fact sheet 2 - antioxidants in mushrooms

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; Savoie 2008).

Mushrooms are very high in the powerful antioxidant ergothioneine, in amounts similar to that found in animal foods (Ey 2007). Ergothioneine is found in very few vegetables or fruit. Ergothioneine appears to protect blood cells, especially monocytes and red blood cells that transport nutrients and oxygen to body cells (Martin 2010). It also protects your artery lining from atherosclerosis (fatty deposits).

Ergothioneine is not produced by the body. It can only be obtained through your diet. Low levels of ergothioneine start the oxidation (damage) of DNA and proteins. It has been suggested that ergothioneine should be classified as a vitamin because it is so important to health (Paul 2010). Ergothioneine levels do not decrease with cooking, so you get your ergothioneine through both raw and cooked mushrooms.

In 2005, scientists were surprised to find an ergothioneine transporter protein in the blood (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.

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.

References:

• Ey J, Schömig E, Taubert D. Dietary sources and antioxidant effects of ergothioneine. J Agricultural & Food Chemistry 2007; 55: 6466-6474
• Gründemann D, Harlfinger S, Golz S, Geerts A, Lazar A, Berkels R, Jung N, Rubbert A, Schömig E. Discovery of the ergothioneine transporter. Proc National Academy of Sciences 2005; 102: 5256-5261
• Martin KR. The bioactive agent ergothioneine, a key component of dietary mushrooms, inhibits monocyte binding to endothelial cells characteristic of early cardiovascular disease. Journal of Medicinal Food 2010; 13 (6): 1340-1346
• Paul BD, Snyder SH. The unusual amino acid L-ergothioneine is a physiologic cytoprotectant. Cell Death & Differentiation 2010; 17: 1134-1140
• Pellegrini N, Serafini M, Colombi B, Del Rio D, Salvatore S, Bianchi M, Brighenti F. Total antioxidant capacity of plant foods, beverages and oils consumed in Italy assessed by three different in vitro assays. J Nutrition 2003; 133: 2812-2819
• Savoie JM, Minvielle N, Largeteau ML. Radical-scavenging properties of extracts from the white button mushroom, Agaricus bisporus. J of the Science of Food & Agriculture 2008; 88: 970-975

Mushroom, prawn & asparagus stir-fry

Serves 4

1/3 cup oyster sauce

2 tbs soy sauce

1 tbs brown sugar

600g green medium-king prawns*, peeled and deveined

300g cup mushrooms, thickly sliced

2 tbs olive oil

1 small red onion, peeled and cut into wedges

1 bunch choy sum, trimmed, leaves separated and stems chopped

1 bunch asparagus, trimmed and cut into 3cm lengths

rice or noodles, to serve.

1. Combine oyster sauce, soy sauce and brown sugar in a small jug. Place prawns and mushrooms into separate bowls. Pour 1/2 the soy mixture over prawns and remaining soy mixture over mushrooms. Toss well to coat. Cover and place in the fridge to marinate for 15 minutes.
2. Heat a wok over high heat until hot. Add 1 tbs oil and prawns and stir-fry for 1-2 minutes or until pink. Remove and set aside.
3. Add remaining oil and onion to wok and stir-fry for 1 minute. Add choy sum stems and asparagus and stir-fry for 1 minute. Add mushrooms and stir-fry for 2 minutes or until mushrooms are almost tender.
4. Add prawns and choy sum leaves and stir-fry for 1 minute or until leaves just wilt. Serve immediately with rice or noodles.

* Note: Prawns can be replaced with sliced chicken, beef or pork fillet.

Nutritional information:
Mushroom, prawn & asparagus stir-fry