Rosemary is an evergreen shrub native to the Mediterranean that’s revered for its culinary and therapeutic uses alike. Its pungent aroma and sharp lemon-pine flavor make it popular in French, Italian and other cuisines, and it’s been used for centuries as a tool to strengthen memory.1
A member of the mint family along with oregano and basil, rosemary is as versatile in medicine as it is in cooking. With potent antibacterial and antioxidant properties, rosemary is often used to help extend the shelf life of perishable foods, and rosemary extract is approved as a natural antioxidant for food preservation in the European Union.2
Among its many other pharmacologically validated uses in medicine are anticancer, antidiabetic, anti-inflammatory and hepatoprotective properties, but it’s also notable for its ability to improve cognitive function.3 In fact, it’s said that in ancient Greece, students would wear rosemary garlands while studying and would eat the herb to improve memory.
“Herball,” a classic plant reference written by English botanist John Gerard and published in 1597, even described rosemary as a “comfort” to the brain useful for improving memory and inward senses while being “especially good for infirmities of the head and brain.”4 Numerous modern studies support rosemary’s brain-boosting potential, courtesy of polyphenolic diterpenes such as carnosic acid.
Small Amounts of Rosemary Yield Cognitive Benefits
What is perhaps most exciting about rosemary is that benefits have been demonstrated at very low amounts, such as those you might use while cooking. In a study of 28 adults with a mean age of 75 years, dried rosemary leaf powder was blended with tomato juice in order to study its effects on cognitive function in older people.5 The subjects received juice with either no rosemary, which served as a placebo, or a dose of:
- 750 milligrams (mg) (0.15 teaspoons)
- 1,500 mg (0.3 teaspoons)
- 3,000 mg (0.6 teaspoons)
- 6,000 mg (1.2 teaspoons)
The lowest dose led to improvements in speed of memory, which may be a predictor of cognitive function during aging, compared to placebo, while the highest dose led to a memory impairment. This suggests that using rosemary at “culinary” doses may be best for your brain.
“In conclusion, rosemary powder at the dose nearest normal culinary consumption demonstrated positive effects on speed of memory … The result points to the value of future studies on effects of low doses of rosemary on memory and cognition over the longer term,” the researchers noted.6
What’s more, the subjects also subjectively reported “significantly less impairment to their alertness compared with placebo” at the lowest dose, which the researchers said “strengthens the findings, particularly as there is research suggesting that mood is an underlying driver of cognitive function.”7
Rosemary Protects the Brain From Free Radicals
Carnosic acid is one of the active ingredients in rosemary, and researchers believe it helps protect the brain by staving off free radical damage that may lead to stroke and neurodegenerative conditions.
In fact, researchers from Iwate University in Japan and colleagues found that carnosic acid activates a signaling pathway that protects brain cells from free radicals and is activated by the free radical damage, which means it’s innocuous until it’s needed.8,9 Researchers detailed this impressive process in Advances in Experimental Medicine and Biology:10
“Carnosic acid, one of the major phenolic constituents of rosemary, is a pro-electrophile specifically activated by the oxidative stress pathological state resulting in its conversion from the hydroquinone to the oxidized quinone form, before it activates the Keap1/Nrf2 pathway leading to gene induction of the antioxidant response element (ARE) and gene products that protect against oxidative stress.”
Rosemary diterpenes are also known to inhibit neuronal cell death and are multifunctional in nature, offering antioxidant-driven neuronal protection against brain inflammation and amyloid beta formation, which may be implicated in Alzheimer’s disease.11
The amount of carnosic acid in dried leaves is thought to range from 1.5% to 2.5%, although higher amounts have been recorded. Environmental factors, including sunlight and water exposure, are known to affect the concentration of carnosic acid and other diterpenes in rosemary.12
Could Rosemary Help Prevent or Treat Alzheimer’s?
Drug companies have promoted off-label usage of anti-inflammatory COX-2 inhibitor drugs for treating Alzheimer’s, but rosemary does this naturally. “If a synthetic COX-2 inhibitor could prevent Alzheimer’s disease, so could a natural COX-2 inhibitor,” said the late Jim Duke, an emeritus member of the American Botanical Council Board of Trustees.13 Rosemary contains numerous natural COX-2 inhibitors, including:14
A 2011 review also concluded that “carnosic acid [in rosemary] may be useful in protecting against beta amyloid-induced neurodegeneration in the hippocampus” and reduced cellular death in certain brain regions.15
It’s possible that rosemary compounds, including not only carnosic acid but also carnosol and rosmarinic acid, could be protective against a range of neurological disorders, including Alzheimer’s and other forms of dementia, Parkinson’s disease, epilepsy and migraines, wrote researchers in Natural Bio-active Compounds, who noted:16
“… R. officinalis L. [rosemary] and its bio-active metabolites [have a protective role] against various neurological disorders via targeting amyloid-beta (A-β) aggregation, neuronal cell death, acetylcholinesterase (AChE), neuroinflammation, β-secretase (BACE-1) activity, mitochondrial redox status, etc.
