Efficacy of ground flaxseed on constipation in patients with irritable bowel syndrome

We studied in an investigator-blinded trial the efficacy of roughly ground partly defatted flaxseed on constipation in 55 patients suffering from constipation predominant irritable bowel syndrome. Fifty-five patients were randomised to receive 6-24 g/d either flaxseed or psyllium for 3 months. During the blinded treatment period 26 patients received flaxseed and 29 received psyllium. In flaxseed group, constipation and abdominal symptoms were decreased significantly (p=0.002) whereas in psyllium group the reduction was not statistically significant. After the blinded treatment period, the difference between groups was statistically significant in constipation (p=0.05) and in bloating and pain (p=0.001). Forty patients continued to the open period with flaxseed treatment only, 18 from flaxseed group and 22 from psyllium group. After the open period of 3 months, constipation and abdominal symptoms were further significantly reduced (p=0.001). Safety laboratory values were unchanged with exception of serum thiocyanate that increased from 40.9 to 153.7 mmol/l in flaxseed group. After additional 3 months treatment with flaxseed this value was decreased to 104 mmol/l. Blood cadmium was normal (3.4 nmol/l) after six months flaxseed treatment.