Blood-brain barrier prevents toxins and pathogens from entering the brain from the blood. If this barrier does not function properly, the body becomes susceptible to diseases such as Alzheimer’s and multiple sclerosis. But there are natural remedies and measures you can take to protect your blood-brain barrier.

The tasks of the blood-brain barrier

The blood-brain barrier (BBB) is a barrier between the blood and the brain. It is permeable to nutrients, so that the brain is supplied with everything it needs. The blood-brain barrier is impermeable to most pollutants and pathogens – it thus serves to protect the brain. However, the BBB cannot protect against all pollutants: Drugs such as cocaine and ecstasy make you high because they can cross the blood-brain barrier. As a result, they inflict long-lasting harm.

How the blood-brain barrier works

How exactly does the blood-brain barrier work? It consists of the following components that cooperate with each other – if one component fails, it no longer works properly (1) (2) (3):

1. Endothelial cells: The brain is crisscrossed by a network of blood vessels. So-called endothelial cells line the blood vessel walls from the inside and control which substances are allowed to enter the nerve tissue of the brain and which are not. The endothelial cells are so close together that they can seal the small cell spaces (“tight junctions”) between them if necessary. The cell layer, which consists of the adjacent endothelial cells, is called the endothelium.
2. Basal membrane: The endothelium is surrounded by a membrane that, in simple terms, holds everything in place. In addition, it communicates with the surrounding cells and is thus also involved in deciding which substances enter the brain and which do not.
3. Pericytes: The pericytes are embedded in the basement membrane. These cells communicate with the endothelial cells, but their functions are not yet clearly understood. Presumably, they are involved in maintaining the blood-brain barrier.
4. Astrocytes: Astrocytes sit around the basement membrane. Among other things, these cells help the endothelium to defend the blood-brain barrier and contribute to the supply of nerve cells. They emit messenger substances that make the endothelium more or less permeable.

These substances damage the blood-brain barrier

The blood-brain barrier is not only permeable to substances that benefit the brain. Some substances, such as alcohol, nicotine and cocaine, consist of particles that are also small enough to cross the blood-brain barrier. They not only cause damage to the brain, but can also affect the blood-brain barrier, so that it suddenly becomes permeable to many other substances that are toxic to the brain (4) (5).

The well-known cold hands after smoking, for example, indicate circulatory disorders of the small vessels, which can also have a negative effect on the blood-brain barrier.

Researchers suspect that the damage to the blood-brain barrier caused by drugs such as ecstasy and cocaine can persist even years after the drug has been taken. This is especially tragic when drugs are used from an early age. Many young people thus lay the foundation for later illnesses (61) (62). The consumption of nicotine, alcohol, other drugs and many other pollutants also always causes oxidative stress, which can also damage the blood-brain barrier.

Oxidative stress damages the blood-brain barrier

Oxidative stress can occur anywhere in the body and have a wide variety of causes: psychological stress, too little sleep, overexertion of the body, nicotine, alcohol, drugs, etc. If oxidative stress occurs in the brain, individual components of the blood-brain barrier (e.g. pericytes and astrocytes) that are central to the functioning of the BBB are damaged (6) (7).

Cell phone radiation damages the blood-brain barrier

Electromagnetic radiation, such as that emitted by mobile phones, WLAN devices, microwaves and light, surrounds us around the clock. Chinese researchers found that the blood-brain barrier of rats became more permeable when irradiated at 900 megahertz over a period of one month. By way of comparison, the frequency spectrum of mobile communications, Wi-Fi and microwaves ranges from 300 megahertz to 3 gigahertz. Officially, research on humans hasn’t been conducted yet (8) (9).

Artificial additives: glutamate, aspartame and citric acid

Additives in food are also suspected of causing damage to the brain – officially they are considered harmless.

The flavor enhancer glutamate

Natural glutamate produced in the brain is a neurotransmitter that performs important functions for memory. Artificially produced, glutamate, on the other hand, serves as a flavor enhancer in food. It is found in spice blends and all sorts of ready-made meals.

According to the current state of research, the glutamate formed in the brain can be transported across the blood-brain barrier into the bloodstream. Conversely, glutamate from the bloodstream (i.e. glutamate that is ingested through food) should not be able to pass through the BBB (10).

However, not all researchers agree with this finding. The discussion is important because glutamate is suspected of being involved in neurodegenerative diseases such as Alzheimer’s, Parkinson’s and multiple sclerosis. However, it has not been conclusively clarified whether the flavor enhancer glutamate, the naturally formed glutamate or both are responsible (11).

The sweetener aspartame

Aspartame is a synthetically produced sweetener used in the food industry. It is found, for example, in desserts, jams, sauces and soft drinks.

