Most of the substances that are classified as vitamins were discovered decades ago. Required in tiny amounts for normal growth and development, vitamins must be obtained from the diet. Determining vitamin status is not quite as straight forward as this suggests, which is one reason that new vitamins on occasion still are discovered. Ergothioneine, an amino acid that is relatively abundant in certain mushrooms, currently is being proposed by a number of scientists as the latest new vitamin. Evidence includes the existence of a specific cellular transporter, accumulation of the compound in cells followed by its retention.1,2 Solomon Snyder at the Johns Hopkins University School of Medicine not only has suggested that ergothioneine may be a vitamin, but also has concluded that for some purposes this would-be vitamin is as potent as glutathione, one of the body's most potent endogenous antioxidants and detoxifiers.3
Anti-Aging Potential for Heart and Mind
Mushrooms are rich sources of both ergothioneine and the well-known nutrient, glutathione.4 The edible fungi that are high in the one have been found to be high in the other. As a dietary source of these compounds, it is significant that mushrooms remain viable sources even after cooking,something not true of many nutrient sources.
The antioxidant functions of glutathione include recycling (reducing) the vitamins C and E as well as serving as a critical free radical scavenger to support antioxidant activity in all tissues, especially the liver and phase 2 detoxification reactions. In its reduced (non-oxidized) form, glutathione acts as a substrate in conjugation reactions. Whereas phase 1 detoxification makes fat-soluble toxins more water soluble in preparation for elimination from the body, a step that actually can increase toxicity, phase 2 detoxification binds toxins to carriers, such as glutathione, sulfate, glycine and glucuronic acid. One role for ergothioneine may be cardiovascular protection.5 This could involve amelioration of chronic inflammatory states, such as are found in heart disease and related condition.6 As part of its anti-inflammatory function, it is interesting that ergothioneine is found together with glutathione in mushroom sources. Although glutathione is often almost totally depleted in the face of oxidative stress, ergothioneine concentrations tend to remain relatively stable. "These properties suggest a role for ET [ergothioneine] as a bulwark, a final defense for cells against oxidative damage. Its stability may help mitochondria cope with otherwise overwhelming stresses encountered even during relatively physiologic metabolism."7
Ergothioneine has been shown to be involved in protecting injured tissues.8 In this and a number of other functions, there is a clear overlap with glutathione. Of particular interest is the impact on neurodegenerative diseases. As one of the primary ergothioneine researchers, Robert Beelman of The Pennsylvania State University, recently commented,
"It's preliminary, but you can see that countries that have more ergothioneine in their diets, countries like France and Italy, also have lower incidences of neurodegenerative diseases, while people in countries like the United States, which has low amounts of ergothioneine in the diet, have a higher probability of diseases like Parkinson's Disease and Alzheimer's. Now whether that's just a correlation or causative, we don't know. But, it's something to look into, especially because the difference between the countries with low rates of neurodegenerative diseases is about 3 milligrams per day, which is about five button mushrooms each day."9
A study published last year by researchers in Singapore adds support for Dr. Beelman's hypothesis that ergothioneine is neuroprotective. As already mentioned, the compound seems to accumulate preferentially in tissues subject to oxidative stress and inflammation. Based on this, the Singapore-based scientists looked at whole blood levels in older individuals. Their finding was that ergothioneine levels were significantly lower in those over 60 years of age. In subjects suffering from mild cognitive impairment, blood levels, again, were lower than in age-matched controls. Researchers concluded that the decline suggests that deficiency in ergothioneine may predispose individuals to neurodegenerative diseases.10
Of common edible mushrooms, ergothioneine concentration is highest in the porcini, an Italian favorite. Also tested and found adequate as sources, descending order of richness (strongly dependent on which portion of the growth cycle is involved), are shiitake, oyster, maitake, king oyster, and then, in a dead heat, portabellas, crimini and white button mushrooms.
Let's face it, consuming mushrooms merely as sources of an arcane newly discovered vitamin is not nearly as appealing as eating your favorite fungi for properly gourmet reasons (pizza topping, steak sauce, ravioli filling, etc.) while accruing unexpected benefits, such as weight maintenance or even weight loss. Recent studies suggest that one can be both gourmand and lean.
For instance, University of Minnesota research found that mushrooms are more filling based on roughly equal amounts of calories than is 93 percent lean ground beef.11 Thirty-two healthy participants (17 women, 15 men) consumed two servings of mushrooms or meat for ten days, i.e., mushrooms (226 grams) and meat (28 grams) eaten in a randomized open-label crossover study. On the first day, fasted participants consumed protein-matched breakfasts of containing either mushrooms or meat. Participants rated their satiety using visual analogue scales at start and at regular intervals after the meal. Three hours later, participants were served an ad libitum (eat as much as desired) lunch. Participants were given mushrooms or meat to consume at home for the following nine days. Under these conditions, mushroom eaters consumed more fiber, but there was no significant difference in calorie intake over the ten days of the trial. The findings were that consuming the mushrooms led to less hunger during the day, greater feelings of satiety after meals and less desire to eat within three hours of the mushroom meal.
