Thoraiya DyerMagnetic Jewellery and Blankets – Happy Zap Or Load of Crap?
June 8th 2008 22:14
When I started looking into therapeutic uses of magnetic jewellery, I’ll admit I expected to find no real evidence that it worked. This expectation was based on various hematite necklace displays I’d come across at airports and small town Sunday markets - right next to the mood rings and viking runes “guaranteed” to make your high school crush fall desperately in love with you.
Papers like this one ( Really Long Link ) from the Journal of the American Medical Association in 2000, seemed to back up my assumptions, reporting that:
“Chronic low back pain is one of the most prevalent and costly medical conditions in the United States. Permanent magnets have become a popular treatment for various musculoskeletal conditions, including low back pain, despite little scientific support for therapeutic benefit.
…
For each patient, real and sham bipolar permanent magnets were applied, on alternate weeks, for 6 hours per day, 3 days per week for 1 week, with a 1-week washout period between the 2 treatment weeks.
…
Application of 1 variety of permanent magnet had no effect on our small group of subjects with chronic low back pain.”
Yup. Might as well stuff ferrets down the back of your shirt as magnets.
BUT then I found this study, by Harlow et al, in the BMJ 2004;329:1450-1454, which involved 194 men and women aged 45-80 years with osteoarthritis of the hip or knee. They found that:
“Pain from osteoarthritis of the hip and knee decreases when wearing magnetic bracelets.”
It works? Cool. But what kind of magnetic bracelets were they?
“Treatments consisted of identical looking bracelets containing three different components. The manufacturer's specifications were:
Group A—Standard neodymium magnets set in a steel backing cup, with the open side facing the ventral wrist, creating a fluctuating magnetic pattern across the bracelet (fig 1). The field strength at the wrist contact surface was 170-200 mTesla.
Group B—Weak magnets with no backing plate. The field was strong enough to seem magnetic on testing (21-30 mTesla), but previous research suggests this is insufficient to be therapeutic.15 This was intended to provide an undetectable placebo.
Group C—Non-magnetic steel washers.
The National Physical Laboratory tested five bracelets of each type before the study, confirming the manufacturer's specification.”
Only the group A magnets were successful. In the study’s conclusions, the researchers offer the following comments on previous magnetic therapy studies:
“Studies that have failed to show an effect on pain (10 /12) generally used weaker magnets (19 to 50 mTesla). Studies that have shown an effect used stronger magnets (47 to 180 mTesla), which were comparable with our standard strength magnets.(2/ 4/-8) Together these findings suggest that field strength is important.”
So what’s a Tesla?
All About Circuits ( Really Long Link ) offers this explanation of the unit:
“The Tesla is the SI unit of Field Flux… Field Flux is the quantity of total field effect, or "substance" of the field. Analogous to electric current.”
Right. Not sure that that helped, but let’s move along.
What about neodymium? What the heck is it? I couldn’t remember seeing it in my standard periodic table.
Turns out it’s lurking in the fold-out section, one of the lanthanides, and according to Dan’s Data ( Really Long Link :
“… neodymium iron boron (NIB) magnets… commonly just referred to as "neodymium" or "rare earth" magnets…(are) both more powerful and cheaper than the previous king of the permanent magnet world, samarium cobalt.”
Wikipedia says,
“Neodymium magnets are the strongest permanent magnets known - Nd2Fe14B. These magnets … appear in high-quality products such as microphones, professional loudspeakers, in-ear headphones, Dokodemo Magnets, guitar and bass guitar pick-ups and computer hard disks where low mass, small volume, or strong magnetic fields are required.”
Fun.
But there’s another important concept from Dan’s Data worth mentioning:
“Well, the smallest magnets in the above picture are little gold-plated cylinders only 6.4 by 2.3mm in size. The field extending from these magnets doesn't reach far with any strength, because the smaller a magnet of a given intrinsic strength is, the smaller will be the volume of space it can fill with a magnetic field of a given strength.
Magnetic field strength drops off as the inverse cube of the distance from the magnet, too; get twice as far away and the field strength drops by a factor of about eight. So two of these little tackers barely notice each other over a distance of more than an inch.”
