Mushrooms and Vitamin D

The Lowdown on Vitamin D

The Canadian Cancer Society recommends that light-skin people should obtain 1000 IU (International Units) per day during fall and winter, and dark-skin people should obtain 1000 IU year-round.

Health Canada recommends the following for Vitamin D Consumption:

Age Group	Recommended Dietary Allowance (RDA) per day**	Tolerable Upper Intake Levels (UL) per day
Infants 0-6 months	400 IU (10 mcg)*	1000 IU (25 mcg)
Infants 7-12 months	400 IU (10 mcg)*	1500 IU (38 mcg)
Children 1-3 years	600 IU (15 mcg)	2500 IU (63 mcg)
Children 4-8 years	600 IU (15 mcg)	3000 IU (75 mcg)
Children and Adults 9-70 years	600 IU (15 mcg)	4000 IU (100 mcg)
Adults > 70 years	800 IU (20 mcg)	4000 IU (100 mcg)
Pregnancy & Lactation	600 IU (15 mcg)	4000 IU (100 mcg)

* Adequate Intake rather than Recommended Dietary Allowance. ** The IOM report states that there are no additional health benefits associated with vitamin D intakes above the level of the new RDA. Total vitamin D intake should remain below the level of the new UL to avoid possible adverse effects. Long-term intakes above the UL increase the risk of adverse health effects.

The Daily Recommended Intake for Vitamin D

Since 1920, it has been known that the main role of Vitamin D is to work with Calcium and Phosphorus to make strong bones. Recent findings suggest that Vitamin D also helps to:

prevent bone fractures
reduce the risk of diabetes in young people
protect against heart disease
reduce the risk of multiple sclerosis
improve lung function

Mushrooms Have Vitamin D

Mushrooms are the only vegetable that contains Vitamin D, naturally. All other natural food sources of Vitamin D are of animal, poultry or seafood origin. Also, some foods, such as milk, orange juice and cereals may be fortified with Vitamin D, up to 100 IU.

Cultivated mushrooms contain a plant sterol called ergosterol, which is the precursor of Vitamin D². In fresh mushrooms, ergosterol is stimulated to convert to Vitamin D² by ultraviolet light, either from sunlight or artificial lights.

The vitamin D levels of common varieties of mushrooms are listed below for a standard 100 g serving. 200 IU is recommended for adults up to the age of 50.

Adding Vitamin D to Fresh Mushrooms

It has been demonstrated in recent studies that the level of Vitamin D² in White/Brown mushrooms can be increased significantly (up to 100% of the Daily Value), by exposure to ultraviolet light for a few minutes, either pre-harvest or post-harvest. When this technology is perfected, Super-D mushrooms may be available, to the public, as a vegetable source of Vitamin D.

How the World is Working to Add More Vitamin D to Mushrooms

In order to incorporate a UV treatment system into a commercial mushroom farm, some technical questions must be answered. For example:

Where is the best location for UV-treatment, in the growing rooms (pre-harvest) or in the packing room (post-harvest)?
What is the best source of UV light, distance from the mushrooms and duration of exposure?
What is the shelf life of treated mushrooms?
Do white mushrooms discolour? How much?
If so, are brown mushrooms the preferred variety?
Does the level of Vitamin D decrease with time?

In Canada, Mushrooms Canada has sponsored research at the Guelph Food Technology Centre (GFTC) to determine the appropriate UVB light dosage to achieve 100% RDA levels (400 IU) in fresh, white and brown mushrooms. The study includes shelf-life, discolouration, and microbiology of the treated products.

Commercialization of Vitamin D Enhanced Mushrooms by UV light Treatment. Mushrooms Canada and the Guelph Food Technology Centre.

The Australian Mushroom Growers Association (AMGA) has researched intermittent UV-light exposure in a growing room, pre-harvest. Vitamin D² will be measured in the mushrooms, 4 and 8 days post-harvest. The objective was to license a Vitamin D² process for mushroom growers.

Critical Issues for Intending Producers of Vitamin D Mushrooms. Warmish Scientific.

In the USA, The Mushroom Council and the Agricultural Research Service of the USDA are studied the time and dosage of UVB light treatment up to 4 days post-harvest and Vitamin D² degradation during storage.