Cannabis Sativa Seed Oil

Cannabis Sativa Seed Oil — sold almost everywhere as hemp seed oil — is the fixed oil pressed from the seeds of the hemp plant, Cannabis sativa L. It is a non-fragrant plant oil, ranging from pale gold to deep green depending on how the seeds were cleaned and processed, with a light, quick-absorbing feel that sits somewhere between a dry oil and a classic emollient.

It is worth separating it from CBD straight away. This oil is pressed from the seed, not from the flower or leaf, and the seed itself carries essentially no cannabinoids. Analyses of pressed seed oil find only trace amounts, generally attributed to residue transferred from surrounding plant material at harvest. If an ingredients list shows Cannabis Sativa Seed Oil, you are looking at a fatty oil; CBD appears separately on an INCI list as Cannabidiol.

What makes the oil interesting to formulators is its fatty acid profile. Published analyses put unsaturated fatty acids above 90 per cent of the total, with polyunsaturates dominant: linoleic acid (an omega-6) is the largest single fraction, followed by alpha-linolenic acid (an omega-3), typically in a ratio close to 3:1. Smaller amounts of gamma-linolenic and oleic acid are present, alongside naturally occurring tocopherols — mostly the gamma form of vitamin E.

In cosmetics it is used as an emollient and skin-conditioning agent, turning up in facial oils, moisturisers, cleansing balms, lip products, body oils and hair care.

An emollient's job is to settle into the microscopic gaps between the cells at the skin's surface and smooth out the roughness that makes skin look dull and feel flaky. Hemp seed oil does this with an unusually light touch. Because it is dominated by polyunsaturated fatty acids — which are thinner and more mobile than the heavier saturated fats found in oils such as coconut — it spreads readily and leaves far less of a greasy film behind.

Its high linoleic acid content also gives it a compositional resemblance to the lipids skin makes for itself. Linoleic acid is one of the components of the skin's own surface lipid film, the layer that governs how well the surface holds onto water. Linoleic-rich oils applied topically are thought to complement that film, which is the likeliest reason skin looks plumper and feels more comfortable after use. This is a cosmetic, surface-level effect rather than a change to how skin is built.

Alongside that, the oil forms a light film that slows the rate at which water evaporates from the surface, so humectants and hydrating serums applied underneath stay effective for longer. The tocopherols naturally present work mainly as antioxidants for the oil itself, slowing the oxidation that polyunsaturated oils are prone to.

Hemp seed oil slots into most routines easily, but it rewards a little care in how you apply and store it.

• Use it near the end of your routine. Oils do not push through a cream, so apply after water-based serums and moisturiser — or press two to four drops into your moisturiser in the palm of your hand.
• Once or twice a day suits most people. Many prefer it at night; in the morning, give it a minute to settle before sunscreen and make-up.
• No pH to work around. As an oil it has no pH of its own and will not destabilise acids, retinoids or vitamin C — though layering everything at once can feel heavy, so introduce it on its own first.
• Buy cold-pressed and store it cool, dark and tightly capped. Polyunsaturated oils oxidise readily and heat and light speed that up — replace the bottle if the smell turns sharp or fishy.