A 2017 review, published in the journal Nutrition Reviews, summarized the findings of numerous studies on aspartame. It has been shown that aspartame leads to oxidative stress in the brain and damages the blood-brain barrier – not only in high amounts but also in amounts that are actually considered safe (less than 40 mg per kg of body weight). So far, however, the investigations have only been carried out on animals (12).

The food additive citric acid

Citric acid is added to various finished products, beverages and sweets as a preservative and acidifier. It is found, for example, in gummy bears, lemonades, jam and canned fruits, but also in processed cheese.

Citric acid has the property of binding metals to itself. Since it can cross the blood-brain barrier, it enters the brain together with the bound metals, such as calcium, magnesium, potassium, but also aluminum. The combination of aluminum with citric acid is called aluminum citrate and is harmful to health (13).

Aluminum passes through the blood-brain barrier

Aluminum enters the brain even without citric acid. However, studies show that citric acid additionally promotes the absorption of aluminum. This means that with the consumption of foods containing citric acid, the absorption of aluminum into the brain is increased. This is where the aluminum citrate is deposited (14).

Aluminum is also degraded, but much more slowly than it is absorbed. With increasing age, more and more aluminum is deposited in the brain, where it can lead to cognitive dysfunction. In addition, aluminum is suspected of playing a role in neurodegenerative diseases (e.g. Alzheimer’s disease) and autoimmune diseases (e.g. multiple sclerosis). To prevent aluminum from being stored in the body you can start by avoiding cookware from which aluminum could come loose.

Viruses and bacteria damage the blood-brain barrier

Some bacteria and viruses are able to cross the blood-brain barrier. For this purpose, they attach themselves to brain-permeable substances and use them to reach the brain – similar to a Trojan horse (15).

Bacteria that are known to pass through the BBB are, for example, pneumococci. In the case of pneumococci, it is assumed that they form a toxin that causes the endothelial cells to die. In the brain, they can lead to meningitis.

Viruses that are known to pass through the blood-brain barrier are, for example, the mumps virus or the herpes simplex virus. Both can trigger inflammation of the brain (encephalitis).

Not all viruses and bacteria that travel in our body migrate into the brain. However, if the immune system is weakened, it can sometimes not prevent pathogens from spreading in the body. In the worst case, they then make their way through the blood-brain barrier.

The blood-brain barrier is impaired by brain inflammation

If a pathogen crosses the blood-brain barrier, it can trigger inflammation in the brain. The brain’s own immune cells are responsible for this: the microglia. The microglia keep the inflammation going until the pathogen is rendered harmless. This is a natural defense mechanism (16).

However, such inflammations can also damage the blood-brain barrier and other sensitive parts of the brain by leading to the death of nerve cells. Research suggests that a damaged blood-brain barrier contributes to the development of autoimmune diseases (16).

Diseases damage the blood-brain barrier

Diseases can also lead to inflammation in the brain. In multiple sclerosis, epilepsy and Alzheimer’s disease, there are repeated episodes of inflammation. With each episode of inflammation, the blood-brain barrier becomes more permeable. This leads to a vicious circle in which the diseases continue to progress and the blood-brain barrier becomes weaker and weaker.

A stroke or traumatic brain injury can also cause the blood-brain barrier to become permeable, for example by damaging the blood vessels or closing temporarily. Other diseases associated with a permeable blood-brain barrier include Parkinson’s disease and diabetes (17).

Research assumes that diabetes damages the barrier effect of the blood-brain barrier. Too high blood sugar is said to make the BBB more permeable and increase the risk of secondary diseases. This is said to be related to the transport of glucose and insulin across the blood-brain barrier. However, the exact mechanisms have not yet been sufficiently researched (18).

In many cases, researchers are also unsure whether diseases are caused by a disturbed blood-brain barrier in the first place, or whether they themselves are the cause of the damage to the BBB. Both factors are suspected to play a role.

The blood-brain barrier is an obstacle to medication

The blood-brain barrier is usually so effective that it even complicates the drug treatment of many neurological diseases. This is because the foreign substances are treated like toxins and repelled by the blood-brain barrier. For example, the barrier causes problems in the treatment of brain tumors, Alzheimer’s and Parkinson’s disease – i.e. diseases in which the drugs are primarily intended to act in the brain.

Parkinson’s, for example, is treated with dopamine. Since dopamine cannot pass through the BBB, precursors of dopamine are used. The precursors pass through the BBB and are only converted into dopamine in the brain (19). Other ways science is trying to circumvent the blood-brain barrier include the following (20) (21) (22) (23):

1. For example, by transporting the active pharmaceutical ingredients through the BBB with the help of other substances that serve as transporters;
2. The development of active ingredients with certain properties that pass through the barrier in a simplified manner (e.g. fat solubility, small molecular size, etc.)
3. The opening of the barrier by means of ultrasound or bypassing the blood-brain barrier by injecting the drug directly into the brain.

