Three or four button mushrooms are able to make enough vitamin D for the average person’s estimated daily needs, says a respected Australian scientist.
But there’s a catch. Like humans, button mushrooms need exposure to sunlight for the photochemical manufacturing to kick into action.
Button mushrooms need two hours unwrapped on a plate in the midday summer sun – a bit longer in winter – to get the vitamin D boost, says Professor Rebecca Mason, head of physiology at Sydney Medical School and past president of the ANZ Bone and Mineral Society.
Placing the mushrooms a couple of extra hours in the shade will allow time for the full chemical reaction, she says.
This step, she says, doesn’t affect the mushroom or the taste either.
Prof Mason says she loves eating good-quality button mushrooms with a vinegar dressing, but cooking them maintains the goodness too.
Vitamin D plays an essential role in bone health, but many people have vitamin D deficiencies, especially during winter, according to Osteoporosis Australia.
Scientists do not fully understand why mushrooms can make so much vitamin D, but the idea is backed by good evidence, says Prof Mason.
Three or four button mushrooms provide about 10 micrograms of vitamin D – the estimated daily need for the average adult according to the National Health and Medical Research Council.
Prof Mason says this amount is enough for active people, while people who are housebound or unwell could up their dose of button mushrooms to increase their levels of vitamin D.
While there are other methods of getting boosting vitamin D levels such as moderate exposure to morning or afternoon sun or taking supplements, no other food in its natural state provides sufficient vitamin D as button mushrooms.
Dietitian Glenn Cardwell says sun-exposed mushroom are a great source of vitamin D and good news for people concerned about sun exposure.