The above trial lasted only ten days. The real question is "what happens if mushrooms are substituted for meat, say, for a year?" In fact, that trial has been conducted. A one-year, randomized clinical trial conducted by researchers at the Weight Management Center at Johns Hopkins Bloomberg School of Public Health and funded by the Mushroom Council found that substituting white button mushrooms for red meat enhanced weight loss and helped maintain that loss in among 73 obese adults (64 women and 9 men).12 Subjects substitute one cup of mushrooms per day for a protein serving while keeping the rest of their diet the same. Controls followed their normal diets. At the end of the trial, participants on the mushroom diet reported lower intakes of energy and fat, had lost more pounds and percentage body weight (an averaged seven pounds), had a lower body mass index, exhibited a smaller waist circumference (decreased by an average of 2.6 inches), had less total body fat, and had lower systolic and diastolic pressure (-7.9 and -2.5 mmHg, respectively).
Mushrooms are relatively high in fiber and low in calories, meaning that they are not calorically dense. They also help to modulate blood sugar, a benefit that likely factors in to their impact on satiety. Whatever the mechanisms of action, being useful for achieving and maintaining significant weight loss over the course of a year while adding variety and taste to meals is a worthy achievement.
The Latest on Mushroom Supplements
Mushrooms used in cooking are the fruiting bodies, not mere mycelium. This is an important distinction, as well, for mushrooms used as dietary supplements. Unfortunately, supplements far too often are based only on the mycelium. A recent United States Pharmacopeia study confirms a lack of medicinal compounds in many Reishi supplements. As pointed out in a press release by the Nammex company, nineteen different Reishi mushroom products sold in the United States were tested for the compounds that characterize real Reishi mushroom (fruiting body).
Researchers used scientifically identified and validated Reishi mushrooms as their standard. Various highly accurate testing methods were utilized, including HPTLC, Colorimetric method, GC-MS, and High Performance Size-exclusion Chromatography. The results of their study demonstrated clearly that only 5 of 19 samples could be verified as genuine Reishi mushroom. Most of the other products lacked characteristic triterpenoids and also had a starch-like polysaccharide profile that was inconsistent with Reishi mushroom.
The researchers themselves concluded that the "results showed that the measured ingredients of only 5 tested samples (26.3%) were in accordance with their labels, which suggested the quality consistency of G. lucidum dietary supplements in the U.S. market was poor, which should be carefully investigated." 13
- Gründemann D, Harlfinger S, Golz S, Geerts A, Lazar A, Berkels R, Jung N, Rubbert A, Schömig E. Discovery of the ergothioneine transporter. Proc Natl Acad Sci U S A. 2005 Apr 5;102(14):5256–61.
- Gründemann D. The ergothioneine transporter controls and indicates ergothioneine activity—a review. Prev Med. 2012 May;54 Suppl:S71– 4.
- Paul BD, Snyder SH. The unusual amino acid L-ergothioneine is a physiologic cytoprotectant. Cell Death Differ. 2010 Jul;17(7):1134 – 40.
- Kalaras MD, Richie JP, Calcagnotto A, Beelman RB. Mushrooms: A rich source of the antioxidants ergothioneine and glutathione. Food Chem. 2017 Oct 15;233:429– 433.
- Servillo L, D'Onofrio N, Balestrieri ML. Ergothioneine Antioxidant Function: From Chemistry to Cardiovascular Therapeutic Potential. J Cardiovasc Pharmacol. 2017 Apr;69(4):183–191.
- Grigat S, Harlfinger S, Pal S, Striebinger R, Golz S, Geerts A, Lazar A, Schömig E, Gründemann D. Probing the substrate specificity of the ergothioneine transporter with methimazole, hercynine, and organic cations. Biochem Pharmacol. 2007 Jul 15;74(2):309–16.
- Paul BD, Snyder SH. The unusual amino acid L-ergothioneine is a physiologic cytoprotectant. Cell Death Differ. 2010 Jul;17(7):1134–40.
- Halliwell B, Cheah IK, Drum CL. Ergothioneine, an adaptive antioxidant for the protection of injured tissues? A hypothesis. Biochem Biophys Res Commun. 2016 Feb 5;470(2):245–250.
- Cheah IK, Feng L, Tang RMY, Lim KHC, Halliwell B. Ergothioneine levels in an elderly population decrease with age and incidence of cognitive decline; a risk factor for neurodegeneration? Biochem Biophys Res Commun. 2016 Sep 9;478(1):162–167.
- Hess JM, Wang Q, Kraft C, Slavin JL. Impact of Agaricus bisporus mushroom consumption on satiety and food intake. Appetite. 2017 Oct 1;117:179–185.
- Poddar KH, Ames M, Hsin-Jen C, Feeney MJ, Wang Y, Cheskin LJ. Positive effect of mushrooms substituted for meat on body weight, body composition, and health parameters. A 1-year randomized clinical trial. Appetite. 2013 Dec;71:379–87.
- Wu DT, Deng Y, Chen LX, Zhao J, Bzhelyansky A, Li SP. Evaluation on quality consistency of Ganoderma lucidum dietary supplements collected in the United States. Sci Rep. 2017 Aug 10;7(1):7792.
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Dallas Clouatre, PhD
Dallas Clouatre, Ph.D. earned his A.B. from Stanford and his Ph.D. from the University of California at Berkeley. A Fellow of the American College of Nutrition, he is a prominent industry consultant in the US, Europe, and Asia, and is a sought-after speaker and spokesperson. He is the author of numerous books. Recent publications include "Tocotrienols in Vitamin E: Hype or Science?" and "Vitamin E – Natural vs. Synthetic" in Tocotrienols: Vitamin E Beyond Tocopherols (2008), "Grape Seed Extract" in the Encyclopedia Of Dietary Supplements (2005), "Kava Kava: Examining New Reports of Toxicity" in Toxicology Letters (2004) and Anti-Fat Nutrients (4th edition).