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High-Salt Diet Kills Beneficial Gut Bacteria, Leading to Disease

A team of international researchers has found a high-salt diet reduces the population of the beneficial gut bacteria Lactobacillus. This, in turn, impacts immune cells which can lead to the development of hypertension and autoimmune disease. Probiotics may help to curb these effects.

Gut Flora and Salt-Sensitive Diseases

A high-salt diet has long been identified as a contributing factor to high blood pressure, stroke, heart disease and heart failure. When salt accumulates in the bloodstream, the body retains fluid in order to dilute the sodium. The heart and blood vessels then have to work harder to deal with the excess water, which causes the blood vessels to stiffen and can lead to cardiovascular complications and potentially death.

Higher intake of salt has also been linked to the development of stomach cancer, and it may further exacerbate osteoporosis symptoms. Previous research has shown that reducing salt intake both lowers your risk for cardiovascular disease and related deaths over the long term, but scientists are still trying to understand the mechanisms underlying these connections.

Imbalances in the gut’s microbiota have been implicated as underlying factors in systemic inflammatory conditions and immune system disruptions. Research has shown that gut bacterial imbalance may be involved in many of the same cardiovascular health problems that arise from a high-salt diet. “But so far, nobody had studied how salt affects the bacteria in the gut,” said the lead researcher of the study, Professor Dominik Müller of the Experimental and Clinical Research Center (ECRC) and Max Delbrück Center for Molecular Medicine in Berlin, Germany.

Müller and his colleagues felt that this was a deserving point of focus. According to fellow team member and ECRC researcher Dr. Nicola Wilck, “gut bacteria influence the host organism, and the immune system is also very active in the gut.” The team decided to investigate the effect that salt has on the bacterial populations of the gut to determine what changes occur and discern if those changes may be linked to the detrimental effects of a salt-laden diet. The team’s research has been published in the journal Nature. Their findings were recently presented at the British Cardiovascular Society Conference in Manchester in the United Kingdom.

High-Salt Diet Kills Off Lactobacillus Populations

With their research, Müller and his team have successfully demonstrated that excess sodium decreases the Lactobacilli in our guts while raising blood pressure and increasing the number of Th17 helper cells, immune cells that stimulate inflammation, cause hypertension and are associated with autoimmune diseases such as multiple sclerosis. According to Müller, “we should start to see our gut microbiome as a viable target for treating conditions that we know are aggravated by salt, such as high blood pressure and inflammation.”

In their experimentation, the team fed mice a high-salt diet in which sodium made up 4 percent of their daily intake, compared to the 0.5 percent sodium intake of a normal diet. The team found that the higher salt intake led to a decline in the population of Lactobacillus murinus bacteria. Mice fed this diet had higher blood pressure and were also found to have increased populations of the Th-17 cells. When the mice with high blood pressure were given a probiotic which contained Lactobacillus murinus, Th-17 populations declined and the symptoms of hypertension decreased.

The researchers then decided to investigate if this effect would carry over to human subjects. The team investigated the gut microbiota of 12 healthy men who were administered six additional grams of salt, roughly doubling their sodium intake, every day over the course of two weeks. As was observed with the mice, within human test subjects, lactobacilli were sensitive to salt intake, becoming almost undetectable after 14 days. As expected, participants’ possessed higher blood pressure and an increase in the number of Th-17 helper cells in their blood. Participants who took an over-the-counter probiotic for a week prior to starting the high-salt diet retained normal blood pressure levels, and their Lactobacillus populations remained intact.

A Window Into Future Therapies

According to the researchers, “it is still unclear exactly how Th-17 cells contribute to the development of high blood pressure and other ill effects of a high-salt diet,” but they are hopeful their research will help shed light on potential treatments for salt-sensitive illnesses.

Fellow researcher, Dr. Ralf Linker from the Friedrich-Alexander University said, “multiple sclerosis may be one of the salt-sensitive diseases which we might be able to treat in the future with individually-tailored probiotics as add-on to standard immune therapies.”

