A taste for salt in the history of medicine

Eberhard J. Wormer

Leonrodstr. 32, 80636 München,Germany

"There must be something sacred in salt. It is in our tears and in theocean." (Khalil Gibran)

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Is human life without salt imaginable? Probably not. Salt symbolizes life itself.Basic physiological functions depend on a balance between salts and liquids inthe body. When the balance is upset, disease may occur.

Salt has been an essential, virtually omnipresent, part of medicine forthousands of years. It has been used as a remedy, a support treatment, and apreventive measure. It has been taken internally or applied topically and beenadministered in an exceedingly wide variety of forms.

We shall take a journey through the history of the use of salt in medicineand discover that empirical knowledge of the benefits - and sometimes drawbacksof salt - has been a hallmark of many civilizations.
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When Lot's wife looked back to catch a last glimpse at the burning city ofSodom, she turned into a pillar of salt. Roman priests scattered salt where thecity of Carthage once stood to prevent any return of life. These allegoriescontradict what we know about salt today. Dissolved common salt (sodiumchloride) isipresent in all the human body and plays crucial physiologicalroles in life-sustaining processes (a) . Life cannot exist without salt. But when did salt becomeassociated with healing powers? And what are its healing powers? (1) (2) (3) (4) (5)

Our journey through the history of medicine will illustrate how the propertiesof salt have been viewed with time.

Salt in Egyptian medicine

Salt is mentioned as anessential ingredient in medical science in some of the oldest medical scripts.The ancient Egyptian papyrus Smith, which is thought to refer to the famousmaster-builder and doctor Imhotep of the third pre-Christian millennium,recommends salt for the treatment of an infected chest wound. The belief wasthat salt would dry out and disinfect the wound (b) . The papyrus Ebers (1600 B.C.) describes many salt recipesespecially for making laxatives and anti-infectives. They were dispensed ineither liquid, suppository or ointment form. For instance, there was asuppository containing honey, vegetable seeds and ocean salt that was used as alaxative and one with incense, vegetable seeds, fat, oil and ocean salt againstanal infections. Salt-based remedies were also prescribed for callous skin,epidemic diseases, to check bleeding, as an eye ointment, and to acceleratechildbirth (a vaginal suppository).

Salt in Greek medicine

Both sea salt and rock saltwere well known to the ancient Greeks who noted that eating salty food affectedbasic body functions such as digestion and excretion (urine and stools). Thisled to salt being used medically. The healing methods of Hippocrates (460 BC) especially made frequent use of salt. Salt-based remedies were thoughtto have expectorant powers. A mixture of water, salt, and vinegar was employedas an emetic. Drinking a mixture of two-thirds cow's milk and one-thirdsalt-water, in the mornings, on an empty stomach was recommended as a cure fordiseases of the spleen. A mixture of salt and honey was applied topically toclean bad ulcers and salt-water was used externally against skin diseases andfreckles. Hippocrates also mentions inhalation of steam from salt-water. Weknow today that the antiinflammatory effects of inhaled salt provide relieffrom respiratory symptoms (c) . Thus, 2000 years ago, Greek medicine had already discoveredtopical use of salt for skin lesions, drinking salty or mineralized waters fordigestive troubles and inhaling salt for respiratory diseases!

Roman salt-containing recipes

The Roman military doctor Dioskurides (100 A. D) is regarded as one of the most important medical authors ofAntiquity. His work Materia Medica summarises the botanical and pharmacologicalknow-how of his time. Dioskurides considered "honey-rain-ocean water"to be an excellent emetic. Salty vinegar was helpful against "binging androtting callosities" and bites (dogs and poisonous animals), to checkbleeding after surgery, as a gargle to kill leeches and to get rid of"scab and crust". Salt added to wine and water was a laxative.

Both sea and rock salt were used in remedies but rock salt was considered to bethe strongest. The salt was generally mixed with other ingredients (e.g.vinegar, honey, fat, flour, pitch, resin) and could be dispensed in severalforms (drink, suppository, clyster (enema), ointment, oil). The mainrecommended indications were skin diseases, dropsy, infections, callosities,ear-ache, mycosis, digestive upsets, sciatica.

The inheritance of classical Antiquity

The Greek doctor Galen from Pergamon (129–200 A.D.), physician-in-ordinary to the Roman emperor MarcusAurelius, summarised the medical concepts of antiquity and left his mark onwestern medicine for over 1000 years. His medical system also made use of salt(sea salt, rock salt, salt foam) in recipes against many diseases: infectiouswounds, skin diseases, callosities, digestive troubles. His list ofsalt-containing remedies also included emetics and laxatives.

