No one will argue that preventing Vitamin D deficiency is a very good idea, but who is truly at risk, how much Vitamin D is needed and from what sources is where it gets tricky. In my own research I’ve seen recommendations from reputable medical practitioners that say fortified foods and 10-15 minutes of sunshine 3 times a week is perfectly adequate to physician’s prescribing 50,000 IU’s per day for patients with severe health issues. Furthermore, in the last two months alone three more studies published on the subject of Vitamin D have been released and there is a 5-year National Institute of Health study costing $22 million underway which the government is funding so obviously this issue has quite a bit of traction. Here we’ll take a look at the historical discovery of Vitamin D and why it’s essential to our health, the most recent research, who’s susceptible to a Vitamin D deficiency and where a Vegan can find the best sources.
Vitamin D: A Short but Interesting History
Rickets: It all began in post-Industrial Revolution Europe in the late nineteenth century. A new disease was “discovered” called rickets and even though physicians didn’t understand at the time what the cause was, they were eager to figure it out as they kept seeing thousands of children in London and Warsaw with stunted growth, muscle wasting and deformed legs. From there, the disease “spread” to children dwelling in big industrial cities in the Northeastern U.S. In fact, by 1900 approximately 80% of children living in Boston suffered from rickets. By the 1930’s the link between Vitamin D and rickets was well established which led to the fortification of milk with Vitamin D.
Sunshine: Around this same time it was also discovered that the primary way our bodies get Vitamin D is by sunshine(or the UVB rays) coming into contact with our skin where it is synthesized and then carried into the blood stream. However, this can only take place effectively if you don’t apply sunscreen. Sunscreen with an SPF of 8 or higher reduces the ability of the skin to form Vitamin D by more than 95%. Interestingly enough, this fact directly contradicts what most American’s are told to do, which is to use sunscreen generously in order to prevent skin cancer and premature aging.
Vitamin D is really a HORMONE: A hormone is a substance that is produced in one part of the body, enters the bloodstream and exerts its effects at sites distant from the original site of its production. The main reason why this is an important point is that scientists started looking at what else Vitamin D might be responsible for beyond preventing rickets. Also, when Vitamin D enters the bloodstream it goes to the liver and undergoes a chemical change turning it into cholecalciferol. From there it goes to the kidneys where it changes again to calcitriol (which is ultimately the active form). Calcitriol then goes back into the bloodstream and exerts its actions. So what are these actions?
- They found that in order to absorb calcium and phosphorus from the intestines that Vitamin D had to be present in adequate amounts. Calcium and Phosphorus is the primary way we build strong bones and maintain healthy muscle tissue. Also, prevention of osteopenia and osteoporosis were noted as well as seeing improvements in Bone Mineral Density in those already suffering from these two diseases.
- People with kidney failure on dialysis cannot produce calcitriol, leaving them highly susceptible to a myriad of health issues.
- Studies in the past 20 years have linked adequate Vitamin D levels to a better functioning immune system, prevention of certain types of cancers (especially colon, prostrate, pancreas and breast), stimulates the production of insulin, reduces insulin resistance, inhibits Renin Angiotensin Aldosterone System(which in turn reduces high blood pressure and aids in the prevention of coronary heart disease), can improve skin disorders such as Psoriasis, better teeth and may prevent mood disorders such as depression.
Current RDA: Is it enough?
In 2010, the Recommended Dietary Allowances (RDA), historically very conservative, increased the recommended levels from 400 IU(international units)/day to 600 IU/day, the first change since 1997. Although many practitioners still believe this is still too low. According to endocrinologists Dr. Sarfraz Zaidi, based on his clinical experience and the 2006 American Journal of Clinical Nutrition’s recommendation that we maintain a blood level of 30 ng/ml, this cannot be achieved by most people at the current daily dosage recommendation. (For every 100 IU’s of Vitamin D, a person’s blood level will raise 1 ng/ml.) He believes that a “one size fits all” approach is misguided and unhelpful, especially to those suffering from particular diseases that can be helped with high dose supplementation. On the flip side, with all the recent research and media coverage many people are self-supplementing at very high doses without consulting a physician, believing that “you can’t get too much” and that it’s an inexpensive, cure-all solution. And this too has it’s flaws.
