Ahhh, sandalwood! The sandalwood tree has been cherished for thousands of years for its beautifully aromatic wood, but did you know that an oil is available from the nut of this tree rather than from the wood? Sandalwood essential oil has come under scrutiny due to sustainability issues as it is distilled from the heartwood and even roots of this tree. But Sandalwood Nut CO2 extract comes from the nut of the tree, potentially reducing this issue. And, surprise! This extract is not considered aromatic, but rather is a carrier oil. Let’s explore Sandalwood Nut CO2 extract, and find out how it can enhance our aromatic skin care products.
What is Sandalwood Nut CO2 Extract?
While essential oils, by definition, are steam distilled (or expressed from the rinds, in the case of citrus oils), CO2 extracts use liquified carbon dioxide gas (CO2) rather than water in the extraction process. The result is an “extract”, not an essential oil, containing more of the plant material, so generally a thicker liquid closer to the makeup of the full plant part being used. The result of the process can be aromatic and used similarly to an essential oil, or not, as in the case of Sandalwood Nut CO2.
Where does Sandalwood Nut CO2 Extract come from?
Though Sandalwood Essential Oil is more often steam distilled from the Santalum album tree, the CO2 Nut Extract comes not from that same tree, nor from the wood, but from the tree nuts of Santalum spicatum – a species grown in Western Australia.
In fact, if you seek out essential oil from this species, you will find that it is commonly called Western Australian Sandalwood. Typically, Western Australian Sandalwood is more sustainably grown than Santalum album. Note that for the essential oil, other species than album are available (including spicatum), and may be more sustainably grown and harvested.
Sandalwood trees are considered to be “hemi-parasitic”, surviving in part by getting nutrients from the roots of other plants. The Santalum spicatum tree is drought tolerant, somewhat shrubby and small, but in some cases can reach heights of up to 20 feet. The nuts of the spicatum species, the source of the CO2 extract, have been used for thousands of years by Indigenous Australians both as a food and smoked in ceremonies. The spicatum species is also used in some chewing tobacco, particularly in India. The nut consists of a hard shell surrounding the softer, edible kernel.
The tree itself has been valued for centuries for its aromatic wood. So valued, that it has been overharvested, leading many concerned aromatherapists to shy away from its use. Recently, though, more sustainable practices have arisen, and if one is mindful of the source, it is possible to obtain both Sandalwood Essential Oil, and Sandalwood Nut CO2 extract that has been sustainably grown.
Creating a market for the extract of the nut may also encourage farmers to allow the trees to mature longer before harvesting the tree for its wood1. Another consideration when purchasing Santalum spicatum products, other than the CO2 extract, is that they are often solvent extracted (most often with hexane), so look for a trusted source assuring clean and sustainable practices have been maintained from growing to extraction.
What makes Sandalwood Nut CO2 Extract special?
Although Sandalwood Nut CO2 is not considered to be an aromatic oil, I find it has a lovely nutty, sweet, buttery and uplifting aroma (it does not smell like Sandalwood Essential Oil). You’ll want to keep this in mind when blending it with other carrier oils and with essential oils so that aromas are harmonious.
With its anti-inflammatory quality, and affinity to our natural skin sebum as well support for the skin’s protective barrier, Sandalwood Nut CO2 is a lovely choice in combination with other carriers, particularly for aging and mature skin. Although it has some occlusive, thus protective properties, Sandalwood CO2 extract is still considered to be a “dry oil” – one that absorbs well, and does not feel greasy on the skin.
What is the fatty acid profile of Sandalwood Nut Co2 Extract?
The 3 primary fatty acids making up Sandalwood Nut CO2 are Oleic Acid, Ximenynic Acid (not to be confused with Ximenic Acid) and Palmitic Acid.
