Antioxidants: The antidote to aging and disease?

Lisa Petty, PhD @ 2021-11-10 09:56:22 -0800

Several decades of dietary research suggest that eating plenty of antioxidant-rich foods might help to protect against diseases. Who doesn’t want that? Read on to learn how antioxidants protect your body from the damaging effects of free radicals. 

What’s going on?

Reactive oxygen species (ROS) or free radicals are highly reactive chemicals that are the by-product of natural oxygen metabolism (a.k.a. breathing) as well as exposure to X-rays, cigarette smoking, air pollutants, and industrial and household chemicals.[1] In scientific terms, these molecules contain an unpaired electron in their atomic orbital. This makes them unstable and highly reactive, and they circulate around either donating electrons or accepting them from other molecules. ROS play important roles in immunity, cell growth, and cell signaling. In excess, however, ROS become lethal to cells. Excess free radicals are linked with chronic and debilitating conditions including cardiovascular disease and Alzheimer’s.[2]

Antioxidants to the rescue

An antioxidant is stable molecule that can donate an electron to a rampaging free radical to neutralize it, which limits its ability to wreak havoc. Familiar antioxidants include vitamins and minerals. For example, Vitamin C is a water-soluble vitamin that provides multiple health benefits, but as an antioxidant its key role is to regenerate vitamin E and other antioxidants. Vitamin E prevents oxidation of lipid (fat) peroxidation and protects lipid membranes of cells.

Minerals including selenium and zinc are also powerful antioxidants. Although selenium isn’t itself a free radical scavenger, it is an important part of antioxidant enzymes such as glutathione peroxidase (which will be described soon). Likewise, zinc doesn’t thwart ROS directly, but it does help to prevent them from forming.[3]

Antioxidants that don’t get as much attention in the popular press include flavonoids and polyphenols. These compounds are naturally present in the pigment of fruits, vegetables, mushrooms and herbs. The most abundant flavonol is quercetin, and this antioxidant scavenges free radicals to prevent cell death. Phenolic compounds like ferulic acid, gallic acid and ellagic acid act as chelators and ROS scavengers.1 Antioxidant vitamins, minerals, flavonoids and polyphenols are nutrients that the body can’t manufacture from other raw materials, so we need to be sure to include food sources of them in the diet.

Self-made antioxidants

You may be surprised to learn that your body can make some (endogenous) antioxidants, including a network of enzymatic and non-enzymatic molecules found within cells. Melatonin is a non-enzymatic endogenous antioxidant that combats oxidative stress and restores tissue function. Uric acid, formed in the kidneys, can prevent lipid peroxidation only as long as ascorbic acid is present. Co-factor coenzyme Q10 neutralizes the lipid peroxyl radicals and regenerates vitamin E.

Antioxidant enzymes, such as superoxide dismutase (SOD), several peroxidases and catalase, trigger a cascade of reactions to convert ROS to more stable molecules.  For example, catalase is an endogenous enzyme that triggers the breakdown of hydrogen peroxide into water and oxygen.

Antioxidants + mushrooms

Mushrooms provide antioxidant ascorbic acid, carotenoids, phenolics, polysaccharides, and tocopherols, among others.[4] Two powerhouse antioxidants available in mushrooms include ergothioneine and glutathione.[5] Ergothioneine (ET) was first isolated in the ergot fungus in 1909.[6] Although ET is produced only by certain fungi and bacteria – and not by humans – it’s found in high concentrations in certain human tissues. And unlike many other powerhouse antioxidants like polyphenols that are rapidly metabolised and then discarded from the body, researchers have discovered that ET has a dedicated transporter. This means that obtaining ET and retaining it in our tissues may be essential for health.

ET is found in high concentrations in injured tissue, which lead early researchers to believe it was more harmful than beneficial. More recently, researchers have determined that ET accumulation helps to protect tissues from further injury by ROS. In other words, the build-up of ET in tissues doesn’t cause disease but may be present to help  prevent it.