The U.S. Preventative Task Force recently advised that women 65 years and older take at least 800 IU’s/day after the University of Zurich shared its findings after pouring over 11 different Vitamin D studies, which included 30,000 women.
While there is still a lot to be determined definitively regarding Vitamin D and its effect on the body, we know enough at this point to feel confident that making sure you’re getting adequate amounts regularly is essential to maintaining good health and preventing ill-health.(Links to all the studies can be found below in the resource section).
Is Vitamin D from sunshine and food sufficient? What about Vegans?
Sunshine: The most natural way to get Vitamin D is through sunshine. For maximum benefit, you need to spend 10-15 minutes a day in the sun without sunscreen between the hours of 10am and 3pm and making sure that a sufficient amount of your skin in exposed. However, you also must consider the factors involved that will determine how much Vitamin D you can actually get from the sun. For instance, the farther north you live the less intense the UVB rays hitting the earth will be. Also, the suns intensity during the winter months is less and may require more exposure time but this might be unrealistic due to weather conditions. Sunscreens, pollution, shade, glass windows and clothing all decrease the amount of UVB rays absorbed by the skin. Also, the skin of the elderly typically manufactures 25% of Vitamin D3 compared to the skin of a young person. Skin pigment is a huge variable as well. For example, an African American person may need more than 10 fold the time in sun in order to produce the same amount as a fair-skinned person.
Vegan Food Sources of Vitamin D: Other than a few natural sources of plants containing low amounts of Vitamin D, a Vegan’s only other option are fortified foods such as nut mylks, orange juice and cereals and these are not in large amounts.
Raw Shiitake Mushrooms(10 ounces)= 76 IU
Fortified Nut Mylk(8 ounces)=100 IU
Fortified Orange Juice(8 ounces)=100 IU
Fortified Cereal=40-80 IU/serving
As you can see, even if you followed the RDA’s guidelines of 600 IU/day, that’s the equivalent of 8 cups of nut mylk or up to 10 servings of cereal or several pounds of shiitake mushrooms!
Vegan Supplementation: Natural Vitamin D comes in two forms: Vitamin D3 (cholecalciferol) and D2(ergocalciferol). Vitamin D3 is the form synthesized from the sun as well as found in animal-based food sources such as fatty fish and D2 is found in vegetables. However, D3 is the most common form found in multivitamins so you have to look at the nutrition facts label to find out the source.
Conclusion: Use Common Sense!
Do you live in a cold climate or do you tend to stay indoors due to lifestyle or professional pursuits? Do you have a strong family history of skin cancer or regularly avoid the sun for other reasons? Are you elderly? Do you have other health issues such as kidney disease, osteopenia or osteoporosis? Then I would say you should be very diligent in making certain your Vitamin D levels are sufficient. The only way to do this properly is by consulting a physician and getting a blood test.
I’m a huge advocate of getting your nutrition through whole, unadulterated foods but when it comes to certain nutrients, one has to be realistic. In this case, especially for Vegans who live in the shade or who are not interested in consuming large quantities of the food sources mentioned above, that making sure you take a multivitamin with Vitamin D2 just makes good sense.
- Low Vitamin D Levels Linked to Weight Gain in Older Women. Medline Plus, June 26, 2012. http://www.nlm.nih.gov/medlineplus/news/fullstory_126659.html
- Are We Overselling the Sunshine Vitamin? By Richard Nox, March 29, 2010. http://www.npr.org/templates/story.php?storyId=125226703
- Low Vitamin D Level is Linked to Greater Chance of Risk Factors for Type 2 Diabetes by The Endocrine Society Newsroom. June 24, 2012. http://www.endo-society.org/media/press/
- How Much Vitamin D Is Too Much? By Futurity.org, January 11, 2012. http://futurity.org/top-storis/how-much-vitamin-d-is-too-much/
- The Power of Vitamin D by Sarfraz Zaidi, MD. Revised Edition for Digital, April 2012. Outskirts Press.
by Melissa Sanborn of Nutritional Brands, PureVegan