This doesn’t seem to bode well for your standard magnetic hematite necklace, such as this one, from Happy Daze in Queensland ( Really Long Link ):
Happy Daze is kind enough to remind the buyer to beware:
“There are many costume styles with small ineffective (Or no) magnetism installed and many examples of Plain Hematite which has minimal effect except cosmetic… An example of low grade product when recently we actually caught a person rubbing plain hematite jewellery over a powerful speaker magnet.
The effect would only last a short period "but", long enough to mis-represent the quality product that is available, Con the buyer, and make our job of convincing clients with pain, of the Magnificent Benefits of Quality Magnets.”
Thanks for that.
However, your credibility falls short later on, where you claim:
“A good quality Magnetic Hematite Necklet should care for the upper part of the Torso (Head, Neck, Shoulders, Upper Spine)”
Take another look at the little beads that make up the necklace. Remember what we learned from Dan.
Now, just a hunch here, but if the MOST POWERFUL magnets available “barely notice each other” when they’re more than an inch away, how is a magnetic hematite necklace going to work on your head and shoulders, unless you look like this?
And how powerful is a hematite bead, anyway?
The website of the journal of Biomagnetic Research and Technology ( http://www.biomagres.com/ ) shows zero search results for “hematite” or “haematite.”
Why would a publication dedicated to magnetism not mention hematite at all?
Possibly, the confusion stems from this fact, garnered at long last from Mineral Information and Data ( Really Long Link ):
“Magnetic Hematite: An artificially created magnetic material (this contains NO natural Hematite) widely sold as 'magnetic hematite' or simply 'hematite'. Please note that the name 'hematite' is quite misleading, as this is NOT a natural stone.
Investigation of one item offered for sale as 'magnetic hematite' showed it was composed of a ceramic barium-strontium ferrite magnet: (Ba,Sr)Fe12O19 …Other items were identified as magnetoplumbite-type SrFe12O19.”
Great. As if I wasn’t finding it difficult enough. REAL hematite, or Fe2O3, is “not ferromagnetic,” according to magnetricity.com, “but it does still respond to a magnetic field and will be attracted to the poles of a permanent magnet.”
What a minefield!
One site which actually gives you the field strength of its magnetic hematite is Magnetic Therapy Magnets ( Really Long Link ), which, for example, advertises this anklet as containing ceramic magnets:
“Magnetic hematite anklets are both attractive and easy to wear. Containing powerful ceramic magnets to help relieve pain and swelling in the ankles and lower leg. These magnetic anklets promotes healing from sprains and fractures.”
They provide this statistic:
“Surface Gauss: 400 - 1000 Gauss (each magnet) Depending on bead size”
Converting the figures, (1 Tesla =10,000 Gauss), we get a minimum surface field (with the smaller beads) of 0.04 Tesla, or 40mTesla.
If we go back to the BMJ study, which suggested that only the stronger magnets (47 to 180 mTesla) had an effect on pain relief, then you probably want to buy an anklet, not with the delicate beads depicted, but with the biggest suckers available, to get you over the effective threshold.
If it’s magnetic blankies you’re after, you might want to slash the underlays open and stick the magnets to your skin. New Zealand company Body Magnetix ( Really Long Link ) puts 396 magnets in its queen-sized underlay, but although each magnet has a 960 Gauss (96 mTesla) surface rating, depending on how much padding is between you and the magnet, you might be missing out on the (unproven but possible) benefits.
For those after neodymium, Vitality Magnetic Jewellery ( Really Long Link ) offers a wide range of stainless steel bracelets, necklaces etc, generally listing these specifications: “Contains 14 x 3,000 Gauss (2,100m Tesla) Neodymium magnets.”
This vastly exceeds BMJ’s recommendation, but is it being misleading by simply totalling up the Teslas of all the magnets combined? Doesn’t evidence suggest ( Really Long Link ) that a string of magnets will “waste” some of their magnetic energy by attracting one another?
I’m guessing a necklace with 14 x 3000 Gauss magnets could reliably provide, at the point of contact with the skin, 300mTesla, not 2100mTesla.
