Millions of Australians are believed to have inadequate levels of vitamin D, a problem exacerbated by the increased use of sunscreen which blocks the sun’s rays, nature’s natural source of vitamin D. Health issues caused by insufficient levels include high blood pressure and increased risk of breast, kidney and prostate cancer and rickets.
- Australian Mushroom Growers research
Our bodies need Vitamin D in order to use calcium and produce healthy muscles and bones, and regulate the levels of calcium in the blood. Vitamin D deficiency can result in bone and muscle issues such as rickets or osteoporosis, and can contribute to an increased risk in developing heart disease, mental illnesses such as schizophrenia, type 1 and 2 diabetes, multiple sclerosis, colon cancer and autoimmune diseases (!).
Vitamin D deficiency is not uncommon in Australia (particularly in the southern states), possibly because people like me are afraid of developing skin cancer from the Ultraviolet (UV) radiation from the sun. Of course sunshine is the best natural source of Vitamin D, but is also the primary cause of skin cancer. So, if we can't spend time in the sun during the day, especially in winter, we need to look to other ways of introducing Vitamin D to our system.
Enter a balanced and healthy diet. The main dietary sources of Vitamin D in Australia are foods such as margarine, canned fish (salmon and herrings). eggs, lean meat, liver, butter and cheese. Mushrooms that grow in the wild are naturally high in vitamin D (but we need to take care when picking any wild mushrooms), and cultivated mushrooms that are exposed to light also contain vitamin D.
There has been an interesting and (I think) exciting development in the world of mushrooms. Allow me to elaborate. Not unlike the human body, mushrooms can convert the sun’s rays into vitamin D. According to a rather technical explanation from the Australian Mushroom Growers, 'when sunlight hits the surface of the mushroom it stimulates the conversion of a substance called ergosterol (a component of the mushroom cell walls) to vitamin D2. When consumed, this vitamin D2 converts to the active form of vitamin D via the liver and the kidneys'.
The good news is that growers are now mimicking nature and exposing mushrooms to a short burst of ultraviolet light to generate vitamin D. A series of experiments undertaken since 2005 examined the effect of light on vitamin D2 production in mushrooms. By using UV light in the growing process to stimulate consistent levels of vitamin D, the experiments successfully replicated nature. In 2010, the University of Western Sydney completed a 'light exposure trial' and concluded that mushrooms can easily reach the Australian daily Adequate Intake levels of vitamin D in a single 100g serve. This study also showed that vitamin D is stable and well absorbed from the mushroom.
Vitamin D mushrooms are now available in stores throughout Australia. Mushroom growers are using a pulsed UV light as part of the production process in order to trigger the generation of vitamin D. After they are picked, mushrooms are placed on a conveyor belt and passed under pulsed light for one to two seconds. This small amount of light is able to produce vitamin D2 levels of at least 10 mcg (400 IU), the amount recommended each day for adults 51-70 years. This is a good thing! Consumers can also enrich store bought or home-grown mushrooms by placing them in direct sunlight for one to two hours.
My friend, accredited nutritionist and author, Catherine Saxelby, says 'Here is a food that now has the capacity to supply high quality vitamin D , similar in status to cod liver oil or oily fish. This has been verified by separate testing and is correct.'
Around 100g of mushrooms provides our daily needs...
A video interview about mushrooms and Vitamin D...
An hour in the sun...
The flavour of the mushrooms is not affected...
My favourite quick and simple mushroom recipe...
My mother often cooked mushrooms in this way and we ate them with chunks of Continental bread. The cooking method is so simple, it barely needs a recipe, but here we go.
500g assorted mushrooms, sliced
juice of 1-2 lemons
1-2 tablespoons butter (or cholesterol-lowing margarine, if preferred)
parsley for garnish
Melt the butter or margarine in a heavy based pan and when it begins to bubble, toss in the sliced mushrooms and saute gently for 2-3 minutes or until tender. Sprinkle with lemon juice and serve immediately. If you like, you can season with salt and pepper. For a delicious variation, add some chopped garlic, sliced chilli and a scant tablespoon of low salt soy or tamari sauce. You can also throw in some baby spinach. Serves 2-4.