Short-term increase in fiber alters gut microbiome

 

• Researchers have previously identified a link between fiber intake and positive health outcomes.
• Fiber promotes a healthy gut microbiome once bacteria metabolize it.
• A recent study found that a 2-week increase in fiber intake significantly altered the gut microbiome.

Researchers have found that a 2-week increase in fiber intake can significantly alter a person’s gut microbiome, including increasing species of bacteria that break down fiber.

However, the quantity of short-chain fatty acids (SCFAs) did not increase. SCFAs are the result of bacteria breaking down fiber, and they have diverse roles within the body.

For instance, SCFAs are used as a source of energyTrusted Source for the cells of the colon and are involved in cell signaling. Some SCFAs also have anti-inflammatoryTrusted Source properties and might influenceTrusted Source insulin sensitivity and body weight.

The research, which appears in the journal mSystems, lays the groundwork for future studies to explore in more detail the relationship between fiber intake, gut bacteria, and SCFAs.

Benefits of fiber

Fiber plays an important role in human health. For example, a recent review of various meta-analyses found that people who eat the most fiber significantly reduce their chances of dying due to a cardiovascular event.

However, only 1 in 20 people in the United States consume the recommended amount of fiber.

According to Dr. Katrine Whiteson, associate professor of molecular biology and biochemistry, co-director of the University of California, Irvine (UCI) Microbiome Initiative, and co-author of the present study.

The small intestine cannot digest fiber. Instead, according to the authors of the present study, it passes into the colon, where microbes are able to break the fiber down.

This process results in the production of SCFAs. Experts believe they are important for a range of factors affecting a person’s health.

The authors of the present study wanted to study the relationship between a short-term increase in dietary fiber, the makeup of the gut microbiome, and the presence of SCFAs.

Two-week diet

To investigate, the researchers conducted a study involving 26 undergraduate students enrolled on a biology course at UCI, as well as their instructors.

In week 1, participants ate their normal diet and provided three stool samples for analysis.

In week 2, the participants started a high fiber diet. They tracked their nutritional intake using a fitness app, aiming for 40 grams (g) of fiber each day. To assist, the researchers provided them with 10 meals each week that were high in fiber from a range of different plants.

In the third week, the participants were encouraged to increase their fiber intake to 50 g per day. During this week, participants provided another three stool samples.

According to graduate student Andrew Oliver, a teaching assistant for the course, “students raised their fiber intake by an average of 25 g per day, but the variability of pre-intervention fiber intake was substantial.”

“A few students had to go from nearly zero to 50 g daily by the end of the study. We all became a little obsessed with how much fiber was in the food we were eating.”

The researchers then analyzed the samples using DNA sequencing to identify the makeup of the bacteria. They used gas chromatography to measure SCFAs.

Source: Medical News Today

COVID-19: High vitamin D levels may protect Black people

 

• Previous research has linked vitamin D deficiency to a higher risk of getting COVID-19 and experiencing more severe disease, especially among Black and Hispanic individuals.
• A new observational study suggests that even “sufficient” vitamin D levels, as guidelines currently define them, are associated with a higher risk of COVID-19 for Black people.
• Current guidelines for assessing vitamin D status are based on maintaining bone health rather than immune function.

Vitamin D plays a wide range of roles in the body, including regulating calcium levels, maintaining healthy bones and teeth, and supporting the immune system.

In addition to getting vitamin D from dietary sources, the body can make its own in the skin through exposure to sunlight.

However, it can be difficult for people with dark skin and those with low exposure to sunlight to maintain sufficiently high levels of the vitamin, especially during the winter months.

One studyTrusted Source

Trusted Source

PubMed Central

•  Highly respected datab
• ase from the National Institutes of Health

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 found that, overall, about 42% of people in the United States were deficient in vitamin D. The figure rose to 82% among Black people and 70% among Hispanic people.

Accumulating evidence has shown that people with deficient vitamin D levels are more likely to test positive for SARS-CoV-2, which is the virus that causes COVID-19. They may also be more likely to develop severe disease.

This association may partly explain why the pandemic has disproportionately affected Black, Hispanic, and other non-white populations.

Clinical trialsTrusted Source have found that vitamin D supplements can help protect people against other respiratory infections resulting from viruses.

The research suggests that taking a vitamin D supplement can even reduce viral infections among people who are not deficient in the vitamin, based on the recommended intake in the current guidelines. These recommendations are based on the levels necessary to maintain healthy bones.

Dr. David Meltzer, Ph.D., and his colleagues at the University of Chicago, IL, wondered whether the same could be true of vitamin D and COVID-19.

Vitamin D blood tests

The researchers analyzed the medical records of 4,638 individuals who had a vitamin D blood test in the 12 months before having a PCR test for SARS-CoV-2 at the University of Chicago Medical Center (UChicago Medicine).

