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Hemp Oil in Cosmetics.

This notorious, natural material imparts real benefits to leave-on and rinse-off personal care products.

IT IS FASHIONABLE in cosmetic circles these days to include all sorts of rare, often exotic materials in skin care preparations. Such additions are usually accompanied by a variety of beneficial claims that are often based on folklore rather than rigorous scientific evaluation.

Be that as it may, consumer acceptance is always the final measuring stick of a product's success. Many additives are high quality oils obtained from nuts and seeds such as grape, blackcurrant, Brazil, hazel, calendula, macadamia, pecan and poppy, to name just a few. The list is expanded on a regular basis and one of the newest to grab the attention of the cosmetics industry is hemp. Ordinary hemp oil has been available for many years, but now high quality grades are commercially available which are suitable for use as cosmetic ingredients and other purposes. The trend captured widespread attention three years ago when The Body Shop became the first major retailer in the UK to introduce an innovative, hemp-based range of cosmetic products for dry skin.

The hemp plant originated in Central Asia and India, although there is the reported use of hemp in China as long ago as 2000 B.C. Hemp was cultivated for its fiber, seed and oil content as well as for hashish, a narcotic, the latter being obtained from the flowers and the upper leaves of certain varieties. It was widely cultivated throughout Europe during the Middle Ages because its flax-like fiber was used to make rough, but durable, clothing. Hemp was introduced into Chile in the 1500s and North America during the 1600s before finding its way to most of the temperate climates of the world.

Hemp belongs to the Cannabaceae family, which consists of erect climbing plants. One species, Cannabis sativa, an annual, can grow to a height of 1.8 meters in a single season if grown specifically for its fiber content. Fibers are obtained from the hollow stalks of the plant after washing, drying and removing the extraneous material. Such fibers are longer but less flexible than flax, but equally strong and durable, and have been widely used to manufacture twine, yarn, rope and coarse canvas fabrics.

A Versatile Plant

Like flax, hemp is a remarkably versatile plant with a wide variety of uses. Unlike flax, however, its development has been seriously impaired in the past when the U.S. and other countries criticized its cultivation on the grounds of it being a primary source of the hallucinogenic drug hashish. The plant became known as marijuana, "the killer weed from Mexico," around the time of the war between Mexico and the U.S., and its cultivation was subsequently banned in many countries--a ban that continues, to this day, in the U.S. However, hemp can be grown under strict license in other countries. Because hemp fibers, seeds and oils have little active drug content, their use is now permitted in Europe.

When hemp is grown for oil extraction, modern seed variants are available to produce short- and multi-spiked plants with compound palmitate leaves and small, greenish-yellow flowers. The seeds are quickly gathered and dried after maturation, when the oil can be extracted. Dried hemp seed is still widely used as a feed for caged birds and contains 30-33% of the oil. High quality oils are now commercially available using innovative extraction procedures. Statfold Seed Developments, Tamworth, UK, produces a wide range of seed oils in bulk for use in cosmetics and other products. The company's extraction process uses state-of-the-art expellers operating at temperatures below 50 [degrees] C. This allows the retention of vital oil constituents without the use of added chemicals. A refining stage is often then carried out. European seed sources include France, Turkey, Romania and certain Eastern European countries, where the hemp is grown under license.

Hashish is a drug preparation derived from resin secreted by the flowers and upper leaves of non-fiber producing varieties of Cannabis sativa. It contains 10-15% of the active ingredient 9-tetrahydrocannibol (THC) which induces hallucinogenic effects when consumed or smoked. It also exerts a powerful narcotic effect on the central nervous and cardiovascular systems. Illegal hasish is exported from many sources including Nepal, the Middle East and Latin America.

Analysis of Refined Hemp Oil

Refined hemp oil resembles sunflower oil. It is pale yellow, has little taste and low odor. It has a refractive index of 1.469-1.472 and normally contains no additives other than optional natural antioxidants. The THC level is very low, with a maximum content of five parts per million.

According to Stafold Seed Oils, refined hemp oil contains:
Free fatty acid 0.1 (max.)
 (% as oleic)
Peroxide value 5.0 (max.)
 (mg/kg of oil)
Color 4.0 red (max.)
 (Lovibond 5.25 in cell)
Iodine value 145-165
Moisture (%) 0.1 (max.)