However, overcoming the barrier is far from being sufficiently researched and will probably keep science busy for many years to come.

The blood-brain barrier in babies and toddlers

Again and again it can be read that the blood-brain barrier in newborns and infants is not yet fully developed. Many pediatricians and neurologists also assume this. However, if you look for studies that prove this, you will hardly find what you are looking for.

On the contrary, the authors of a 2012 research paper uncover some fallacies that are said to have led to this assumption. The researchers believe that the blood-brain barrier of infants and young children is by no means “leaky” or “immature” (24). A review from 2018 comes to the same conclusion: The blood-brain barrier in infants and toddlers is not immature, it says, but the brain is fundamentally more sensitive to toxins and pollutants during its development (25).

The fact is that there are still many unanswered questions about the development of the blood-brain barrier, e.g. when (in which phase of pregnancy) the blood-brain barrier in the unborn baby is fully formed. This is important in order to understand how, for example, taking medication during pregnancy affects the baby.

How to protect your blood-brain barrier?

Once the blood-brain barrier is damaged, it can no longer regulate itself sufficiently. People are already looking for ways to “repair” the blood-brain barrier. Nonetheless, it’ll take a while before this becomes feasible. However, with a healthy lifestyle, you can already do a lot to protect the blood-brain barrier from damage.

1. Omega-3 fatty acids protect the blood-brain barrier

Omega-3 fatty acids are very important for the nervous system and many brain functions. Researchers at Harvard Medical School have found that omega-3 fatty acids maintain the blood-brain barrier. In order for them to perform this function, the omega-3 fatty acids must be in the correct proportion to the omega-6 fatty acids (26) (27) (28).

2. Consume enough minerals

Minerals are essential for optimal brain function: they are involved in the transmission of stimuli in the nervous system and protect nerve cells from dying. Magnesium also makes the blood-brain barrier less permeable. According to an American review, magnesium deficiency plays a role in the development of Alzheimer’s, strokes, epilepsy and Parkinson’s disease (29) (30) (31).

You can find more information about mineral deficiency here. There you will find a useful overview of the minerals, learn more about how a deficiency is diagnosed and how you can take a blood test at home.

3. Have vitamin B12 deficiency clarified

Vitamin B12 protects the nervous system and helps in the regeneration of nerve cells. A vitamin B12 deficiency is also closely related to Alzheimer’s disease. The disease, in turn, is associated with decreased function of the blood-brain barrier, as we described above.

Vitamin B12 deficiency affects far more people than you would think. But the other B vitamins also perform important functions in the brain and should not be ignored. Therefore, have your vitamin balance checked and adjust your diet if necessary.

4. Caffeine protects the blood-brain barrier

In Alzheimer’s and Parkinson’s disease, the blood-brain barrier usually becomes more permeable. Studies show that regular consumption of caffeine can protect against Alzheimer’s and Parkinson’s disease by maintaining the blood-brain barrier.

For Alzheimer’s prevention, just one cup of coffee per day was enough – in Parkinson’s disease, the protective effect only occurred at 5 cups per day. Whether so much coffee is healthy for other parts of the body is another question (18) (19).

5. These plant compounds protect the brain

The following phytochemicals can cross the blood-brain barrier and have a positive effect on the brain. In parentheses, examples are given in each case of the foods in which the substances occur. In higher doses, they can also be taken via dietary supplements (20) (21) (22) (23) (24) (25) (26) (27) (28) (29) (30) (31).

1. Sulforaphane (broccoli, cabbage): May prevent disorders of the blood-brain barrier and is said to help fight cancer and arthritis. In addition, sulforaphane can reduce the permeability of the BBB after a traumatic brain injury.
2. Curcumin (cabbage vegetables): Protects nerve cells and helps reverse the damage that alcohol abuse leaves in the brain.
3. Astaxanthin (algae): Astaxanthin protects the nerve cells of the brain and is considered one of nature’s most powerful antioxidants.
4. Alpha-lipoic acid (spinach, broccoli): Slows the progression of Alzheimer’s and protects the nerve cells of the brain.
5. Lutein and zeaxanthin (spinach, kale): Lutein and zeaxanthin are both said to be good for memory.

Of course, there are many other phytochemicals that can cross the blood-brain barrier that have not yet been investigated by science in this regard.

