The use of thermal water for therapeutic purposes has ancient roots, with its benefits recognized across various cultures. In recent decades, there has been a resurgence in the use of mineral water for treating a range of conditions. Balneotherapy, or water therapy, is now practiced in many countries, utilizing mineral springs that vary significantly in origin, temperature, and chemical composition.
Introduction to Thermal Water and Balneotherapy
Thermal water and balneotherapy offer several advantages, including the avoidance of chemicals or potentially harmful drugs, minimal side effects, and a low risk to overall health. Thermal medicine is considered a medical branch that uses thermal water properties for curative and rehabilitative purposes, with documented efficacy in dysfunctions ranging from rheumatic to cardiovascular diseases.
Historical Perspective
The balneotherapeutic effects of spring water on skin diseases have been known since ancient times. The Greeks were the first to discover thermalizm, but it was during the Roman Era when thermal baths became a regular regimen for health. Hydrology evolved into a science, and thermal treatments were prescribed with specific indications under medical supervision. In more recent times, balneotherapy and spa therapy regained popularity, first in Europe and then in the United States. The cosmetic industry has also marketed thermal spa waters as cosmeceuticals.
Composition and Properties of Thermal Water
Water therapy is practiced in many countries with a variety of mineral sources that are different in their chemical and physical properties. Temperature is the first property that mineral waters acquire during their origin, determined by geothermal gradient, ascent speed, and exothermic reactions. Thermal waters can originate with magma (“juvenile waters”) or they can contact it during their ascent. Magma is between 650 and 1200 °C, and the heat gives the water hydrogen bond a great energy charge, which is released during cooling. In addition, the individual particles in solution acquire movement called “thermal noise”: waters can transmit these vibrations to the surfaces in contact with them. During the process of ascent, thermal waters acquire different characteristics. In fact, claimed beneficial effects are supposed to derive from waters’ specific properties: fixed residue and chemical composition. Fixed residue mg/L at 180 °C is the total amount of inorganic solvent. Fixed residue is one of the most important parameters allowing for the official classification of waters with therapeutic properties. Chemical composition is defined by the presence of anions and cations. When an ion is present in quantities greater than 20 meq/L it gives the name to the water. The presence of several predominant ions can define a classification of multi-ion waters.
Applications of Thermal Water
Hydrotherapy can have several applications. Cold and hypothermal waters cause physiologic reactions such as a decrease in local metabolic function, local edema, nerve conduction, muscle spasm, and an increase in local anesthetic effects. Thermal stimulation causes vasodilatation, enhances blood circulation, and decreases blood pressure. Hyperthermia also has important effects on granulocyte mobility and microbial and enzymatic activities. Other beneficial effects of thermal stimulation include increased extensibility of collagen-rich tissues. On the other hand, hyperthermal waters are used as short-term thermal stress: human skin can release significant amounts of opioid peptides, modifying the threshold of pain.
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Thermal Water in Dermatology
In dermatology, thermal waters are chosen for different indications according to salts concentration. For example, thermal water used in cosmetics is hypertonic. The high concentration of minerals is easily assimilated by the skin improving its physiological functions. The large presence of minerals is the main feature that makes thermal water effective for the well-being of the skin. Mineral waters (in particular salty and sulfur waters) are considered particularly useful for therapeutical applications in dermatology due to their keratolytic, regenerative, and antioxidant effects. Furthermore, bathing in mineral waters at different temperatures can remove microbial peptides that cause many skin diseases, reduce inflammation, improve microcirculation, regulate immune processes, and increase the quality of life. As demonstrated in several clinical studies, these beneficial effects of thermal waters are related either to the skin absorption of mineral elements or to skin temperature regulation. The physical and chemical composition of thermal waters significantly contributes to their therapeutic activity and they must be carefully selected when prescribing a therapy for different dermatologic diseases.
Therapeutic Effects on Skin Diseases
Dermatologic diseases frequently treated by balneotherapy with a high rate of success are psoriasis (PSO) and atopic dermatitis (AD). Other conditions treated by balneotherapy include acne vulgaris, lichen planus, pruritus, rosacea, seborrheic dermatitis, and xerosis.
Anti-inflammatory and immunomodulatory effects have been attributed to thermal baths and spa therapy. The heat stimulates the body to release a range of immunomodulatory mediators such as β-endorphin, enkephalin, and irisin. In particular, β-endorphin and enkephalin influence pain perception and regulate the proliferation of immune cells, whereas irisin ameliorates the overall metabolic status and cognitive capacities. Moreover, spa therapy has been shown to increase blood flow by dilating capillaries and decrease fibrinogen concentration. Apart from this, body exposure to thermal waters stimulates the immune and antioxidant systems.
Cumulative studies have reported that the application of minerals like sulfur, manganese, magnesium, zinc, selenium, strontium, silica, and calcium bicarbonate might have immunomodulatory effects on skin disorders including AD, contact dermatitis (CD), and PSO. Among the minerals, sulfur can dose-dependently inhibit T-cell proliferation and cytokine production such as interleukin (IL)-2, IL-8, IL-23, IL-17, and interferon (IFN)-γ. It also impairs keratinocyte cell growth and adhesion inhibiting mitogen-activated protein kinase signaling. Both sulfur and manganese have bactericidal activity against Staphylococcus aureus (S. aureus) which is commonly detected in AD, and hidradenitis suppurativa (HS) lesions. Magnesium and zinc reinforce the skin barrier and immune system, whereas the combination of magnesium and calcium salts accelerate skin recovery. An in vitro study has shown that selenium and strontium inhibit cytokine production, mainly IL-6, by epidermal cells. Further, selenium can suppress inflammatory response by Langerhans cells (LCs). Concerning silica and calcium bicarbonate, they inhibit mast cell histamine release and decrease cutaneous basophil degranulation potentially preventing the itch-scratch cycle in AD. Additionally, the combination of ions such as magnesium, calcium, chlorine, manganese, sulfur, and strontium reduces the AD-like inflammation in hairless mice via immune-modulation and redox balance. Particularly, a reduction of AD signature cytokines such as IL-1β, tumor necrosis factor (TNF)-α, and Th2 cytokine IL-13 was reported.