The researchers used the length of time since the vitamin D test and subsequent treatments to estimate the participants’ vitamin D levels 14 days before the PCR test.

In addition, they accounted for factors that are known to increase a person’s risk of COVID-19, such as age, sex, race, and medical conditions.

In total, 211 Black participants and 102 white participants tested positive for SARS-CoV-2.

The researchers discovered that among Black participants, the risk of testing positive was 2.64 times as high for those with a serum vitamin D level of 30–39.9 nanograms per milliliter (ng/ml) — a “sufficient” level — as it was for those with a level of at least 40 ng/ml.

In other words, there appeared to be a significant protective effect from having levels above the range that experts consider to be sufficient.

Among Black participants with a vitamin D level of at least 30 ng/ml, every incremental 1 ng/ml increase in the level of the vitamin led to a 5% decrease in the risk of testing positive for SARS-CoV-2.

“These new results tell us that having vitamin D levels above those normally considered sufficient is associated with decreased risk of testing positive for [SARS-CoV-2], at least in Black individuals,” says Dr. Meltzer, who is chief of hospital medicine at UChicago Medicine and lead author of the study.

“This supports arguments for designing clinical trials that can test whether or not vitamin D may be a viable intervention to lower the risk of the disease, especially in Persons of Color,” he adds.

There were no statistically significant associations between vitamin D levels and the risk of testing positive for SARS-CoV-2 among white individuals.

The researchers attribute this to the relatively low number of positive SARS-CoV-2 tests among white people in their sample.

Similarly, the numbers of participants from other racial groups, including Hispanic people, were too small to yield statistically significant results.

Source: Medical News Today

Can a common food preservative harm the immune system?

 

• A recent study has assessed the harmful effects of chemical food additives and food contact substances on the immune system.
• The study compared laboratory toxicology testing (ToxCast) results with data from previous animal tests and epidemiological Trusted Sourcestudies.
• The ToxCast results and available animal study data confirmed that a common food preservative called tert-Butylhydroquinone (TBHQ) might negatively affect immune system functioning.
• The study affirmed the need for updated research and a thorough Food and Drug Administration (FDA) review of chemical food additives and food contact substances to assess immune system toxicity and protect public safety.

Various common chemicals may harm the immune system, causing it to malfunction. This is known as immunotoxicityTrusted Source. These harmful effects may be temporary or permanent.

Possible immunotoxic effects include:

• hypersensitivity
• chronic inflammation
• immunosuppression, or an impairment of the body’s ability to fight off infections
• immunostimulation, which can cause tissue damage through immune responses
• autoimmunity

In particular, if an immunotoxic substance causes the body to produce fewer antibodies, it can have an effect on the fight against active infections and the protection against future ones.

The FDA currently require immunotoxicity testing for food additives. However, most food additives received approval decades ago, and the FDA do not mandate updated testing on previously approved additives.

TBHQ and PFAS

TBHQ is a common preservative that manufacturers use to prolong their products’ shelf lives.

According to the Environmental Working Group (EWG), it is present in almost 1,250 processed foods, including Cheez-It crackers, Pop-Tarts, Reese’s Peanut Butter Cups, and Little Debbie Swiss Rolls.

However, this chemical has had immunotoxic effects in animal studies.

Chemicals may also leach from packaging or food processing equipment into food. Some bags, boxes, and food wrappers are coated with per- and polyfluoroalkyl substances (PFAS).

PFAS-based materials are also common in non-stick coatings on cookware, gaskets in food processing equipment, and repeat-use plastics.

The FDATrusted Source require immunotoxicity testing only for food contact substances with a high daily exposure. The immunotoxicity of many food additives and food contact substances is largely unknown.

The Environmental Protection Agency (EPA) use high throughput in-vitro testing in their ToxCast program. This type of testing exposes living cells, proteins, or biological molecules in a laboratory environment to chemicals to assess and identify any potential toxic effects. This potentially limits the need for animal testing.

The sparsity of current immunotoxicity data prompted the researchers from the EWG to conduct a study to evaluate the immunotoxic effects of common food additives and food contact substances. They also assessed the utility of ToxCast data in screening for immunotoxicity.

Lead study author Dr. Olga Naidenko, Ph.D., EWG’s vice president for science investigations, emphasizes the urgency of this research:

“The pandemic has focused public and scientific attention on environmental factors that can impact the immune system. Before the pandemic, chemicals that may harm the immune system’s defense against infection or cancer did not receive sufficient attention from public health agencies. To protect public health, this must change.”

The researchers analyzed a total of 63 direct food additives present on more than 10 product labels sold in the U.S. in 2018–2020. They also specifically assessed nine identified PFAS that migrate from food packaging to food.

The findings now appear in the International Journal of Environmental Research and Public Health.

