Do you get enough Vitamin D?
An article in the Archives of Internal Medicine suggests that up to 77% of all Americans have lower levels of Vitamin D consistent with increased risk for deficiency. Given these stats one might expect Canadians would have a higher rate of deficiency, as it is physically impossible to get enough sunlight between October and March in Canadian due to their distance from the equator. Surprisingly according to The Canadian Health Measures Survey (CHMS) in 2007-2009 approximately one-third or 37% of Canadians had lowered levels of Vitamin D.
What's the big deal?
Vitamin D, also called "the sunshine vitamin", has been linked to the prevention of what seems to be an ever growing list of diseases. Vitamin D is said to:
- Prevent cancer
- Reduce heart attack risk
- Boost immunity
- Decrease risk of high blood pressure
- Prevent osteoporosis and promote good bone health
- Possibly linked to the prevention of Alzheimer's disease
- Prevention of Multiple Sclerosis
- Prevention of Diabetes
- Prevention of Rheumatoid Arthritis
- Prevention and treatment of depression
- Prevention of pregnancy-related problems
- Treat fertility issues
- Prevent birth defects
Vitamin D is said to help the uterus develop a lining that is adequate for an embryo to implant. Some claim that if you are Vitamin D deficient, this lining may not be thick enough and your embryo will not have enough to "hang on" to, which may result in early miscarriage.
A study out of Yale University looked at a group of women who were considered infertile and checked their Vitamin D levels. Of the 67 women involved, only 5 of them had what were considered to be adequate levels of Vitamin D. The remaining 93% of the women had either low levels, or displayed a clinical deficiency.
Vitamin D is not only important for the ladies. A study out of Denmark looked at the sperm quality and motility of 300 men. They found that Vitamin D makes sperm "better at swimming towards the egg, have greater speed and be more penetrative." More info on this study is available here.
Vitamin D and PCOS
The study previously mentioned out of Yale looked a little deeper into their participants medical histories and found that of the women involved in the study that had PCOS or ovulatory disturbances, every single one of them either had low levels of Vitamin D or were clinically deficient. 39% of the women with ovulatory disturbance and 38% of the women with PCOS were clinically classified as Vitamin D deficient.
Daily Recommended Intake vs. Daily Limit - Can you OD on Vitamin D?
You may have heard that it is possible to "OD" on Vitamin D. This is because Vitamin D (along with Vitamins A, E & K) is a fat soluble vitamin, unlike Vitamin C or B, which are water soluble. If you have too much Vitamin C or B you simply pee it out, which is why you may notice that your urine turns an alarming shade of fluorescent yellow when you take your multi-vitamins. But, any excess Vitamin D in your diet is stored in fat. This is means that it is theoretically possible to OD on Vitamin D, but you'd be hard pressed to find a case where this has actually happened. According to wikipedia, it takes over 50,000 IU per day over several months to over dose on Vitamin D.
Now, this is where it gets kinda confusing. You may look at the back of your bottle of multi-vitamins and think that is says you are getting 100% of your Daily Recommended Intake (RDA). But is this enough? First of all, you need to know that in November 2010 the Institute of Medicine TRIPLED the RDA for Vitamin D in the United States to reflect more recent findings. The RDA went from 200 IU per day to 600 IU per day. Additionally the safer "upper limit" for adults was increased from 2000 IU per day to 4000 IU per day. Many doctors still feel that these increased limits and RDAs are still not enough.
So, when looking at your multi-vitamin it is important to question if it was manufactured before the RDA changes took place. Your "100%" may actually be only 33% of the current RDA.
Also, many of the studies involving disease prevention recommend intakes closer to the upper daily limit.
While it appears that more research needs to be done on the topic, I know one thing for sure. I have added a Vitamin D supplement to my diet. Anything that might increase my chances of conceiving is okay with me.