Based on the multifunctional nature due to effective bio-active secondary metabolites, R. officinalis can be a terrific alternative therapeutic source against many neurodegenerative diseases.”
Speaking of migraines, a 2013 study published in Food Chemistry points to rosemary as having a long history in tradition for treating headaches due to the potent anti-inflammatory and pain-relieving compounds it contains.17
To use rosemary essential oil for migraine headache relief, try adding one or two drops to a cup of tea, water or soup and drinking it. You can also mix two drops of rosemary oil with two drops of peppermint oil and a teaspoon of coconut oil to massage your forehead, temples and the back of your neck.
Healthy Adults May Benefit From Rosemary’s Brain Boost
Rosemary may also be useful for improving cognitive function in healthy adults. In one example, eight healthy adults consumed either 250 milliliters (8.4 ounces) of rosemary water or plain mineral water, then completed a series of cognitive tasks.
Multiple statistically significant beneficial effects were noted among those who drank the rosemary water, including increased levels of deoxygenated blood in the brain, an indication that rosemary may facilitate oxygen extraction during times of cognitive demand — a previously unknown finding.18
In addition, those who consumed rosemary had a 15% average boost compared to the placebo group when it came to performing working memory tasks. The benefits were described as similar to those previously demonstrated via the inhalation of the aroma of rosemary essential oil. Study author Mark Moss of the U.K.’s Northumbria University said in a news release:19
“[R]osemary offers a number of interesting possible health promoting applications, from antioxidant and antimicrobial to hepatoprotective and antitumorigenic activity …
The results of this research show there are statistically reliable improvements in memory function thanks to the ingestion of … Rosemary Water. In fact, I’d say that the shots act like a turbo charger for the brain.”
Even Smelling Rosemary May Improve Cognition
If you’re not fond of rosemary’s flavor, you can still get a quick boost simply by inhaling its scent. The aroma of rosemary essential oil led to a significant enhancement of performance in memory quality and secondary memory factors in a study of 144 people.20
Rosemary’s characteristic scent comes from 1,8-cineole, which is also found in bay leaves, wormwood, sage and eucalyptus. It’s possible that 1,8-cineole, a common monoterpene found in many essential oils, is responsible for some of its aroma benefits, as its been linked to performance on cognitive tasks.
When 20 volunteers performed a series of math problems and other cognitive tasks while in a cubicle diffused with the aroma of rosemary, their performance improved in relation to higher concentrations of 1,8-cineole, levels of which were measured via blood testing. Both speed and accuracy improved in association with 1,8-cineole concentrations.
“These findings suggest that compounds absorbed from rosemary aroma affect cognition and subjective state independently through different neurochemical pathways,” the researchers, which included Moss, explained.21
A small study in 2009 also found that 28 days of aromatherapy involving rosemary, lemon, lavender and orange essential oils helped enhance cognitive function, especially in Alzheimer’s patients, with no side effects.22
What Else Is Rosemary Good For?
Beyond your brain, rosemary also offers a host of additional benefits that extend bodywide. This powerful herb may help heart health, including after a heart attack, while favorably affecting body weight and dyslipidemia. Rosemary also offers pain-relieving qualities and the potential to fight infection, while also protecting your liver, fighting the proliferation of tumor cells and even reducing stress and anxiety.23
Rosemary, in fact, “may control physiological disorders similar to or superior to the usual medications,” according to a review in the Journal of Biomedical Science.24 While you can find rosemary in a variety of forms, from extracts and supplements to teas and essential oils, one of the best ways to enjoy the benefits of this perennial plant is to grow it in your own garden. Then, you’ll have access to fresh rosemary whenever you need it.
Fortunately, rosemary is easy to grow and thrives on little care. In warmer climates it grows quicker, so you’ll want to plant them at least 3 feet apart to allow ample room for growth. If you live in northern climates and commonly experience freezing weather lower than 15 degrees F, you’ll want to grow your rosemary in a pot and bring it in during the winter months.
When harvesting rosemary, snip the tender end shoots that aren’t woody, as they’re best for cooking. It’s simple to strip the leaves once the stems are dry simply by running your fingers along the stem. Feel free to use rosemary generously in your cooking, as well as diffuse the essential oil around your home, especially when you feel like you need a brain boost.