What Foods Are High in Glutathione? The Measured List

In the one laboratory analysis with published food-by-food glutathione values, asparagus, avocado and spinach contained the most (349, 339 and 313 nanomoles per gram, about 10 mg per 100 g for asparagus), with green beans, papaya and cucumber next and none detected in cabbage, apples, grapes or bananas.^{1, 2} Fresh and frozen foods keep it; most other processing causes extensive losses.³ Glutathione has no authorised health claim in the UK; what follows is what the studies measured.⁴ In the one study that checked, how much people ate did not predict how much was in their blood.⁵ The hub, what does glutathione do in the body, has the molecule and the trials.

Which foods have the most glutathione?

The figures are from a 2004 analysis of fresh fruit and vegetables by high-performance liquid chromatography, in nanomoles per gram of wet weight, reproduced in a 2019 review.^{1, 2} The milligram column is our conversion (glutathione weighs 307.3 g per mole): 349 nmol/g is about 10.7 mg per 100 g. No UK food composition table lists glutathione.⁶

Green vegetables lead; the review singles out "the green foods, asparagus, avocado, cucumber, green beans, and spinach".² One laboratory, three samples per food: a ranking of which foods are high, not exact figures for the asparagus in your fridge.

Which foods have little or none?

In the same analysis none of the thiols measured, glutathione included, was detected in cabbage, red grapes, blackberries, apples or peaches; banana measured none; broccoli, carrot, potato, lemon and orange sat at 4 to 5 nmol/g, under 0.2 mg per 100 g.^{1, 2} Broccoli and cabbage are often listed online as glutathione foods; by measurement they are not.

A 1992 US survey of the foods on a national food-frequency questionnaire found that "dairy products, cereals, and breads are generally low in GSH; fruits and vegetables have moderate to high amounts of GSH; and freshly prepared meats are relatively high in GSH".³ Its per-food figures are not in the abstract, so this page does not quote them.

Does cooking destroy glutathione?

Partly, and processing does more. The 1992 survey found that "frozen foods generally had GSH contents similar to fresh foods, whereas other forms of processing and preservation generally resulted in extensive loss of GSH".³ The 2019 review's advice for the foods in the table is to "eat preferably raw or mildly steamed to preserve the integrity of sulfur compounds".² In practice: fresh or frozen, raw or lightly steamed, rather than tinned, dried or kept.

How much glutathione do people eat, and does it reach the blood?

In 69 American adults, estimated intake ranged from 13.0 to 109.9 mg a day, mean 34.8 mg, with fruit and vegetables supplying over half and meat under a quarter.⁵ Intake did not track blood levels: the correlations between dietary and plasma glutathione were small, negative and usually not statistically significant, and the authors concluded that plasma glutathione is "not simply related to dietary glutathione intake or supply of precursor amino acids".⁵

The absorption studies do not all agree. The 1992 survey cited rat work showing glutathione "absorbed intact" in the small intestine and human work in which oral glutathione raised plasma levels.³ The same year, seven volunteers given a single dose of about 3 g showed no significant rise in plasma glutathione over 270 minutes, and those authors wrote that "dietary glutathione is not a major determinant of circulating glutathione".⁷ Longer trials measured stores: four weeks of 1,000 mg a day in 40 healthy adults left red-cell glutathione and two urinary oxidative-stress markers unchanged, while six months of 250 or 1,000 mg a day in 54 adults raised glutathione in red cells, plasma and lymphocytes by 30 to 35% at the higher dose and by 17 to 29% in blood and red cells at the lower, with levels back at baseline a month after stopping.^{8, 9}

What depletes glutathione in the body?

What has been measured is age and processing. In 169 healthy adults, red-cell glutathione in the 60 to 79 age group was 17% lower than in 20 to 39-year-olds.¹⁰ In eight older and eight younger adults, the older group's red-cell glutathione was 1.12 mmol/L against 2.08, with a fractional synthesis rate of 45.8% a day against 83.1%: lower because less was being made.¹¹ In food, the losses come from processing and preservation.³ No published study was found showing that any food, drink or supplement cancels out glutathione in a healthy adult.

Which foods supply the building blocks?

Cells make glutathione from glutamate, cysteine and glycine. In the stable-isotope study, two weeks of cysteine and glycine raised the older adults' red-cell glutathione by 94.6%, to the younger group's level.¹¹ Four routes have been measured:

• Cysteine-rich protein. In 31 healthy adults, 45 g a day of a pressurised whey protein for two weeks raised lymphocyte glutathione by about 24%; 15 g a day did not raise it.¹²
• Vegetables that carry cysteine. The 2004 analysis measured cysteine too: red pepper 349 nmol/g, asparagus 122, spinach 84, green beans 67, tomato 55.^{1, 2} Whether eating them changes blood glutathione has not been tested.
• Glycine. Its food sources and trials are on does glycine help you sleep and what foods are high in collagen.
• Vitamin C. 13 weeks of 500 or 1,000 mg a day raised lymphocyte glutathione by 18% in 48 adults with low plasma vitamin C, falling back on placebo; in a small 1993 study, 500 mg a day raised red-cell glutathione by nearly 50%, with no further rise at 2,000 mg and a return to baseline on withdrawal.^{13, 14} Vitamin C's authorised wording, protection of cells from oxidative stress, belongs to vitamin C, not glutathione.⁴ Food sources: what is vitamin C good for.

