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Ask Dr. Mike: Magnesium Stearate & New Peanut Allergy Study

Here you'll find the answers to a wealth of health and wellness questions posed by Healthy Talk fans. Listen in because what you know helps ensure healthy choices you can live with. Today on Healthy Talk, you wanted to know:

What is the deal with magnesium stearate? It seems like most supplement companies put this in all their products.

Dr. Mike wants to be clear that magnesium stearate is not a preservative, it's actually used as a flow agent. This means it helps prevent clumping within the manufacturing process. This could explain why some of the magnesium citrate ends up in the supplement. However, it's a very small amount and you shouldn't be worried.

I understand that a breakthrough occurred with peanut allergies, called the Leap study. Can you explain that please?

Peanut allergies (along with other allergies) have been drastically on the rise. In fact, according to the Centers for Disease Control and Prevention (CDC), up to 15 million Americans have a food allergy.

The Leap study was conducted to look into a way to prevent peanut allergies in high-risk infants and young children. To determine if your child has a peanut allergy, you would need to have a skin test done. The leap study shows that after the skin test is done on high-risk infants, exposing them to small amounts of a peanut product can actually decrease the risk of developing a full-blown allergy later in their life.

If your child already has a peanut allergy, this approach would not work. Dr. Mike wants to make it clear that you cannot treat them with peanuts.

If you have a health question or concern, Dr. Mike encourages you to write him at This email address is being protected from spambots. You need JavaScript enabled to view it. or call in, toll-free, to the LIVE radio show (1.877.711.5211) so he can provide you with support and helpful advice.

RadioMD Presents:Healthy Talk | Original Air Date: February 24, 2015
Host: Michael Smith, MD

You’re listening to RadioMD. It’s time to Ask Dr. Mike on Healthy Talk. Call or email to ask your questions now. Email: This email address is being protected from spambots. You need JavaScript enabled to view it. or call: 877-711-5211. The lines are open.

So, my first question comes from Bart Taylor. He says, “Hi, Dr. Mike. What is the deal with magnesium stearate? It seems that most supplement companies put this in all their products.” So, magnesium stearate is—some people think it’s a preservative. That’s not what it is. It’s a flow agent. What that means is, in the manufacturing process in order to keep the active powders that are eventually going to fill up the capsule, in order to prevent them from clumping and keeping them flowing through the machinery, essentially, magnesium stearate is used. It prevents that clumping. It allows the material to go through the manufacturing process, eventually ending up in that capsule so that you can take it as a supplement.

