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Vitamin D & Its Role in Women & Children

In Post Dates - Think Aloud/Allowed, I began hypothesizing that perhaps Vitamin D has a role in women's post-dates issues. Biochemist Ethel egged my mind (and hers) on. Giant leaps of wonderings came about when it was brought up that calcium deficiencies might affect women's abilities to begin labor or keep the uterus contracting once labor began. Searching "Uterine contractions calcium" pulls up a slew of studies I don't have access to plus most seem to be studying rats and bunnies. But, what if calcium is a crucial mineral to a contracting uterus?

Sometimes I think the most inane things are studied (the effect of a doula, problems with episiotomies, whether uterine rupture can be determined before labor or on admission to the hospital), yet something as interesting or possibly valuable to birthing women and their care providers is left to languor with animal testing.

This topic/post is long. It's going to give basic information about Vitamin D, but calcium is another vital piece to this puzzle as is the need for essential fatty acids to kick off the whole shebang. I am hoping this piece is a jumping off point for all of us to explore our own needs with these nutrients.

What comes first? The body's need for Vitamin D to absorb everything (malabsorption affects all three ingredients (?), supplements (no... wrong word), nutrients (that's a better word!).


Vitamin D is crucial in the absorption of calcium in the body.

Vitamin D is now believed to aid in the prevention and treatment of Type 1 and Type 2 diabetes, hypertension, glucose intolerance and multiple sclerosis. It's likely that Vitamin D has a hand in hypothyroidism, definitely in hypoparathyroidism, causes joint and muscle pain (fibromyalgia?!), and can cause extreme fatigue (chronic fatigue disorders?!).Some of these are auto-immune disorders (perhaps all are rooted in auto-immune disorders!) and can be devastating. If there turns out to be a cheap and easy way to prevent them, I'm all for learning more how!

Research is showing that Vitamin D supplementation works better than lightboxes for Seasonal Affective Disorder - SAD. Who knew?!

Because of my own serious Vitamin D deficiency, I began learning more about the proloferation of the deficiency in our country (not to mention many other countries as well).

Several factors inhibit the absorption of Vitamin D: aging, intestinal problems, (my) gastric bypass, sunscreen, worries about skin cancer, obsesity and darker skin.

I watched a morning show a couple of weeks ago where the doctor spoke about Vitamin D deficiency and breastfeeding infants. They were one of the largest groups with the lowest levels of the vitamin. Alarmed, I talked to my apprentice Donna and told her we needed to research this more, to see if we might need to recommend Vitamin D supplements to our clients.

Now, after years and years explaining that breastfed babies have lower iron levels when tested at a year and that many doctors believed this is a natural dip for breastfed babies... and that the iron in breastmilk is more easily absorbed, the same can be wondered about Vitamin D.

However, one can't argue that the main group with rickets is exclusively breastfed babies!

"But every ethnic group was breast-feeding more, while rickets was primarily affecting just one group. "The bulk of them were African American," Bhatia notes, "about 75 percent, 80 percent African American children." Kids with darkly pigmented skin produce only about 5 percent of the vitamin D of children with lighter skin. The result, if they're breast-fed with no vitamin D supplements? Rickets."

The above article, quoted even in a Lactivist's blog, definitely speaks more about darker skinned babies, but is relevant to all of us who are nursing without Vitamin D supplementation.

"Although Nora was exclusively breastfed for 6 months and drank breastmilk until she was about 13 months, we never supplemented with Vitamin D drops. When I spoke with my pediatrician, he said that as long as she had about 10-30 minutes of exposure to sunlight each day, she'd get all the Vitamin D she needed.

It makes me wonder if part of the issue here is not so much the lack of vitamins, but a city verses a country thing. Not sure how much time babies and children in cities like Boston and NYC, but out here in the midwest, there doesn't seem to be much trouble getting plenty of sun exposure for our kids."

This Mothering article counters the need for Vitamin D supplementation in infants and smartly suggests that mothers increase their intake not only for their benefit, but that of their babies.

Note, also, that this article is from 2003 and says babies need 30 minutes a week of sun; most information now says babies need 10-30 minutes a day of sunlight.

(We have to be very careful with our newborns in the sun! They burn fast and easily.)

Does My Baby Need Vitamin D Supplements speaks about supplements for breastfed babies with disdain and uses (very) outdated clips from studies and sites to defend her position.

Moving backwards, we read Vitamin D Deficiency Widespread During Pregnancy and I can't help but wonder if this might be where the low Vitamin D in breastmilk begins. The article says:

"In our study, more than 80 percent of African-American women and nearly half of white women tested at delivery had levels of vitamin D that were too low, even though more than 90 percent of them used prenatal vitamins during pregnancy.

