Macadamia Oil: Evidence and Safety

Quick safety points

• Macadamia is a tree nut, and tree nut allergies are often severe and can last for life. If you have a tree nut allergy, ask your allergy doctor before putting macadamia oil on skin or taking it by mouth. [8]
• Skincare made for eczema often contains nut ingredients. In a Polish store survey, almonds and macadamia nuts were among the most common food-allergen ingredients, and the authors warned that food-derived ingredients on inflamed skin may promote sensitization. [7]
• US food-labeling law does not count a highly refined oil as a "major food allergen". That is a food-label rule, not a cosmetic rule, and we did not find a source we read that measured nut protein in macadamia oil. [9]
• Macadamia nuts are listed as toxic to dogs. The source we read says nothing about the oil. [11]
• The "omega-7" claim is not proven in people: reviews say benefits of purified palmitoleic acid supplements remain unproven. [4][5]

What macadamia oil is

Macadamia oil comes from the kernel (the nut meat) of Macadamia integrifolia Maiden & Betche, a tree in the Proteaceae family. [1] The kernels are pressed to release the oil; research papers also describe other ways of extracting it, such as water-and-enzyme extraction. [13] In a study of 15 cultivars grown in China, pressed oils were mostly oleic acid (about 57 to 63%) and palmitoleic acid (about 12 to 19%), with small amounts of tocopherols (a vitamin E family), squalene and polyphenols. The place where the nuts grew shaped the oil more than the cultivar did. [2] In another analysis of commercial oils, palmitoleic acid was about 21 to 23%. [3] So the numbers on any bottle will vary.

Palmitoleic acid is called "omega-7". It is a fatty acid the human body also makes. [5] How the oil feels on skin (often called light to medium and quick to absorb) is a common description in cosmetic writing; we did not find a source we read that measured it.

How it is used

• Skin: as a plain oil, or as an ingredient in creams, lotions and balms.
• Hair and scalp: as a leave-in or pre-wash oil. No trial we read tested it on hair.
• Massage: as a massage oil. This is a fixed oil, so essential-oil dilution charts do not apply to it.
• Food: the oil is also eaten, and the nuts are a common food. For nutrition, see macadamia nuts.

Traditional use (not proof)

The sources we read do not describe a traditional medicinal use of macadamia oil. The skin and hair uses seen today are mostly marketing and cosmetic use. A product being sold for years is not evidence that it works.

What research shows

We found one small human study of macadamia oil on skin and none on hair, wounds, eczema or stretch marks.

Lab and animal findings: reviews describe palmitoleic acid acting on insulin signaling, liver fat handling and inflammation in cells and animals. Results differ between studies and its role in people is not fully understood. [4][5] None of this tests a skin or hair product.

Proper evidence not found in the sources we read for macadamia oil helping hair growth, scars, stretch marks, eczema, acne or wounds.

Claims checked

• "Macadamia oil is rich in omega-7, so it fights aging." The oil does contain palmitoleic acid, but amounts differ by origin and product. [2][3] Reviews found benefits of purified palmitoleic acid unproven in people, and neither review tested skin aging. [4][5] The one skin study read compares two creams that both had the oil. [6]
• "Macadamia has the most omega-7." Not among the products compared: in one analysis, algal oil and fish-oil concentrates had far more palmitoleic acid than macadamia oil, and avocado oil had less. Sea buckthorn products varied widely. [3]
• "It is just like our skin's own oil." We did not find a source we read that tests this for macadamia oil, so we cannot confirm it.
• "It will not clog pores." We did not find a source we read that tested macadamia oil for pores or acne. The popular ratings are discussed on comedogenic ratings checked.
• "Refined macadamia oil is safe for nut-allergic people." The FDA statement that highly refined oils are not a "major food allergen" is about food labeling. [9] A large cosmetic safety review found 244 plant-derived oils safe as used in cosmetics, but the abstract we read does not say whether people with nut allergy were considered. [10] Ask an allergy doctor.

Forms, grades and why they matter

• Cold-pressed or pressed, unrefined: kernels are pressed without much heat. In one lab comparison, water-and-enzyme extraction gave an oil with lower peroxide and acid values (signs of spoilage) than a pressed oil, so how the oil is made affects its freshness. [13]
• Refined: processed further. Whether a specific refined oil still contains nut protein depends on the product; we did not find a source we read that measured it. [9]
• Cosmetic and food grade, and blends: a bottle labeled "macadamia" may be a blend, or an ingredient in a cream. Read the ingredient list. On labels you may see Macadamia integrifolia seed oil. See cosmetic vs food grade oils.

Safety and cautions

• Tree nut allergy: tree nut allergies are often severe and can cause anaphylaxis, which is treated with epinephrine. [8] Food-based allergens in skincare can matter more when the skin barrier is broken. [7]
• Patch test: the sources we read do not report macadamia oil skin reactions. A patch test is still a sensible step with any new product; see patch testing.
• Eczema and babies: the survey found nut-derived ingredients in skincare marketed for eczema and in products for infants and children. [7] Check the label and ask a clinician.
• Dogs: the ASPCA lists macadamia nuts as toxic to dogs, with weakness, vomiting and tremors. The page does not mention the oil. [11] Keep nuts and any oily nut products out of reach and call a vet or poison control if a dog eats some.
• Pregnancy, breastfeeding and medicines: not described in the sources we read.

Quality and storage

Researchers describe macadamia oil as rich in monounsaturated fat but susceptible to oxidation (spoiling on contact with air). [12] We did not find a source we read that gives a shelf life for cosmetic use. A sour, crayon-like or paint-like smell suggests it has gone off; see rancidity and storage of natural oils. Keep the bottle closed, cool and out of sunlight.

Related pages

• Carrier oils explained
• Check before you use natural oils and butters
• Patch testing natural oils and butters
• Macadamia nuts (food)
• Nut and seed allergy basics
• Comedogenic ratings checked