Nigella sativa L. seeds modulate mood, anxiety and cognition in healthy adolescent males

Previous studies conducted on animals linked consumption of Nigella sativa L. seeds (NS) to decreased anxiety and improved memory. The present study, which was carried out at a boarding school in Bangladesh, was designed to examine probable effect of NS on mood, anxiety and cognition in adolescent human males.

Forty-eight healthy adolescent human males aged between 14 to 17 years were randomly recruited as volunteers and were randomly split into two groups: A (n=24) and B (n=24). The treatment procedure for group A and B were one capsule of 500 mg placebo and 500 mg NS respectively once daily for four weeks. All the volunteers were assessed for cognition with modified California verbal learning test-II (CVLT-II), mood with Bond-Lader scale and anxiety with State-Trait Anxiety Inventory (STAI) at the beginning and after four weeks of either NS or placebo ingestion.

No parameter showed statistically significant variation between A and B in measurements in the beginning, but after 4 weeks of one capsule of NS 500 mg intake, there was statistically significant variation of mood within group B but there was not statistically significant variation between group A and B. No significant variation was found in state anxiety within groups and between group A and B but in case of trait anxiety, significant variation was found within group B but not between group A and B. In case of CVLT II, there was significant variation within B in immediate short-term recall at trial 4 and 5 whereas this difference was found only in case of trial 5 between group A and B. Within group B, short term-free recall, long-term free recall and long-term cued recall had statistical difference whereas between group A and B long-term free recall and long-term cued recall had statistical difference. No parameters had significant variation within group A after placebo intake for 4 weeks.

Over the 4 weeks study period, the use of NS as a nutritional supplement been observed to- stabilize mood, decrease anxiety and modulate cognition positively. However, long term study is suggested before using NS extensively.