About henna – what you should know

Henna, lawsonia inermis, is a plant. It is a large bush, or small tree, that grows in hot, dry climates. There is evidence from Egypt that henna was regularly used to dye hair five thousand years ago, and may have been used in Jericho as early as eight thousand years ago. Henna was used to keep hair healthy and to color gray hair.

Henna leaves are harvested, dried, and powdered. When mixed with a mildly acidic liquid, henna will stain skin, hair, and fingernails reddish-orange.

Henna´s leaves have a red-orange dye molecule, lawsone. You can see it in young leaves in the center vein of the leaf. Henna leaves have 1% to 4% lawsone content, depending on climate and soil conditions. The lower dye content leaves are harvested, roughly powdered and sifted, and sold to the hair dye industry.

The highest dye content henna, the best 5% of the crop, is powdered and finely sifted to make design on skin, such as are used for celebration in North Africa, in the Middle East and South Asia. This is body art quality (BAQ) henna. Body art quality henna is wonderful for your hair because the fine powdering and sifting make it rinse out easily, and will dye hair a richer color.

History

Mention of henna can be found already on Ebers papyrus from ancient Egypt dated to the year 1500 BC, however, it is believed to have copied from earlier texts, perhaps dating as far back as 3400 BC. Among the some 700 magical formulae and remedies, a detailed coverage was dedicated to henna as tribute of the complexity of the product and its plant, lawsonia inermis.

From ancient Egypt and neighbor countries, the use of henna has continued for thousands of years in Arabian countries and nowadays it is expanded all over the world. The main use is cosmetic, to dye hair and nails and for decorative bodypainting. However, the use of hair dyes has dramatically increased during the last decades.

Types of henna

Several types of henna are on the market: commercial red henna is based on Lawsonia inermis, black henna on Indigofera tinctoria, neutral henna on Cassia obovata and blond henna on Cassia obovata with addition of several other plants.

The commercially available henna hair dyes that come in “colors,” such as black, brunette, chestnut, blonde, and so on, are compound hennas. The manufacturers take lower quality henna and add toxic metal salts, chemical dyes, other ingredients, even para-phenylenediamine, to create a range of colors! These added ingredients are often not listed, because the countries of origin do not require declarations for cosmetics, and once exported to the west; there is no requirement that the additives be declared. These pre-packaged hennas are often termed “natural herbal henna.”
This is very misleading as these are not natural products; they are full of chemicals. Metallic salts alter and fix color in lieu of higher quality henna. The compounds of henna and metallic salts can react disastrously with synthetic hair dye, seriously damaging hair.
Body art quality henna does NOT have metals, lead, and it does NOT “coat the hair”. The molecules in pure body art quality henna penetrate and bind with your hair´s keratin, and make your hair thick, strong, and silky!

Safety

The coloring action of red henna is usually due to lawsone, present in the leaves together with its glucosides (hennosides). In the dried leaves, besides lawsone (0,5 – 2 %), other compounds are also present, co-occurring in the activity as well as in characterization of the raw material like polyphenols (flavonoids, gallic acid) and glucides. Henna is considered safe, although one study claimed that the application can induce a severe haemolytic anaemia and may contribute to neonatal hyper bilirubinemia. However, a real toxicity for henna should be excluded on the basis of investigation on large populations and on consumers of professional exposures.

The lawsone position is different. Its content has to be checked and essayed for its potential toxicity because some cases of renal damage and bladder cancer have been reported. Thus, in EU the content of lawsone in cosmetic preparations must be avoided and limited to 1,5 % in products based on Henna and declared in the label.

However, most of the quality problems are related to the plant ingredients: henna can contain fruits and twigs, as well as parts of other plants. The aim of the addition of other plants or natural or chemical substances could be the modification of the hair color or to improve the penetration or the fixing of the dye or to reinforce the hair color or to improve the hair protection, effects given by a lot of associated additives, from keratin to heavy metals. Actually, natural henna has very law allergic potential, and allergic reaction are caused by the chemical coloring additives that are added to henna mixtures to improve or modify dyeing. Several products marked as henna do not contain any natural constituent or only in law quantity.

How to know the compound henna

How can you find out if the hair dye you’ve been using is compound henna full of toxic metallic salts? It’s probably NOT listed on the label.
Harvest some of your hair from your hairbrush. Mix one ounce (30 ml) of 20-volume peroxide and 20 drops of 28% ammonia. Put your harvested hair in the peroxide-ammonia mix (this is in synthetic hair dye). If there’s lead in the compound henna you’ve used, your hair will change color immediately.
If there’s silver nitrate in the compound henna you’ve been using, there will be no change in hair
color, because silver is coating the hair. However, silver nitrate leaves a greenish cast to your hair,
so you can tell by that.
If there’s copper in the compound henna you’ve used, your hair will start to boil, the hair will be hot and smell horrible, and the hair will disintegrate.
With all the unlisted ingredients in compound henna products, no wonder henna’s gotten a bad rap!

Zdroje:

Studies in Natural Products Chemistry – Atta – ur – Rahman – Volume 37 (svazek)

Henna for Hair “How To” – Catherine Cartwright-Jones

preview image from pixabay.com

Leave a Reply

Your email address will not be published. Required fields are marked *