Hemp seed oil

Hemp seed oil is a fatty vegetable oil and consists, like other vegetable oils, of a homogeneous mixture of liquid triglycerides. Its taste is somewhat herbaceous, the taste slightly nutty. Hemp seed oil is, as the name suggests, obtained from the seeds of the commercial hemp (Cannabis sativa). The most important producing countries are France, China and Chile. Hemp oil is mostly used as an edible oil.

Hemp seeds - unlike the resin of the plant - contain only small amounts of tetrahydrocannabinol (THC). Instead, higher concentrations of the non-psychoactive cannabiol are found, which is why hemp seed oil has no psychoactive effect. In hemp seed oil, the concentrations of tetrahydrocannabinol vary from 0.3 to 19.73 μg/mL, and the cannabiol concentrations vary from 6.66 to 63.40 μg/mL (Jang E et al. 2020).

Note: The non-psychoactive hemp seed oil is often confused with other cannabinoid-containing oily hemp products from which it must be distinguished. So also from the essential hemp oil (obtained from distilled leaves and flowers) or the hashish oil(oily, strongly THC-containing resin extract). The latter are extremely psychotropic due to their high content of tetrahydrocannabinol (THC).

The seeds are obtained during the preparation of the harvested hemp plants and processed further. If one wants to obtain a high-quality hemp oil from the hemp seeds, a gentle harvest and oil extraction are indispensable. Then the hemp nuts are pressed in an oil mill. Cold pressing is best suited for this, as the pressing temperature is between 40 °C and 60 °C, and thus the valuable ingredients of the hemp oil are not damaged and reduced by heat. The colour of hemp oil differs depending on the method of production. Thus, cold-pressed hemp oil is green-yellowish (chlorophyll content).

The lipid profile in hemp seed oil is characterized by the following fatty acids:

• Oleic acid (10-15 %)
• linoleic acid (50-60 %)
• linolenic acid (up to 29 %)
• palmitic acid (7 %).

Other fatty acids present to a lesser extent are:

• Gadoleic acid
• Stearic acid
• Stearidonic acid
• Arachidic acid

The content of saturated fatty acids is 8-13%, monounsaturated fatty acids 12-17%, polyunsaturated fatty acids 70-80%.

Unsaponifiables are present in 1.84-1.92% in Cannabis sativa L. seed oil (Montserrat-de la Paz S et al. 2014). The most interesting compounds here are:

• β-sitosterol (1905.00 ± 59.27 mg/kg oil),
• Campesterol (505.69 ± 32.04 mg/kg oil),
• Phytol (167.59 ± 1.81 mg/kg oil),
• Cycloartenol (90.55 ± 3.44 mg/kg oil), and
• γ-tocopherol (73.38 ± 2.86 mg/100 g oil).

Cosmetics: Hemp seed oil is used in the cosmetics industry in the manufacture of various products such as massage oils, ointments, creams, soaps and shampoos.

• Scalp care: Hemp seed oil can also be used for scalp care (depending on the length of the hair, spread 1 - 2 teaspoons of the oil in towel-dried hair and leave on for a few hours. Then wash out with mild shampoo. Be careful with light blond, white and grey hair: due to its chlorophyll content, the greenish hemp oil can have a colouring effect). To what extent hemp seed oil has advantages over other vegetable oils is not to be clarified, since appropriate comparative studies are missing.

Medicine: In medicine, the oil is used for the treatment of inflammations of the ears, nose and throat. Dermatologically, it is used for inflammatory skin diseases, however, antibacterial efficiency of the oil was not proven in reviewing studies (Mikulcová V et al. 2017).

• Atopic dermatitis: The effects of hemp seed oil on atopic dermatitis are controversial (Bath-Hextall FJ et al. 2012). This concerns both their internal use and external application. As externals, hemp seed oils can be considered as well tolerated skin care products. This also applies to other vegetable oils such as borage seed oil or jojoba oil, olive oil, almond oil or sesame oil. Skin oils are applied in a thin layer and spread best on moist skin. The result is a fat-water mixture which is well absorbed by the skin.

1. Bath-Hextall FJ et al (2012) Dietary supplements for established atopic eczema. Cochrane Database Syst Rev 2:CD005205
2. Callaway J et al (2005) Efficacy of dietary hempseed oil in patients with atopic dermatitis. J Dermatolog Treat 16:87-94.
3. Jang E et al. (2020) Concentrations of THC, CBD, and CBN in commercial hemp seeds and hempseed oil sold in Korea. Forensic Sci Int 306:110064.
4. Mikulcová V et al.(2017) Formulation, Characterization and Properties of Hemp Seed Oil and Its Emulsions. Molecules 22:700.

5. Montserrat-de la Paz S et al. (2014) Hemp ( Cannabis sativa L.) seed oil: analytical and phytochemical characterization of the unsaponifiable fraction. J Agric Food Chem. 2014 Feb 5;62(5):1105-10.