Salt in the Arab world

Eight hundred years later, themedical precepts of the well-known Arab doctor and scientist Avicenna (Ibn Sina, 980–1037 A.D.) laid the foundations of modern scientific medicine.His recipes also used salt. He emphasised the presence of iodine and iron incoastal sea salt. The Jewish doctor Maimonides (1135–1204 A.D.),physician-in-ordinary to the caliph in Persia, wrote in his Dianetic forsoul and body that only bread with enough salt was healthy food.

Salt in medicines of the Middle Ages

The School of Salerno (11th -13th Century A.D.) founded western European academic medicine in theMiddle Ages. It is seen as the first European university to bring togethermedical knowledge of Greek and Arab origin and transcribe it in latin. Itswritings reveal an awareness of the use of a mixture of salt, oil and vinegaras an emetic and of suppositories of salt and honey as an effective remedyagainst constipation (see Egyptian medicine above). Powdered and roasted saltwas said to have a pain-killing effect and rock salt was considered to be agood remedy against fever.

The School published a book on The Art of Staying Healthy which was acollection of sayings and poems providing Crusaders with life regimens theycould understand. It was in fact one of the first popular medical manuals forpeople versed in latin and for academically trained physicians. The bookexplicitly recommended salted bread and food. Salt not only made food tasty butdrove off toxins. However, it also warned against too much salt: "Toosalty food diminishes semen and eyesight – salt burns, makes one fretful,shabby, scabby and wrinkly."

Salt in Renaissance medicine

The doctor and alchemist Paracelsus (1493–1541 A.D.) introduced an entirely new medical concept. He believed thatexternal factors create disease and conceived a chemically oriented medicalsystem which contrasted with the prevalent herbal medicine. Only salted foodcould be digested properly: "The human being must have salt, he cannotbe without salt. Where there is no salt, nothing will remain, but everythingwill tend to rot." He recommended salt water for the treatment ofwounds and for use against intestinal worms. A hip-bath in salt water was asuperb remedy for skin diseases and itching: "This brine - he said- is better than all the health spas arising out of nature." Hedescribed the diuretic effect of salt consumption and prescribed saltpreparations of different strengths that were used for instance againstconstipation.

Salt in 16th-19th century pharmacies

The pharmacies of the 16thcentury continued to relate the various uses of salt to its external aspect(rock salt, sea salt, refined salt and roasted salt). Respect for salt was asdeep as prices were high. Until the 18th century, the preferred and most commonpharmacy salt was rock salt which, in Germany, came chiefly from the CarpathianMountains, Transylvania, the Tyrol, and Poland. Rock and sea salt were stilllisted separately in the 1833 chemical-pharmaceutical handbook but, as from 1850,the origin of the salt was no longer specified.

The pharmacists of the 19th century recommended internal use of salt againstdigestive upsets, goitre, glandular diseases, intestinal worms, dysentery,dropsy, epilepsy, and syphilis. Externally applied salt (e.g. cold or warmhip-baths) was said to be locally stimulating but acerbic to skin and mucousmembranes at high doses. External application was advised in cases of rash andswelling and, in ophthalmology, to drive off stains and stain-obscurations ofthe cornea. A clyster (enema) of salt was even supposed to work forpatients who were "seemingly dead and apoplectical".

Salt in encyclopaedias and popular medicine in the 18th and 19th centuries

The encyclopaedias of the 18thcentury published extensive treatises on salt, in particular rock and sea salt,and referred to current knowledge on the healing powers of salt. A particularlyinfamous book was the Dirty Pharmacy by Paulini (1734) which held acollection of the nastiest imaginable mixtures for diseases of all kinds. Saltwas a frequent ingredient. For instance, red watering eyes could be treated bycovering them with a mush of fresh manure from a black cow, beer-vinegar, andhalf a knife's tip of salt.

Medical practitioners of the 19th century paid particular attention to theeffects of natural salt. In 1860, in eastern Bavaria, a sodium chloridesolution was used as a compress against inflammation. Further west,inflammations of the belly button of children were washed with salt water.Warts were removed by spreading the juice of a snail that had been sprinkledwith salt. Hot foot-baths containing salt and ashes were used to alleviateheadaches. Burns were treated with brandy, vinegar or salt water.

Salt in 20th century medicine

As indicated above, salt was animportant ingredient of remedies in Europe, on a par with natural products suchas herbs, until the late Middle Ages. From then onwards, it became an item inthe medicine chest of popular rather than academic medicine. It was not untilspa therapy gained popularity in the 19th century that its healing powersgradually began to be investigated scientifically and not until the 1950s thatits effects were studied in any detail.