While the role gut microbiota plays in our health is increasingly an important focus of research attention, there is much we still don’t know about how other organisms impact and interact with our gut flora. “Our study goes beyond just describing the changes caused by salt. We want to consider interrelated processes,” said Dr. Müller. “We can’t exclude the possibility that there are other salt-sensitive bacteria that are just as important as Lactobacillus,” he continued. “This could be the tip of the iceberg in targeting gut bacteria for treating serious illnesses.”

“We’re learning that the immune system exerts a lot of control on the body, above and beyond what we generally think of as immunity. The mechanisms by which it exerts that control are still being unraveled,” said team member Professor Eric Alm of MIT. “We hope that our findings, along with future studies, will help to shed more light on the mechanism by which a high-salt diet influences disease.”

New Links Between Sleep and Health Highlight the Importance of Getting Your Zzzs

Feb 07 by Ewcopywriting Leave a Comment

Millions of people struggle to get adequate, restful sleep. New research on sleep and health suggests that not getting enough sleep can have more serious effects on your health than previously realized.

Have you ever struggled to fall asleep? Have you ever woken from a deep slumber unable to get back to sleep? If so, you are not alone. Sleep disorders are a common problem that leaves many people fatigued and sleepy throughout the day. However, the effects may go far beyond temporarily feeling too tired. New studies have found links between sleep and health that suggest that getting enough high-quality sleep is one of the most important parts of a healthy lifestyle.

Sleep and Health: Immune Effects

Many people notice that they are more likely to get sick when they are overworked or simply worn out. Scientific research supports this observation. Studies of twins have found that even among identical twins, the twin who does not get enough sleep is more likely to become sick when they are both exposed to bacteria or viruses. They also have measurably lower levels of white blood cells circulating in their bloodstream, which are the first line of defense against pathogens.

This is especially important when you consider that people in the Western world are getting less sleep than ever before; as many as one to two hours less per night. This can have a very negative effect on our immune systems, which we rely upon to keep out foreign pathogens and fight the ones that somehow breach our barriers. The result is that we may be more prone to infections than ever before, spending more days ill and living at higher risk of developing an infection that can be deadly.

Cognitive Impairment: A Side Effect of Insomnia?

Sleep disturbances may also have an effect on how you well you think and remember. Doctors tested elderly people with cognitive impairments and those without them. They found that those who have better cognition also report better sleep patterns. A similar link has been found in several other studies as well: Older people who sleep well suffer less of the loss of thinking skills that we associate with aging. While we think of retirement as a time of rest, many older people do not appear to be getting enough sleep.

This makes intuitive sense to people who have suffered a sleepless night or even jet lag. Most people who have not had adequate sleep find that they struggle with concentration and memory for one or more days. Although more study is needed, it is logical that people who struggle with sleep throughout their lives may see more long-term effects.

The Circadian Rhythm of Respiratory Health

Although we think of asthma as a childhood disease, it affects many adults as well. This and other chronic respiratory illnesses are a major cause of emergency room visits in the United States. While most adults with asthma develop it as children, some actually do not get the disease until well into adulthood. Doctors and scientists have struggled to determine exactly why this happens. Obesity, pollution and other factors have been linked to adult asthma, but insomnia also appears to play a role. Researchers looked at adults with sleep disorders and those without. Over an 11-year period, those with sleep disorders were around three times as likely to develop asthma and other respiratory illnesses.

How can asthma be linked to sleep? Researchers believe that the effect of insomnia on the immune system may be partially to blame. People who do not sleep as well are more likely to live with high levels of inflammation, which is a key feature of asthma and several other respiratory illnesses. This link suggests that the issue of sleep and health may be extremely important in preventing costly chronic illnesses and even in preventing deaths from respiratory failure.

In the Bedroom and Beyond

One final area that modern research suggests may be impacted by sleep is sexuality. In a study of almost 100,000 pre-menopausal and menopausal women, researchers found a clear link between sexual satisfaction and getting high-quality sleep. Women who report sleeping seven to eight hours a night, which most researchers consider ideal, are also more likely to experience higher sexual satisfaction.

