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Can Probiotics Improve the Health of Your Brain?

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By Dr. Ruairi Robertson

Did you know that there are roughly 40 trillion bacteria living in and on you?

Most of these bacteria reside in your gut and don't cause any health problems.

Now compelling new research has found these bacteria may also be beneficial for your brain and mental health.Shutterstock

In fact, scientists have begun to realize that these bacteria are essential for your physical health.

Now compelling new research has found these bacteria may also be beneficial for your brain and mental health.

This article explains how your brain is affected by gut bacteria and the role probiotics may play.

What Are Probiotics?

Probiotics are live microorganisms, usually bacteria. When consumed in sufficient quantities, they provide a specific health benefit (1).

The word "probiotic" is derived from the Latin words "pro," meaning to promote and "biotic," meaning life.

Importantly, in order for a certain species of bacteria to be termed "probiotic," it must have a lot of scientific evidence behind it showing a specific health benefit.

Unfortunately, the word probiotic has become overused by food and pharmaceutical companies who were calling some bacteria probiotics even if they had no scientifically proven health benefit.

This led the European Food Safety Authority to ban the word "probiotic" on all foods in the European Union.

However, there is a lot of new scientific evidence showing that some bacterial species have true benefits for health.

They may benefit those with conditions including irritable bowel syndrome (IBS), eczema, dermatitis, unhealthy cholesterol levels and liver disease (2, 3, 4, 5, 6).

Most probiotics belong to one of two types of bacteria: Lactobacillus or Bifidobacteria. There are many different species and strains within these groups and they may have different effects on the body.

Bottom Line: Probiotics are live microorganisms that have a proven health benefit for the body.

How Are Your Intestines and Brain Connected?

The intestines and brain are connected physically and biochemically.

The physical connection between the intestines and brain is through the central nervous system, which controls all of the activities of the body.

The vagus nerve is a large nerve that sends signals between the intestines and brain (7).

The brain is also connected to the intestines through your gut microbes. Molecules that they produce can act as signals that the brain can detect (7).

In the past, scientists have estimated that a person has approximately 100 trillion bacterial cells in their body and only 10 trillion human cells, meaning your own cells are outnumbered by 10 to 1 (8).

However, recent estimates suggest that you have roughly 30 trillion human cells and 40 trillion bacteria. This is still pretty impressive and means that, by number of cells, you are more bacteria than human (9).

The majority of these bacteria are in your gut, so they're in direct contact with the cells that line your intestines and with everything that enters your body. That includes food, medicines and microbes.

Alongside your gut bacteria, there are many other microbes, such as yeasts and fungi. Collectively, these microbes are known as the gut microbiota or gut microbiome (10).

Each of these bacteria can produce different compounds, such as short-chain fatty acids, neurotransmitters and amino acids. Many of these substances have effects on the brain (11).

In addition to producing brain-altering substances, gut bacteria can also influence the brain and central nervous system by controlling inflammation and hormone production (12, 13).

Bottom Line: There are thousands of different species of bacteria in the human body, mostly in the intestines. In general, these bacteria are good for your health and may even influence brain health.

An Altered Microbiota May Contribute to a Number of Diseases

The term "gut dysbiosis" refers to when the intestines and gut bacteria are in a diseased state. This may be due to the presence of disease-causing bacteria, which may also lead to chronic inflammation.

An altered microbiota has been observed in people with obesity, heart disease, type 2 diabetes and other diseases (14, 15, 16, 17).

Some studies have shown that certain probiotics can restore the microbiota to a healthy state and reduce symptoms of these diseases (18, 19, 20, 21).

Interestingly, some studies have shown that people with certain mental disorders also have an altered microbiota. However, it is unclear if this is a cause of such diseases or the result of an altered diet and lifestyle (22, 23, 24, 25).

Since the gut and brain are connected and gut bacteria produce substances that can influence the brain, probiotics may be able to benefit the brain and mental health.

A number of recent studies have investigated this, but most have been in animals. However, a few have shown interesting results in humans.

Bottom Line: A number of diseases, including mental disorders, are associated with higher disease-causing bacteria in the intestines. Some probiotics may be able to restore healthy bacteria to reduce symptoms.

Taking Probiotic Supplements May Reduce Symptoms of Stress, Anxiety and Depression

Stress and anxiety are increasingly common and depression is one of the leading causes of disease worldwide (26).

A number of these disorders, especially stress and anxiety, are associated with high blood levels of cortisol, the human stress hormone (27, 28, 29).

Only one study has examined how probiotics affect patients with clinically diagnosed depression.

