The nutrient profiles of seven mushroom varieties were created by Agricultural Research Service (ARS) nutritionists at the Beltsville Human Nutrition Research Center.
The mushrooms, including white button, oyster and portabella varieties, were collected from retail outlets around the country, in order to ensure an nationally representative sampling. Other varieties tested included shiitake enoki, crimini and maitake.
Although most of the varieties were analyzed raw, white button mushrooms, which are commonly used in recipes, were also analyzed after stir-frying and microwaving to gauge the levels of nutrients retained after cooking.
Portabella mushrooms were analyzed after grilling, and shiitake mushrooms were analyzed after stir-frying. Most nutrients were found to be fully retained when cooked, while others were retained at between 80 and 95 percent of their levels in raw mushrooms.
According to the results, which will shortly be published in the USDA's National Nutrient Database for Standard Reference, all of the varieties tested were found to provide a significant amount of copper, which helps the body produce red blood cells and drives a variety of chemical reactions that are key to human health.
One cup of stir-fried white-button mushrooms were found to provide 0.3mg of copper, which is about one third of the recommended daily intake for adults, said the ARS.
The mushrooms were also found to provide a significant amount of potassium, a mineral that helps the body maintain normal heart rhythm, fluid balance, and muscle and nerve function. Two-thirds of a cup of sliced, grilled portabella mushrooms contains the same amount of potassium as a medium-sized banana, according to the new data.
Other key nutrients present included folate and niacin.
The mushroom varieties were also analyzed for fat, fiber, protein, carbohydrate, vitamins and minerals, and for ergosterol, a precursor to vitamin D.
Indeed, recent statistics from around the US, the EU and Australia have shown a sharp increase in the demand for mushrooms, as modern consumers are increasingly seeking health-added benefits to their foods.
One of the biggest triumphs for the mushroom industry came from Pennsylvania State University research, which recently showed white button mushrooms to be the richest source of ergothioneine. The sought after super-antioxidant is present in mushrooms at 12 times the levels of wheat germ - once thought to be the highest natural source of ergothioneine.
Processed mushrooms account for 55 per cent of the total world market, largely because of the fungi's short life span. Of this 55 per cent, 50 per cent are canned and 5 per cent are dried. The Netherlands has the strongest hold on canned mushroom processing with a 39 per cent share, closely followed by China.
Fourty-five per cent of the world's supply is consumed in un-processed form. This market is making moves to pass processed mushrooms as new consumers, lured by health benefits, are drawn to fresh mushrooms. Indeed, it is this sector that is expected to experience the most growth in the coming years.