Mushrooms and Vitamin D

Source: Mushrooms Canada

Lately there has been alot of buzz around the issue of Mushrooms and Vitamin D. To clear up some of the questions you all might have, here is the official statement from Mushrooms Canada.

"Mushrooms and Vitamin D: A Status Report
Vitamin D Vitamin D has become the health story of the year, largely because a U.S. study* indicated that supplemental Vitamin D cuts the risk of cancer by 60 percent. Based on that evidence, the Canadian Cancer Society recommended that light-skin Canadians should obtain 1000 IU (International Units) per day during fall and winter, and dark-skin Canadians should obtain 1000 IU year-round.

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

• helps to prevent bone fractures
• reduces the risk of diabetes in young people
• protects against heart disease
• reduces the risk of multiple sclerosis
• improves lung function

The best source of Vitamin D for humans is sunlight. Subcutaneous glands in the skin use sunlight to form Pre-vitamin D which is converted to Vitamin D by the liver and kidneys. But, other factors influence our exposure to sunlight, such as distance from the equator, body coverings and age. Skin colour also affects the body’s ability to produce Vitamin D. On a bright summer day, a fair-skinned person needs less than 30 minutes to make the daily requirement of Vitamin D. A dark-skinned person may need two to three hours. Winter light, in most parts of Canada, is ineffective for Vitamin D production, and vitamin D production decreases with age.

Besides sunlight, there are only a few natural sources of Vitamin D, and all of them are seafood or animal origin, such as eggs, margarine, butter, beef and chicken livers. Sardines, Mackerel, Cod, Salmon and Shrimp are good sources. Milk, some juices and breakfast cereals may be fortified at low levels, and multi-vitamin pills may contain up to 400 IU. D2 is the form found in foods and supplements, D3 is the form made by the skin.

Canadians in general, are considered to be at risk of Vitamin D deficiency, especially those with dark skin and/or vegetarian. Health Canada recommends a minimum of 200 IU (5 mcg.) from birth to 50 years; 400 IU (10 mcg.) from 51 to 70 years and 600 IU (15 mcg.) over 70 years of age.

Mushrooms
The Food and Drug Administration (FDA) in the USA has been seeking a natural, non-animal food, rich in Vitamin D. That led them to mushrooms. It has been demonstrated that when white button mushrooms are exposed to Ultraviolet B radiation, for a short period of time, the level of Vitamin D increases to levels many times the minimum daily requirement, i.e. 10 mcg. Normally, a serving** of white button mushrooms contains 18 IU (0.45 mcg.). Treated mushrooms contain over 80 mcg.***

Mushrooms show great promise as a natural, non-animal source of Vitamin D. That being the case, there are some hurdles to overcome before Super-D Mushrooms are featured in the produce section of supermarkets. The hurdles involve not only production-line technology and shelf-life, but also bio-availability of the vitamin. These hurdles are being addressed in Canada, the USA and Australia.

Hurdle #1. Commercialization
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?
• Are brown mushrooms better?
• Is there an impact on food safety and/or microbiology?
• Does the level of Vitamin D decrease with time?

The Australian Mushroom Growers Association (AMGA) has initiated a study of intermittent UV-light exposure in a growing room, from pinning to harvest. D2 will be measured in the mushrooms, 4 and 8 days post-harvest. The objective is to license a D2 process for the growers. In the USA, the Agricultural Research Service of the USDA is studying the time and dosage of UVB light treatment up to 4 days post-harvest and D2 degradation during storage. In Canada, Mushrooms Canada is sponsoring research at the Guelph Food Technology Center at the University of Guelph, Ontario, to determine the appropriate UVB light dosage to achieve 100% RDA levels (400 IU) in fresh, white and brown mushrooms. Shelf-life, discolouration and microbiology of the treated products are included.

Hurdle #2. Bio-availability.
Is the Vitamin D absorbed by humans when they eat the mushrooms? This question has not been answered. There are studies that demonstrate that the ingestion of Vitamin D supplements (likely pills) does result in increased levels of Vit. D in the blood****.

The Centre of Food Safety and Applied Nutrition of the FDA has commenced a study to determine if enhanced Vitamin D mushrooms will raise the Vitamin D levels in mice and rats, determining bio-availability. The experimental material, dehydrated UV-treated mushroom powder, was supplied by the Guelph Food Technology Centre and Mushrooms Canada.
In 2007, the Mushroom Council (USA) proposed a clinical-study of humans, to determine the bio-availability of vitamin D from mushrooms.

Conclusions
Mushrooms have the potential to become a nutraceutical or functional food. They may even be the Omega-3 egg of the produce section. We know that the Vitamin D level in mushrooms can be enhanced by simply treating them with Ultraviolet light. Mushrooms Canada will know the answers to commercialization within 6 months, but bio-availability studies will take more than 2 years."

*Lappe, J. et al., American Journal of clinical Nutrition, June 2007.
** 1 serving is equal to 100g of white button mushrooms.
***Mattila, P.H., Food Chemistry, 2002
****Holick, M. et al, Journal of Clinical Endocrinology & Metabolism. December 2007