While most people believe that menopause is a time when women lose their sex drive, this does not always appear to be true. Over half of women who get adequate slumber report feeling sexually active and satisfied with their sex lives.

Many of these new links between sleep and health are correlations, which means that they merely show a link between two variables and do not offer definitive proof that one causes the other. However, it is clear that getting enough high-quality sleep is important in maintaining the good health that we all wish to enjoy over our lifetimes.

Losing the Night Sky: The Harmful Effects of Light Pollution on Human Health

Jun 25 by Ewcopywriting Leave a Comment

The night sky is an important part of human culture. We refer to famous people as “stars” and make endless references to the night sky without even realizing it. Van Gogh’s “Starry Night” and other great works of art based on the night sky are still an inspiration to millions. While darkness at night has historically been an important part of human life on an existential level, it also is crucial to human health.

Losing the Night Sky

Modern technology has enabled human civilization to flourish as never before. We can work odd shifts, entertain ourselves until late at night, and continue living our lives long after the sun has set. We even can walk in relative safety late at night thanks to street lights. However, light can pollute an area just as a toxic chemical can. Many people live in places where they can no longer experience the night sky. The haze of nighttime light in cities and suburbs leaves over half of all Americans and up to 80 percent of Europeans unable to see the Milky Way. In addition, many people live in areas of the Western world where they can see only less than one hundred of the tens of thousands of stars we used to experience. Once a huge part of human imagination, the night sky is now foreign to many people. When Los Angeles lost power in 1994, there was a mild panic over a strange silver cloud in the sky at night. This cloud was actually the Milky Way, which many residents of the area had never seen due to the light pollution of city.

Is Light Pollution a Threat to the Environment?

Although we mainly discuss circadian rhythm in the context of human health, all living things live according to a rhythm of some sort. These include circadian, or 24-hour rhythms, seasonal rhythms and monthly rhythms. Light levels are a major cue of the time of day, month and year to a wide variety of organisms. A modern world filled with constant light can have serious effects on the environment.

The New York Times recently listed the many ways that light pollution is affecting our environment. Coral release eggs and sperm according to the cycles of the moon. With light pollution obscuring levels of moonlight, populations are dying as there is no coordinated breeding. Baby sea turtles hatch on beaches and crawl toward boardwalks and suburbs rather than toward the moon’s reflection on the ocean, creating wide-scale death. Attracted to light, many birds and insects fly into buildings and lights rather than breeding or migrating. While the effects on humans may be less noticeable, light pollution indeed has a measurable effect on us.

Light Pollution and Human Health

The human circadian rhythm is controlled by light or the lack thereof. When our retinas stop sensing light, they send signals to the suprachiasmatic nucleus (SCN) of the brain, which then cues other brain centers to produce biochemicals and hormones that induce sleep. These hormones also play a variety of other important roles, such as repairing DNA, consolidating memories and cleaning metabolic waste from cells. Light pollution does not just leave us tired, but has a variety of negative effects that accumulate over our lifetimes.

Medical authorities are increasingly recognizing that nighttime light may be a powerful health risk. We are warned to avoid screens and dim our lights at least an hour before we go to bed. However, the light pollution resulting from human civilization may have equal or even greater effects. People in well-lit urban areas are more likely to have sleep disorders and report feeling fatigued during the day. As a result, the American Medical Association has warned against bright, high temperature lighting such as LED street lights. This type of light travels further, illuminates the night more, and has a greater effect on our brains. Although lighting cities and suburbs with street lamps is necessary for human safety, the choice of light may make a huge difference in how area residents sleep at night.

Stephen Hawking once advised people, “Look up at the stars and not down at your feet.” It is crucial to both human health and the health of the environment that we have a dark night. However, modern life makes this difficult and even, at times, impossible. Restoring a dark, starry night and thus a healthy circadian rhythm to our existence may be an important and necessary public health measure.