Vitamin D and Iodine are Game Changers for Optimized Fertility!

pregnant woman in grassy field getting vitamin D from the sun

By Dr. Chris D. Meletis

There are two critical nutrients that tens of millions of North Americans are overtly low in; Vitamin D and Iodine. Both of these nutrients are crucial for one’s overall health and wellbeing regardless of one’s fertility goals. Yet, when it comes to seeking peak fertility Vitamin D and Iodine are Game Changers! Let’s examine together the powerful statistics and research as to how BIG a game changer these nutrients can be as you seek pregnancy.

Vitamin D- A Missing Link to Fertility

Vitamin D is both a vitamin and a hormone. It is made from cholesterol, the same building block that is needed to make estrogen, progesterone, testosterone and other steroidal hormones. Thus, sustaining a healthy vitamin D status is essential for male and female wellness and fertility.

While there are a few good food sources of Vitamin D, for example, eggs, liver and fatty fish, our primary source of vitamin D is the sun. But, over the last few decades, we have been told to fear the sun, as it is a potential cause of skin cancer. With the advent of sunscreen for sunny days and also the fact that sunscreen is built into many cosmetics, it is no wonder that most of us test lower in vitamin D than is optimal for overall wellness and fertility. It is important to note that those that work indoors and those that have darker complexions are at even higher risk for suboptimal vitamin D levels compared to those that are lighter complexioned or work outdoors in the sun.

Yale University School of Medicine studied 67 infertile women. A mere 7 percent had normal vitamin D levels and the remainder had either insufficient levels or overt clinical deficiency. Dr. Lubna Pal, from Yale, said: "Of note, not a single patient with either ovulatory disturbance or polycystic ovary syndrome demonstrated normal Vitamin D levels; 39 percent of those with ovulatory disturbance and 38 percent of those with PCOS had serum 25OHD levels consistent with deficiency.”

Getting Pregnant

British researchers discovered that women that maintained vitamin D (25-OH Vitamin D) levels within the reference range were 34 percent more likely to achieve a positive pregnancy test and 46 percent more likely to achieve a clinically viable pregnancy and another third more likely to have a live birth than women with low vitamin D levels.

I routinely advise trying to conceive (TTC) couples to get their vitamin D levels tested. My patients target a blood level of 50 to 70 ng/mL in the United States, and it is essential to test and not guess before and after supplementing vitamin D. Having too low or too high of level of vitamin D is not healthy.

Staying Pregnant

There is growing evidence from test tube and animal studies that low vitamin D may contribute to some miscarriages. Clinically it has been noted that the body shifts the conversion of vitamin D within the body to the most potent form of vitamin D during the first few months of a pregnancy and these levels can jump by up to three times the normal level; which has been theorized to help modulate the immune system from rejecting the pregnancy. After all, baby is ½ mother and ½ father, thus the mother’s immune system must modulate to tolerate the pregnancy.

Denmark researchers measured vitamin D levels on 1,684 pregnant women early in their pregnancy and monitored miscarriage events. They discovered the following:

  • Women who were more likely to miscarriage had lower vitamin D levels. At levels of 22 ng/mL or lower there was increased miscarriage risk compared to those with levels of 26 ng/mL or greater; relative to vitamin D status. (My clinical comment is both of these levels are generally considered quite low in the functional medicine field).

  • Women with levels less than 20 ng/mL were 2.5 times more likely to have a miscarriage than women with levels above 20 ng/mL.

These trends were statistically significant during the first trimester, though healthy vitamin D levels should be maintained throughout pregnancy for a variety of reasons.

In the words of the researchers, it was concluded:

“In conclusion, we found an association between 25(OH)D concentrations and first-trimester miscarriage, indicating that vitamin D concentrations, 50 nmol/L (20 ng/mL) in the first trimester were associated with a 2.5 times higher risk for a subsequent first-trimester miscarriage. These findings suggest a protective role for vitamin D against miscarriage. To test this hypothesis, randomized controlled trials should be performed to investigate the possible effect of increasing 25(OH)D concentrations by supplementation in early pregnancy or even pre-conceptually.”

It is important to restate that there are many potential causes of miscarriage, but vitamin D status is a relatively easy one to control. Also remember that cell phone and wireless non-ionizing radiation also increases risk of miscarriage.

Vitamin D Status and Men

Vitamin D levels have been associated with the development of the nucleus of the sperm cell, semen quality and sperm count. There is also evidence that low vitamin D has been discovered as one of the factors associated with lower testosterone levels.

In November 2009, a research study showed that human sperm have a vitamin D receptor. Suggesting that vitamin D is likely involved in the signaling between cells in the reproductive system. The researched concluded: "an unexpected significance of this hormone [vitamin D] in the acquisition of fertilizing ability," and the results imply that vitamin D is involved in a variety of sperm signaling pathways.

Beyond Vitamin D—Time for some Iodine?

An often overlooked, yet vital, nutrient for fertility and pregnancy is Iodine. Even though iodine is relatively easy to find in foods (iodized-salt is the primary source for most people), recent reports reveal that an increasing number of women are deficient in iodine. According to an article in March 2018 in Human Reproduction, it has been shown that upwards of 30 percent of women of childbearing age have iodine blood levels below 100 micrograms per liter. Mills’ research team found that 44% of the urine samples were in the deficient range for iodine. With a quarter of women testing in the moderate to severe deficiency range. (To read more I have placed a link in the references for those wanting to see the actual study).

Why is Iodine Important?

Researchers followed more than 500 women trying to conceive over about five years and found that, overall, those with moderate to severe iodine deficiency had 46% lower odds, per cycle, of becoming pregnant.

Dr. James Mills, the lead author shared with Reuters Health:

“We were surprised that moderate to severe deficiency was so common and that it reduced the chance of a woman becoming pregnant by almost 50% in each menstrual cycle.”

Not only is adequate iodine important to support optimal fertility, it is important for healthy fetal development, including thyroid function of both mom and baby, brain and IQ development as well.

Take Home Message for the TCC Community:

Both vitamin D and iodine are simple to control variables that can help tip the scales in your favor when it comes to manifesting your dream of parenthood. Both the male and female contributors to pregnancy are routinely tested in my clinical practice for vitamin D blood levels and almost all of my patients supplement with iodine. Indeed, the prenatal we use in our clinical practice delivers 100 percent of daily iodine recommendation. If you are low in vitamin D, work with your healthcare provider to determine the correct supplemental dose of vitamin D for you, and always be sure to retest levels within 3 to 6 months to ensure you have achieved an optimal vitamin D level. Wishing you great success and abundant health, as both of these nutrients are essential for foundational wellness and optimal fertility.

Dr. Chris Meletis

Dr. Chris MeletisDr. Chris Meletis is an educator, international author and lecturer. His personal mission is “Changing World’s Health One Person at a Time.” Dr Meletis has authored 18 books and over 200 national scientific articles in journals including Natural Health, Alternative and Complementary Therapies, Townsend Letter for Doctors and Patients, Life Extension, Natural Pharmacy, and PubMed.gov articles.

Dr. Meletis served as Dean of Naturopathic Medicine and Chief Medical Officer for 7 years for the National College of Naturopathic Medicine (now the National University of Natural Medicine). He was awarded the 2003 Physician of the Year by the American Association of Naturopathic Physician of the Year by the American Association of Naturopathic Physicians. He has a deep passion for helping the underprivileged and spearheaded the creation of 16 free natural medicine healthcare clinics in the Portland metropolitan area of Oregon.


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