Still, 300 is plenty. I’d be going for this kind of jewellery, if I was inclined to buy any at all. The lesson here is either to buy from sources which provide information about the strength of their product’s magnetic field, OR carry one of these around:
Time to phone my husband and find out if he’s already got one. I’d like to take it down to the markets on Sunday.
Papers like this one ( Really Long Link ) from the Journal of the American Medical Association in 2000, seemed to back up my assumptions, reporting that:
“Chronic low back pain is one of the most prevalent and costly medical conditions in the United States. Permanent magnets have become a popular treatment for various musculoskeletal conditions, including low back pain, despite little scientific support for therapeutic benefit.
…
For each patient, real and sham bipolar permanent magnets were applied, on alternate weeks, for 6 hours per day, 3 days per week for 1 week, with a 1-week washout period between the 2 treatment weeks.
…
Application of 1 variety of permanent magnet had no effect on our small group of subjects with chronic low back pain.”
Yup. Might as well stuff ferrets down the back of your shirt as magnets.
BUT then I found this study, by Harlow et al, in the BMJ 2004;329:1450-1454, which involved 194 men and women aged 45-80 years with osteoarthritis of the hip or knee. They found that:
“Pain from osteoarthritis of the hip and knee decreases when wearing magnetic bracelets.”
It works? Cool. But what kind of magnetic bracelets were they?
“Treatments consisted of identical looking bracelets containing three different components. The manufacturer's specifications were:
Group A—Standard neodymium magnets set in a steel backing cup, with the open side facing the ventral wrist, creating a fluctuating magnetic pattern across the bracelet (fig 1). The field strength at the wrist contact surface was 170-200 mTesla.
Figure 1 from Harlow's study
Group B—Weak magnets with no backing plate. The field was strong enough to seem magnetic on testing (21-30 mTesla), but previous research suggests this is insufficient to be therapeutic.15 This was intended to provide an undetectable placebo.
Group C—Non-magnetic steel washers.
The National Physical Laboratory tested five bracelets of each type before the study, confirming the manufacturer's specification.”
Only the group A magnets were successful. In the study’s conclusions, the researchers offer the following comments on previous magnetic therapy studies:
“Studies that have failed to show an effect on pain (10 /12) generally used weaker magnets (19 to 50 mTesla). Studies that have shown an effect used stronger magnets (47 to 180 mTesla), which were comparable with our standard strength magnets.(2/ 4/-8) Together these findings suggest that field strength is important.”
So what’s a Tesla?
All About Circuits ( Really Long Link ) offers this explanation of the unit:
“The Tesla is the SI unit of Field Flux… Field Flux is the quantity of total field effect, or "substance" of the field. Analogous to electric current.”
Right. Not sure that that helped, but let’s move along.
What about neodymium? What the heck is it? I couldn’t remember seeing it in my standard periodic table.
Turns out it’s lurking in the fold-out section, one of the lanthanides, and according to Dan’s Data ( Really Long Link :
“… neodymium iron boron (NIB) magnets… commonly just referred to as "neodymium" or "rare earth" magnets…(are) both more powerful and cheaper than the previous king of the permanent magnet world, samarium cobalt.”
Wikipedia says,
“Neodymium magnets are the strongest permanent magnets known - Nd2Fe14B. These magnets … appear in high-quality products such as microphones, professional loudspeakers, in-ear headphones, Dokodemo Magnets, guitar and bass guitar pick-ups and computer hard disks where low mass, small volume, or strong magnetic fields are required.”
Fun.
But there’s another important concept from Dan’s Data worth mentioning:
“Well, the smallest magnets in the above picture are little gold-plated cylinders only 6.4 by 2.3mm in size. The field extending from these magnets doesn't reach far with any strength, because the smaller a magnet of a given intrinsic strength is, the smaller will be the volume of space it can fill with a magnetic field of a given strength.
Magnetic field strength drops off as the inverse cube of the distance from the magnet, too; get twice as far away and the field strength drops by a factor of about eight. So two of these little tackers barely notice each other over a distance of more than an inch.”
This doesn’t seem to bode well for your standard magnetic hematite necklace, such as this one, from Happy Daze in Queensland ( Really Long Link ):
Happy Daze is kind enough to remind the buyer to beware:
“There are many costume styles with small ineffective (Or no) magnetism installed and many examples of Plain Hematite which has minimal effect except cosmetic… An example of low grade product when recently we actually caught a person rubbing plain hematite jewellery over a powerful speaker magnet.