None of these routes is a claim: the EU assessors refused the whey (register ID 424) and N-acetylcysteine (ID 1745) claims that mentioned glutathione, so each route above is a trial finding with its number of people and its duration.⁴ The NAC and GlyNAC trials, reported together, are in the hub section what NAC and GlyNAC have to do with glutathione.

Do supplements raise glutathione more than food?

The two routes have been measured in different ways, and neither measurement ranks the other. Food: an average intake of about 35 mg a day did not correlate with plasma glutathione in 69 people.⁵ Supplements: the four-week trial above found no change in markers, and the six-month trial raised stores by 17 to 35%, returning to baseline a month after stopping.^{8, 9} The amounts differ widely: 100 g of asparagus holds about 10.7 mg; the six-month trial used 250 to 1,000 mg a day, roughly 25 to 95 times that (our arithmetic). No trial has compared a glutathione-rich diet with a supplement head to head. The capsule trials' dosing and timing: how to take glutathione; the one liposomal study, with its caveats: does liposomal glutathione work; the trials' stomach reports: glutathione side effects.

Frequently asked questions

Is turmeric, amla or okra rich in glutathione?

None of the three was in the 2004 analysis, and we found no published measurement of glutathione in any of them, so this page lists no value for them.^{1, 2}

Which fruit has the most glutathione?

Avocado, at 339 nmol/g (about 10.4 mg per 100 g); among sweet fruit, papaya at 136, then mango 59 and strawberry 39. Banana, apple, peach, red grape and blackberry had none detected.^{1, 2}

How do I raise glutathione naturally?

What has been measured: fresh or frozen produce eaten raw or lightly steamed keeps the glutathione in the food,^{2, 3} though intake did not predict blood levels.⁵ The building-block routes with measured rises are 45 g a day of whey for two weeks and 500 mg a day of vitamin C, with the figures above.^{12, 13, 14} No food route has been tested against a health outcome.

Does glutathione deplete B12?

No published study was found that measured vitamin B12 in people taking glutathione or eating glutathione-rich foods. If you have symptoms you think could be low B12, see a GP.

What should I not eat with glutathione?

No study has tested food pairings with glutathione supplements; the six-month trial reported dose and duration, not meal timing or diet rules.⁹

Sources

1. Demirkol O, Adams C, Ercal N. Biologically important thiols in various vegetables and fruits. Journal of Agricultural and Food Chemistry, 2004. PubMed 15612810.
2. Minich DM, Brown BI. A review of dietary (phyto)nutrients for glutathione support. Nutrients, 2019. PubMed 31484368.
3. Jones DP, et al. Glutathione in foods listed in the National Cancer Institute's Health Habits and History Food Frequency Questionnaire. Nutrition and Cancer, 1992. PubMed 1574445.
4. Department of Health and Social Care. Great Britain nutrition and health claims (NHC) register. gov.uk.
5. Flagg EW, et al. Dietary glutathione intake in humans and the relationship between intake and plasma total glutathione level. Nutrition and Cancer, 1994. PubMed 8183721.
6. Public Health England. Composition of Foods Integrated Dataset (CoFID), 2021. gov.uk.
7. Witschi A, et al. The systemic availability of oral glutathione. European Journal of Clinical Pharmacology, 1992. PubMed 1362956.
8. Allen J, Bradley RD. Effects of oral glutathione supplementation on systemic oxidative stress biomarkers in human volunteers. Journal of Alternative and Complementary Medicine, 2011. PubMed 21875351.
9. Richie JP Jr, et al. Randomized controlled trial of oral glutathione supplementation on body stores of glutathione. European Journal of Nutrition, 2015. PubMed 24791752.
10. Lang CA, et al. Low blood glutathione levels in healthy aging adults. Journal of Laboratory and Clinical Medicine, 1992. PubMed 1431500.
11. Sekhar RV, et al. Deficient synthesis of glutathione underlies oxidative stress in aging and can be corrected by dietary cysteine and glycine supplementation. American Journal of Clinical Nutrition, 2011. PubMed 21795440.
12. Zavorsky GS, et al. An open-label dose-response study of lymphocyte glutathione levels in healthy men and women receiving pressurized whey protein isolate supplements. International Journal of Food Sciences and Nutrition, 2007. PubMed 17710587.
13. Lenton KJ, et al. Vitamin C augments lymphocyte glutathione in subjects with ascorbate deficiency. American Journal of Clinical Nutrition, 2003. PubMed 12499341.
14. Johnston CS, et al. Vitamin C elevates red blood cell glutathione in healthy adults. American Journal of Clinical Nutrition, 1993. PubMed 8317379.

This article is general information, not medical advice; ask your GP or pharmacist before taking any supplement.