Blood-Brain Barrier: What is It, and How Does It Affect Detoxification of the Brain?

By Irina Bright.

This article is part of our Health & Foods section

tulips white red Photo: Kwang Mathurosemontri

Recently, I have been thinking about why we have such a high number of slow-developing but long-lasting diseases related to the malfunction of the brain, and why it is so hard to deal with them - especially in old age.

Conditions like memory loss, Alzheimer's disease, Parkinson's disease, and other neurodegenerative disorders are far too common to ignore.

We know that it is very hard to treat them and keep their symptoms under control, let alone cure them completely.

Since all these conditions stem from the problems in the brain & central nervous system, we should obviously try to find solutions by focusing on the brain as well.

So, what are some of the Causes of brain-related conditions?

A) Oxidative stress in neurodegenerative diseases.

There is plenty of evidence that oxidative stress in the brain plays a major role in neurodegenerative disorders. (Ref. 1)

Oxidative stress is defined as "a disturbance in the balance between the production of free radicals and antioxidant defences". (Ref. 2)

This means, that the body produces too many free radicals, while producing not enough antioxidants to fight them. Excessive amounts of free radicals are damaging to the body, leading to oxidative stress. When the brain accumulates too many free radicals, inflammation takes place and a neurodegenerative disorder may occur.

Here is an excerpt from one study:

The brain consumes a lot of oxygen and antioxidants, and therefore oxidative stress can easily occur in the brain. Oxidative damage to lipids is important in neurodegenerative disease development because polyunsaturated fatty acids are abundant in the lipid bilayer of the brain. Increases in lipid peroxidation end products [i.e. free radicals] were found in Alzheimer’s, Parkinson’s, and Huntington’s disease. (Ref. 1)

B) Heavy metals toxicity in the brain may be another major cause of such diseases. As an example, one more study names an excessive accumulation of metals ex. copper, iron, zinc and aluminium in the brain as a cause of neuro-degeneration in Alzheimer's disease. (Ref. 3)

The same study points out that some nutrients - including unique phytochemical compounds curcumin and epigallocatechin, as well as common green tea - have the potential to bind toxic metals and thus offer protection to the brain in cases of neurodegenerative disorders. (Ref. 3)

Heavy metals intoxication may somehow be related to oxidative stress as well, with both leading to harmful inflammation.

This leads us to believe that a targeted detoxification of the brain and a reduction of oxidative stress & inflammation may help with neurodegenerative diseases.

But ... how do we do it??

Blood-Brain Barrier: What is It?

I believe that one of the main reasons why it is generally difficult to deal with neurodegenerative disorders and brain detoxification is a very low permeability of the Blood-Brain Barrier (BBB).

But what *is* the Blood-Brain Barrier?

Here is one definition of BBB:

The blood-brain barrier is a dynamic interface that separates the brain from the circulatory system and protects the central nervous system from potentially harmful chemicals while regulating transport of essential molecules and maintaining a stable environment. (John Hopkins University, Ref. 4)

Here is another one:

The blood-brain barrier is a diffusion barrier, which impedes influx of most compounds from blood to brain. (Ref. 5)

In other words, the brain is such an important organ of the body, that Nature made sure it is protected really well, by a barrier that stops potentially harmful elements from passing it easily.

On the other hand, the barrier also prevents beneficial nutrients from easily entering the brain - which isn't that great either.

How Does the Blood-Brain Barrier Affect Brain Detoxification?

So, if free radicals are excessive in the brain and antioxidants fight free radicals, then we can try to remove at least some free radicals with the help of such antioxidants.

We can classify antioxidants as (ref. 6):

1. Endogenous (internal) antioxidants - the ones which are produced by the body, ex. superoxide dismutase, catalase, glutathione peroxidase and glutathione; and

2. Exogenous (external) antioxidants - the ones which come from the diet, ex. vitamin C, vitamin E, carotenoids and polyphenols.

Let us imagine now that we can use exogenous, dietary antioxidants - which are within our direct control - to effect change and bring about a deep detoxification of the brain.

