By Rosemary Barrow, B.S. Exercise Science, NASM Certified Personal Trainer
In the first part of this article, the focus points were on the significance and role of vitamin D as it pertains to human health and disease prevention, and how we can attain optimal levels in our bodies through adequate UVB sunlight exposure, consuming appropriate animal or animal-based food sources (i.e., salmon, tuna, mackerel, fish oils, egg yolks, and some cheeses), and through supplementation. Lately it seems every other study published in health news is boasting the amazing breakthroughs in vitamin D research. The overwhelming amount of relative information in this area is deepening our understanding of this hormone's powerful effect on our ability not only to thrive but to survive, it seems—rather timely considering that roughly 60% of Americans have low levels of or are vitamin D deficient, according to a study published in the March 2010 issue of the Journal of Clinical Endocrinology and Metabolism. In fact, vitamin D deficiency “may be the common denominator behind our most devastating modern degenerative diseases,” according to Mike Adams, editor of Natural News Network. Individuals suffering from kidney failure, diabetes, cancer, osteoporosis, and multiple sclerosis are almost always universally deficient in the sunshine vitamin.
Our health as a nation is disintegrating in a nasty downward spiral. Modern lifestyles lend themselves to behaviors and circumstances that reduce our potential for attaining ideal levels of vitamin D, among other health-giving factors. We spend more time indoors, whether it's work or play, thus reducing our sunlight exposure. When we are outside we slather on the sunscreen, once again reducing our chances of soaking up those necessary UVB rays that allow us to manufacture enough cholecalciferol (vitamin D3) in our skin. Our diets are severely lacking in both quality of content and in vitamin D-rich foods. To make things more interesting, there's a sea of misinformation in all forms of media as well as rampant over-medication and lack of quality healthcare. So in light of these latest findings, we could come to a few simple conclusions: Get more healthy sun exposure, exercise regularly, eat “real food” (you know, the kind that comes out of the ground, off of a tree, or from an animal that eats these same things), and then maybe we won't even need to supplement! While these are pretty clear-cut, well-founded conclusions, it's worth considering a few more details and asking a few more questions. If optimal vitamin D levels are so integral to our well-being, how then do we optimize this component of health?
There are many factors that determine your vitamin D status as well as your ability to make and properly utilize it. As mentioned in Part I of this article, age, weight, body fat percentage, latitude of where you live, skin coloration, season, use of sunscreen, and individual sun exposure are the major determinants. Here are some general rules of thumb that are easy to remember:
· Older individuals need more vitamin D than younger individuals.
· Big people need more than smaller people.
· Heavier people need more than skinny people.
· Individuals living in northern latitudes (above 35 N latitude—we're just above the 45 N latitude) need more than those in southern latitudes (below 35 N latitude & closer to the equator).
· Darker complected people need more than fairer complected people.
· Sunblock users need more than those who forgo the sunblock.
· “Sunphobes” need more than sun worshipers.
· Ill individuals need more than well individuals.
So how do you know if you're making or getting enough vitamin D? The most accurate and reliable way is through a blood test administered by your doctor or by obtaining a home test kit from ZRT Laboratories (available through www.vitamindcouncil.org) that measures 25-hydroxyvitamin D, or 25(OH)D. This tests for calcidiol in the blood, a pre-hormone and storage form of vitamin D in our bodies that's made in the liver. The Vitamin D Council states that optimal levels of 25(OH)D for health and disease prevention fall between 50-80 ng/ml (125-200 nM/L), and some estimates have been as high as 100 ng/ml. These are the values you want to look for when you receive your test results. According to the Vitamin D Council, about 20% of U.S. doctors order the wrong test. In this case they're measuring 1, 25-dihydroxyvitamin D which measures calcitriol, the most potent steroid in our bodies, and is more a measure of kidney function than an accurate reflection of vitamin D status. This particular pre-hormone is an adaptive hormone and fluctuates with calcium intake, so test results of this could show normal or even high levels but a vitamin D deficiency could still exist.
Dr. John Cannell of the Vitamin D Council suggests taking 1,000 IU per 25 pounds of body weight for eight weeks and then testing. At that point, depending on your results, you can adjust accordingly for any variable (i.e., sun exposure, food sources, supplementation) that affects vitamin D levels. Dr. Cannell estimates that “each 1,000 IU increase in supplemental vitamin D will generally produce a 10 ng/ml increase in the vitamin D blood level.” These are general recommendations so it's important to note that we all differ somewhat physiologically and in our vitamin D receptor (VDR) capabilities. When using supplements, be sure to test blood levels every several months to monitor your status.
Making and consuming enough vitamin D may be essential to our ability to thrive and survive, as suggested by researchers at Oregon State University in the conclusion to a study they published in August 2009. They discovered a vitamin D-mediated immune response encoded and conserved in the genome of “every primate species ever examined for its presence, ...and did not disappear long ago through evolutionary variation and mutation.” This genetic marker is “shared only by primates, including humans – but no other known animal species” and the fact that it “is still found in species ranging from squirrel monkeys to baboons and humans, suggests that it must be critical to their survival...” the researchers said.
We have an “innate immune response” that occurs immediately, as with a cut or infection, as well as an “adaptive immune response” associated with the exposure to new pathogens whereby antibodies are formed and retained for future defense. The OSU researchers are studying a specific type of genetic material which composes over 90% of the human genome and “is believed to play a major role in the proper function of the "innate" immune system in primates” in that it “allows vitamin D to boost [this response] by turning on an antimicrobial protein. The overall effect may help to prevent the immune system from overreacting.” Another study led by Professor Carsten Geisler from the Department of International Health, Immunology and Microbiology at the University of Copenhagen, also discovered that vitamin D “activates the immune system by 'arming' T cells to fight off infections” and without vitamin D, these cells “remain dormant.” This has very important implications in the prevention and treatment of autoimmune and degenerative diseases.
Another characteristic of this system that sets it apart from other steroid hormones is its potential to prevent and fight cancer cells. When cholecalciferol/D3 is produced in the skin there are two initial pathways it takes—first, conversion to calcidiol in the liver (storage from of vitamin D) and then to calcitriol in the kidneys (to regulate calcium in the blood). If enough cholecalciferol has been made to satisfy the requirements for both pathways, any excess calcitriol is sent to other tissues (i.e., organ, organ systems) that can continue independently making more of it in order to fight cancer cells. No other steroid hormone system works this way. To ease any concern regarding vitamin D toxicity, it should be added that this is an extremely rare occurrence. To read more on this topic, visit the Vitamin D Council's website at www.vitamindcouncil.org.
So what all this means is you may have some “vitamin D homework” to do, and now that you're a more informed consumer, it's time to get outside more this year to enjoy the beautiful Oregon spring and summer weather!