The effect would only last a short period "but", long enough to mis-represent the quality product that is available, Con the buyer, and make our job of convincing clients with pain, of the Magnificent Benefits of Quality Magnets.”
Thanks for that.
However, your credibility falls short later on, where you claim:
“A good quality Magnetic Hematite Necklet should care for the upper part of the Torso (Head, Neck, Shoulders, Upper Spine)”
Take another look at the little beads that make up the necklace. Remember what we learned from Dan.
Now, just a hunch here, but if the MOST POWERFUL magnets available “barely notice each other” when they’re more than an inch away, how is a magnetic hematite necklace going to work on your head and shoulders, unless you look like this?
And how powerful is a hematite bead, anyway?
The website of the journal of Biomagnetic Research and Technology ( http://www.biomagres.com/ ) shows zero search results for “hematite” or “haematite.”
Why would a publication dedicated to magnetism not mention hematite at all?
Possibly, the confusion stems from this fact, garnered at long last from Mineral Information and Data ( Really Long Link ):
“Magnetic Hematite: An artificially created magnetic material (this contains NO natural Hematite) widely sold as 'magnetic hematite' or simply 'hematite'. Please note that the name 'hematite' is quite misleading, as this is NOT a natural stone.
Investigation of one item offered for sale as 'magnetic hematite' showed it was composed of a ceramic barium-strontium ferrite magnet: (Ba,Sr)Fe12O19 …Other items were identified as magnetoplumbite-type SrFe12O19.”
Great. As if I wasn’t finding it difficult enough. REAL hematite, or Fe2O3, is “not ferromagnetic,” according to magnetricity.com, “but it does still respond to a magnetic field and will be attracted to the poles of a permanent magnet.”
What a minefield!
One site which actually gives you the field strength of its magnetic hematite is Magnetic Therapy Magnets ( Really Long Link ), which, for example, advertises this anklet as containing ceramic magnets:
“Magnetic hematite anklets are both attractive and easy to wear. Containing powerful ceramic magnets to help relieve pain and swelling in the ankles and lower leg. These magnetic anklets promotes healing from sprains and fractures.”
They provide this statistic:
“Surface Gauss: 400 - 1000 Gauss (each magnet) Depending on bead size”
Converting the figures, (1 Tesla =10,000 Gauss), we get a minimum surface field (with the smaller beads) of 0.04 Tesla, or 40mTesla.
If we go back to the BMJ study, which suggested that only the stronger magnets (47 to 180 mTesla) had an effect on pain relief, then you probably want to buy an anklet, not with the delicate beads depicted, but with the biggest suckers available, to get you over the effective threshold.
If it’s magnetic blankies you’re after, you might want to slash the underlays open and stick the magnets to your skin. New Zealand company Body Magnetix ( Really Long Link ) puts 396 magnets in its queen-sized underlay, but although each magnet has a 960 Gauss (96 mTesla) surface rating, depending on how much padding is between you and the magnet, you might be missing out on the (unproven but possible) benefits.
For those after neodymium, Vitality Magnetic Jewellery ( Really Long Link ) offers a wide range of stainless steel bracelets, necklaces etc, generally listing these specifications: “Contains 14 x 3,000 Gauss (2,100m Tesla) Neodymium magnets.”
This vastly exceeds BMJ’s recommendation, but is it being misleading by simply totalling up the Teslas of all the magnets combined? Doesn’t evidence suggest ( Really Long Link ) that a string of magnets will “waste” some of their magnetic energy by attracting one another?
I’m guessing a necklace with 14 x 3000 Gauss magnets could reliably provide, at the point of contact with the skin, 300mTesla, not 2100mTesla.
Still, 300 is plenty. I’d be going for this kind of jewellery, if I was inclined to buy any at all. The lesson here is either to buy from sources which provide information about the strength of their product’s magnetic field, OR carry one of these around:
Time to phone my husband and find out if he’s already got one. I’d like to take it down to the markets on Sunday.
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