Fennel Tea for Constipation, Indigestion, IBS & Bloating:The tea is considered very useful to help indigestion, bloating and constipation because of the oils found in these seeds. Fennel seeds contain estragole, fenchone and anethole, which contribute to the plant's antispasmodic and anti-inflammatory properties. For those with IBS, the volatile oils found in fennel seeds can help kick start digestion by promoting the production of gastric enzymes. For its multitude of gastrointestinal benefits, fennel tea is sure to help the digestive tract be healthy and happy.