As we have demonstrated above, the blood-brain barrier puts up a strong protection for the brain, meaning that only the most important nutrients permeate it to feed the brain.

So, yes sure - the blood-brain barrier may well be in the way of an efficient brain detoxification process and hamper our efforts to deal with brain-related conditions.

The challenge here is, of course, to find the antioxidants which will have NO TROUBLE passing through the Blood-Brain Barrier.

Antioxidant Foods That Easily Pass Through the Blood-Brain Barrier

We believe that many common & wild-growing berries are amongst the most antioxidant-rich foods on the planet. Berries offer a whole variety of antioxidant compounds, including numerous vitamins & polyphenols - which are NOT found in common foods in such big amounts as in berries.

Of special interest to us here are berry polyphenols which are believed to be very powerful antioxidants indeed. Some research suggests that:

Polyphenols are also beneficial in ameliorating the adverse effects of the aging on nervous system or brain. Paramount importance for the relevance of food polyphenols in the protection of the aging brain is the ability of these compounds to cross the blood-brain barrier. (Ref. 7)


Because polyphenols are highly antioxidative in nature, their consumption may provide protection in neurological diseases. (Ref. 7)

Another study suggests that:

... the polyphenolic compounds found in berry fruits, such as blueberries and strawberries, may exert their beneficial effects either through their ability to lower oxidative stress and inflammation or directly by altering the signaling involved in neuronal communication, calcium buffering ability, neuroprotective stress shock proteins, plasticity, and stress signaling pathways. These interventions, in turn, may exert protection against age-related deficits in cognitive and motor function. (Ref. 8)

All quite interesting & encouraging observations!

From this point of view, it is hard to imagine what foods could be a better source of polyphenol antioxidants that berries.

Learn more about health benefits of berries here.

Consuming copious amounts of antioxidant-rich foods combined with a general healthy diet and other novel approaches such as intermittent fasting, may become a good foundation for brain detoxification - which may alleviate neurological disorders.

Written by:     Irina Bright
Original publication date:     2015
Updates:     2020
Republication date:     2020


1. Raynoo Thanan, Shinji Oikawa, Yusuke Hiraku, Shiho Ohnishi, Ning Ma, Somchai Pinlaor, Puangrat Yongvanit, Shosuke Kawanishi, and Mariko Murata (24 December 2014). Oxidative Stress and Its Significant Roles in Neurodegenerative Diseases and Cancer. Published in International Journal of Molecular Sciences. Retrieved February 19, 2015 from:

2. Betteridge DJ (February 2000). What is oxidative stress? Published in Metabolism. Retrieved February 19, 2015 from:

3. Muralidhar L. Hegde, P. Bharathi, Anitha Suram, Chitra Venugopal, Ramya Jagannathan, Pankaj Poddar, Pullabhatla Srinivas, Kumar Sambamurti, Kosagisharaf Jagannatha Rao, Janez Scancar, Luigi Messori, Luigi Zecca, and Paolo Zattah (July 2009). Challenges Associated with Metal Chelation Therapy in Alzheimer's Disease. Published in Journal of Alzheimer's Disease. Retrieved February 19, 2015 from:

4. Blood-Brain Barrier (Working Group). Published by John Hopkins University. Retrieved February 19, 2015 from:

5. Ballabh P, Braun A, Nedergaard M. (June 2004). The blood-brain barrier: an overview: structure, regulation, and clinical implications. Published in Neurobiology of disease. Retrieved February 19, 2015 from:

6. Jaouad Bouayed and Torsten Bohn (July-August 2010). Exogenous antioxidants—Double-edged swords in cellular redox state. Published in Oxidative Medicine and Cellular Longevity. Retrieved February 19, 2015 from:

7. Kanti Bhooshan Pandey and Syed Ibrahim Rizvi (November-December 2009). Plant polyphenols as dietary antioxidants in human health and disease. Published in Oxidative Medicine and Cellular Longevity. Retrieved February 19, 2015 from:

8. Shukitt-Hale B, Lau FC, Joseph JA (February 2008). Berry fruit supplementation and the aging brain. Published in Journal of agricultural and food chemistry. Retrieved February 19, 2015 from: