Should Pregnant Women Take Calcium Supplements to Lower Lead Levels?

Michael Greger M.D. FACLM · January 1, 2018 · Volume 39

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What are the effects of sodium and calcium intake on blood lead levels in pregnant and breastfeeding women?

Discuss

Transcript

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Although our skeleton “has predominantly been considered a storage site for sequestering absorbed lead, bone is not simply an inert storage site. Once deposited in bone, lead can be remobilized from bone” back into the bloodstream if we lose bone—for example, osteoporosis. Even just normal menopause can do it—rising lead levels as our bones start to lose their integrity. But, it’s the “[m]obilization of long-term stores of lead from [the] maternal skeleton…during pregnancy and lactation” that’s the biggest concern. So, to maintain maternal lead levels “as low as possible” during this critical period, we need to minimize bone loss.

How do we do that? Well, “habitual excessive [salt] intake could be a factor in promoting bone loss.” So, is there a “[r]elationship between maternal sodium intake and blood lead [levels] during pregnancy”? We didn’t know, until this study. They did find that higher salt intake was associated with higher lead levels, but only for women who were getting less than 840mg of calcium a day. This suggests “that adequate [calcium] with low [sodium] intake may play a beneficial role in decreasing the blood [lead] concentration in pregnant women.”

“Higher calcium intake [has been] associated with lower blood lead concentrations [during] pregnancy.” But, you don’t know if it’s cause and effect—unless you put it to the test.

What if you gave women calcium supplements? We explored previously how milk may actually make things worse. But what about just straight calcium, especially for women with low calcium intake? These poor African women, getting only 350mg of calcium a day—just 35% of the 1,000-milligram RDA. Let’s step in and give them a whopping 1,500 milligrams of calcium a day. That will protect their bones—how did they ever get along without us? Without the calcium, just getting 350 milligrams of calcium a day in their diet, they lost some bone in their spine and hip. But, the group we gave, in our wisdom, 1,500 milligrams of calcium a day, lost even more bone! “Those women who had received the calcium…supplement[s] had a significantly lower bone mineral [density] at the hip,” and greater bone loss in the spine and wrists. Oops.

What happened? It looks like we messed up their body’s natural adaptation. Remember? They were only eating 350 milligrams of calcium a day. So, their body wasn’t stupid, and was maximizing absorption, minimizing loss, and then, we step in with calcium pills, and undermine the whole process—turn off those adaptations, leave their body thinking they were always going to get these massive doses. And then, when the study stopped, they went into major calcium deficit, and had to steal more from their bones. The researchers went back later, hoping they’d catch back up, and while the women lucky enough to have ended up in the placebo group bounced back, those given the extra calcium continued to suffer the effects.

What about in Western women, though—already taking in over 1,000 milligrams a day? Would giving them an extra 1,200 milligrams a day cut down on some of that bone flux? Yes, it did seem to cut down on bone resorption by about 16%, “and, thus, may constitute a practical intervention to prevent [the] transient skeletal loss associated with childbearing”—which could release any lead trapped there. But, you don’t know, until you put it to the test.

This is a different paper from the same study. The researchers measured what was happening to their lead levels, and that drop in bone borrowing led to a drop in lead release, and so, may help lower exposure to the fetus, as well as the infant, as the benefits continue through breastfeeding. Okay. But, these were women living in Mexico City, who may have been exposed to lead-glazed ceramics, with lead levels approaching 10. What about for women with lead levels closer to the current U.S. average—under 5? We didn’t know, until you put it to the test.

Well, half the breastfeeding women were randomized to take 500 milligrams of extra calcium a day. Their lead levels started out the same during pregnancy, but shot up during breastfeeding, as presumably some of the lead was released from their bones. But, that was in the regular, non-supplemented group. In the group that got the 500-a-day calcium supplement, there was no spike in lead in their bloodstream, providing “evidence that calcium supplementation during [breastfeeding] may be effective in limiting mobilization of lead from bone stores, thus reducing the risk of lead transfer to the nursing infant through [breast] milk.”

Now, breast is still best, regardless. Supplementation or not, “the risks are outweighed by the benefits of [breastfeeding].” But, calcium supplementation may help reduce any risk even further. Of course, better to not build up lead in your bones in the first place. As a famous occupational medicine paper put it a half century ago, yes, there’s all methods of dietary interventions, but there’s only one way, “and one way only,” to prevent lead poisoning: not get poisoned in the first place—anything else just “divert[s] attention” from treating the underlying cause.

For other toxic heavy metals, like mercury, for example, that would mean advising women “to avoid the consumption of [fish-that-eat-other-] fish during pregnancy and when breastfeeding to decrease” mercury levels in breast milk. In fact, maybe even before pregnancy, “women of child-bearing age,” period—so you don’t build up mercury in your body in the first place. For lead, that means not living next to a smelter plant, avoiding smoking.

Now, there’s one other way to detox your body of lead to protect some of your future children, but it’s not ideal. Remember that menopause study, where postmenopausal women had higher blood lead levels than premenopausal women? Well, even higher still were postmenopausal women who never had children. “The postmenopausal increase in lead levels was less in women with prior pregnancies,” presumably because they had already detoxed some of their lead into their children.

Please consider volunteering to help out on the site.

