Most Supplements Contain Magnesium Stearate — Is It Safe?
One
of the most widely used additives in drugs and supplements today is
magnesium stearate. You’ll actually be hard-pressed to find any
supplement sold on the market today that doesn’t include it, though you
many not see it named directly. Commonly referred to by other names,
such as “vegetable stearate” or derivatives like “steric acid,” it’s
virtually everywhere.
In
addition to being ubiquitous, magnesium stearate is also one of the most
controversial ingredients in the supplement world. In some ways, it’s
similar to the vitamin B17 controversy,
and there’s debate on whether it’s a poison or a cancer cure. For
magnesium stearate, I find this shocking because the detractors don’t
have much of a leg to stand on in regard to the peer-reviewed research.
Nonetheless, it’s been the focus of a heated debate for decades.
Unfortunately
for the general public, natural health experts, supplement companies’
researchers and health care practitioners regularly site conflicting
evidence to support their personal opinions — and it’s extremely
challenging to get to the facts! If you’ve read some of the reports out
there, you know what I mean. Personally, I try to take a practical
approach to these types of debates, and I’m always leery of siding with
extreme perspectives.
The
bottom line is this: Like most fillers and bulk additives, magnesium
stearate isn’t healthy in high doses, but it’s definitely not as harmful
to consume as some make it out to be because it’s typically only
available in minuscule doses.
What Is Magnesium Stearate?
Magnesium stearate is a magnesium salt of stearic acid. Essentially, it’s a compound containing two stearic acids and magnesium. Stearic acid is a saturated fatty acid found in many foods, including animal and vegetable fats and oils. Cocoa and flaxseeds are examples of foods that contain substantial amounts of stearic acid. (1, 2)
After
magnesium stearate is broken back down into its component parts in the
body, its fat is essentially the same as that of stearic acid. Some
sources even claim that the magnesium part of it can be used to supply the body with this essential mineral. (3) Considering the widespread prevalence of magnesium deficiency, this suggests that magnesium stearate can actually have a beneficial effect on the body.
The Purpose of Magnesium Stearate
Magnesium
stearate is the most common ingredient used in forming tablets because
it’s a fabulous lubricant. Known as a “flow agent,” it helps speed up
the manufacturing process because it prevents ingredients from sticking to the mechanical equipment. Just a miniscule amount is required to coat a powder blend of virtually any drug or supplement mixture.
Not
only is it fantastic for manufacturing purposes because it allows for
smooth transport on the machines that produce them, but it makes the
pill easier to swallow and move down the gastrointestinal tract. Magnesium stearate is also a common excipient,
which means it helps enhance the therapeutic effect of the active
ingredient of various medications to promote drug absorption and
solubility. Known as safe vehicles for drugs, excipients also help give
pills a uniform consistency.
Some claim that it’s
possible to produce a drug or supplement without excipients like
magnesium stearate, which begs the question why they’re used when more
natural alternatives are available. But that may not be the case. In the
words of the largely popular NOW Foods company:
NOW is reformulating some products with alternatives to mag stearate, using such natural excipients as ascorbyl palmitate, but we’re doing it where it makes sense and not because we misunderstand the science. These alternatives don’t always work, though, having different physical properties. (4)
At this point, it’s still unclear whether magnesium stearate alternatives are probable or even needed.
Magnesium Stearate’s Potential Side Effects
NOW is quite confident that magnesium is non-toxic. Its website states that:
Just like other chelated minerals (magnesium ascorbate, magnesium citrate, et al), [it] has no inherent negatives based on its being in a stable neutral compound comprised of a mineral and a food acid (vegetable sourced stearic acid neutralized with magnesium salts). (5)
On
the other hand, in its report on magnesium stearate, the National
Institute of Health (NIH) poses the threat of magnesium overdose in
impairing neuromuscular transmission, and that it can cause weakness and
diminished reflexes. Although extremely rare, the NIH reports that:
Thousands of exposures occur every year, but severe manifestations are very rare. Severe toxicity is most common after intravenous infusion over multiple hours (usually for pre-eclampsia), and can occur after chronic excessive doses, especially in the setting of renal insufficiency. Severe toxicity has been reported after acute ingestion but is very rare. (6)
Nonetheless,
this report hasn’t put everyone’s mind to rest. Just a quick glance at
Google, and you’ll find magnesium stearate connected to a number of side
effects, such as:
Poor Intestinal Absorption
Because
it’s hydrophobic (“water loving”), there are reports suggesting that
magnesium stearate can slow down the rate at which drugs and supplements
are dissolved in the gastrointestinal tract. (7)
Directly affecting the ability of the body to absorb chemicals and
nutrients, the protective nature of magnesium stearate can theoretically
make a drug or supplement veritably useless if the body can’t break it
down properly.
