Improvement to Foot and Skin Appearance by Using Copper Oxide Impregnated Socks-A Report of a Large Scale Internet Based User Survey

Copper has two key properties that make it an attractive component to introduce into textiles and socks in particular – it has potent biocidal properties and is an essential trace element vital for the normal function of skin. The capacity of copper oxide impregnated socks to kill fungi that causes tinea pedis (athlete’s foot) and to enhance skin elasticity has already been demonstrated. In the current study, we assessed the beneficial effect on the skin of the foot in the wider population by supplying socks impregnated with microscopic copper oxide particles to 5,000 individuals that were identified via an internet survey as people who had experienced athlete’s foot within the past 6 months or were concerned about the appearance of their feet. Each individual received 3 complementary pairs of socks and was asked to use them as they would normally use their own socks. After 90 days 3,603 paricipants answered an online questionnaire. The vast majority (82%) of responders that felt uncomfortable showing their bare feet in public before using the socks reported a meaningful improvement to their foot skin following the use of the socks for at least 5 hours a day. 61% of respondents reported elimination or reduction of their foot odor, and 60% reported stopping using a foot care regime or therapy due to using the supplied socks. 51% indicated that the socks improved the appearance of their feet and 58% indicated they were now more comfortable showing their feet in public. In view of the above, it can be concluded that the simple use of copper oxide impregnated socks for at least 5 hours a day helps improve the foot skin well-being and overall appearance of the skin.


Introduction
Copper is one of the essential trace minerals needed for the ordinary function of most tissues in our body [1]. In the skin, copper serves as a cofactor of many enzymes and polysaccharides, such as metalloproteinases, lysyl oxidase, glycosaminoglycans and small proteoglycans. These factors are needed for cell proliferation, epithelization, production and secretion of collagen, elastin, integrins and fibrinogen, protection against free radicals and extracellular matrix protein cross-linking stabilization [2][3][4][5][6][7][8][9]. The absorption of copper ions through skin has previously been demonstrated [10,11].
Copper also has intrinsic potent wide spectrum biocidal properties [12,13]. Copper was used throughout human history by many geographically separated civilizations to treat skin pathologies [14]. It is for the biocidal properties of copper that copper and copper-based compounds are widely used today in many consumer applications [15][16][17][18][19]. In medicine, copper is used mainly for preventing contraception in intrauterine devices [20].
More recently, a platform technology has been developed by which copper oxide particles are permanently embedded in polymeric matrixes used in the production of fibers and yarns [21,22]. Textile products, made with these fibers and yarns are cosmetotextiles that in contact with the skin have a positive effect [23]. For example, pillowcases containing microscopic copper oxide particles have been shown in several double blind placebo controlled trials to reduce wrinkles and fine lines and improve the well-being of the skin [24][25][26].
Tinea pedis (also referred to as athlete's foot) is a contagious fungal foot infection estimated to affect ~15% of the general population, and even affect higher proportions of some specific populations, such as miners and soldiers [27,28]. Those infected may be asymptomatic, while others may experience burning, stinging, or itching. In addition, the skin may become scaled, fissured, inflamed and/or painful [29].
In the current study, we evaluated the effect of using copper oxide impregnated socks on the well-being and appearance of the foot skin by analyzing the responses obtained from 3,585 individuals who used the socks and participated in an internet feedback survey.

Screening
Via BzzAgent (www.bzzagent.com), a screener survey was sent to identify people who have experienced tinea pedis within the past 6 months and/or were concerned about the appearance of their feet enough to actively do something to improve the appearance of their feet. BzzAgent runs word-of-mouth networks in North America and Europe, enlisting unpaid volunteers to try products from companies and then share their opinions about those products with others, inperson and online. The first 2,500 men and the first 2,500 women that responded positively were included in the study.

Socks
Each of the 5,000 individuals included in the study received 3 pairs of the Copper Sole socks (also known as Cupron's PRO Therapy System (PTS) socks). The socks ( Figure 1) were composed of 88% polyester, 11% nylon and 1% lycra, with the Cupron polyester being present only in the foot area of the sock at a composition of 75% polyester staple yarn and 25% nylon staple yarn. The copper oxide load per polyester staple yarn was 2.6% weight/weight (w/w), thus at the active area the copper oxide load was 1.95% (2.6% × 0.75=1.95%) w/w.

Procedure
The volunteer participants were asked to use and wash their socks on a regular basis as they would use their regular socks. The participants were asked to fill the questionnaire detailed in Appendix A.

Results
Out of the 5,000 individuals that received the socks, 3,603 answered the survey within 90 days from receiving the socks. The vast majority of the participants (82%) used the socks at least 5 hours a day ( Figure  2). Eighteen participants (~0.5%) answered that they eventually did not use the socks at all, and thus they were excluded from further analyses. 68% of the analyzed participants (2,429 participants) reported that they had a problem showing their bare feet in public before the campaign. Out of these 2,429 participants, 2,001 (82%) reported that after using the socks they felt more comfortable showing their feet in public. In addition, following the use of the test socks, 2,167 participants (60%), out of the 3,585 that were included in the analyses, reported that they stopped using foot remedies. From these 2,167 participants, 61% reported stopping using foot lotions, creams or ointments; 63% reported stopping the use of sprays and/or foot powders; 11% reported stopping pedicures; 9% reported stopping treatments at the doctor's office; 12% stopped using other socks specially designed to help treat foot issues; and 2% reported stopping using other remedies/routines.

Discussion
It is estimated that more than 15% of the population suffers from foot fungal infections, mostly caused by dermatophytes [30,31]. These infections reduce the integrity of the skin, may result in secondary bacterial infections, inflammation, redness, itching and even pain [32]. These infections also have a cosmetic effect, as the skin is usually dry, may have fissures, scales and cracks, and look unhealthy, causing those suffering from these infections to be concerned of the appearance of their foot. Foot fungal infection often goes unnoticed, sometimes mistaken for dry skin [29].
The impregnation of copper oxide particles in socks takes advantage of both properties of copper, i.e. its potent biocidal properties including against fungi and its beneficial effect on the skin. Copper oxide impregnated socks have been shown to be effective in help treating acute and chronic athlete's foot infections [32][33][34]. In addition, a double blind, placebo-controlled study demonstrated that wearing socks impregnated with copper oxide particles increases skin elasticity [35]. Increased skin elasticity is important especially in diabetic individuals, as their skin is less elastic and very dry, increasing significantly the susceptible of their skin to infection and breakdown [29]. We hypothesized that the copper ions liberated from the copper oxide particles impregnated in the socks, by reducing the risk of fungal and bacterial infection of the foot and increasing the skin elasticity, may help protect the feet of diabetics from skin complications [36].
This study did not monitor for the medical condition of the study participants, other than including those who indicated that they have experienced tinea pedis within the past 6 months or that were concerned with the appearance of their feet. This study also did not take into consideration other factors that may have affected the participant's responses, such as their economic or education status. However, taken together, the current study indicates that the use of copper oxide impregnated socks may be also beneficial to the wider population who may be suffering from fungal infections and/or may be concerned with the cosmetic appearance of their feet.