Claim

It has been said that sniffing rosemary increases memory.

Verdict

Sniffing rosemary actually slowed speed of memory in a randomised controlled trial in Britain.

Origin

The British Daily Mail featured a post on the ‘memory enhancing effects of rosemary’. This was followed by a piece on Robert Tisserand’s website (a leading manufacturer and promoter of essential oils) and worldhealth.net.

In Shakespeare’s Hamlet, Ophelia says, “There’s rosemary, that’s for remembrance.” (Hamlet, iv. 5.). The British link to rosemary continues. Researchers in the University of Northumbria studied the effects of the essential oils of lavender (Lavandula angustifolia) and rosemary (Rosmarlnus officinalis) on cognitive performance and mood in healthy volunteers (1). Tisserand pure essential oils were used in the study.

One hundred and forty four healthy volunteers participated in this randomized controlled study. Participants performance was compared across conditions of ambient rosemary aroma, ambient lavender aroma or no aroma (control).

The study volunteers were told that they were helping to validate a new cognitive assessment tool and they were not aware of the true purpose or design of the study.

The study assessed immediate word recall, reaction time, picture recognition and mood. Information from these mini-tests were combined into general categories including quality of memory, speed of memory, alertness and mood.

Inhaling lavender reduced the quality of working memory and slowed reaction time. Inhaling rosemary oil improved overall quality of memory but also produced an impairment of speed of memory compared to controls. Both the control and lavendar group were less alert than the rosemary group. The control group was less content than the lavendar and rosemary group.

The rosemary oil was well tolerated in the study but rosemary is known to cause allergic dermatitis and asthma (23).

When the Tisserand team reported on the study on their website, they raised the possibility that the beneficial effect of rosemary on quality of memory may just have been a placebo effect. This is interesting considering the fact that none of the study participants were aware of the use of the essential oils. Perhaps they should have talked about observer effect rather than placebo effect.

This study had very complex assessments of memory which makes it difficult to make any generalizations about the effect of rosemary on memory. Despite this, numerous other blogs have claimed that ‘rosemary improves memory’. It is worth noting that one popular blog talks about the ‘Mark Ross rosemary paper’ but the lead author on the study is actually Mark Moss.

More recent studies have shown that extracts from spearmint and rosemary have beneficial effects on learning, memory and brain tissue markers of oxidation that occur with age in laboratory mice (4).

The authors of the British study continue to try to figure out the relationship between rosemary and memory but have not reached any definite conclusions yet (5).