The numbers also were striking for their newborns -- 92.4 percent of African-American babies and 66.1 percent of white infants were found to have insufficient vitamin D at birth." (emphasis mine)

This article published in the UK talks about a study that was done in Boston between 2005-2007 with babies and toddlers from 8 months to 2 years:

"Forty-four of the children (about 12%) had a vitamin D deficiency and seven (about 2%) had a severe vitamin D deficiency. Overall, 146 children (40%) had below the ideal level of vitamin D.

Children’s gender, time spent outside, skin colour and sun sensitivity and sunscreen use did not affect their risk of vitamin D deficiency, nor did the season in which the measurement was taken.

Infants whose mothers breastfed them but who did not take any vitamin D supplements, were more likely to have vitamin D deficiency compared with those who were bottle fed. There was no difference between infants of breastfeeding mothers who took vitamin D supplements and those who exclusively bottle fed."

An expected question would wonder if the appropriate levels in humans have changed and perhaps we are experiencing the normal rates, reading the levels through old guidelines. From what I have found, the rates the human body needs haven't changed, but our lives and lifestyles have.

It seems our lack of sun (and sunscreen) as well as the changes in our diets away from fish have combined to put far too many of us at risk.

Vitamin D: Vital Role in Your Health speaks of the importance of supplementing even when you try to get your D from food and if you are unable to religiously get 20-30 minutes a day in the mid-day, summer sun (naked arms, hands, backs and faces are the most researched areas). I'd read that egg yolks have Vitamin D and got all excited! I love eggs! And then I read one yolk has a mere 25 IUs!! I'd have to eat 8 yolks to make the measly "adequate intake" our government has outlined. No one in my life could handle my eating 8 eggs a day. Even if it were just the yolks.

So the government doesn't have a "Recommended Daily Allowance" for Vitamin D. Instead it has an Adequate Intake and the AIs are as follows:

Birth to 13 years - 200 IU
14-18 years - 200 IU (including pregnant women)
19-50 - 200 IU (including pregnant women)
51-70 - 400 IU
71+ - 600 IU

But, even the government's own sites say the AI might be incredibly low. The American Academy of Pediatrics says breastfed infants should be supplemented with 400 IUs a day!

Government Daily Vitamin D Recommendations May Be Inadequate says:

"An article by Dr. Michel Holick in the New England Journal of Medicine claims that current government recommendations for daily intake of vitamin D are far too low. Dr. Holick charges that the RDA of 200 IU per day is inadequate to prevent vitamin D deficiency in many people. He would raise the recommendation to 800-1000 IU per day."

In Current Vitamin D Recommendations Fraction of Safe, Perhaps Essential Levels for Children, Science Daily, on May 28, 2008, says:

"The current recommended daily allowance (RDA) of vitamin D for children is 200 International Units (IUs), but new research reveals that children may need and can safely take ten-times that amount. According to new research this order-of-magnitude increase could improve the bone health of children worldwide and may have other long-term health benefits."
The above article is one of the most important I quote in this post. Please read it!

So, with all the confusion about how much Vitamin D a person needs, how do we figure out what we need? It's unsafe to super-dose on Vitamin D because it is a fat soluble vitamin and has (eventually) toxic doses. Finding those toxic doses can be extremely difficult, especially without regular blood tests. (I will share what toxic symptoms are below.)

The Mayo Clinic's information sheet on Vitamin D speaks about using massive amounts of D for treatment purposes. They say when treating hypoparathyroidism, patients are taking 8,000 to 200,000 IUs a day depending on the type of D given.

Rickets is treated extremely aggressively, giving 5,000 - 10,000 IUs daily for 2-3 months. For resistant rickets, the dosage jumps to 12,000 - 500,000 IUs a day.

Doses for infants (under a year) shouldn't, according to this piece, exceed 1000 IUs a day. For children older than a year, their dosage shouldn't exceed 2000 IUs a day.

NOTE! This does NOT include the 10,000 IUs that come naturally from 10-30 minutes a day in the mid-day sun or the IUs that come from foods. These dosages are for supplements only.

From the Vitamin D Council:

"The single most important fact anyone needs to know about vitamin D is how much nature supplies if we behave naturally, e.g., go into the sun. Humans make at least 10,000 units of vitamin D within 30 minutes of full body exposure to the sun (minimal erythemal dose). Vitamin D production in the skin occurs within minutes and is already maximized before your skin turns pink."