In the study, consuming a mixture of three Lactobacillus and Bifidobacteria strains for eight weeks significantly reduced depressive symptoms. The probiotic also reduced inflammation in the patients (30).

A handful of other studies have examined how probiotics affect depressive symptoms in healthy subjects. In healthy people, certain probiotics may reduce:

  • Symptoms of anxiety (31, 32, 33)
  • Depressive symptoms (34)
  • Psychological distress (35)
  • Academic stress (36)

Bottom Line: Certain probiotics may reduce anxiety, stress and depressive symptoms in healthy people. More research is needed about potential benefits for people with clinically diagnosed psychological disorders.

Taking Probiotic Supplements May Reduce Symptoms of Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is directly related to the function of the colon, but the disease is sometimes considered a psychological disorder (37, 38).

Anxiety and depression are common in IBS sufferers. Interestingly, people who have IBS also tend to have an altered microbiota (39, 40, 41).

Many studies have shown that certain probiotics can reduce symptoms of IBS, including pain and bloating (42, 43, 44).

Bottom Line: IBS is commonly associated with elevated levels of anxiety and depression. Probiotics appear to help reduce IBS symptoms.

Certain Probiotics May Enhance Mood

In healthy people without a psychological disorder, some probiotics may help improve mood.

One study treated participants daily for four weeks with a probiotic mix containing eight different Lactobacillus and Bifidobacteria strains.

The researchers found that taking the supplements reduced participants' negative thoughts associated with a sad mood (45).

Another study showed that consuming a milk drink containing a probiotic called Lactobacillus casei for three weeks improved mood in people who had the lowest mood before the treatment (46).

Interestingly, this study also found that people scored slightly lower on a memory test after taking the probiotic. Further research is needed to validate these results.

Bottom Line: A few studies have shown that taking certain probiotics for a few weeks may slightly improve mood.

Certain Probiotics May Have Benefits After Traumatic Brain Injury

Traumatic brain injury usually involves admission to an intensive care unit. During this time, food is usually administered enterally, meaning through a tube.

In some cases, breathing also has to be assisted with a tube, which can increase the risk of infection. Infections in people with traumatic brain injuries can lead to further complications.

A few studies have found that adding certain probiotics into enteral nutrition can reduce the number of infections in the patients with traumatic brain injury and the length of time they spend in the intensive care unit (47, 48, 49).

The effects of the probiotics on these outcomes may be due to their benefits for the immune system.

Bottom Line: Administering probiotics after traumatic brain injury may reduce patients' rate of infections and length of stay in intensive care.

Other Beneficial Effects of Probiotics on the Brain

A handful of other studies have shown that probiotics may have interesting benefits for the brain.

One intriguing study looked at images of women's brains after they consumed a mix of Bifidobacteria, Streptococcus, Lactobacillus and Lactococcus strains.

Consuming the probiotic affected regions of the brain that control emotion and sensation (50).

Other studies have shown that providing specific probiotics may reduce certain symptoms of multiple sclerosis and schizophrenia, but much more research is needed (51, 52).

Bottom Line: Some probiotics may influence the function of the brain and symptoms of multiple sclerosis and schizophrenia. However, this research is still very new, so the results aren't clear.

Should You Be Taking a Probiotic for Your Brain?

At the moment, there is not enough evidence to definitively say that probiotics benefit the brain. Therefore, they cannot yet be considered a treatment for any brain-related disorders.

If you're looking to treat such disorders, consult a doctor.

That said, there is good evidence that probiotics can benefit other aspects of health, including heart health, digestive disorders, eczema and dermatitis (3, 4, 5, 53).

Thus far, scientific evidence does show a clear connection between the gut and the brain. It's an exciting area of research that is expanding rapidly.

A healthy gut microbiota can usually be obtained by a healthy diet and lifestyle. A number of foods such as yogurt, sauerkraut, kefir and kimchi usually contain beneficial bacteria.

If necessary, taking probiotic supplements can help you increase the beneficial bacterial species in your intestines. In general, consuming probiotics is safe and causes few side effects.

If you're buying a probiotic, choose one that has scientific evidence behind it. Lactobacillus GG (LGG) and VSL#3 have both been widely studied and shown a number of health benefits.

Bottom Line: Probiotics have been shown to benefit other aspects of health, but not enough research has been done to definitively demonstrate whether probiotics have positive effects on the brain.

Take Home Message

Although the research is promising, it is too soon to recommend any probiotic specifically to boost brain health.

Still, current evidence gives some food for thought about how probiotics may be used to enhance brain health in the future.

Reposted with permission from our media associate Authority Nutrition.