Today, salt is a natural healing principle used in the form of inhalations,salt-water baths and in drinking-therapy. An important discovery of 20thcentury medicine is that salt water - in the form of an isotonic sodiumchloride (saline) solution - has the same fluid quality as blood plasma.This has led to the use of salt solutions as intravenous infusions. However,salt solutions are also used subcutaneously, intramuscularly, as an enema orexternally.

Infusing saline

In 1832, the English doctors R. Lewins and T. Latta used a sodium chlorideinfusion successfully against cholera for the first time. Nowadays, isotonicsodium chloride solution (saline) has many uses:
- as a "replacement fluid" in emergencies. Saline cantemporarily replace large amounts of lost blood and thus often saves the livesof accident victims. It can palliate prolonged loss of gastric juices.
- as a "tool and washing liquid". Chilled saline is used todetermine cardiac output per minute, for medically founded forced drainage, towash red blood cells for blood transfusions, and, at body temperature, toirrigate organs (e.g. gastro-intestinal tract, bladder).
- as a "carrier" solution for drugs.

From applying salt to bathing in salt

Our journey through history has revealed that the antiseptic action of salt onthe skin and mucous membranes has been known for a very long time. Scientificstudies have now confirmed the effectiveness of salt therapy in severalindications. The antiseptic and bactericidal qualities of dental salt (seasalt) help remove plaque which is a cause of gingivitis and caries. Salt isbeing increasingly used as support treatment for skin diseases. Chronicallyinflamed skin is treated with medical bath salt from the Dead Sea (d) or table salt. The salt peels off dandruff, reduces inflammation,itching and pain, and helps regenerate the skin. Salt-baths are frequently usedto treat psoriasis, atopic dermatitis, chronic eczema as well as arthritis.Sometimes (as in psoriasis), this therapy is followed by ultraviolet lightradiotherapy under strict medical control so that the combination of salt waterand UV light does not expose patients to an increased risk of skin cancer.

The ancient Greeks had already recommended seaside health resorts to cure skindiseases and Paracelsus mentioned the effectiveness of "salt brine".Sea-water baths later led to salt-water baths in regions closely linked withthe extraction of salt (salt mines, springs and works) but it was not until1800 that doctors from the German town of Bad Nauheim introduced a methodicalsalt-bath therapy (6) . They tried to obtain scientific evidence for claims regarding thehealing effects of the waters. Current medical indications for salt-baththerapy rest, as a matter of principle, on the empirical traditions ofcenturies. They include support treatment for skin diseases due to theanti-inflammatory action of salt. Patients suffering from rheumatic conditionsoften experience relief from joint pain when moving about in a salt bath.

Finally, common or Dead Sea salt can be used as an additive especially in bodycare products (ointments, shampoos, gels, washes and body lotions).

Inhaling salt

Steam from salt water is inhaled in chronic diseases of the upper and lower respiratory track (pharynx, paranasal sinuses, and bronchial tree) or to easethe discomfort of a common cold. Let's not forget that Hippocrates had already recommended this treatment! The age-old method is to heat a salt solution to obtain steam but modern ultrasound atomising can now transport minute salt particles directly to tiny bronchia. The main effects of salt on the bronchial system are to stimulate secretion, loosen and help eliminate viscous secretions, inhibit inflammation, reduce irritation causing cough, clean the mucous membrane of the kinocilium, and contract (bronchoconstriction) or extend (dilatation) the respiratory ducts.

Drinking salt water

Salt water when drunk has an expectorant effect in the stomach and increases gastric juice secretion. It raises the level of stomach acid, hastens its production, impedes or stimulates stomach motricity and emptying-rate (depending upon the salt concentration), increases the secretion of the pancreas, and at higher salt concentrations stimulates the formation of bile acids.

Salt as a vector

Rock salt is of higher purity than sea-salt which can be contaminated with many minerals and other substances. Some of these contaminants, such as iodine, can be beneficial to health. Iodine deficiency is a major health risk. It gives rise to a thyroid gland disease characterised by hormonal disturbances causing cretinism and by a goitre which can be so large that it may blocs air flow through the throat or reach externally right down to the collar bone (7) . Goitre used to be endemic in regions far from the sea such as the Alps but was rarely encountered in countries of southern Europe bordering the Mediterranean. Nowadays, Germany is the only industrial nation where goitre due to a lack of iodine is still common. This is because,despite the known health risk, part of the German food industry still uses the cheaper iodine-free salt for economic reasons. No legal measure makes the use of iodised salt compulsory in Germany. The health authorities must rely on public information campaigns promoting the benefits of salt with iodine.

