Fennel seeds contain a specific aromatic essential oil that possesses antibacterial properties that help to freshen your breath. 
The goodness of fennel seed essential oils stimulates the secretion of digestive juices and enzymes that improves your digestion. 
Fennel seeds are rich in potassium that regulates the fluid amount in the bloodstream. It helps to control your heart rate and blood pressure.
The high amount of phytonutrients present in fennel seeds helps to clear sinuses. These tiny seeds offer bronchial relaxation that helps to reduce symptoms of asthma, bronchitis and congestion. 
Many studies suggest that fennel seeds have anti-cancerous properties. They have powerful antioxidant properties that neutralize free radicals and beat oxidative stress. It may be the reason that prevents the development of cancer.