Fatty Acid Nomenclature

Most fatty acids are better known by their trivial names rather than by their systematic names, but in some cases this can be quite confusing. The systematic name of a fatty acid is derived from its parent hydrocarbon having the same number of carbon atoms. The position of unsaturated carbon atoms may be indicated in two ways: by a numerical system which designates the carbon of the carboxyl group as 1 subsequent carbon atoms as 2, 3, 4, etc. A second method uses letters of the Greek alphabet to denote the position of carbon atoms in the chain, but in this case the carbon atom of the carboxyl group is not designated. Omega (w) is used to denote the terminal carbon atom.

A simple naming system is also used where the carbon number is shown followed by the number of the double bonds; e.g., C16:0 for palmitic acid (16 carbon atoms with no double bonds) and C16:1 for palmitoleic acid (16 carbon atoms with one double bond, etc.). The position of unsaturated bonds is also indicated by reference to the terminal or omega positions. This system is frequently used to describe essential fatty acids.

Hemp oil, like all other natural fixed oils, is largely composed of mixed fatty glycerides or mixed esters of fatty acids and glycerol, and it is the nature of these component acids which determine the general properties of the oil. The fatty acid composition of hemp oil varies slightly according to variety, growing conditions, geographical location and climate, but resembles that of borage and evening primrose. The oil is characteristically rich in polyunsaturated acids, especially in linoleic and alpha-linolenic acids, with up to 2% content of the important gamma-linolenic acid. Here's the principal fatty acid profile of refined hemp oil:
Fatty Acid %
C16:0 Palmitic 5-12
C16:1 Palmitoleic 0.5 (max.)
C18:0 Stearic 1-4.5
C18:1 Oleic 10-16
C18:2 Linoleic 45-65
C18:3 Alpha linolenic 14-30
C18:3 Gamma linolenic 1 (min.)
C18:4 Octadecatetratraenoic 0-2
C20:0 Arachidic 0-2
C20:1 Eicosenoic 1 (max.)
C22:0 Docosanoic 1 (max.)
C24:0 Tetracosanoic 1 (max.)

Essential Fatty Acids

The human body requires some 50 essential ingredients to maintain its normal healthy fuction, two of which are obtained from oils and fats. These are the so-called essential fatty acids (EFAs) and are usually referred to as omega 6 (linoleic acid, C18:2 w6) and omega 3 (alpha-linolenic acid, C18:3 w3). Both acids occur in hemp oil in a unique ratio of omega 6/omega 3 of 3:1, together with gamma linolenic acid, C18:3 w6. Essential fatty acids are important because they cannot be synthesized by the body and must be sourced from natural oils. The term essential implies ingestion of the individual acids where most other fatty acids can be produced by the body from other fatty sources. This combination of unsaturated fatty acids ensures that any long-term use of an oil such as hemp is able to supply the necessary EFAs without causing problems of either excess or deficiency.

Cosmetic Uses of Hemp Oil

Hemp oil, like many other natural seed and nut oils, is increasingly being used in cosmetic skin preparations in the UK and Europe. The application of hemp oil to the skin helps minimize various conditions associated with an EFA deficiency such as dry and flaky skin. Hemp also has conditioning and moisturizing properties.

The Body Shop was well aware of the skin care benefits of hemp oil. Its original hemp oil-based personal care line includes seven products--dry oil spray, lip protector, lip conditioner, hand protector, foot protector, bath oil and body butter. The products are recommended for men and women of all ages, particularly those with dry skin.

Hemp oil can be directly included into products such as lipsticks or rubbing and massage oils. It may also be directly added to toilet soap noodles at the mixer stage along with perfume and other ingredients and processed in the usual manner. It is possible to make it available as a "hot" pourable soap for incorporating into a translucent soap base without significantly compromising the degree of transparency or workability. It is also possible to prepare it in a solubilized form by mixing with an appropriate blend of surfactants for direct addition to aqueous products such as bath or shower liquids and gels, shampoos and conditioners. In typical cosmetic hand creams and lotions, the usual levels of hemp oil are 1-2%, but these levels can be much higher for wash-off products such as soaps.

COPYRIGHT 2001 Rodman Publications, Inc.
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Copyright 2001 Gale, Cengage Learning. All rights reserved.

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Author:Whalley, George R.
Publication:Household & Personal Products Industry
Date:Oct 1, 2001
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