On the flip
side, a study conducted at the University of Maryland claims that
magnesium stearate didn’t affect the amount of chemicals that were
released from propranolol hydrochloride (a drug used to control rapid
heart rate and bronchospasm), so the jury is still out on this one. (8)
Suppressed T Cells
A
key component of your body’s immune system to attack pathogens, T cells
are affected not by magnesium stearate directly, but by steric acid
(the main component of the common bulking agent). The landmark study
first describing this was published in the journal Immunology in 1990, which uncovered how T-dependent immune responses were inhibited in the presence of steric acid. (9)
Formaldehyde Risk
In a Japanese study evaluating common excipients, vegetable magnesium stearate was actually discovered to be a formaldehyde-causing agent! (10)
This may not be as scary as it sounds, though, as formaldehyde is
naturally found in many fresh fruits, vegetables and animal products. (11)
To help put your mind to rest, magnesium stearate produced the least amount of formaldehyde out of the entire selection of excipients tested at 0.3 nanograms per gram of magnesium stearate. To put this into proper perspective, eating a dried shitake mushroom produces upward of 406 milligrams of formaldehyde per kiligram consumed! (12)
Manufacturing Contamination
In
2011, the World Health Organization published a report outlining how
several batches of magnesium stearate became contaminated with
potentially harmful chemicals, including bisphenol A, calcium hydroxide,
dibenzoylmethane, Irganox 1010 and zeolite (sodium aluminium silicate).
Because it was an isolated incident, we can’t jump to premature
conclusions that people who take supplements and prescription drugs with
magnesium stearate should be concerned with toxic contamination.
Before
you boycott all of your supplements and natural health foods that
include it as a bulking agent or filler, it’s important to think in
terms of “dose dependency.” In other words, next to intravenous overdose
for severe medical conditions, magnesium stearate has only been shown
to be harmful in laboratory studies where rats were force-fed such as
exorbitant amount that no human on the planet could ever consume that
much.
Case in point, in 1980 the journal Toxicology
described the results of a study that took 40 rats and fed them a diet
of either 0 percent, 5 percent, 10 percent or 20 percent magnesium
stearate in a semisynthetic diet for three months. Here’s what it found:
(13)
- 20% group: Decreased weight gain, reduced liver weight, increased amount of iron, kidney stones and nephrocalcinosis (a condition where too much calcium is deposited in the kidneys, which has been linked to premature babies).
- 10% group: Reduced liver weight.
- 0% – 5% group: No side effects observed, which corresponds to less than 2500 milligrams per kilogram of body weight per day.
As explained by Gene Bruno, MS, MHS:
It should be noted that the amounts of stearic acid and magnesium stearate typically used in a tablet is relatively minute. Stearic acid typically ranges between 0.5 [percent]–10 percent of the tablet weight, while magnesium stearate typically represents 0.25 [percent]–1.5 percent of the tablet weight. Therefore, in a 500 milligram tablet, the amount of stearic acid would probably be about 25 milligrams, and magnesium stearate about 5 milligrams. (14)
Too
much of anything can be harmful, and people can die from drinking too
much water, right? This is important to keep in mind because for someone
to be harmed by magnesium stearate, that person would need to consume
literally thousands of capsules/tablets in one day!
The Bottom Line
Truth
is, magnesium stearate and all of its derivatives are cost-effective
additives for pharmaceutical and supplement manufactures. Yet, at the
same time, they pose little-to-no threat to people who consume them as a
part of their natural health supplement regimens. All of the reports
out there claiming that the bulking agent will cause harm are simply not
founded on science.
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