Encyclopedia · oil or butter
Sunflower seed oil
In the classic Marico study sunflower oil did nothing for protein loss, though later work suggests oils of its type can penetrate hair.
What it is
A linoleic-acid-rich triglyceride oil, described by the study authors as the second most used base in Indian hair oils.
How it works
Rele and Mohile concluded that sunflower oil did not reduce protein loss, blaming bulky unsaturated chains. Rele 2003 However, sunflower oil films thinned over time like coconut oil Keis 2005, and Procter & Gamble found unsaturated triglycerides penetrated well Marsh 2024, so the conflict is unresolved.
What the studies show
- Sunflower oil did not reduce protein loss, in a study from Marico, a coconut-oil seller. Rele 2003
- The sunflower oil film thinned over time and with heat. Keis 2005
- No randomised head-to-head human trial of hair oils exists (see oils and hair).
How it's used in studies
The study used pre- and post-wash application at defined tress doses.
Side effects and safety
Low risk. Linoleic-rich oils oxidise and can go rancid.
Bottom line
A cheap emollient that was not shown to prevent damage in the one head-to-head test. We are unsure, and the evidence conflicts. Whether unsaturated oils penetrate and help is an open question.
Studies 3
Rele AS, Mohile RB. Effect of mineral oil, sunflower oil, and coconut oil on prevention of hair damage. J Cosmet Sci. 2003
Tested: mineral, sunflower and coconut oil
Result: Mineral oil did not reduce protein loss from combing in either undamaged or damaged hair; coconut oil did.
Read the study ↗Keis K et al. Investigation of penetration abilities of various oils into human hair fibers. J Cosmet Sci. 2005
Tested: several oils
Result: Oil films thicker than about 0.5 micrometres hid the cuticle scale structure, and the film thinned as oil soaked in, faster with heat.
Read the study ↗Marsh JM et al. Penetration of oils into hair. Int J Cosmet Sci. 2024
Tested: pure plant triglyceride oils including coconut, Camellia oleifera and safflower
Result: Several plant oils entered the hair's lipid-rich cement and improved single-fibre fatigue strength; shorter and unsaturated chains penetrated better.
Read the study ↗Related
- Coconut oilThe best-studied hair oil; in lab work it cut protein loss and fatigue damage when used before washing, but almost all studies come from coconut-oil sellers.
- Mineral oilA cheap, non-penetrating hydrocarbon oil that coats hair for shine and slip but, unlike coconut oil, did not protect against protein loss in lab tests.
- Olive oilA traditional hair oil whose only supporting hair data is that its film thinned on hair like coconut oil did, suggesting some absorption.
- Oils and hairOils coat hair and some enter it, which can cut damage from washing, but they do not repair split ends or add moisture.