Zinc is an essential micronutrient for humans. Its importance can be gauged from the fact that it is an essential component of more than 300 metalloenzymes and over 2000 transcription factors that are needed for regulation of lipid, protein and nucleic acid metabolism, and gene transcription.
An average adult weighing 70 kg has a body zinc content of 1.4–2.3 grams, the highest tissue concentration being in the skin, prostate, seminal fluid and uveal tissue. While about half of the total body zinc is in your bones, your skin contains nearly 6% of total body zinc.
your skin contains nearly 6% of total body zinc
As movement of zinc across various tissues is limited and there is no storage depot, the continuous external supply of zinc is important for metabolic needs, growth, and tissue repair. The recommended daily allowance of zinc for an average adult male is 11mg and the requirement increases from 8mg/d to up to 12mg/d in females during pregnancy and lactation. Animal foods like meat, eggs, fish, and oysters are rich in zinc. Although cereals and legumes contain moderate amount of zinc, only 20–40% of ingested zinc is absorbed.
Zinc also possesses antioxidant properties and has been found useful in preventing UV-induced damage and reducing the incidence of malignancies. It has also been demonstrated to possess antiandrogenic properties as it causes modulation 5-alpha-reductase type 1 and 2 activity, the enzyme implicated in acne breakouts (it converts testosterone to DHT, a super-charged testosterone that increases sebum production, causing clogged pores and breakout).
Zinc is an antioxidant
Zinc has been used as a therapeutic modality for centuries. Topical preparations like zinc oxide, calamine, or zinc pyrithione have been in use as photo-protecting, soothing agents or as active ingredients. Its use has expanded over the years for a number of dermatological conditions including infections (warts, leishmaniasis), inflammatory dermatoses (acne vulgaris, rosacea), pigmentary disorders (melasma), and neoplasias (basal cell carcinoma).
Prevention of Photodamage and Skin Cancers
Zinc oxide provides UV-A protection
Zinc oxide is widely used as a broad-spectrum physical sunscreen. Its advantage lies in its low cost and an excellent safety profile. It has been used alone and in combination with other physical (titanium oxide) or chemical sunscreen agents. The availability of microfine and nano zinc oxide, provides better cosmetic appeal and photoprotection than traditional zinc oxide preparations, without the whitening effect. Zinc oxide provides protection against UV-A1 (340–380) superior to titanium oxide providing better spectrum protection. In formulations, generally one gains 1 SPF unit per 1% zinc oxide added.
Oral and topical antibiotics and/or retinoids are commonly used acne therapies. With the emergence of resistance to common antibiotics the need for new and novel agents in acne management has become necessary. Zinc has been used extensively both topically and systemically for the management of acne vulgaris since the time its favourable effect on acne was recognized by research studies conducted in 1974. Zinc, with or without niacinamide, is an emerging alternate acne treatment to reduce possible adverse effects of antibiotics and in view of P. acnes strains developing resistance to conventional antibiotics. The exact mechanism of zinc in acne treatment remains poorly explained. Topical zinc alone as well as in combination with other agents is effective perhaps because of its anti-inflammatory activity and ability to reduce P. acnes counts by inhibition of P. acnes lipases and free fatty acid levels. Another proposed mechanism for the benefit of zinc in acne is suppression of sebum production by its antiandrogenic activity. Interestingly though, 2% green tea extract was found to be more effective in treating acne than 5% zinc sulphate.
Our new Balance cream formulation contains a niacinamide-zinc combination (amongst many other anti-acne ingredients).
Copper-Zinc complexes enhance skin elasticity
The effects of bi-metal, 0.1% copper-zinc complexes, on elastin biosynthesis and elastic tissue accumulation has been researched with amazing results. After 8 weeks, significant elastic fibre regeneration was seen in the papillary dermis, leading to effacement of wrinkles. The combined photoprotective and elastic regenerative properties of zinc provides exciting possibilities for new products. At OptoDerm, we use a proprietary copper-zinc-magnesium complex in our Collastin serum, as well as our XyloPrep (a professional Microneedling gel).
