Rosemary Protects Against Macular Degeneration And Eye Damage Caused By Light
A fascinating scientific study  has found that carnosic acid, a substance found in the herb rosemary, protects against oxidative stress, which is thought to contribute to age-related macular degeneration and retinal damage.Rosemary’s active components have already been established to be beneficial antioxidants and anti-inflammatories.  Previous studies have also established that carnosic acid crosses the blood-brain barrier , however this new study noted that carnosic acid also crosses the blood–retina barrier. The evidence showed that a very significantly greater number of photoreceptors survived in rats after exposure to damaging light. 
Age-related macular degeneration is the most common eye disease in the USA, affecting one third of people over the age of 76, resulting in blurred vision and even blindness. Risk factors are thought to include risk factors include smoking, sun/UV light exposure, high blood pressure and obesity.
As you may be aware, we have already reported on rosemary’s amazing positive effects on memory. It now appears that rosemary has further benefits to the brain than previously thought.
carnosic acid molecule
Small molecules such as the aromatic terpene components of essential oils are thought to cross the blood-brain barrier.  The science behind this is fascinating: Terpene molecules are astonishingly small: One drop contains a staggering 40,000,000,000,000,000,000 molecules and according to one source “Considering that it only takes one molecule of the right kind to open a receptor site and communicate with the DNA to alter cellular function, you can see why even inhaling a small amount of oil vapor can have profound effects on the body, brain, and emotions.”  The remarkable science of how essential oils and other scents affect the brain is still in its infancy as the topic is intricate and complex.
Rosemary has been prized for its flavor for centuries in addition to being noted for numerous health benefits. It can be taken as a culinary herb or as an extract.
Rosemary essential oil (see our full report on rosemary EO at this link) can also be used in aromatherapy, for example in a diffuser or added to a carrier oil for massage. Carnosic acid is also found in the leaves of sage. Dried leaves of rosemary or sage contain 1.5 to 2.5% carnosic acid. 
The team who discovered the benefits of rosemary for the eyes are also researching whether rosemary may be useful in preventing certain forms of dementia. Given rosemary’s associations old and new with memory enhancement, it seems possible that another great discovery may be on the way soon.
Note – this report is not medical advice. It’s still advisable to protect your eyes against harmful effects of UV rays.
 Protective Effect of Carnosic Acid, a Pro-Electrophilic Compound, in Models of Oxidative Stress and Light-Induced Retinal Degeneration (Retinal Cell Biology, November 2012)http://iovs.arvojournals.org/article.aspx?articleid=2127627 (free full text)
 Pharmacology of rosemary (Rosmarinus officinalis Linn.) and its therapeutic potentials. (Indian J. Exp. Biol. 1999) http://www.ncbi.nlm.nih.gov/pubmed/10641130
 Carnosic acid, a catechol-type electrophilic compound, protects neurons both in vitro and in vivo through activation of the Keap1/Nrf2 pathway via S-alkylation of targeted cysteines on Keap1. (J. Neurochem. 2008) http://www.ncbi.nlm.nih.gov/pubmed/17995931
 David Stewart, Ph.D.,R.A. – “The Blood-Brain Barrier.”http://www.rnoel.50megs.com/pdf/theblood.htm
 Carnosic acid – wikipedia https://en.wikipedia.org/wiki/Carnosic_acid