Most know rosemary as an aromatic, woody sprig found garnishing pan-roasted beef tenderloin, lamb shank, or salmon steak at a fine restaurant. Along with basil, lavender, oregano, and a number of other fragrant herbs, Rosmarinus officinalis is a member of the mint family.

Rosemary plants, which can easily reach 5 feet in height, feature small, bluish-purple flowers.1 Growing wild along coastal sea cliffs in the United States and Europe, rosemary’s leaves and stems hold volatile oils that give off entrancing fragrances and flavors — and rosemary also may hold the key to relieving muscle and nerve pain. 


Background


In 16th-century Europe, rosemary was often burned in the rooms of sick people, as its pungent aroma was thought to act as a disinfectant, killing any residual germs.2 Before that, the ancient Greeks believed rosemary to be a magical plant that could strengthen memory.2 To this day in some cultures, rosemary sprigs are scattered on the grave of a beloved family member as a symbol that they will not be forgotten. 


Science


R. officinalis is rich in iron, calcium, and vitamin B6.3 Aside from these nutritional aspects, rosemary has been credited with improving cognition and memory.4

A 2003 study, designed to assess the olfactory impact of rosemary and lavender oils on cognitive performance and mood in healthy adults, measured accuracy and productivity in 144 office workers.4 After randomizing the workers into groups of negative control, lavender aroma, or rosemary aroma, researchers infused these aromas into the ventilation system. Workers exposed to the rosemary aroma showed improved memory and accuracy, whereas both the control and lavender groups were significantly less alert than those subjects exposed to rosemary oils.4

In a second study examining the herb’s effect on cognition, researchers enrolled 28 older adults (mean age 75 years) into a placebo-controlled trial using an oral rosemary formulation.5 Baseline function was assessed using the cognitive drug research computerized assessment system (COGDRAS). Repeat assessments were conducted at intervals of six hours post-ingestion of rosemary or placebo. The lowest dose of rosemary, more or less equivalent to a dietary level, had a positive effect on cognition and speed of memory when compared with placebo. 


In animal studies exploring the potential toxicity of R. officinalis in rats, researchers found unexpected hepatoprotective and antimutagenic activities.6 These findings correlate with those of another trial examining the effect of a R. officinalis extract on two types of human cancer cell lines: A standardized extract of rosemary was applied to human leukemia and breast cancer cells while the rate of tumor cell proliferation was monitored.7 A significant inhibitory effect on cell division indicated the possibility of using R. officinalis extract in antineoplastic therapy. 


In another laboratory study, scientists applied R. officinalis extract to cultures of Chang liver cells and RAW 264.7 cells (mouse leukemic monocyte macrophage cell line).8 Treated cell lines showed a dose-dependent inhibition of tumor necrosis factor alpha and no evidence of cytotoxicity.


Rosemary oil was applied to three Gram-positive bacteria, three Gram-negative bacteria, and two fungi to monitor a time-kill dynamic.9 Rosemary oil showed a positive MIC (mean inhibitory concentration) with results indicating both a synergistic and antagonistic potential for this compound.9

Anti-inflammatory actions also have been illustrated using rosemary extracts. In two separate studies, rosemary exhibited inhibitory activity against lipid peroxidation and activation of antioxidant enzymes as well as the ability to stabilize and protect normal cellular membranes against radial propagation.10,11

Safety, interactions


Rosemary interferes with the gastric absorption of iron and could worsen cases of iron-deficiency anemia.12 Rosemary also appears to have slight epileptogenic activity.12 Rosemary is not recommended for use during pregnancy or lactation and has not been studied for safety in infants and children.12 Rosemary also inhibits platelet aggregation and should not be used in patients with an increased risk of bleeding or those on blood-thinning agents.13

How supplied, dosage


Rosemary oils and extracts in fresh and dried form can be found at most health-food stores. 


Summary


Rosemary may be complementary to traditional medicines in certain cases. As always, known contraindications must be noted. So, the next time a sprig of rosemary appears on your plate, consider not pushing it aside.

References


  1. Complementary Medicine: rosemary page. University of Maryland Medical Center website.
  2. History of the Magical Rosemary Plant page. Ad Lunam Labs, Inc. website.
  3. Natural Nutrient Database page. United States Department of Agriculture website. 
  4. Moss M, Cook J, Wesnes K, Duckett P. Aromas of rosemary and lavender essential oils differentially affect cognition and mood in healthy adults. Int J Neurosci. 2003;113:15-38.

  5. Pengelly A, Snow J, Mills SY, et al. Short-term study on the effects of rosemary on cognitive function in an elderly population. J Med Food. 2012;15:10-17.

  6. Fahim FA, Esmat AY, Fadel HM, Hassan KF. Allied studies on the effect of Rosmarinus officinalis L. on experimental hepatotoxicity and mutagenesis. Int J Food Sci Nutr. 1999;50:413-427.

  7. Cheung S, Tai J. Anti-proliferative and antioxidant properties of rosemary Rosmarinus officinalis. Oncol Rep. 2007;17:1525-1531.

  8. Peng CH, Su JD, Chyau CC, et al. Supercritical fluid extracts of rosemary leaves exhibit potent anti-inflammation and anti-tumor effects. Biosci Biotechnol Biochem. 2007;71:2223-2232.

  9. Fu Y, Zu Y, Chen L, et al. Antimicrobial activity of clove and rosemary essential oils alone and in combination. Phytother Res. 2007;21:989-994.

  10. Takaki I, Bersani-Amado LE, Vendruscolo A, et al. Anti-inflammatory and antinociceptive effects of Rosmarinus officinalis L. essential oil in experimental animal models. 
J Med Food. 2008;11:741-746.

  11. Pérez-Fons L, Garzón MT, Micol V. Relationship between the antioxidant capacity and effect of rosemary (Rosmarinus officinalis L.) polyphenols on membrane phospholipid order. J Agric Food Chem. 2010;58:161-171.

  12. Use of rosemary extracts as a food additive page. European Food Safety Authority webpage. A reprint from the EFSA Journal. 2008;721:1-29.
  13. Naemura A, Ura M, Yamashita T, et al. Long-term intake of rosemary and common thyme herbs inhibits experimental thrombosis without prolongation of bleeding time. Thromb Res. 2008;122:517-522. 

  14. All electronic documents accessed on December 3, 2012
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