Let Mushrooms Turbocharge Your Vitamin D Levels (Video)


If you’ve ever read anything about the importance of vitamin D, then you may be aware how important vitamin D is in protecting many tissues in your body against cancer, multiple sclerosis (MS), reduced bone mineral density, impaired cell growth, impaired immune function and chronic inflammation (1). Vitamin D deficiency is required for normal bone growth and remodeling, and a lack of vitamin D can set the stage for osteopenia and osteoporosis (2). In addition, Vitamin D deficiency has been linked to impaired glucose metabolism, insulin resistance and an increased risk for type 2 diabetes (3–7).

How Much Sunlight is Necessary?

Your skin manufactures vitamin D in response to sun exposure. As long as you achieve a minimum of 15 minutes of direct sunlight between 10am and 3pm on a daily basis, the skin on your arms and legs will manufacture adequate vitamin D (8). The lighter your skin, the more vitamin D you make. The darker your skin, the less vitamin D you make. So ultimately the pigment in your skin determines your need for sun exposure. In light skinned individuals, as little as 5 minutes of daily sun exposure is adequate, while dark skinned individuals may require up to 30 minutes of sun exposure per day.

The Reality of Sun Exposure in Today’s World

In theory, you could eat zero vitamin D in your diet and maintain a healthy vitamin D status through sun exposure. In practice however, achieving 15 minutes of sun exposure on a daily basis is not practical for most people who work demanding indoor desk jobs. Especially in northern climates where the sun does not show its beautiful face very often, achieving even 15 minutes of sun exposure on a daily basis can be a difficult task indeed. The FDA recommends that adults get 400 IU (international units) of vitamin D per day, while many nutritionists recommend that adults supplement up to 4,000 IU per day to overcome vitamin D deficiency.

Vitamin D in Food

As a result of our modern day lifestyles, supplementing with vitamin D can be very beneficial. Determining the best dietary sources of vitamin D can be difficult. In truth, very few foods contain vitamin D, which is why food manufacturers fortify packaged food products like milk, ready-to-eat breakfast cereals, orange juice, yogurt and margarine. So for the past 20-25 years, millions of Americans have purchased packaged and processed foods fortified with vitamin D, thinking that those choices were the best sources of vitamin D. Until now. Mushrooms are a rich source of “bioavailable” vitamin D. The term “bioavailable” simply refers to the fact that the vitamin D found in mushrooms is easily absorbed, transported and utilized by tissues all throughout your body, making mushrooms a high-quality source of vitamin D.

Sunbathe Your Mushrooms!

In the book Mycelium Running: How Mushrooms Can Help Save the World, Paul Stamets writes about the unbelievable effect that sunlight can have on pre-picked mushrooms. In a series of elegantly designed experiments, Stamets discovered that shiitake mushrooms are capable of manufacturing vitamin D even after they have been picked, as long as their gills are exposed to sunlight (9). Freshly picked shiitake mushrooms contain about 110 IU of vitamin D per 100 grams. When placed in the sun for 6 hours, the vitamin D content increased to 10,900 IU (gills facing down), and 46,000 IU (gills facing up). By comparison, 1 cup of milk contains about 125 IU of vitamin D (10).

Six hours of direct sun exposure can increase vitamin D content in mushrooms by between 100 and 418-fold. In the science world, these numbers are astonishing.

Below is a table that lists the vitamin D content of many common foods available in the grocery store, in order of vitamin D content. Note that sun-bathed shiitake mushrooms are the highest of any food source. vitamin D food table

Simply follow these instructions to turbocharge your mushroom’s vitamin D status:

  • Place freshly picked shiitake mushrooms in the sunlight upside down (gills facing up)
  • Set a timer for six hours
  • Allow mushrooms to sunbathe in direct sunlight for six hours
  • Remove mushrooms from sunlight
  • Lightly steam, boil for bake mushrooms. This is important because raw mushrooms often contain dangerous levels of toxins that can impair nervous system function. It is always best to lightly cook mushrooms for 5-10 minutes to completely inactivate these toxins before eating




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  1. Campbell T. Shining a Light on Vitamin D [Internet]. Available from: http://nutritionstudies.org/shining-light-vitamin-d/
  2. Vitamin D Factsheet (NIH) [Internet]. Available from: http://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
  3. Peterson CA, Tosh AK, Belenchia AM. Vitamin D insufficiency and insulin resistance in obese adolescents. Ther Adv Endocrinol Metab. 2014 Dec;5(6):166–89.
  4. Mezza T, Muscogiuri G, Sorice GP, Prioletta A, Salomone E, Pontecorvi A, et al. Vitamin D deficiency: a new risk factor for type 2 diabetes? Ann Nutr Metab. 2012;61(4):337–48.
  5. Sung C-C, Liao M-T, Lu K-C, Wu C-C. Role of vitamin D in insulin resistance. J Biomed Biotechnol. 2012;2012:634195.
  6. Al-Sofiani ME, Jammah A, Racz M, Khawaja RA, Hasanato R, El-Fawal HAN, et al. Effect of Vitamin D Supplementation on Glucose Control and Inflammatory Response in Type II Diabetes: A Double Blind, Randomized Clinical Trial. Int J Endocrinol Metab. 2015 Jan;13(1):e22604.
  7. Dalgård C, Petersen MS, Weihe P, Grandjean P. Vitamin D Status in Relation to Glucose Metabolism and Type 2 Diabetes in Septuagenarians. Diabetes Care. 2011 Jun 1;34(6):1284–8.
  8. Holick MF. Vitamin D deficiency. N Engl J Med. 2007 Jul 19;357(3):266–81.
  9. Stamets P. Mycelium Running: How Mushrooms Can Help Save the World. First edition. Berkeley: Ten Speed Press; 2005. 356 p.
  10. Four Unexpected Food Facts - Dr. Weil [Internet]. [cited 2015 Mar 23]. Available from: http://www.drweil.com/drw/u/ART02935/Four-Unexpected-Food-Facts.html

About The Author

Cyrus Khambatta

Diagnosed with type 1 diabetes at the age of 22, I have spent over a decade learning the fundamentals of nutrition at the doctorate level. My goal is to share my knowledge of practical nutrition and fitness with people with prediabetes, type 1 and type 2 diabetes. Diabetes is an OPPORTUNITY to attain excellent health. Reversing the effects of insulin resistance can be a fun and enjoyable process if the right system is in place. That's why I've spent over 10 years developing a rock solid system that can minimize blood glucose variability and insulin resistance.

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