Monday, January 5, 2015

Be sure to Get in Enough Vitamin D this Winter

My guess is that a Vitamin D supplement is probably the #1 prescribed supplement by physicians over the past few years. It seems like most of my clients were told they are deficient in Vitamin D and have been told to take a supplement. Typically, I tell my clients that I do not think most supplements people take are necessary, and can actually be doing damage. What is especially concerning is many people are taking supplements, for example, because Dr. Oz recommended it (which a new study shows 50% of what he recommends is not valid) and they aren’t even sure what the supplement does. If you are eating an adequate amount of calories and consuming a well balanced diet – especially one that is very high in non-starchy vegetables – you should be getting close to most of the vitamins and minerals your body requires. It’s when you start cutting out specific food groups like grains and dairy when it is troublesome to get in all the nutrients you need.  However, Vitamin D is a very challenging nutrient to get in through diet alone for almost everybody and I do back up the advice that people showing suboptimal levels should take a supplement. 

 For most people, the IOM recommendation for Vitamin D is 600 IU per day and adults over the age of 70 are recommended to get in 800 IUs per day because synthesis decreases with age. Vitamin D is critical for bone development and a deficiency is known to cause rickets, osteomalacia and osteoporosis. The best sources of dietary Vitamin D are cod liver oil (my favorite!), swordfish, salmon, tuna, and fortified foods such as milk, yogurt, and cereals. Three ounces of salmon or swordfish will get you the recommended amount of Vitamin D for younger people… but it is rare that people are eating that amount on a regular basis. From doing diet analyses on a regular basis, I can tell you that the average person has a lot of trouble getting Vitamin D in through dietary sources.
Alas, there is good news since Vitamin D is so hard to get in through diet: the best source is through synthesis in the skin from the sun’s UV rays.  It seems there is definitely a relationship between Vitamin D deficiency and a higher risk of most major diseases and conditions prevalent in the US (diabetes, certain cancers, depression, weight gain, etc.). In grad school I wrote a comprehensive research paper on Vitamin D as an anti-cancer agent and found there is ample evidence showing a link between Vitamin D status and breast, colon, prostate, and pancreatic cancers.  However, they have not found if Vitamin D deficiency increases the risk, or if higher levels of Vitamin D in the blood is protective against these cancers.

If you spend much time outside during the summer, you probably do get in enough Vitamin D, since a fair-skinned person can get a whole day worth of Vitamin D synthesized from amount fifteen minutes in sunlight. However, darker skinned individuals and the obese need more exposure.  During the winter, it is much harder due to make enough because the intensity of the sun’s rays are lacking due to the angle of the sun, but being outside in sunlight is incredibly important. You still will synthesize some Vitamin D by being outside during the winter, and certainly it is important to get outside to combat depression associated with the doldrums of winter. That being said, there is also some link between depression and Vitamin D deficiency, go figure!

If you have had blood work done recently and found that you have suboptimal Vitamin D levels, I recommend you ask your doctor if a supplement is warranted. To figure out how much you should be taking, ask your doctor, or visit the Mayo Clinic’s dosing guidelines page here. In May 2013, Consumer Reports rated the best Vitamin D supplements, and the best bang for your buck seems to be Trader Joe’s Vitamin D softgels, and Costco’s Kirkland Signature (for Calcium + Vitamin D supplement) seem to be the best value. One note is that more is not better when it comes to Vitamin D, especially because it is fat soluble and your body cannot excrete excess. According to WebMD, taking 4,000 mg or more for a prolonged period of time is deemed possibly unsafe and too much Vitamin D can cause kidney problems.

The research regarding the “Sunshine Vitamin” and its link to disease prevention is very exciting and there is a lot more to come. The majority of the research shows that a deficiency of this Vitamin can definitely harm your health. So, my recommendation is get your blood work done, see how you are doing, and possibly consider taking a supplement if need be. However, I always recommend getting outside for a walk as much as possible- even if it’s cold! You won’t get the optimal amount of UV exposure for Vitamin D synthesis if you are living in the north during the winter, but it’s definitely beneficial. Visit my blog on how walking and regularly exposing your body to cold is actually advantageous for losing weight!


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