6. Eat a healthy and balanced diet

Researchers have found that an unhealthy diet harms the brain: it reduces cognitive performance and intensifies inflammatory processes. Above all, you should avoid industrially processed foods and reduce the following pro-inflammatory foods (32) (33) (34) (35):

1. Ready meals, ready-made sauces, etc.
2. Sugary foods, such as sweets
3. Products made from wheat flour
4. Dairy products
5. Meat (especially sausage)
6. Alcohol

Cytokines play an important role in inflammation – they are formed in the body. Some of these cytokines cause or increase inflammation, while others attenuate or stop inflammation. It is believed that an unhealthy diet promotes the formation of pro-inflammatory substances in the body. Cytokines are able to cross the blood-brain barrier and cause inflammation in the brain (36) (37).

Instead, you should incorporate anti-inflammatory foods into your diet.

7. Gut health influences the blood-brain barrier

A healthy diet is also the be-all and end-all for a healthy intestinal flora. A well-known proverb says: “Health begins in the gut.” And that includes the health of the brain. The intestine and the brain are in close contact with each other via the so-called gut-brain axis where they communicate via nerves and hormones.

In recent years, more and more researchers have discovered that a disturbed intestinal flora plays a role in the development of Alzheimer’s, Parkinson’s and depression, among other things. Bacteria from the intestinal flora are said to be able to influence the blood-brain barrier and thus the course of diseases. Nevertheless, investigations in this field are still in their early stages (38) (39).

However, it is already clear that a healthy intestinal flora can prevent diseases and help treat them through its close connection with the immune system – even if they affect the brain.

8. Get enough sleep

A study in mice showed that the functioning of the blood-brain barrier was significantly impaired after only 6 days, during which the mice only slept between 4 and 7 hours each. Of course, this cannot be transferred one-to-one to humans – after all, most mouse species usually sleep half of the day, so they have a greater need for sleep than humans. However, the study suggests that too little sleep in humans could also damage the functioning of the blood-brain barrier (40).

The American Academy of Sleep Medicine recommends at least 7 hours of sleep for healthy adults. On the other hand, only adolescents, sick people or people who are recovering from a previous lack of sleep should regularly sleep more than 9 hours (41).

The above-mentioned study also showed that it is possible to make up for lost sleep: After the 6 days, the mice were allowed to sleep for a whole day. During this time, the permeability of the blood-brain barrier dropped back to its normal level.

9. Ketogenic diet protects the blood-brain barrier from inflammation

The blood-brain barrier plays a major role in the ketogenic diet. Those who eat a ketogenic diet eat only a few carbohydrates. In this process, the body enters a special state: instead of glucose from carbohydrates, the body now uses its fat reserves.

Normally, glucose serves as a source of energy for the brain. It is passed through the blood-brain barrier and then utilized in the brain. With the ketogenic diet, however, the brain is naturally supplied with energy despite the lower glucose intake. During fat loss, so-called ketones are produced in the body. Ketones can also pass through the BBB and serve the brain as a replacement source of energy for glucose.

According to a study, the ketogenic diet reduces inflammatory processes in the brain. The researchers suspect that the lower glucose intake is the reason for this. However, the precise correlation remains unclear at present. In any case, this reduces inflammation in the brain, which of course can also affect the BBB. The ketogenic diet is already being used successfully for epilepsy.

10. Avoid stress

Stress can trigger inflammation in the brain and aggravate existing ones. Such inflammation, as mentioned above, is closely related to disorders of the blood-brain barrier. For example, researchers found that stress makes the blood-brain barrier more permeable (43) (44) (45).

11. Do sports

Regular physical activity stimulates the formation of new nerve cells at the blood-brain barrier – and this continues into old age. With exercise, you are not only doing something good for your muscles and joints, but also for your brain. Previously, it was long assumed that dead nerve cells in the brain of adults could no longer be replaced.

Scientists are now using this knowledge to develop therapies that rebuild the BBB and other parts of the brain, e.g. after a stroke (46).

12. Essential oils for the brain

Scent molecules of essential oils are also able to cross the blood-brain barrier. They are transported through respiration – and when applied directly to the skin also via the surface of the skin – into the blood and from there into the brain. In studies with mice, the fragrances were detected in the brain.

Scent molecules are also able to bind to receptors in the brain, such as the sleep receptor. For this reason, essential oils such as lavender and jasmine have a sleep-inducing effect (47).

Other essential oils are also said to have a positive effect on the brain: rosemary, peppermint and lemon have a stimulating effect and strengthen concentration. Bergamot, lavender and rose reduce stress and thus indirectly have a protective effect on the blood-brain barrier (see point 10). For good essential oils that won’t harm your body click here

Preventing disorders of the blood-brain barrier

A healthy lifestyle with a plant-based diet that is as varied as possible, plenty of sleep, exercise and little stress is the basis for preventing disorders of the blood-brain barrier and even protecting it from harmful influences.

Also keeping your microbiome healthy and active by regularly coming in for a check-up or reminder of what else you can do to improve your gut health, will support your blood-brain barrier.