Fatty Acids By Percentage Contained in Sandalwood Nut CO2:
- Oleic Acid – 〜48-56%
- Ximenynic Acid – 〜28-36%
- Palmitic Acid – 〜1-5%
Oleic acid is a common omega-9 fatty acid and is contained in most vegetable oils. It gets its name from olive oil in which it makes up around 50 to 80%. Sandalwood Nut CO2 Extract is also made up of a significant amount of Oleic acid at around 50% of its total fatty acids. Of the natural fatty acids in our skin, Oleic Acid makes up about a third. Power of the Seed author Susan Parker reminds us that on the skin “this fatty acid helps maintain suppleness, flexibility, and softness” – qualities we all want our skin to have. As our own sebum produces this fatty acid, Oleic Acid is well received by our skin, and can help prevent transepidermal water loss while also offering anti-inflammatory benefits. While good for most skin types, it may contribute to increased sebum production, thus oils high in this fatty acid may not be the best option for acne sufferers.
Ximenynic Acid, aka Santalbic Acid, occurs at up to 36% of Sandalwood Nut CO2 extract, and is a polyunsaturated fatty acid rarely seen in other oils. Polyunsaturated fatty acids are known to be unstable, and oxidize quickly. So, it may be wise to store Sandalwood Nut CO2 in the fridge (like most other carrier oils), and consider adding Vitamin E or other antioxidants to products you make containing it. Ximenynic Acid is known to have anti-inflammatory, antibacterial and antifungal properties. Ximenynic Acid is also thought to increase microcirculation in the skin, benefiting skin health and vitality. Due to the association of inflammation and cancer, Ximenynic Acid is being studied for possible anti-cancer activity as well2. Note that Ximenynic Acid in Sandalwood Nut Extract is not the same as Ximenic Acid (an Omega 9 fatty acid found in a fruit tree of the genus – Ximenia).
Palmitic Acid is another fatty acid found in our skin’s sebum as well as in Sandalwood Nut CO2 Extract. Because it is a saturated fatty acid, it is much more stable than Ximenynic Acid, thus helping balance its effect on shelf life of the overall extract. Palmitic acid is antimicrobial and as a saturated fatty acid, provides a protective barrier on the skin.
Sandalwood Co2 Extract for Facial Serums:
With its nourishing, anti-inflammatory, protective nature, and benefits of increasing microcirculation, this extract is an ideal choice in a facial serum, particularly for mature or aging skin. The folks at Eden Botanicals suggest using Sandalwood Nut CO2 Extract as up to 50% of your carrier oil blend in serums for aging skin, though it can be used as up to 100% of your carrier. Some sources suggest that the higher percentages may be most effective for dry skin. For oily skin, be more conservative and consider a very small percentage in a blend of a light oil such as Argan. Due to the significant percentage of Ximenynic Acid in this CO2, it may also be a good choice in a serum for sun-damaged skin.
Other Uses
You might explore including Sandalwood Nut CO2 Extract at around 20% or less in massage oil blends of sunflower, jojoba or any other of your favorite oils for massage or body oil.
So, if you love Sandalwood, and are looking for a unique carrier oil to include in your product making adventures, you might add Sandalwood Nut CO2 Extract to your ingredient palette. As you consider working with this lovely oil, remember: All species of Sandalwood are so highly prized and overused, that we are called upon, as responsible consumers, to be both aware and respectful of this resource and process of production. Though this is always good practice, it is particularly important for Santalum trees and the beautiful extracts and oils they offer to us. I hope you enjoy respectfully including this lovely oil in your natural skin care product making adventures!
References:
1Eden Botanicals, Sandalwood Nut CO2 Extract, https://www.edenbotanicals.com/products/essential-oils-pure-therapeutic-grade/co2-extracts/sandalwood-nut-co2.html
2Cai, F., Li, J., Liu, Y., Zhang, Z., Hettiarachchi, D.S., & Li, D. (2016). Effect of ximenynic acid on cell cycle arrest and apoptosis and COX-1 in HepG2 cells. Molecular Medicine Reports, 14, 5667-5676. https://doi.org/10.3892/mmr.2016.5920
National Center for Biotechnology Information (2023). PubChem Compound Summary for CID 5312688, Ximenynic acid. Retrieved February 28, 2023 from https://pubchem.ncbi.nlm.nih.gov/compound/Ximenynic-acid.
Parker, Susan M., (2014), Power of the Seed: Your Guide to Oils for Health & Beauty, Process Media, Port Townsend, WA
Wikipedia, Sandalwood, https://en.wikipedia.org/wiki/Sandalwood
Wikipedia, Ximenynic Acid, https://en.wikipedia.org/wiki/Ximenynic_acid