The therapeutic effects of thermal waters (salty or spring ones) on the skin might depend on the concentration of the aforementioned minerals. Salty thermal sources highest in minerals can reduce: (i) the human leukocyte elastase enzyme (involved in PSO), (ii) the transforming growth factor (TGF)-β (which is increased in psoriatic patients), (iii) the LCs of the skin, (iv) the aging markers, and (v) the skin infections, through the removal of yeasts and bacteria which classically contribute to seborrheic dermatitis (SD). Regarding spring thermal sources, the regulation of immunomodulatory parameters by spa water-supplemented media was observed in human psoriatic keratinocytes (Comano Thermal Water-CTW, Italy), LCs (La Roche Posay-LRP, France), mast cells (Avène Spa Water-ASP, France), and CD4+ T lymphocytes (ASP, France). Most notably, TNF-α and IL-8 production was reduced in psoriatic keratinocytes by CTW, and a partial shift from a Th2 to a Th1 cytokine profile was observed by ASW, offering a rationale for the treatment of PSO and AD, respectively. Preliminary studies using cultured fibroblasts suggest enhanced plasmatic membrane fluidity by ASW. Moreover, differentiation of skin keratinocytes as measured by the expression of involucrin, and cytokeratins-1 as well as cytokeratins-10 was induced by ASW.
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Microbial Composition of Thermal Waters
Since 1998 there has been a growing interest in the characterization of the microbial community of thermal waters. On one side, the microbial evaluation of water for human use is subjected to sanitary control, in order to search for coliform bacteria, Salmonella spp., and fecal Streptococci and on the other side, the analysis of the microbial composition of the thermal waters revealed the presence of dynamic microbial communities that function in different microenvironmental conditions, made up of peculiar and unusual microbial species with potential therapeutic effect.
Benefits of Thermal Water in Beauty Products
Thermal water itself does have some skin-nourishing qualities, even though it may not be the magic cure-all it’s sometimes said to be. It contains minerals that have been shown to enrich the skin and offers calming and anti-inflammatory effects. Various minerals have been shown to penetrate and benefit skin. The most common soluble minerals include calcium, bicarbonate, silicates, iron compounds, sodium and magnesium salts, sulfur compounds, and metals, along with trace elements like selenium. A spring’s location plays a role in a thermal water’s effectiveness, since each source has its own unique physical properties and chemical composition.
Thermal spring water has been shown to help inflammatory conditions like eczema and rosacea. Selenium-rich water, for example, has been used for decades in balneotherapy for eczema and psoriasis, while the Dead Sea’s high levels of magnesium salts have been shown to be effective in treating psoriasis.
Some relatively promising benefits of thermal water include:
- Hydrate skin: Some research suggests that using thermal water on skin can make it feel more soft, supple, and comfortable.
- Reverse UV damage: The minerals in thermal water appear to have antioxidant properties that some studies suggest help neutralize free radicals and possibly reduce sunburn risk.
- Reduce inflammation: Thermal waters have been shown to calm irritation from harsh skin treatments like retinoids and reduce skin inflammation in eczema.
- Balance the microbiome: Thermal water helps balance the microbiome (or levels of healthy and unhealthy bacteria that naturally live in your skin) and reduces inflammation in people with skin conditions like psoriasis and eczema.
Thermal Water Sprays
Thermal spring water skin care products offer anti-inflammatory and skin soothing benefits. The water can be used in the form of a spray or mist or as an ingredient in a moisturizer.
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Examples include:
- Avène Thermal Spring Water: Rich in minerals and silicates along with probiotics that help balance the natural collection of microorganisms on the skin.
- Vichy Volcanic Water: Sourced from French volcanoes and contains anti-inflammatory minerals. The water has a neutral pH close to that of the skin.
- Uriage Thermal Water Spray
- Evian Facial Spray
Thermal water sprays can help to soothe skin that’s in need of a little TLC. Thermal water is often used to help reduce the irritation associated with eczema, burns and psoriasis because it’s soothing and hydrating.
Thermal spring water is also known to decrease the production of inflammation caused by chemicals, radiation, sunburns, thermal burns, etc. On skin that is not affected by disease or inflammation, it hydrates and soothes it and potentiates the benefits of any topical skin care product. Many people who travel frequently or for long distances on a flight use it to revive their dry, tired, “airplane” skin. Additionally, the thermal spring water spray can be used to set your makeup as the final step, leaving the skin on your face dewy and hydrated. It is also a refreshing boost after exercise, shaving, or a long day’s work in the office.
How to Incorporate Thermal Water into Your Routine
Thermal water sprays can help prime your skin with a little hydration before you moisturize. Some thermal waters have been blended with essential oils or fruit essences and can be left to sit on the skin and slowly sink in. Antioxidants, like those found in the La Roche-Posay Thermal Spring Water Face Mist, can help give those free radicals an alternative partner to cling to.
Precautions
While thermal spring water is generally safe to use, there are some potential risks to be aware of. The high mineral content of thermal spring water can be irritating to some people, particularly those with sensitive skin.