evidence that almonds can increase glutathione levels. One study [9] showed that the intake of 83 g/d of almonds increases glutathione levels amongst smokers by 16%, while their DNA damage decreased by 29%.

Turmeric

Turmeric is a herb that has a vibrant yellow colour. You will often see turmeric in famous Indian cuisine as a yellow spice.

Turmeric is rich in polyphenols, with curcumin as the most abundant. One animal study reported that curcumin increased glutathione levels in rat liver cells exposed to cytotoxic compounds [10].

This demonstrated curcumin’s cytoprotective properties in cells attacked by toxins. It would appear from the study that curcumin from turmeric conjugates with glutathione, thereby increasing the level of glutathione in the cells.

In another study, curcumin induced glutathione biosynthesis in alveolar epithelial cells (cells in the lungs) [11]. These findings add evidence to the ability of curcumin to increase glutathione levels and protect cells from further oxidative stress and damage.

Baru almonds

Baru almonds come from the Baru tree, a native plant species in Brazil. The almonds are dark brown seeds of the fruits of the tree. More than half, or 51%, of the composition of Baru almond, is made up of monounsaturated fatty acids, while 31% o is made up of polyunsaturated fatty acids. The rest of the almond is made up of carbohydrates, dietary fibre, vitamin E, calcium, phytates, iron, zinc, and tannins [12].

In an animal study, 10% of the diet of rats was made up of Baru almonds [13]. At the end of the study, there was a significant reduction in oxidative stress.

In a randomised clinical trial that recruited obese and overweight women, the experimental group ate 20g of Baru almonds each day for eight weeks as part of their diet [14]. Results of the trial revealed increased glutathione peroxidase activity in women who were obese and overweight.

The positive effects in the clinical trial were attributed to the selenium levels in Baru almonds. Selenium is needed to increase glutathione peroxidase activity. Glutathione peroxidase protects cells and tissues from oxidative damage.

Milk thistle

The milk thistle plant (Silybum marianum) has three active compounds: silibinin, silicristin and silibinin. These three compounds are collectively called silymarin. Animal studies [15, 16] demonstrate how silymarin increased glutathione levels in laboratory cells and rats. In turn, there was a reduction in oxidative stress and prevention of cellular damage.

Avocado

Avocado is a popular fruit that is likewise found to increase glutathione levels in cells. An animal study demonstrated how avocado oil increased glutathione levels and reduced lipid peroxidation and the production of ROS in diabetic rats [17]. This showed that avocados could potentially increase glutathione levels and reduce cellular damage in the long term. Notably, the study was conducted for 12 months, which is relatively long.

Okra

Okra (Abelmoschus esculentus) is a green vegetable widely cultivated in subtropical and tropical areas. A laboratory study revealed that okra seeds have antioxidant and anti-inflammatory properties [18]. The seeds increase glutathione peroxidase levels and superoxide dismutase, which are essential in improving the antioxidant properties of okra.

Green asparagus

Green asparagus spears are rich in phytochemicals and are known to have antioxidant and anti-inflammatory properties. It is a rich source of glutathione and can be used to increase glutathione levels in the body [19]. However, concerns on whether high heat during cooking can destroy glutathione contents in asparagus. A study revealed that prolonged cooking of asparagus could decrease glutathione concentrations.

Dry heat cooking, such as pan-frying, baking, and grilling, reduces glutathione levels in green asparagus. If you want to retain glutathione levels in asparagus, it is best to cook asparagus quickly. The benefits of asparagus can be maintained by reducing cooking time. However, the antioxidant property of asparagus did not appear to be affected by dry cooking.

Broccoli

Broccoli (Brassica oleracea var. Italica) is a vegetable grown in areas with cool temperature weather. An animal study demonstrated that broccoli could increase glutathione synthesis in the liver, resulting in increased antioxidant activities in the liver [20]. However, clinical trials are needed to determine if broccoli can also increase glutathione synthesis in the human liver.

It is also necessary to examine if cooking or boiling broccoli can reduce its ability to increase the hepatic synthesis of glutathione. The method and duration of cooking could affect the antioxidant properties of vegetables such as broccoli.

It should be noted that there are vegetables that contain naturally-occurring glutathione. These include spinach, okra, asparagus and avocados.

However, storage conditions and cooking methods can decrease amounts of glutathione. Hence, it is important to cook these vegetables for a relatively short period to retain natural glutathione.

The list of foods potentially increasing glutathione levels is not exhaustive. There is still a need to examine which types of vegetables or fruits contain high amounts of glutathione.

Additionally, there is a need to discuss the antioxidant effects of vegetables in clinical trials. Results could inform individuals on what type of vegetables have the highest glutathione level.

Finally, choosing the right food will help protect you from free radicals that damage your cells and tissues. So, you can start by enjoying healthy avocados or eating almonds on your next meal!