Some of the magnesium stearate does end up in that capsule as well. However, it’s pretty miniscule. It’s a pretty small amount. It’s pretty insignificant overall. Now, I know that some health experts with some pretty famous websites have come out really strongly against magnesium stearate and I’ve got to be honest with you, Bart. I think it’s a little overblown. I don’t think you want high quantities of magnesium stearate in your system but you’re talking about very, very small amounts—almost unmeasurable—that actually end up in the capsule. Without it, we wouldn’t be able to make these capsules. Let’s also look at how it’s made—magnesium stearate. It’s magnesium—that’s not bad. And it’s stearic acid, which is a saturated fat. Again, if you overdo saturated fats, that’s not good but, we’re talking about very little amounts actually coming into the capsule. So, it’s magnesium and a saturated fat—stearic acid. So again, I think some of these claims have been overblown. I looked it up. It looks like most of the negative press for magnesium stearate started in the 1990’s and there was a study that’s often quoted by doctors against its use, but when you really look at this study, I don’t know why they’re quoting this study. In this particular study that started all of this stuff with magnesium stearate, researchers took T cells, T lymphocytes, immune cells, from mice. And, loaded them up in a Petri dish and then injected the Petri dish with stearic acid. No magnesium, just high dose stearic acid and that did destabilize the membranes of these T cells and they weren’t able to function. It caused, in a sense, in the Petri dish, at the cell level, an immunosuppression. But, you see, the problem with this, number one, is mice T cells and human T cells act very differently than mice T cells. Human T cells, Bart, are able to desaturate fatty acids. Our human T cells wouldn’t act the same way as mice T cells in a Petri dish with stearic acid. So, right there, there’s a problem. Number two, it was like a high, high dose of stearic acid and that’s where, I think, a lot of the negative press started with magnesium stearate was this mouse T cell study in a Petri dish that wasn’t even about magnesium stearate. So, that was one. I also know that in maybe the mid-2000’s, maybe 2005, 2006 or 2007, something like that, there was some talk that magnesium stearate would decrease the absorption. So, it wasn’t that it was unsafe. It was disrupting how well the active constituents in that capsule could absorb into your system. But since the mid-2000’s, there’s been several studies looking at that and no one’s been able to reproduce those original absorption studies showing that it actually inhibited absorption. So, we haven’t been able to reproduce that. Some of the more recent things about magnesium stearate? I saw one website talking about it forms a biofilm in your gut that is going to damage the lining of your gastrointestinal tract, but no evidence of that whatsoever was offered. It was just all theory about how salts form and how biofilms form. It was just very esoteric and more like an opinion piece than any science. So, there’s no evidence for biofilm formation. And then, there was another website recently that talked about how it’s an allergy and they were reporting on a case report of a woman who developed hives from magnesium stearate. Of course, she was taking a capsule that had all kinds of other stuff in it, so how are they blaming magnesium stearate for that? Keeping in mind that magnesium stearate is almost immeasurable in these capsules and we don’t form allergies against magnesium or fat. We form allergies against allergens which are protein particles. So, that makes no sense to me whatsoever.

So, Bart, just to sum up here, magnesium stearate is needed to produce the capsule. It’s a flow agent, they call it. That’s what they call it in the manufacturing world. It’s a flow agent. I just really believe a lot of the negative press has just been overblown. It’s magnesium and saturated fat. And what ends up in a capsule is pretty much—you can’t even measure it. It’s insignificant. So, my personal opinion is that it’s not a big deal.

Now, we’ll see how many emails I get for that.

Okay. Let’s go to the next question. I think I’ve got time for this. So, “I understand that a breakthrough occurred with peanut allergies. It’s called the LEAP study. Can you explain it, please?

This is awesome. I’m so glad this question came in because I think the media is getting this LEAP study a little wrong. As a matter of fact, I saw TIME Magazine, at least their online version--TIME Online--they just published today, a report on the LEAP study and the title of this online article was, “Surprising Way to Treat Peanut Allergy”. Well, the LEAP study is not about treating peanut allergy. It’s about preventing it. It’s about identifying infants that are at high risk for peanut allergy. You figure that out by putting them through a peanut allergy skin test. If they respond to that skin test, they’re at a high risk. What the LEAP study showed was that if you, then, take these high risk infants and expose them to a little bit of peanut product, that that actually can decrease developing a full-blown allergy later in life. If your child already has developed a full-blown peanut allergy, you don’t want to treat them with peanuts. So, this is not a treatment. This is a prevention that is administered to infants. Okay? So, I think we’ve got to be careful. I’m hoping that I don’t see more and more headlines talking about “We found a new way to treat peanut allergies,” because that’s not what this is about. There are other new things out there for peanut allergies. There’s a patch that seems to desensitize older kids who have a true peanut allergy and there’s some promise in these peanut patches. I’m not sure if that’s what they’re called but that’s what I’ll call it—a peanut patch. But, the LEAP study is really about prevention and decreasing the development of the peanut allergy. So, I’m going to review the full report here pretty soon. Maybe I’ll do a whole segment on the LEAP study and maybe turn that into more of an allergy type segment for RadioMD, but I just wanted to make this clear. The LEAP study was a study done on infants at high risk for peanut allergy and what they found was exposing those infants to peanut products decreased the risk of developing, later in life, a full-blown peanut allergy. So, this is not a treatment. If your child has a full-blown peanut allergy, don’t give them peanut products. That would not be safe and that would not be a good idea.

This is Healthy Talk on RadioMD. I’m Dr. Mike. Stay well.