Depending upon the principal causative factors, the eczema may be endogenous eczema (atopic dermatitis, seborrhoeic dermatitis, discoid or nummular eczema, and asteatotic eczema) or exogenous or contact eczema (allergic or irritant contact dermatitis, photoallergic contact dermatitis). Zinc has anti-inflammatory properties and increases re-epithelialisation, supporting its use for treating eczemas. Zinc oxide paste has been used for the treatment of diaper dermatitis for decades. Although it is less effective compared to other treatment modalities like topical corticosteroids, it is a useful soothing and antipruritic agent
Topical zinc oxide, known for its strong antioxidant and antibacterial action, has been also used in treating atopic dermatitis, a chronic inflammatory eczematous dermatosis characterized by the impairment of the skin-barrier function, increased oxidative cellular stress, and bacterial colonisation.
Premalignant and Malignant Dermatoses
Zinc in high concentration has been found to possess a direct cytotoxic effect and is well known to induce apoptosis of malignant cells and tissue necrosis. This property of zinc has been utilised for its use in premalignant and malignant conditions of skin like xeroderma pigmentosa, actinic keratosis, and basal cell carcinoma. Topical therapy with zinc sulfate solution has been found to have both therapeutic and prophylactic role in patients with xeroderma pigmentosa. The beneficial effects of zinc in xeroderma pigmentosa or actinic keratosis (a premalignant condition resulting from proliferation of aberrant epidermal keratinocytes, that occurs primarily on sun-exposed skin) are attributable to enhanced wound healing, antioxidant action, sunscreen property, enhanced DNA repair, improved immunity, and accelerated apoptosis of malignant cells
Zinc enhances DNA repair
Vitiligo is a common depigmenting disorder is seen in about 0.1%–2% of the population. As vitiligo patients have been found to have significant low serum zinc levels than normal controls, zinc was postulated to play a role in the management of vitiligo. Zinc possesses significant antiapoptotic and antioxidant activity and along with other micronutrients like copper and manganese also postulated to play an important role in melanogenesis.
Melasma, a common pigmentary dermatosis, causes significant psychological stress due to cosmetic morbidity in affected patients. It affects all races with a predilection for Hispanics and Asians and accounts for 0.25 to 4% of the patients seen in dermatology practice in Southeast Asia. Genetic predisposition, pregnancy, oral contraceptives, endocrine dysfunction, hormone treatments, or exposure to UV light have been implicated frequently in its pathogenesis. Clinically, it presents in three distinct patterns – centrofacial, malar, and mandibular pigmentation (in ratios of 55–75%, 24–43%, and 1.5–2%). Topical zinc sulphate has also been tried in the management of melasma owing to its peeling and sunscreen properties.
Scars and Keloids
Hypertrophic scars and keloids of any origin are associated with considerable disfigurement. The beneficial effect of topical zinc in the treatment of keloids in few studies has been attributed to its ability to inhibit lysyl oxidase and stimulate collagenase that leads to decreased production and increased degradation of collagen.
Calamine lotion contains zinc oxide or zinc carbonate and is used frequently for symptomatic relief in pruritus because of its soothing properties. Zinc also inhibits mast cell degranulation and thereby reduces the secretion of histamine, an important mediator of inflammatory response and an inducer of itch, making it a useful treatment option in pruritic conditions.
Psoriasis is a common disorder affecting nearly 2-3% of general population, with joint involvement being a common disabling complication. A large range of drugs, ranging from time tested modalities like coal tar and phototherapy, methotrexate, and retinoids to newer “biotech” modalities are currently used. However, the chronically relapsing nature of the disease has always compelled the researchers to look for novel and safe therapies. Zinc has been tried for the management of psoriasis and psoriatic arthritis, especially zinc pyrithione cream. The benefit is attributed to antiproliferative effect of zinc pyrithione. Oral zinc sulphate was found to be effective for psoriatic arthritis. However, oral zinc sulphate did not produce clinically significant improvement as a treatment modality for plaque psoriasis.