Garlic, Onions, Rosemary, and Sage - Interesting Health Findings for Brain and BodyThis week, the New York Times reported that compounds in rosemary reduce heterocyclic amines (HAs)- a type of carcinogen created when meats are cooked at high temperatures. Previous studies have shown similar benefits from combining allium vegetables (garlic and onions) with grilled meats. The research suggests that if you marinate your meat in rosemary, garlic, and/or onions, the HAs are significantly reduced, and your carcinogen burden is lessened.

If you like a summer barbeque as much as I do, this is good news. But right about now you might be asking yourself: What does this have to do with brain health, exactly?

Actually, a lot. Things like herbs and garlic have long been thought to have medicinal and health value, for both physical and mental ailments, but it’s only in recent years that we have a preponderance of published scientific studies that have begun to test some of those claims. As common sense might suggest, some of these foods and herbs have multiple benefits for both brain and body. Of course, this is a very new field and as such I have to mention that age-old caveat: further research must be done to definitively make claims about the compounds found in these foods. For example, even if benefits are found in a study, it’s not clear how much is the optimal amount to ingest, or how factors like food combination, time of day, or frequency of intake affect the potential for health benefits.

That being said, let’s start with garlic. Aside from being an excellent source of antioxidants (which prevent and ameliorate oxidative stress in the brain and body and maintain healthy cognitive functioning), studies in mice and humans have shown that garlic may improve memory and cognitive performance in healthy and impaired subjects, and may even stave off Alzheimer’s.

Onions are rich in the antioxidant quercetin, which has been shown to protect against ischemic brain damage (a type of stroke) and may improve impaired memory. Quercetin has also been implicated as a potential anti-depressant.

What about the herbs? Rosmarinic acid is a key component of both rosemary and sage, one of the compounds that plays a role in detoxifying those carcinogenic HAs. In one interesting study, researchers found that participants exposed to the aroma of rosemary saw improved cognitive performance, while those exposed to lavender aroma saw their performance on memory tasks worsen after the exposure. There are a host of studies on sage and its extracts that strongly suggest that it has the potential to improve memory, attention, and mood in healthy young adults, and may even improve outcomes in Alzheimer’s disease.

It bears mentioning that all of us here at Posit Science advocate a holistically brain healthy lifestyle. Of course, we believe that includes committing to a brain training program as one component, but diet, exercise, and lifestyle all have roles to play in maintaining brain health and staying mentally fit. This type of research is exciting because it gives us a few more tools to put in our brain health toolbox that we can easily integrate into our daily lives.


Here are links to the PubMed abstracts of studies referenced in this article:

  1. A large prospective study of meat consumption and colorectal cancer risk: an investigation of potential mechanisms underlying this association.
  2. Nutritional Carcinogenesis.
  3. Inhibition of heterocyclic amine formation in beef patties by ethanolic extracts of rosemary.
  4. Effect of oil marinades with garlic, onion, and lemon juice on the formation of heterocyclic aromatic amines in fried beef patties.
  5. Repeated administration of fresh garlic increases memory retention in rats.
  6. Amelioration of early cognitive deficits by aged garlic extract in Alzheimer’s transgenic mice.
  7. Antioxidative activity and ameliorative effects of memory impairment of sulfur-containing compounds in Allium species.
  8. Multiplicity of garlic health effects and Alzheimer’s disease.
  9. Neuroprotective effects of onion extract and quercetin against ischemic neuronal damage in the gerbil hippocampus.
  10. Antidepressant-like effect of onion (Allium cepa L.) powder in a rat behavioral model of depression.
  11. Neuroprotective effect of methanolic extracts of Allium cepa on ischemia and reperfusion-induced cerebral injury.
  12. Onion flesh and onion peel enhance antioxidant status in aged rats.
  13. Aromas of rosemary and lavender essential oils differentially affect cognition and mood in healthy adults.
  14. An extract of Salvia (sage) with anticholinesterase properties improves memory and attention in healthy older volunteers.
  15. Salvia lavandulaefolia (Spanish sage) enhances memory in healthy young volunteers.
  16. Effects of Salvia officinalis L. (sage) leaves on memory retention and its interaction with the cholinergic system in rats.
  17. Positive modulation of mood and cognitive performance following administration of acute doses of Salvia lavandulaefolia essential oil to healthy young volunteers.