Although researchers find it difficult to define ET deficiency as it’s found throughout the body, lower blood levels of ET have been linked with mild cognitive impairment, Parkinson’s disease, Crohn’s disease, age-related macular degeneration and ocular disorders, and frailty. Higher levels of ET link with lower risk of cardiometabolic disorders and associated mortality. What isn’t clear is whether ET deficiency increases risk of disease, or if lower levels of ET is a result of the disease. Stay tuned for more research![7]

Glutathione is the second antioxidant in the dynamic duo found in mushrooms.

Discovered in 1888, this nutrient is made up of three amino acids: cysteine, glutamic acid, and glycine. Along with being found in foods like mushrooms, glutathione is synthesized in the body. As one of the most potent antioxidants, glutathione has a reciprocal relationship with Vitamin C: Glutathione helps to regenerate worn-out Vitamin C, while Vitamin C may spare glutathione and help to convert oxidized glutathione back to its active form.[8]

Glutathione plays a critical role in drug detoxification and elimination, so it gets used up when phase I liver detoxification is over-active. Unfortunately, depleted glutathione increases risk of damage by toxins.[9]  Glutathione depletion is also associated with neurogenerative disorders (Alzheimer’s and Huntington’s diseases); pulmonary diseases (acute respiratory disease, asthma, COPD); cardiovascular diseases (hypertension, cholesterol oxidation); and immune diseases.  

Top up your mushroom intake

If your goal is to be as healthy as possible for as long as possible, look for protection against free radical damage to your cells. Keep in mind that the antioxidant potential in mushrooms is higher than most vegetables and fruits.3 Aim to get your 7-10 servings of multi-coloured fruits and vegetable daily – and be sure to add a few mushrooms on top.

References: 

[1] Lobo, V., Patil, A., Phatak, A., & Chandra, N. (2010). Free radicals, antioxidants and functional foods: Impact on human health. Pharmacognosy reviews4(8), 118–126. https://doi.org/10.4103/0973-7847.70902

[2] Liguori I, Russo G, Curcio F, Bulli G, Aran L, Della-Morte D, Gargiulo G, Testa G, Cacciatore F, Bonaduce D, Abete P. Oxidative stress, aging, and diseases. Clin Interv Aging. 2018;13:757-772
https://doi.org/10.2147/CIA.S15851

[3] Sotler, R., Poljšak, B., Dahmane, R., Jukić, T., Pavan Jukić, D., Rotim, C., Trebše, P., & Starc, A. (2019). Prooxidant activities of antioxidants and their impact on health. Acta clinica Croatica58(4), 726–736. https://doi.org/10.20471/acc.2019.58.04.20

[4] Sánchez C. (2016). Reactive oxygen species and antioxidant properties from mushrooms. Synthetic and systems biotechnology2(1), 13–22. https://doi.org/10.1016/j.synbio.2016.12.001

[5] Kalaras, M. D., Richie, J. P., Calcagnotto, A., & Beelman, R. B. (2017). Mushrooms: A rich source of the antioxidants ergothioneine and glutathione. Food Chemistry233, 429–433. https://doi.org/10.1016/j.foodchem.2017.04.109

[6] Halliwell. (2016). Ergothioneine, an adaptive antioxidant for the protection of injured tissues? A hypothesis. Biochemical and Biophysical Research Communications., 470(2), 245–250. https://doi.org/info:doi/

[7] Cheah, I. K., & Halliwell, B. (2021). Ergothioneine, recent developments. Redox Biology, 42, 101868–101868. https://doi.org/10.1016/j.redox.2021.101868

[8] Lenton KJ, Sané AT, Therriault H, Cantin AM, Payette H, Wagner JR. Vitamin C augments lymphocyte glutathione in subjects with ascorbate deficiency. Am J Clin Nutr. 2003 Jan;77(1):189-95. doi: 10.1093/ajcn/77.1.189. PMID: 12499341

[9] Salguero, M. L. (2007). Chapter 107: Detoxification.  D. Rakel (ed.). W.B. Saunders. Pp 1123-1135. ISBN 9781416029540, https://doi.org/10.1016/B978-1-4160-2954-0.50111-3.