Summer Love: Why Vitamin D (and Sunshine) are Good for Fertility
Strappy sandals, a sundress, plenty of sunshine and a vacation are a great combo for fertility!
Vitamin D is important for male and female fertility too so making sure your Vitamin D levels are adequate and TTC in the summer months can help with getting pregnant. And there are some food sources for Vitamin D, but the best source is the sun!
What is Vitamin D?
Vitamin D is called a Vitamin, but it is actually a hormone and it does many things for your health.
Most of us think about bone health with Vitamin D, but there is SO much more to this vitamin. It helps the body in absorbing calcium, which keeps bones healthy and strong. However, it also helps your immune system and plays a role in cell growth, which is important for a growing baby.
Vitamin D basically balances the immune system and keeps it in check. And interestingly, studies show that women with deficient Vitamin D levels are less likely to get pregnant.
How do I know what my Vitamin D status is?
A simple blood test. Your doctor or any health provider that can order blood work can order a test for your Vitamin D3 level. I strongly suggest you get this tested at your primary care doc or reproductive endocrinologist. I routinely see clients with very low Vitamin D levels that have been struggling with infertility and they simply were unaware of how low their levels were because they had not been tested.
What is low Vitamin D?
A Vitamin D3 level lower than 30ng is considered deficient by lab standards. However, for fertility we want the numbers well above “deficient.” In the summer months, your Vitamin D level is likely to be highest because of sun exposure so it is important to get tested in the summer and the winter to see how much your Vitamin D changes.
How does Vitamin D impact female fertility?
Calcitriol, the active form of vitamin D, plays a number of roles in fertility. When Vitamin D is bound to its receptor, it’s able to control the genes that make estrogen which has several roles in helping you get pregnant.
As the embryo reaches the uterine cavity, shortly before implantation, the uterine lining creates Vitamin D in response to it. Once enough active Vitamin D is produced, it is able to regulate a number of genes that are involved in embryo implantation.
The uterus and placenta continue to produce Vitamin D after a woman becomes pregnant, which helps organize immune cells in the uterus to mitigate any infections without hurting the pregnancy. This is also why it is important to get a pap smear and full STD panel before TTC too.
Does vitamin D affect male fertility as well?
Yes, indeed! There is research to support that Vitamin D is important for sperm health. If you start to see a theme on my blog, it’s that men matter and their sperm health can change based on their lifestyle.
This is why I do fertility coaching with both partners. There are documented experimental studies that show the positive effect of vitamin D on male fertility. Vitamin D can modulate hormone production through genomic (involving DNA) and non-genomic actions (not involving DNA), and improving semen quality.
In addition, Vitamin D can improve sperm motility which is the ability of sperm to swim. Men need to have plenty of sperm, good quality sperm, and sperm that swim to get you pregnant.
Can Vitamin D and sunshine improve my chances for getting pregnant?
Yes, by almost 30%! A retrospective study showed that women who underwent IVF when the prior month was “sunny” were more likely to successfully get pregnant. If you are planning TTC, aiming for spring, summer or early Fall might increase your chances.
There are many fall babies so this is not an absolute rule! If you are TTC in the winter, supplementation, foods and as much sun as you can get—a cool brisk, sunny walk or sitting in the sun in a window—can’t hurt.
What happens if I don’t have enough Vitamin D?
We know from studies that low Vitamin D is associated with being less likely to get pregnant as well as more adverse outcomes in pregnancy and post-partum.
This isn’t new research either. In a 1980 study, scientists tested the effects of vitamin D deficiency on fertility, reproductive capacity, and fetal and neonatal development. The researchers found vitamin D deficient rats had a 75% reduction in overall fertility. This diminished litter sizes by 30% and impaired growth of the offspring. This study is relevant for humans. If a woman has vitamin D deficiency, she is at risk for reduced fertility, various adverse pregnancy outcomes, and low vitamin D content of her breast milk.
A review of several human studies showed trends toward lower clinical pregnancy and higher ongoing pregnancy for women with deficient levels of vitamin D. The probability of live birth for women with deficient levels of vitamin D was significantly lower than cases with sufficient levels of vitamin D. In conclusion, deficient vitamin D was associated with decreased probability of live birth after IVF/ICSI.
How can I get more Vitamin D?
This is an easy fix! There are many sources of Vitamin D.
Food Sources of Vitamin D
Vitamin D can be obtained through two pathways: the diet or your body can make it. There are two forms of Vitamin D: Vitamin D2 which is found in plant sources, or vitamin D3 which is found in animal sources.
Plant-based sources of Vitamin D
Mushrooms
Orange juice
Fortified foods, including healthy fat spreads and breakfast cereals
Animal-based sources of Vitamin D
Oily fish, such as salmon, sardines, herring and mackerel
Red meat
Liver
Egg yolks
The Sun as the best Source of Vitamin D
Vitamin D made from your body’s exposure to sunlight gives you the most bang for your buck. Basically, the sun’s ultraviolet B (UVB) rays convert to Vitamin D3, the active form of Vitamin D.
While you should still eat Vitamin D-rich foods, you do need 30-60 minutes of sunlight exposure a day with your body not covered up! I have clients tell me they go to lunch for 5 minutes from their office and they are wearing long pants and a short sleeve shirt. This does not count.
Get outside! The majority of people should be able to get all of their vitamin D from sunlight on their skin from late March/early April to the end of September.
Supplements as a source of Vitamin D3
The recommended form of vitamin D is vitamin D3 because it is more absorbable. If you are deficient or low-normal, or having trouble getting pregnant, then I suggest supplementing with Vitamin D3.
As a nutritionist, I have found a lot of variability in different products of Vitamin D and their ability to be absorbed by your body. Some clients are on Vitamin D and their levels don’t change or are low, which tells me the supplement is not working for them.
This is why I choose my Vitamin D supplements that I share with my clients very carefully and be sure it has the right co-factors to help with absorption. I dose Vitamin D based on the client’s current Vitamin D levels. As with any supplement, you need to do the right dose and the right product to get the benefit.
How much sun do I need for Vitamin D?
We’ve long heard about the risks for skin cancer and wrinkles, too. On the other hand: the sun has vitamin D and you need Vitamin D. What to do?
It’s a tough one that involves balance. The 1980’s baking in the sun with baby oil wasn’t healthy, but neither is staying inside or wearing full body sun shirts, hats, and chemical-laden sunscreen.
The sun is actually the best way to get your Vitamin D. You need about 15-30 minutes of midday sun several days a week. How many of us actually get that? If you are in an office, a quick lunch run in business wear kinda doesn’t count.
If you are home, laying outside or just going outside is sufficient. Doing a walk in shorts and t-shirt with a baseball cap for 30 minutes would be great if it’s not sweltering hot.
This goes back to my favorite goldilocks rule: not too much and not too little, but just right. :)
If I am out in the sun all day, what do I do?
In my blog on sunscreens, I talked about how many conventional sunscreens can be harmful to fertility. If you are out in the sun all day at the pool, the beach, or at work, you don’t want to get burned. It’s important to protect your skin from prolonged sun exposure that leads to damage by using fertility-safe sunscreens and SPF sun shirts with a hat. Again, you don’t need sunscreen for your 15-30 minutes of sun catching, but for a longer time outside.
Interested in finding out about your
Vitamin D levels and what to do?
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