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Ola Elvestrun, Norway's environment minister, announced Thursday that it is freezing its contributions to the Amazon Fund, and will no longer be transferring €300 million ($33.2 million) to Brazil. In a press release, the Norwegian embassy in Brazil stated:

Given the present circumstances, Norway does not have either the legal or the technical basis for making its annual contribution to the Amazon Fund.

Brazilian President Jair Bolsonaro reacted with sarcasm to Norway's decision, which had been widely expected. After an official event, he commented: "Isn't Norway the country that kills whales at the North Pole? Doesn't it also produce oil? It has no basis for telling us what to do. It should give the money to Angela Merkel [the German Chancellor] to reforest Germany."

According to its website, the Amazon Fund is a "REDD+ mechanism created to raise donations for non-reimbursable investments in efforts to prevent, monitor and combat deforestation, as well as to promote the preservation and sustainable use in the Brazilian Amazon." The bulk of funding comes from Norway and Germany.

The annual transfer of funds from developed world donors to the Amazon Fund depends on a report from the Fund's technical committee. This committee meets after the National Institute of Space Research, which gathers official Amazon deforestation data, publishes its annual report with the definitive figures for deforestation in the previous year.

But this year the Amazon Fund's technical committee, along with its steering committee, COFA, were abolished by the Bolsonaro government on 11 April as part of a sweeping move to dissolve some 600 bodies, most of which had NGO involvement. The Bolsonaro government views NGO work in Brazil as a conspiracy to undermine Brazil's sovereignty.

The Brazilian government then demanded far-reaching changes in the way the fund is managed, as documented in a previous article. As a result, the Amazon Fund's technical committee has been unable to meet; Norway says it therefore cannot continue making donations without a favorable report from the committee.

Archer Daniels Midland soy silos in Mato Grosso along the BR-163 highway, where Amazon rainforest has largely been replaced by soy destined for the EU, UK, China and other international markets.

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An Uncertain Future

The Amazon Fund was announced during the 2007 United Nations Climate Change Conference in Bali, during a period when environmentalists were alarmed at the rocketing rate of deforestation in the Brazilian Amazon. It was created as a way of encouraging Brazil to continue bringing down the rate of forest conversion to pastures and croplands.

Government agencies, such as IBAMA, Brazil's environmental agency, and NGOs shared Amazon Fund donations. IBAMA used the money primarily to enforce deforestation laws, while the NGOs oversaw projects to support sustainable communities and livelihoods in the Amazon.

There has been some controversy as to whether the Fund has actually achieved its goals: in the three years before the deal, the rate of deforestation fell dramatically but, after money from the Fund started pouring into the Amazon, the rate remained fairly stationary until 2014, when it began to rise once again. But, in general, the international donors have been pleased with the Fund's performance, and until the Bolsonaro government came to office, the program was expected to continue indefinitely.

Norway has been the main donor (94 percent) to the Amazon Fund, followed by Germany (5 percent), and Brazil's state-owned oil company, Petrobrás (1 percent). Over the past 11 years, the Norwegians have made, by far, the biggest contribution: R$3.2 billion ($855 million) out of the total of R$3.4 billion ($903 million).

Up till now the Fund has approved 103 projects, with the dispersal of R$1.8 billion ($478 million). These projects will not be affected by Norway's funding freeze because the donors have already provided the funding and the Brazilian Development Bank is contractually obliged to disburse the money until the end of the projects. But there are another 54 projects, currently being analyzed, whose future is far less secure.

One of the projects left stranded by the dissolution of the Fund's committees is Projeto Frutificar, which should be a three-year project, with a budget of R$29 million ($7.3 million), for the production of açai and cacao by 1,000 small-scale farmers in the states of Amapá and Pará. The project was drawn up by the Brazilian NGO IPAM (Institute of Environmental research in Amazonia).

Paulo Moutinho, an IPAM researcher, told Globo newspaper: "Our program was ready to go when the [Brazilian] government asked for changes in the Fund. It's now stuck in the BNDES. Without funding from Norway, we don't know what will happen to it."

Norway is not the only European nation to be reconsidering the way it funds environmental projects in Brazil. Germany has many environmental projects in the Latin American country, apart from its small contribution to the Amazon Fund, and is deeply concerned about the way the rate of deforestation has been soaring this year.

The German environment ministry told Mongabay that its minister, Svenja Schulze, had decided to put financial support for forest and biodiversity projects in Brazil on hold, with €35 million ($39 million) for various projects now frozen.

The ministry explained why: "The Brazilian government's policy in the Amazon raises doubts whether a consistent reduction in deforestation rates is still being pursued. Only when clarity is restored, can project collaboration be continued."