The study evaluated these substances, concentrating on those with the highest number of active ToxCast assays. It focused further analyses on those substances with activity toward multiple immune-related targets and proteins involved in immune response, inflammation, and defense mechanisms.

The study compared the results of high throughput ToxCast data with available data from animal and epidemiological studies.

Source: Medical News Today

Obesity and depression: Investigating the link

 

• There is a two-way relationship between obesity and mental health conditions, including depression and anxiety.
• A study in mice suggests that eating a high fat diet may disrupt a newly discovered neural circuit in the brain that governs both mood and appetite.
• A combination of two drugs that act on this circuit not only reduced signs of anxiety in the animals but also led to weight loss.
• The animals lost weight after the treatment not only because they ate less but also because they preferred more healthy foods.

By 2030, experts predict that nearly half of all adults in the United States will have obesity.

There are well-known links between obesity and a wide range of physical illnesses, including type 2 diabetesTrusted Source, hypertensionTrusted Source, rheumatoid arthritisTrusted Source, and some forms of cancerTrusted Source.

However, there is also a complex two-way relationship between obesity and mental illness.

According to a report from the Centers for Disease Control and Prevention (CDC), 43%Trusted Source of the U.S. adults aged 20 years and over who are living with depression also have obesity. There is also an association between mental illness in general and obesity.

Weight gain is a recognized side effect of many antidepressant medications. Conversely, research suggests that obesity can have a psychological effect on people that predisposes them to depression.

But researchers believe that there may also be a more direct, physiological link between the two conditions.

Among the possible causes that obesity and mental illness may have in common are:

• inflammation
• hormonal disturbances
• genetic factors

Brain circuitry

There is also a possibility that certain neural circuits in the brain predispose people to both obesity and mental health conditions. However, exactly where these circuits are and how they work have been unclear.

Researchers from Baylor College of Medicine in Houston, TX, recently led a team of researchers that may have discovered such a circuit in mice.

The team found that feeding mice a high fat diet disrupted the circuit, which led not only to weight gain but also to signs of anxiety and depression on standard behavioral tests.

When the researchers used genetic techniques to restore the normal functioning of nerve receptors in the circuit, this resulted in weight loss and eliminated the animals’ signs of anxiety and depression.

Remarkably, despite still having a healthy appetite, the mice reduced their food intake and were no longer interested in high fat food.

“We were surprised to see that the animals lost weight not because they lost their appetite but because genetically aided readjustment of the mental states changed their feeding preference from high fat to low fat food,” says Dr. Guobin Xia, a postdoctoral associate at Baylor who is co-first author of the study.

Two drugs that target the same nerve receptors in this brain circuit had similar beneficial effects on the mice and their feeding preferences.

Source: Medical News Today

Hemifacial spasm: What you need to know

 Hemifacial spasm is a condition in which the muscles contract in tics or twitches on one side of the face, usually the left. People do not have control over these spasms, and very often they continue even during sleep.

Hemifacial spasm is usually not painful and not considered a health hazard. In advanced cases, however, the eyes may remain squeezed shut for long enough to become dangerous when driving, for example.

Both men and women can develop these facial twitches, but women, especially middle-aged and older women, develop hemifacial spasm at about twice the rateTrusted Source of men. The condition is also somewhat more common in Asian people.

Types

Hemifacial spasm is different from other nerve and muscle conditions affecting the face because it tends to affect only one side of the face.

However, there are differences between what is considered typical for hemifacial spasm and other forms of the condition.

A study of 215 people being examined for hemifacial spasm found that:

• 62 percent were most likely caused by a vein putting pressure on the facial nerve
• 18 percent had tics that mimicked hemifacial spasm but were not actually examples of the disease
• 11 percent were due to Bell’s Palsy
• 6 percent were the result of injuries to the facial nerve
• 2 percent were linked to hereditary causes

Fewer than 1 percent of cases were caused by direct damage to nerves or the brain’s circulatory system

Symptoms

The first sign of hemifacial spasm is usually a twitching in the muscles of the left eyelid. These spasms can be strong enough to pull the eye closed and cause tears to form.

If left untreated, the symptoms of hemifacial spasm can become more severe and affect more and more facial muscles. Twitches can affect the muscles of the mouth and pull it to one side.

Over time, all the muscles on one side of the face can be pulled into a permanent frown. Some individuals may develop spasms on both sides of the face.

Ear pain, a “clicking” in the ear, and changes in hearing can also be symptoms of this condition. Hearing loss also sometimes occurs.

Around 13 percent of people taking part in one study reported a loss of hearing. However, this hearing loss did not appear to relate to how serious their hemifacial spasm symptoms were.

Symptoms of hemifacial spasm usually develop when people are between 40 and 50 years of age.

Causes

Hemifacial spasm is caused by irritation to the seventh cranial nerve. This nerve is known as the facial nerve and controls the muscles of the face. It also transmits information about the sense of taste from the tongue and sensations in the ear.