It is impossible to store up Vitamin D for the winter. Most research explains that Vitamin D, in its adequate levels, is only available in the body for about 3 weeks. And, important to note, it is the UV/B rays that manufacture Vitamin D in the body and accessing the UV/B rays occurs during the mid-day hours (oft quoted, between 10am-2pm).

"The good news is that you can't overdose on the vitamin D manufactured by your skin."

Looking at the maze of requirements regarding Vitamin D acquisition and absorption, it is easy to understand the necessity, in our culture, for supplementation.

But, can there be too much of a good thing?

"...newer clinical trials conducted in healthy adults found no evidence of vitamin D toxicity at doses ≥10,000 IU/day. Although vitamin D supplements above recommended levels given in clinical trials have not shown harm, most trials were not adequately designed to assess harm. Evidence is not sufficient to determine the potential risks of excess vitamin D in infants, children, and women of reproductive age."

(Note the caveat in italics above.)

"Because synthesis of 1,25(OH)2D (the most active metabolite of vitamin D) is tightly regulated, vitamin D toxicity usually occurs only if excessive doses (prescription or megavitamin) are taken. Vitamin D 1000 μg (40,000 IU)/day produces toxicity within 1 to 4 mo in infants. In adults, taking 1250 μg (50,000 IU)/day for several months can produce toxicity.

How is Vitamin D measured in the body?

The 25-hydroxy vitamin D test is the most accurate measure of the amount of vitamin D in the body.

The normal range is 16.0 to 74.0 nanograms per milliliter (ng/mL). Some providers include the parathyroid test in addition to the 25 OH.

It's important to fast for at least 4 hours before any Vitamin or Mineral blood test.

What do signs of toxicity look like?

The main symptoms come from hypercalcemia (too much calcium in the blood). Anorexia (inability to eat), nausea, vomiting, polyuria (peeing a lot), polydipsia (excessive thirst), weakness, nervousness, pruritus (itching) and eventually renal failure are the danger signs. Earlier, more benign symptoms, include the nausea and vomiting, appetite loss, constipation and weight loss. When the calcium levels are elevated, extreme fatigue and muscle weakness as well as heart palpatations occur.

So, now we all have an idea of how much we can take and understand the signs of toxicity, but what does all of this have to do with pregnancy, labor and postpartum?

One of the best articles I've seen is this American Journal of Nutrition article entitled Assessment of Dietary Vitamin D Requirements During Pregnancy and Lactation. The piece gathers together a multitude of studies and looks at the United States' touted recommendations for Vitamin D supplementation not only during pregnancy, but includes observations of the needs of newborns, infants, children, pregnant and lactating women.

I love that the authors speak about the arbitrary-ness of how the recommendations came about - by guessing!

They also say,

"The question that has intrigued our group for years is the following: How is it possible that the DRI for vitamin D is the same for a 1-kg premature human infant, a 3.5-kg term infant, and a 90-kg adult? The recommendation for all of three of these groups is 400 IU/d (10 µg/d)!"

Some of the notations that seemed most relevant to me:

- what was described in a retrospective study was a dramatic decrease in type 1 diabetes later in life in infants who received high-dose (4000-5000 IUs) daily vitamin D supplementation

- In other words, mothers who were vitamin D deficient at the beginning of their pregnancy were still deficient at the end of their pregnancy after being supplemented with 800–1600 IU vitamin D/d throughout their pregnancy. This result is precisely what the regression analysis from Heaney et al predicted would happen at this vitamin D intake, and this is a problem. The results of this study again point out that the DRI for vitamin D during pregnancy is grossly inadequate, especially in ethnic minorities

- ...the nutritional vitamin D status of the human fetus and neonate is totally dependent on the vitamin D stores of the mother; thus, if the mother has hypovitaminosis D (low Vitamin D levels), her fetus will experience depleted vitamin D exposure throughout the developmental period

- ...let us discuss a scenario that occurs thousands of times daily in the United States. A pregnant woman visits her obstetrician, who prescribes prenatal vitamins containing 400 IU (10 µg) vitamin D. The patient and physician both assume that this supplement will fulfill all the nutritional requirements for the duration of the pregnancy. However, in the case of vitamin D, it will not even come close unless the pregnant woman has adequate sun exposure. The woman, especially if African American, and her developing fetus are at high risk of remaining vitamin D deficient during the entire pregnancy. Even if the physician were to prescribe a vitamin D supplement of 1000 IU/d (25 µg/d), the mother would likely remain vitamin D deficient. As scientists and health care providers, we simply cannot accept this any longer. The true requirement for vitamin D during pregnancy must be determined scientifically.

- ...investigators did not know that the source of vitamin D in the mother’s milk was the mother’s exposure to the sun, which cutaneously generated large amounts of vitamin D. Ultimately, this solar-derived vitamin D ended up in the mother’s milk for the infant....