Homeopathic salt

N. H. Schüßler (1821–1898), a German doctor, developed a special "biochemical"therapy based on 12 mineral salts which he considered crucial for cellfunction. This therapy is still used today. For Schüßler, health resulted froma balance among these salts, disease from a disequilibrium. Common salt (sodiumchloride) was one of his 12 salts. He administered the salts in homeopathicdoses in an extremely wide range of indications (anaemia, loss of appetite,loss of weight, common cold, stomach and intestinal disorders, waterydiarrhoea, constipation, haemorrhoids, rashes, rheumatic troubles, headaches,fatigue) and externally against lip blisters, acne, comedo, skin fungus andsores.

A flip side to the coin?

In the Middle Ages, the Schoolof Salerno warned against the excessive use of salt (see above). The subject ofexcessive salt use has been a matter of great controversy over the last threedecades. Scientific medicine has found that a high salt intake from food,especially by people with an inherited sensitivity to salt, might increase therisk of cardiovascular disease (CVD). Extensive studies have indicatedthat too much salt in food may lead to arterial hypertension. There are thosewho forbid the addition of any salt at all to food and those who suggest thatconsumption should be limited to around 5 or 6 grams a day. There areepidemiological studies that indicate that populations such as the Japanese whoconsume vast amounts of salt have a high incidence of CVD but no direct causallink has yet been definitively established between salt consumption and highblood pressure.

The cumulative past experience of our human ancestors and an increasing volumeof current scientific evidence indicate that salt is a major life-preservingsubstance and effective healing principle. As often, therefore, the question isone of balance. When do possible health risks override the beneficial and vitaleffects of an adequate salt intake? The answer probably depends on theindividual (e) .

Notes

(a) Science and medicine have tried to define the precise roles of saltin the healthy and diseased human organism. Blood, sweat, and tears all containsalt, and both the skin and the eyes are protected from infectious germs by the anti-bacterial effect of salt.
When salt is added to a liquid, particles with opposite charges are formed: apositively charged sodium ion and a negatively charged chloride ion. This isthe basis of osmosis which regulates fluid pressure within living cellsand protects the body against excessive water loss (as in diarrhoea or on heavysweating).
Sodium and chloride ions, as well as potassium ions, create a measurable differencein potential across cell membranes. This ensures that the fluid insideliving cells remains separate from that outside. Thus, although the human bodyconsists mainly of water, our "inner ocean" does not flow away orevaporate.
Sodium ions create a high pressure of liquid in the kidneys and thus regulatetheir metabolic function. Water is extracted through the renal drainagesystem. The body thus loses a minimal amount of essential water. Out of 1500litres of blood which pass daily through the kidneys, only about 1.5 litres ofliquid leave the body as urine.
Salt is "fuel" for nerves. Streams of positively andnegatively charged ions send impulses to nerve fibres. A muscle cell will onlycontract if an impulse reaches it. Nerve impulses are partly propelled byco-ordinated changes in charged particles.

(b) According to modern scientific research, saltdoes indeed have weak disinfectant properties when applied topically.

(c) Inhaling steam from salt water has become anestablished treatment for acute and chronic respiratory diseases in spa-,balneo- and thalasso- therapies.

(d) The mineral composition of Dead Sea salt isslightly different from that of common sea salt . Dead Sea salt is consideredto be particularly useful in chronic skin diseases such as psoriasis.

(e) I acknowledge with thanks Johanna S. Gordon'shelp in translating the German draft of this article.

References

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2. Denton D. The hunger for salt. Ananthropological, physiological and medical analysis. Springer Verlag,Berlin, 1982.

3. Ritz E. The history of salt - aspects of interestto the nephrologist. Nephrol Dial Transplant 11, 969-75, 1996.

4. Wormer EJ. Heilkraft des Salzes. SuedwestVerlag, Munich, 1995.

5. Wormer EJ. Salz in der Medizin. In: TremlM, Jahn W, Brockhoff E (eds.): Salz Macht Geschichte (Collection of essaysand catalogue). Haus der Bayerischen Geschichte, Augsburg, 1995, p. 48-55

6. Porter, Roy (ed.). The medical history ofwaters and spas. Wellcome Institute for the History of Medicine, London1990.

7. Merke F. Geschichte und Ikonographie desendemischen Kropfes und Kretinismus (History and Iconography of EndemicGoitre and Cretinism). Verlag Hans Huber, Bern, 1971.

Science Tribune - Article -March 1999