This is Your Brain on Onions

By Michael A. Smith, MD

In cooking, onions are one of the components of mirepoix (pronounced meer-pwah) — a French culinary term for a finely chopped mix of onion, celery, and carrots. It’s used as a flavor base for a wide variety of dishes.

I know this, not because I cook, but because I love watching the Food Channel. I don’t know why, but watching other people cook simply fascinates me. I digress … back to onions.

Anyway, new research shows that onions are good for mice brains and probably ours as well. Eating them or supplementing with an onion extract may help to lower MDA or malondialdehyde, a marker of oxidative stress and a brain cell killer.

Ischemic Stroke & Oxidative Stress

When a blood clot blocks a vessel supplying blood to the brain, an ischemic stroke occurs. This type of stroke may be caused by clogged arteries. Fat, cholesterol, and other substances collect in the artery walls, forming a sticky substance called plaque. This plaque can become unstable and rupture, resulting in clot formation that then blocks blood flow to the brain.

When blood flow is blocked to a region of the brain, markers of oxidative stress, like MDA, will increase. And the more the blood flow is reduced, the higher the level of MDA and the greater the extent of the damage to brain cells.

So the fact that onions have been shown to lower the level of MDA means brain cells might incur less damage following an ischemic stroke.

Lab Mice Respond Well to Onions

Korean researchers purposively reduced blood flow in the brain of lab mice. Then they compared the effects on the mice that received onions to control mice that were not given onions. After the blood flow was reduced, here’s what they found:1

  • Mice given onions had less brain edema, measured by a reduction in the amount of water.
  • The activity of catalase and glutathione peroxidase were maintained in the onion group, but reduced in the control group. This is an important finding because the two enzymes help to reduce oxidative stress.
  • After initially rising in both groups, MDA (a marker of oxidative stress) was reduced in the mice provided onions. Remember, less MDA probably means less damage to brain cells.
The researchers concluded that onions were associated with less oxidative stress and probably less brain cell damage following a reduction in blood flow.

What You Need to Know About Onions

Onions can improve the activity of two powerful enzymes — catalase and glutathione peroxidase — which help to reduce markers of oxidative stress, like MDA. This is a good thing when you consider that oxidative stress is a leading theory of aging and is especially dangerous following an ischemic stroke.

So, could onions become a component of a post-stroke treatment protocol? Well, probably not in this country any time soon. However, cooking mirepoix and eating onions more often may help to protect against free radical damage characteristic of a high level of oxidative stress.

What do you think: Do you suffer from oxidative stress? Here’s a simple answer: Yes! Toxins, pesticides, synthetic hormones, sunlight, and even aging itself all drive oxidative stress to high levels.

Consider adding onions to your daily diet to reduce the damage caused by oxidation and everyday living. Who knows? It could very well make a difference!


  1. Nutrition. 2012 Jul 6. [Epub ahead of print] PMID: 22771051 (


David said...

The article isn't specific about it, but i would guess the onions for the mice were raw, so to be sure one should eat them raw aswell. Very tasty on a whol grain bread with grassfed butter custard and tomates for example.

Post a Comment

All Contents Copyright ©2020 Life Extension® All rights reserved.
Privacy Notice | Terms of Use
These statements have not been evaluated by the Food and Drug Administration.
These products are not intended to diagnose, treat, cure, or prevent any disease.
The information provided on this site is for informational purposes only and is not intended as a substitute for advice from your physician or other health care professional or any information contained on or in any product label or packaging. You should not use the information on this site for diagnosis or treatment of any health problem or for prescription of any medication or other treatment. You should consult with a healthcare professional before starting any diet, exercise or supplementation program, before taking any medication, or if you have or suspect you might have a health problem. You should not stop taking any medication without first consulting your physician.