Like in caraway, fennel seeds too are rich source of dietary fiber. 100 g seeds provide 39.8 g of fiber. Much of this roughage is metabolically inert insoluble fiber, which helps increase bulk of the food by absorbing water throughout the digestive system and easing constipation condition.
In addition, dietary fibers bind to bile salts (produced from cholesterol) and decrease their re-absorption in colon. It thus helps lower serum LDL cholesterol levels. Together with flavonoid anti-oxidants, fiber composition of fennel helps protect the colon mucus membrane from cancers.
Fennel seeds compose of health benefiting volatile essential oil compounds such as anethole, limonene, anisic aldehyde, pinene, myrcene, fenchone, chavicol, and cineole. These active principles in the fennel are known to have antioxidant, digestive, carminative, and anti-flatulent properties.
Fennel seeds are concentrated source of minerals like copper, iron, calcium, potassium, manganese, selenium, zinc, and magnesium. Copper is required in the production of red blood cells. Iron is required for red blood cell formation. Zinc is a co-factor in many enzymes that regulate growth and development, sperm generation, digestion and nucleic acid synthesis. Potassium is an important component of cell and body fluids that helps controlling heart rate and blood pressure. Manganese is used by the body as a co-factor for the powerful anti-oxidant enzyme, superoxide dismutase.