- circulating 25(OH)D concentrations in breastfed infants are directly related to the vitamin D content of the mothers’ milk. Available evidence indicates that if the vitamin D status of the lactating mother is adequate, her breastfeeding infant will maintain a "minimally normal" nutritional vitamin D status.

...investigators found that white infants who were exclusively breastfed during the winter in a northern climate maintained a "minimally normal" vitamin D status for 6 mo. Note, however, that the circulating 25(OH)D concentrations in the breastfeeding infants from this study actually decreased as the study progressed. This decrease occurred despite a maternal vitamin D intake of 700 IU/d (17.5 µg/d).

In contrast, a Finnish study showed that maternal supplementation with 1000 IU (25 µg) vitamin D/d resulted in a minimal increase in circulating 25(OH)D concentrations in breastfeeding infants. These same investigators repeated a similar study with 2000 IU (50 µg) vitamin D/d and found that the vitamin D status of the breastfeeding infants improved significantly.

Our group recently performed similar studies, supplementing lactating women with 2000 or 4000 IU vitamin D/d for 3 mo. We found that high-dose maternal vitamin D supplementation not only improves the nutritional vitamin D status of breastfeeding infants but also elevates the maternal concentrations into the mid-normal range. Thus, a dual benefit is achieved from high-dose maternal supplementation."

The paper ends by saying long-term use of such doses are unknown and research continues. Dose with informed consent by asking your care provider what dose might be best for you.

An article on Vitamin D and pre-eclampsia, Maternal Vitamin D Deficiency May Increase Risk for Preeclampsia, says,

"Vitamin D deficiency in pregnant women at less than 22 weeks' gestation is an independent risk factor for preeclampsia...."

Pre-Eclampia Linked with Low Vitamin D During Pregnancy continues, saying,

"'Our results showed that maternal vitamin D deficiency early in pregnancy is a strong, independent risk factor for preeclampsia,' said Lisa M. Bodnar, Ph.D., M.P.H., R.D., assistant professor of epidemiology at the University of Pittsburgh Graduate School of Public Health (GSPH) and lead author of the study. 'Women who developed preeclampsia had vitamin D concentrations that were significantly lower early in pregnancy compared to women whose pregnancies were normal. And even though vitamin D deficiency was common in both groups, the deficiency was more prevalent among those who went on to develop preeclampsia.'"

While calcium absorption in pregnancy increases, so does the need for extra calcium. Numerous studies talk about the enormous increase in calcium absorption in pregnant teens and this would make sense because not only are they still growing, but they are also growing the skeleton of another human being. It is well-known that Vitamin D is required for calcium absorption, so for the body to take in as much calcium as possible from foods and supplements, Vitamin D must also be included in the mix. If there isn't enough Vitamin D, there won't be enough calcium.

This post is already long, long, long enough, but I have barely begun scratching the surface when we're talking about Vitamin D, and now calcium. To knock the first domino into all the rest, we need to be taking adequate Omega 3's because their presence in our bodies aids all that Vitamin D and calcium absorption!

Of course, there are questions that aren't answered by what I have written. Instead, I hope I prod you all on to find answers to questions I don't have the knowledge or skill to write about.

- If we know so little about Vitamin D, calcium and Omega-3 supplements and they are incredibly crucial to our health and safety, what else is there in that chemical soup we don't know about?

- How do we ensure compliance and success without requiring blood tests every 6 months? Can someone make some home tests, please?

- Should UV-B ray meters be available by prescription and paid for by insurance the way glucometers are for diabetics?

- If we're going to supplement our foods with these nutrients, who gets to vote for what foods they go into? Who picks what form they take?

- Not that many of us reading this needs the government to take up the nutrition cause on our behalf, but when is the government going to get it together and upgrade/update the amount of Vitamin D we should all be taking in each day?

- Why doesn't the American Academy of Pediatrics speak about supplementing moms who breastfeed with Vitamin D instead of the blanket statement regarding supplementing all breastfed babies with the vitamin?

How has this information changed my life? I am now meticulous in taking my 10,000 IUs a day of Vitamin D, spend at least 10 minutes every mid-day in the sun while being as naked as I can be, take my 2000 mg. calcium (citrate since I don't have gastric juices, which is required for calcium carbonate) every day, varying the dose and timing throughout the day (since the body can only absorb 500 mg at a time), always on an empty stomach (carbonate needs to be taken WITH meals, however). I am also taking 2400 mg of fish oil (still unsure how much of that I should be taking in).

