BACKGROUND:Most cultures have used the herbs available in their locale for medicinal purposes. While herbs from regions such as the Amazon or systems such as traditional Chinese medicine are well known in the West, those of Arabic medicine have received less attention – with the notable exception of the opium poppy. Yet the region around the Middle East has been the cradle of much medical innovation, from Hippocrates to the medieval Arabic physician Avicenna, and the Jewish physician, Maimonides. Arabic medicine took a scientific approach to herbs, examining hundreds of plants and developing long-respected pharmaceutical knowledge.
As with any region undergoing change and turmoil, knowledge of indigenous herbal remedies is threatened. Almost one-third of the native species in some regions of the Middle East are now endangered. To compensate for such losses, and develop local economies, some regions are seeking to cultivate and conduct research on herbs with medicinal potential.
One such herb is Nigella sativa, a small flowering plant with a fruit packed with small black seeds. These are sometimes called blackseed, black cumin or black caraway, although these names are also given to other spices. Their Arabic name literally means "seed of blessing" because of the wide array of health benefits ascribed to the seeds and their oil. Both Jewish and Muslim prophets refer to Nigella, with Mohammed reported to have described the seeds as a remedy for "every illness except death". They are widely used as a nutritious food and to treat inflammatory diseases such as asthma, psoriasis and rheumatism.
EVIDENCE FROM STUDIES
Extensive investigations have been conducted on Nigella seeds and their oil. They contain many nutrients, including polyunsaturated fatty acids, B vitamins, vitamin E, minerals and amino acids. Administering the oil to animals led to improved blood lipid profiles, most likely due to its fatty acids. The seeds and oil also have high antioxidant activity, which may contribute to protection against some illnesses. Other laboratory studies have shown that the seeds and purified components have anti-inflammatory effects.
While such research supports the general nutritional value of Nigella seeds, and helps identify their active ingredients, few studies have examined their specific impact on human health and asthma in particular. Nigella seeds received quite a bit of publicity in 2007 when a study of 29 asthma patients was published. The adults were randomly assigned to either Nigella seed oil or a placebo. The asthmatic symptoms of those taking the Nigella oil had significantly improved after one, two and three months.
While some hailed the oil as a cure for asthma, further studies with much larger numbers of patients are needed to verify these results. Similarly positive results were obtained in another study by the same Iranian researchers last year. However, this study involved only 15 asthma patients.
In other areas, a study with healthy volunteers found that consuming 1g of Nigella seeds twice daily had a positive impact on the immune system. This may be helpful in warding off illnesses. Another study with about 100 healthy adults found that those taking a Nigella seed extract for eight weeks had their blood pressure lowered by 2mmHg more than the control group. However, this is a relatively small reduction which would need to be monitored over a longer period of time.
PROBLEMATIC ASPECTS
The clinical studies to date did not report adverse effects. In general usage, allergic reactions have occurred to Nigella seeds. Some animal research raised questions about potential liver problems, but these have not been reported in humans.
RECOMMENDATIONS
Nigella seeds and oil are highly nutritious and have a long tradition of medicinal use. Few controlled studies in humans have been conducted, but their results are encouraging. Much further research with more patients is needed before some of the claims being made about the seeds can be accepted. The seeds and oil can be recommended as a source of essential fatty acids and vitamins, but whether they effectively prevent or treat any specific disease remains to be seen.
Dónal O’Mathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer in the school of nursing, Dublin City University
