Henna, derived from the leaves of the henna tree, has been a staple in cosmetic and cultural practices for centuries. It originated in ancient Egypt before spreading across West Asia, Arabian Peninsula, North Africa, Central Africa, the Horn of Africa, and later the Indian subcontinent. Today, it permeates a variety of cultures worldwide. Renowned for its rich, reddish dye extracted from dried and powdered leaves, henna imprints a temporary, but vivid stain upon both skin and hair. This stain intensifies over a few days, after which it gradually wears off through the natural process of skin exfoliation, typically within one to three weeks.

Notably, the term 'henna' encompasses various skin and hair dyes, including 'black henna' and 'neutral henna.' Unlike the traditional henna derived from the Lawsonia inermis plant, these are not natural derivatives of the henna plant. The dye that stains the skin a reddish-brown tone is referred to as 'red henna,' while 'black henna' refers to the amalgamation of red henna with p-phenylenediamine (PPD), often used for temporary 'black henna tattoos.'

Beyond its aesthetic contributions, henna harbors medicinal potential. It demonstrated noteworthy antimicrobial properties against common bacteria and fungi, save for having limited effectiveness against Candida albicans and Trichosporon beigelii. Such qualities could pave the way for new therapeutic possibilities, particularly in warding off potentially harmful microbes.

However, henna use is not entirely devoid of repercussions. Red henna appears generally safe, with rare instances of allergic reactions and hypersensitivity. Yet, those with glucose-6-phosphate dehydrogenase deficiency may experience severe health complications, such as haemolysis, from topical application. Black henna tattoos potentially lead to sensitization to PPD, and subsequent use of PPD-containing hair dyes may instigate allergic contact dermatitis. Hence, caution is necessary in the use of these substances, particularly among the young population.

Research into henna's long-term skin effects unveiled potential toxicity associated with the presence of harmful ingredients in some additives used in commercial henna, particularly when combined with sunlight exposure. It's hypothesized that these ingredients, penetrating the skin's epidermal barrier, could result in blistering, vacuolization, and possibly genetic mutation. These findings, although needing further exploration, underline the need for care when choosing and using henna products.

That said, henna has been shown to have some remarkable therapeutic benefits. A study on using henna as a preventive measure against decubitus ulcers, commonly known as bedsores, yielded promising results. It was observed that henna application on patients' sacrum significantly reduced the incidence of bedsores, highlighting its potential role in preventive healthcare, particularly in critical care units.

Interestingly, recent research into Thai henna leaf, specifically its aqueous extract, sought to ascertain its safety and bioactivity, given its rising demand as a natural dye. Findings pointed towards the extract's non-toxicity, as well as significant antioxidant and anti-inflammatory properties, attributed to its high phenolic and flavonoid contents. These promising results open new avenues for the application of henna extracts in health industries hitherto unexplored.

In conclusion, henna's legacy runs deep, with its reach extending beyond intricate body art and hair dyes to find potential applications in the health industry. However, caution is necessary to avoid potential risks related to additives and allergic reactions. As researchers continue to unlock henna's potential, one thing remains evident: henna's vibrant hues are more than just skin deep.

jose (2024/04/18)