vitamin D

I think sunscreen typifies the anxiety that has been bred by the internet and media.  Is it good or bad?  Fifty years ago we would assume it is good as our doctor would have told us to use it, teachers in school would remind us it is important and we'd have no or few resources to check whether they were right.  If the doctor and teachers were right this was a better time.  We would have been saved google searches that doubted the doctor.  I think there would be less anxiety.  Of course, the big assumption is that the doctor and teachers are right.

 

I know the evidence favors using sunscreen but I do take pause when I read the list of ingredients.  One ingredient in a lot of sunscreens is oxybenzone.  Oprah told us to avoid it 10 years ago, Hawaii is considering banning it as it is bad for coral reefs and even the CDC has raised a concern about it.  So if I do use sunscreen I try to avoid those containing oxybenzone.

This week I have been hiking around Banff with my family.  We haven't use sunscreen mostly because I forgot to pack it. I also have been wondering if a bit of sun exposure might be good.  Sure it makes me look 60 when I am 44, but maybe there are other health benefits?

 

The last decade has proven that vitamin D from the sun or supplements might indeed have health benefits. In the case of fertility there is evidence that vitamin D is beneficial, which is why I tell every woman coming to see me to take vitamin D.  I used to measure vitamin D levels in blood, but it turns out that means very little.  Blood vitamin D levels mean so very little that in BC the government will no longer pay for vitamin D testing.  This sounds wrong, doesn't it: vitamin D is important for our healthy but yet we don't want to know your level.  It's true though because WE ARE ALL DEFICIENT unless we take supplements.  

 

A study published this month in Fertility & Sterility followed about 110 couples who were trying to conceive (not necessarily infertile).  They measured the male and female's blood vitamin D levels and asked them about their intake of foods that contain vitamin D.  They then followed them until a pregnancy occured, or 12 months from study entry.  The male and female blood levels of vitamin D did not correlate with the chance of conceiving.  Interesting, though, those couples who consumed (supplements or diet) more vitamin D and whose intake met the estimated daily requirement were more likely to conceive.   Interesting that it was supplementation of both the male and female that mattered which means I am going to expand my supplement advice to include men taking vitamin D 2000 IU in as well as women.

 

Other studies have suggested a benefit of vitamin D supplementation prior to IVF as well. The dose most frequently studied is 2000 IUs: tablets or drops.

 

With respect to sun versus supplements?  Probably supplements are as good as sun exposure - so it is a good idea to avoid sun contact (clothing, shade or sunscreen) and take a supplement.  Best to use a sunscreen that does not have oxybenzone.  If you live in Vancouver it seems we won't be seeing the sun much soon anyway!

 

Reference: Fung JL, Hartman TJ, Schleicher RL, Goldman MB. Association of vitamin D intake and serum levels with fertility: results from the Lifestyle and Fertility Study. Fertil Steril. 2017 Aug;108(2):302-311.

Dr. Beth Taylor MD, FRCSC
Reproductive Endocrinology & Infertility