For a long time, scientists have appreciated the antioxidant effect of fresh produce such as vegetables and fruit. Eating plenty of high anti-oxidant foods seems to protect you from future disease. The body also makes antioxidants.
Antioxidants are natural compounds in food that help neutralise the free radicals produced by the body. Free radicals are also quite natural, although they tend to cause damage to all parts of the body over time, hence speeding up the ageing process. For example, free radicals can damage the DNA found in the nuclei of body cells. When DNA becomes damaged, then antioxidants within the body work to correct the damage before it becomes a cancerous cell.
If the antioxidants made by the body get overwhelmed then the antioxidants in food provide a very useful helping hand to protect the body from free radicals. Mushrooms are a rich source of antioxidants, as confirmed by laboratory analysis. In one study of 30 common vegetables, mushrooms were placed in the top 5 highest antioxidant levels when compared to vegetables (Pellegrini 2003). Subsequent studies have confirmed the antioxidant potential of button mushrooms (Dubost 2007; Savoie 2008).
Mushrooms are very high in ergothioneine, an intracellular antioxidant first identified in 1909. Analysis shows that ergothioneine is in mushrooms, meats (especially liver and kidney), egg yolk, oat bran, wheat germ (but not the endosperm) and some beans and onion (Ey 2007). It was not found in other vegetables and fruit.
Ergothioniene levels are high in red blood cells, bone marrow and semen. It is believed that ergothioneine protects the haemoglobin in red blood cells, and protects monocytes against oxidation (Gründemann 2005).
Professor Penny Kris-Etherton, Pennsylvania State University, who has researched ergothioneine recently commented that red blood cells taking up ergothioneine is very significant because it suggests that the red blood cells are serving as a vehicle to deliver antioxidants to other cells where it can protect them against oxidative stress (Weigand-Heller 2011).
Ergothioneine is not made by the body so it can only be obtained from the diet. The best indication that ergothioniene is essential to humans was the discovery in 2005 that the body has a specific ergothioniene transporter (Gründemann 2005). Transporter proteins only exist in the blood if they have a specific role. For example, haemoglobin is a transporter protein for carrying oxygen to cells. To find one for ergothioneine suggests that humans have long evolved as mushroom eaters. Cells that have the transporter will actively accumulate and retain ergothioneine, while those without the transporter cannot obtain ergothioneine.
Ergothioneine is concentrated in the mitochondria and other cells exposed to oxidative stress and involved in the inflammatory response. When cells are deprived of the transporter there is increased mitochondrial DNA damage, protein oxidation and lipid peroxidation (Paul 2010). Oxidative damage to mitochondrial DNA is linked to neuro-degenerative diseases, especially Parkinson’s Disease. Ergothioneine accumulates in the endothelial cells of blood vessels and appears to protect against atherosclerosis, at least with in vitro tests (Martin 2010).
A study determining the ergothioneine levels in different mushrooms found that both white and brown button mushrooms were rich in ergothioneine and that the levels did not diminish during cooking (Dubost 2006; Dubost 2007).
Mushrooms are particularly high in phenolic compounds that have been long recognised for their antioxidant capabilities. A serve of mushrooms also provides about a quarter of an adult’s requirements of selenium, an antioxidant mineral.
Put all the news together and it makes mushrooms one of the highest antioxidant foods on the market. It is good sense that mushrooms should regularly feature on your healthy eating menu.