Bauxite mines in Paragominas, Brazil. The Bolsonaro administration is urging new laws that would allow large-scale mining within Brazil's indigenous reserves.

Hydro / Halvor Molland / Flickr

Alternative Amazon Funding

Although there will certainly be disruption in the short-term as a result of the paralysis in the Amazon Fund, the governors of Brazil's Amazon states, which rely on international funding for their environmental projects, are already scrambling to create alternative channels.

In a press release issued yesterday Helder Barbalho, the governor of Pará, the state with the highest number of projects financed by the Fund, said that he will do all he can to maintain and increase his state partnership with Norway.

Barbalho had announced earlier that his state would be receiving €12.5 million ($11.1 million) to run deforestation monitoring centers in five regions of Pará. Barbalho said: "The state governments' monitoring systems are recording a high level of deforestation in Pará, as in the other Amazon states. The money will be made available to those who want to help [the Pará government reduce deforestation] without this being seen as international intervention."

Amazonas state has funding partnerships with Germany and is negotiating deals with France. "I am talking with countries, mainly European, that are interested in investing in projects in the Amazon," said Amazonas governor Wilson Miranda Lima. "It is important to look at Amazônia, not only from the point of view of conservation, but also — and this is even more important — from the point of view of its citizens. It's impossible to preserve Amazônia if its inhabitants are poor."

Signing of the EU-Mercusor Latin American trading agreement earlier this year. The pact still needs to be ratified.

Council of Hemispheric Affairs

Looming International Difficulties

The Bolsonaro government's perceived reluctance to take effective measures to curb deforestation may in the longer-term lead to a far more serious problem than the paralysis of the Amazon Fund.

In June, the European Union and Mercosur, the South American trade bloc, reached an agreement to create the largest trading bloc in the world. If all goes ahead as planned, the pact would account for a quarter of the world's economy, involving 780 million people, and remove import tariffs on 90 percent of the goods traded between the two blocs. The Brazilian government has predicted that the deal will lead to an increase of almost $100 billion in Brazilian exports, particularly agricultural products, by 2035.

But the huge surge this year in Amazon deforestation is leading some European countries to think twice about ratifying the deal. In an interview with Mongabay, the German environment ministry made it very clear that Germany is very worried about events in the Amazon: "We are deeply concerned given the pace of destruction in Brazil … The Amazon Forest is vital for the atmospheric circulation and considered as one of the tipping points of the climate system."

The ministry stated that, for the trade deal to go ahead, Brazil must carry out its commitment under the Paris Climate agreement to reduce its greenhouse gas emissions by 43 percent below the 2005 level by 2030. The German environment ministry said: If the trade deal is to go ahead, "It is necessary that Brazil is effectively implementing its climate change objectives adopted under the [Paris] Agreement. It is precisely this commitment that is expressly confirmed in the text of the EU-Mercosur Free Trade Agreement."

Blairo Maggi, Brazil agriculture minister under the Temer administration, and a major shareholder in Amaggi, the largest Brazilian-owned commodities trading company, has said very little in public since Bolsonaro came to power; he's been "in a voluntary retreat," as he puts it. But Maggi is so concerned about the damage Bolsonaro's off the cuff remarks and policies are doing to international relationships he decided to speak out earlier this week.

Former Brazil Agriculture Minister Blairo Maggi, who has broken a self-imposed silence to criticize the Bolsonaro government, saying that its rhetoric and policies could threaten Brazil's international commodities trade.

Senado Federal / Visualhunt / CC BY

Maggi, a ruralista who strongly supports agribusiness, told the newspaper, Valor Econômico, that, even if the European Union doesn't get to the point of tearing up a deal that has taken 20 years to negotiate, there could be long delays. "These environmental confusions could create a situation in which the EU says that Brazil isn't sticking to the rules." Maggi speculated. "France doesn't want the deal and perhaps it is taking advantage of the situation to tear it up. Or the deal could take much longer to ratify — three, five years."

Such a delay could have severe repercussions for Brazil's struggling economy which relies heavily on its commodities trade with the EU. Analysists say that Bolsonaro's fears over such an outcome could be one reason for his recently announced October meeting with Chinese President Xi Jinping, another key trading partner.

Maggi is worried about another, even more alarming, potential consequence of Bolsonaro's failure to stem illegal deforestation — Brazil could be hit by a boycott by its foreign customers. "I don't buy this idea that the world needs Brazil … We are only a player and, worse still, replaceable." Maggi warns, "As an exporter, I'm telling you: things are getting very difficult. Brazil has been saying for years that it is possible to produce and preserve, but with this [Bolsonaro administration] rhetoric, we are going back to square one … We could find markets closed to us."

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