INCREASED MENTAL CONCENTRATION
One of the main traditional uses of rosemary oil is to increase mental concentration and memory. This is supported by a RCT of 140 subjects that found that rosemary produced a significant enhancement of performance for overall quality of memory and secondary memory factors, with an impairment of speed of memory compared with controls. Further support comes from an observational study in 40 adults where 3 minutes’ exposure to rosemary essential oil was seen to decrease frontal alpha and beta power, suggesting increased alertness. Subjects felt more relaxed and alert, had lower anxiety scores and were faster, but not more accurate, at completing maths computations. A small, case series of 10 subjects also found that rosemary essential oil had positive effects on mood concentration and memory.
The traditional use of rosemary to stimulate hair growth is supported by a 7-month, randomised double-blind study of 86 patients that found rubbing oils (thyme, rosemary, lavender and cedarwood) into the scalp helped with alopecia for 44% of patients versus 15% of controls. Although promising, the role of rosemary as a stand-alone substance in achieving these results is unclear.
Rosemary is widely acknowledged to be a carminative and is used internally as an antispasmodic for mild cramp-like gastrointestinal and biliary upsets, as well as for tension headache, renal colic and dysmenorrhoea. It is also used to relax bronchial smooth muscle in the treatment of asthma, but controlled studies are unavailable to determine clinical efficacy.
CHEMOPROTECTIVE AND ADJUNCT IN CANCER THERAPY
Rosemary was used topically to treat cancer in ancient Greece and South America. Although controlled trials are yet to be conducted, it has been suggested that rosemary may delay and inhibit tumour formation in women with breast cancer and that it has potential as a preventive agent or as an adjunct in cancer therapy. An in vitro study in human breast cancer cells found that rosemary extract increased the intracellular accumulation of commonly used chemotherapeutic agents, including doxorubicin and vinblastinevia inhibition of P-glycoprotein, thereby overcoming multidrug resistance in tumour cells. Clinical studies are required to determine whether the effect is significant.
Rosemary: Other Uses
When applied topically, rosemary oil may stimulate the blood supply and act as supportive therapy for rheumatic conditions and circulatory problems. Topically, rosemary has also been used for wound healing, as an insect repellent, and to treat toothache and eczema. Rosemary extract cream preparations have been shown to protect against sodium-lauryl-sulfate-induced irritant contact dermatitis.
In a small, uncontrolled, prospective pilot study of eight women, rosemary in combination with 11 other botanical extracts was found to relieve menopausal symptoms.
Rosemary: Dosage Range
• Infusion of dried leaf: 2-4 g three times daily.
• Fluid extract (45%): 1-4 mL three times daily.
• Topical preparations containing 6-10% essential oil can be applied directly to skin. Often a carrier oil, such as almond oil, is used as a vehicle for the essential oil.
• Bath additive: 10 drops essential oil added to bath.