Repetitive Strain Injury (RSI) and Magnesium and Fluoride Intake
by G.E. Smith (New Zealand Medical Journal, 98:556-557, 1985)
Abstract
Repetitive strain injury (RSI), a "new" clinical syndrome, is
characterized chiefly by a severe pain in wrists, forearms, hands and
fingers. Although to date, the cause and pathogenesis of RSI is
obscure, it is clearly related to frequent physical stresses; it
seems to involve, mainly, musculoskeletal structures.
In 12 RSI subjects fluoride (F-) levels in bone were appreciably
higher than 12 appropriate controls. Estimate of dietary intake of
RSI subjects, revealed a Mg2+ deficit and an excessive F- intake.
Fluorotic bone has an increased Mg2+ content possibly due to some
deposition of MgF2. The amorphous phase in bone may act as a
"reservoir" of ions available to regulate plasma Ca, PO4 and Mg2+
levels. Fluoride accumulates in bone with age, especially in areas
of active ossification. A locally raised F- concentration in an
osteocyte lacunae (during resorption) could interfere with normal
functioning of the cell, or trigger the precipitation of crystalline
apatite, or lead to the formation of MgF2. Any one of these
reactions might interfere with the passage of Mg2+ ions from the bone
"reservoir" into circulating extracellular fluid. A localized Mg2+
deficiency could disturb pyrophosphate metabolism and lead to
deposition of Ca salts in sensitive areas.
Through adjustment of dietary intake of the previously mentioned 12
RSI subjects which included more Mg2+ and less F-, eight of the
subjects experienced market relief from previously painful RSI
symptoms after a six week test period.
In a letter to the editor Dr. Smith stated (New Zealand Medical
Journal, 28 August, 1985, page 710):
....
Chronic fluoride intoxication may play a role in the aetiology of at
least some cases of so-called repetitive strain injury. Data
obtained in a recent pilot study in Melbourne, where the very soft
water has been fluoridated for sever years, support the hypothesis.
In the study, specimens were obtained from alveolar bone after tooth
extraction. The mean fluoride concentration of bone in subjects with
RSI (2737 ppm F) was greater (p=0.0001) than the mean (1687 ppm F) in
those who did not complain of that condition.
While it has been known for many years that an excessive daily
intake of fluoride may lead to deleterious effects on musculoskeletal
structures, the question of the lower toxic fluoride content of bone
has yet to be answered. Roholm suggested that normal bone contains
900 ppm fluoride (range 600-2100 ppm F).
Early bone flurosis is not clinically obvious, and cases often
involve young adults whose only complaints are vague pains in the
small joints of the hands and feet, and lower back. Such cases may
be misdiagnosed as rheumatoid arthritis or ankylosing spondylitis.
As fluoride continues to accumulate in bone radiologically detectable
changes may be diagnostic and these include: calcification along
tendons, fascial and muscular attachments, particularly the
interosseous membranes of the forearms and legs. It seems reasonable
to assume that before x-ray detectable deposits build-up in these
tissues, microcrystals or hydroxyapatite must be present. Tendinitis
and bursitis are occasionally associated with periarticular deposits
of hydroxyapatite. The condition has been called, "calcific
periarthritis" and often mimicks acute arthritis.
Schumacher et all have suggested that apatite crystals, present in
joint effusions in a variety of situations, should be considered as
possibly responsible for several clinical syndromes. They have also
shown that apatite crystals can trigger an acute inflammatory
response. Therefore, it is conceivable that some cases of RSI might
result from deposition of apatite crystals in and around synovial
sheaths and tendons passing through the carpal tunnel.
The posibility that some individuals are now receiving too much
fluoride merits serious attention. The US National Research Council
has tenatively recommended as safe for adults an intake of 1.5-4.0 mg
fluoride per day. However, people are now exposed to fluoride in a
multiplicity of everyday sources, and Marier, of the Canadian
National Research Council, believes that fluoride intake in
fluoridated areas is now 5 mg or more fluoride per day.