Do you have sparse eyebrows and want those thick, dark eyebrows that everyone envies? Castor oil could be your answer. Discover the relationship between castor oil and eyebrow growth, why it works, how to use it and more! Castor Oil and Eyebrow Growth | Why it Works The reason why castor oil WORKS is because it contains a special and unique compound called rinoleic acid. Found only in the castor bean, rinoleic acid has a special molecular structure and contains many therapeutic properties that can help hair grow. Rinoleic acid is rich in anti-inflammatory properties that can help reduce swelling, Continue Reading