Grapefruit Seed Extract (GSE) acts as a natural preservative to help stop the growth of harmful micro-organisms. GSE is useful in a variety of skin treatments such as acne and dermatitis and works well for clogged skin because it removes the build-up of oil in the pores. A review of 16 studies found that taking GSE daily significantly reduced blood pressure. Another study found that consuming GSE improves kidney function.