Fennel Seeds are very high in antioxidants. It has anti-inflammatory properties thus benefit people suffering from arthritis and joint pains. Helps lower blood pressure naturally. The fennel seeds are extensively used as breath freshener. Saunf has the ability to control and bring down high blood pressure. It also contains potassium which is known to have many heart-friendly properties. Helps prevent constipation: Fennel seeds have plenty of soluble dietary fibre.