The most recent paper by Dr. Martine Luxwolda and colleagues of the University Medical Center Groningen in Holland is so remarkable that this is the second of three blogs covering it. If you remember, this same group discovered that free-living hunter-gatherers around the equator have vitamin D blood levels of about twice the modern American, about 45 ng/ml.
Now, they studied how vitamin D levels change with age, how warm water surface lake fish consumption affects vitamin D, including 25(OH)D₂ and 25(OH)D₃ levels, and finally, how levels change before, during, and after pregnancy in naturally living populations. In this part two of the three blog series, I will be covering vitamin D status during pregnancy in natural, equatorial living populations.
They found pregnant native women increase their 25(OH)D to almost 60 ng/ml, almost 15 points higher than they had before getting pregnant. And as reported in part one, they found one pregnant woman had a level of 105 ng/ml. This increase is especially evident in the final trimester. Then, this extra 25(OH)D disappears three days after delivery, but the mechanism of that disappearance is unknown.
Pregnancy suppresses the catabolic (breakdown) vitamin D enzyme, the 24-hydroxylase, raising vitamin D levels. This mechanism may shut off soon as the mother has delivered her child, effectively lowering vitamin D levels. This is the first time scientists have measured vitamin D levels of pregnant women in a sun exposed naturally living equatorial population.
Professor Bruce Hollis and Carol Wagner recently discovered that activated vitamin D levels [1,25(OH)₂D] triple or quadruple during pregnancy when women supplement with 4,000 IU/day. This kind of dosage is similar to what the native women get from sunshine in the Luxwolda study, if not a pinch less. Hollis and Wagner also found reduced complications at 4,000 IU compared to lower doses, which begs the question, what’s the frequency of complications in hunter-gatherer pregnancies?
Other questions that come of Luxwolda and Hollis papers:
- What are “normal” activated vitamin D levels during pregnancy? Bruce and Carol’s discovery that activated vitamin D levels triple or quadruple during pregnancy is based on 25(OH)D levels of about 45 ng/ml during, not before, pregnancy, meaning their women may not have stored much vitamin D in their fat and muscle.
- What do activated vitamin D levels during pregnancy do when enough vitamin D substrate is available in storage for mom’s levels to shoot up to 60 ng/ml in later pregnancy, like in the hunter-gatherers from the Luxwolda paper? We don’t know.
I do know that the Council is satisfied with its recommendation of 40-60 ng/ml for pregnant women, but I’d like to emphasize that 5,000 IU/day before pregnancy (for both the man and woman for at least a year), 5,000 IU/day in early pregnancy and 6,000 IU/day during later pregnancy is the minimal recommended dose to achieve those levels. Regular sunbathing when your shadow is shorter than you are will do the same.
Gynecologists, obstetricians and pregnant women should now be less hesitant in trusting Hollis’s and Wagner’s data and following our recommendations now that Luxwolda examined what natural levels are during pregnancy. Remember, the average natural level in pregnant hunter-gatherers was about 60 ng/ml, with the highest at 105 ng/ml.
The amounts we recommend will result in the natural levels that native peoples have before the woman gets pregnant, and, as Professor Robert Heaney has shown, such levels will normalize the metabolism of vitamin D. Such levels are common in those who live or work in the sun (regular sunbathers, lifeguards, roofers, etc.) in the late summer.
With such a dose, pregnant women should increase their 25(OH)D to around 60 ng/ml in the third trimester on their own. Levels lower than 40 ng/ml will cause “substrate starvation” or inadequate amounts of vitamin D and, without adequate storage, pregnant woman will be unable to follow Nature’s plan to quadruple (or more?) her activated vitamin D levels. Activated vitamin D is crucial to fetal development, especially brain development.
- Vitamin D status in indigenous populations: Part 1
- Vitamin D levels throughout pregnancy: Part 2
- Fish consumption and vitamin D status in native populations: Part 3