Sources

Acknowledgements

Motion graphics by Avocado Video

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Although our skeleton “has predominantly been considered a storage site for sequestering absorbed lead, bone is not simply an inert storage site. Once deposited in bone, lead can be remobilized from bone” back into the bloodstream if we lose bone—for example, osteoporosis. Even just normal menopause can do it—rising lead levels as our bones start to lose their integrity. But, it’s the “[m]obilization of long-term stores of lead from [the] maternal skeleton…during pregnancy and lactation” that’s the biggest concern. So, to maintain maternal lead levels “as low as possible” during this critical period, we need to minimize bone loss.

How do we do that? Well, “habitual excessive [salt] intake could be a factor in promoting bone loss.” So, is there a “[r]elationship between maternal sodium intake and blood lead [levels] during pregnancy”? We didn’t know, until this study. They did find that higher salt intake was associated with higher lead levels, but only for women who were getting less than 840mg of calcium a day. This suggests “that adequate [calcium] with low [sodium] intake may play a beneficial role in decreasing the blood [lead] concentration in pregnant women.”

“Higher calcium intake [has been] associated with lower blood lead concentrations [during] pregnancy.” But, you don’t know if it’s cause and effect—unless you put it to the test.

What if you gave women calcium supplements? We explored previously how milk may actually make things worse. But what about just straight calcium, especially for women with low calcium intake? These poor African women, getting only 350mg of calcium a day—just 35% of the 1,000-milligram RDA. Let’s step in and give them a whopping 1,500 milligrams of calcium a day. That will protect their bones—how did they ever get along without us? Without the calcium, just getting 350 milligrams of calcium a day in their diet, they lost some bone in their spine and hip. But, the group we gave, in our wisdom, 1,500 milligrams of calcium a day, lost even more bone! “Those women who had received the calcium…supplement[s] had a significantly lower bone mineral [density] at the hip,” and greater bone loss in the spine and wrists. Oops.

What happened? It looks like we messed up their body’s natural adaptation. Remember? They were only eating 350 milligrams of calcium a day. So, their body wasn’t stupid, and was maximizing absorption, minimizing loss, and then, we step in with calcium pills, and undermine the whole process—turn off those adaptations, leave their body thinking they were always going to get these massive doses. And then, when the study stopped, they went into major calcium deficit, and had to steal more from their bones. The researchers went back later, hoping they’d catch back up, and while the women lucky enough to have ended up in the placebo group bounced back, those given the extra calcium continued to suffer the effects.

What about in Western women, though—already taking in over 1,000 milligrams a day? Would giving them an extra 1,200 milligrams a day cut down on some of that bone flux? Yes, it did seem to cut down on bone resorption by about 16%, “and, thus, may constitute a practical intervention to prevent [the] transient skeletal loss associated with childbearing”—which could release any lead trapped there. But, you don’t know, until you put it to the test.

This is a different paper from the same study. The researchers measured what was happening to their lead levels, and that drop in bone borrowing led to a drop in lead release, and so, may help lower exposure to the fetus, as well as the infant, as the benefits continue through breastfeeding. Okay. But, these were women living in Mexico City, who may have been exposed to lead-glazed ceramics, with lead levels approaching 10. What about for women with lead levels closer to the current U.S. average—under 5? We didn’t know, until you put it to the test.

Well, half the breastfeeding women were randomized to take 500 milligrams of extra calcium a day. Their lead levels started out the same during pregnancy, but shot up during breastfeeding, as presumably some of the lead was released from their bones. But, that was in the regular, non-supplemented group. In the group that got the 500-a-day calcium supplement, there was no spike in lead in their bloodstream, providing “evidence that calcium supplementation during [breastfeeding] may be effective in limiting mobilization of lead from bone stores, thus reducing the risk of lead transfer to the nursing infant through [breast] milk.”

Now, breast is still best, regardless. Supplementation or not, “the risks are outweighed by the benefits of [breastfeeding].” But, calcium supplementation may help reduce any risk even further. Of course, better to not build up lead in your bones in the first place. As a famous occupational medicine paper put it a half century ago, yes, there’s all methods of dietary interventions, but there’s only one way, “and one way only,” to prevent lead poisoning: not get poisoned in the first place—anything else just “divert[s] attention” from treating the underlying cause.

For other toxic heavy metals, like mercury, for example, that would mean advising women “to avoid the consumption of [fish-that-eat-other-] fish during pregnancy and when breastfeeding to decrease” mercury levels in breast milk. In fact, maybe even before pregnancy, “women of child-bearing age,” period—so you don’t build up mercury in your body in the first place. For lead, that means not living next to a smelter plant, avoiding smoking.

Now, there’s one other way to detox your body of lead to protect some of your future children, but it’s not ideal. Remember that menopause study, where postmenopausal women had higher blood lead levels than premenopausal women? Well, even higher still were postmenopausal women who never had children. “The postmenopausal increase in lead levels was less in women with prior pregnancies,” presumably because they had already detoxed some of their lead into their children.

Please consider volunteering to help out on the site.

Motion graphics by Avocado Video

Doctor's Note

In case you missed the last video, The Rise in Blood Lead Levels at Pregnancy and Menopause offers some background on this issue.

The video I mention about milk making things worse is How to Lower Lead Levels with Diet: Breakfast, Whole Grains, Milk, Tofu?.

Note that whole-food sources of calcium may be preferable, as I document in my video Are Calcium Supplements Safe?.

For more on pregnancy detox, see:

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