I've never been more compliant with supplements! I hope this post nudges you on towards increased health, too. I know I'm looking forward to feeling better and better every sunny day.

References (3)

References allow you to track sources for this article, as well as articles that were written in response to this article.

Reader Comments (8)

I looove being in the sun. Doesn't everyone? And I am so glad you have been able to learn so much to help yourself take your necessary supplements.

I must say though that it seems a little ridiculous to go into such detail with vitamin D supplementation when the source is the sun. If someone does live in the city and isn't often working outside, can't we just recommend more time in the sun? Does finding the exact correct does for supplementation even require our time or money? Perhaps for some populations (darker skin) in specific climates (northern latitude) it does, but not for the general population.

Additionally, weighing the risk factors is also am important part of this issue. People in developed countries do not get rickets (or osteomalacia, the adult version) at anywhere near the rate of developing countries. And in the end breastfeeding is STILL a better choice with or without vitamin supplementation. So just like weighing the risk of sunscreen and prevention of skin cancer for certain individuals versus getting vitamin D from the sun, each person would need to understand where they stand on the vitamin D deficiency risk "spectrum". Of course all the research you have presented would help anyone with that! I just don't think supplementation should be our first choice when a simple lifestyle change could do a huge amount of good as well.

July 16, 2008 | Unregistered CommenterKate

This is a great presentation that all health care providers should watch. It's a bit lengthy (30 mins or so), but well worth it.

One thing he says is that in northern climates (like me), it doesn't matter how much time you spend in the sun in winter because the rays are at such an angle that they can't properly help you.

Supplements need to be D3, that's important.

Watch the presentation before you decide that supplementation isn't needed, it's very convincing.


July 17, 2008 | Unregistered CommenterAnonymous

Thanks for writing this; I've been thinking about Vit. D Supplementation a lot lately, and it really helped me to read everything arranged like that... even if it was long. :)

I didn't supplement with Vit. D with my first nursing baby because I thought supplementation was only for people with darker skin, even in the north. With my new little guy I wasn't intending to, but an online kerfuffle made me check into it further. When I looked into the actual amount of sunlight you'd have to be getting, it was pretty clear that it was impossible to get 10-30 minutes of midday sun for a good part of the year. In the winter we bundle up to avoid freezing to death, and even in the summer we're so concerned (rightly so!) about sunburning tender baby skin that we keep covered up.

Honestly, after looking into the issue for the sake of the baby, I'm pretty sure none of my family gets even close to enough vitamin D, unless it's summer and on the weekend. It's time to institute some mandatory supplements -- and to raise them above the 200 iu we had been doing! Even if it doesn't reduce the risk of diabetes and osteoporosis, maybe it will help with SAD.

July 17, 2008 | Unregistered CommenterBelle

OMG! I can't believe I forgot to mention SAD! Now I have to go edit it. Nothing like making a tome even longer, eh? Thanks for pointing out the glaring omission.

As far as just getting out in the sun more, isn't it obvious that that isn't going to happen? 10-30 minutes of mid-day sun, every single day of the year, naked arms, hands, face and back? That isn't possible for most people in this country and certainly not possible to keep toddlers out in the sun for 50 minutes in northern climes during the dead of winter!

Most of us need to take supplements instead of relying on the sun. Sad, yes, but true. Our lifestyles aren't like lifestyles of old when we were farmers, gardeners, hanging clothes on the line every single day, walking everywhere. Same as there are more posterior babies because of our lifestyles (recliners, SUVs, etc.), there are consequences of not getting enough sun. Blessedly, there is a remedy and it isn't a drug! Miracle of miracles! It isn't a medication.

July 17, 2008 | Unregistered CommenterNavelgazing Midwife

Very good information; I've "archived" it! Thanks so much.

July 20, 2008 | Unregistered CommenterKneelingwoman

I have a child who appears to have psoriasis, and wonder if vitamin D would have held off the onset. He was born in may in the Seattle area and moved to the midwest for a snowy winter. I wonder also about deficiency and the conditions babies may be born with. How does it affect fertilization errors like Down's and the like for mom to have deficiencies in vitamins...or dad? Interesting to think of these things...


July 22, 2008 | Unregistered CommenterAnonymous

Fascinating subject! I've been looking for a research topic for my upcoming thesis. I may give this area a closer look.

July 29, 2008 | Unregistered CommenterKarelle

The only two friends' kids who have tooth decay are the ones who stay WHITE and were ghostly white during pregnancy and certainly weren't sunning their babies.

As far as labor function, look at rate of c-section in Sept compared to, say, March.

Maureen, in a hurry, much love

August 15, 2008 | Unregistered CommenterAnonymous

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