The most frequent source of irritation is a small artery pressing on the facial nerve near the brain stem. Other potential causes include:

• a benign tumor or lesion pressing on the nerve
• abnormal clusters of blood vessels at birth
• nerve injury

Hereditary cases of hemifacial spasm have been identified, although they are not common.

In some cases, hemifacial spasm is the first symptom of multiple sclerosis or MS. When people have MS, their immune system attacks the central nervous system, which results in a wide variety of symptoms.

However, this is extremely rare, with scientific studies showing only 1 to 6 occasions out of several hundred cases in which MS was identified as the cause of a hemifacial spasm.

Although it is rare, doctors still need to check for MS as a possible cause when people under age 40 have a hemifacial spasm.

Source: Medical News Today

Why do muscle spasms happen?

 A muscle spasm is a sudden, involuntary movement in one or more muscles. People may also call it a charley horse or a muscle cramp or twitch.

These movements can happen in any muscle of the body, and they are very common. Muscle spasms often occur as a result of stress, exercise, or dehydration. They are usually not a cause for concern.

Causes

Muscle spasms are very common. They can happen in any part of the body, but they tend to affect the:

• feet
• hands
• arms
• thighs
• abdomen
• intercostal muscles, which are around the rib cage

Muscle pain, fatigue, and overuse are the most common causes of muscle spasms. Other causes include stress or anxiety, which can lead to muscle twitches in the face. Trapped nerves can result in spasms in the back.

Athletes who either do not warm up before they exercise or exercise in very hot conditions may also experience muscle spasms. Charley horse, for example, is a term that people often use to describe spasms in runners’ calf muscles. Drinking insufficient water before exercise can also cause muscle spasms.

Some people are more vulnerable than others to muscle spasms. Those who are most at risk are:

• older adults
• athletes
• people with overweight or obesity
• pregnant women

People who have certain health conditions, such as nerve disorders or thyroid-related problems, also tend to experience a higher-than-average frequency of muscle spasms.

Muscle spasms are not usually anything to worry about, but in some cases, they can be a sign of an underlying neurological health condition. Neurological health conditions affect the brain, which is responsible for making the muscles move.

Symptoms

Not all muscle spasms are painful, but some can cause pain. It can feel as though the muscle is jumping or moving on its own, with this feeling typically lasting just a few seconds. Some people might even be able to see the muscle twitching.

Sometimes, it can feel as though the whole muscle has cramped up and cannot move. This effect most commonly happens in the legs, and it can be quite painful. The muscle may feel hard to the touch. While the cramping sensation tends to pass within several minutes or so, the muscle may continue to hurt for some time afterward.

If a muscle spasm is part of a neurological health condition, the person will usually experience other symptoms. These might include:

• pain in the back, neck, or head
• weakness in the muscles
• skin numbness
• a pins-and-needles sensation
• a tremor
• paralysis
• poor coordination
• slow movements
• double vision
• sleep problems

Source: MEDICAL NEWS TODAY

Everything you need to know about eyelid twitch

 Causes

Sometimes, electrical activity in the brain causes nerve cells to flash signals to the muscles, which causes spasms. These spasms do not result from any internal or external stimuli, and they do not last long.

A one-time eyelid twitch is likely to be a result of this phenomenon.

If an eyelid twitch lasts for a few minutes to a few days, it could be caused by muscle overstimulation or fatigue due to:

• excessive caffeine intake
• disrupted or insufficient sleep patterns
• stress
• dry eyes

Improving sleeping patterns, drinking less coffee, or using lubricating eye drops can usually resolve a simple eyelid twitch without medical attention.

If an eyelid twitch persists, a person should visit an eye doctor (ophthalmologist) as they may have a more serious condition that requires treatment.

Related conditions

The most common forms of chronic eyelid twitch are benign essential blepharospasm and hemifacial spasm.

Benign essential blepharospasm is a rare neurological disorder that causes spasms and muscle contractions around the eyes.

It may initially appear similar to a basic eyelid twitch, but it can deteriorate if left untreated. In some cases, the spasms become severe enough to squeeze the eyelids shut for hours at a time.

Researchers are still unsure as to the causes of essential blepharospasm. Most believe that it is a combination of both environmental and genetic factors.

A common theory is that these factors cause the brain’s basal ganglia to malfunction. The basal ganglia are involved in regulating motor function, and they play a significant role in inhibiting erratic movements.

According to the National Organization for Rare Disorders, essential blepharospasm has several early symptoms that can help to distinguish it from a basic twitch:

• both eyes are involved
• the individual blinks frequently
• other muscles in the face experience spasms
• the eyes become irritated in bright light and stressful situations
• spasms usually last for an hour

Hemifacial spasm may initially be confused for a simple eye twitch as the condition usually begins by affecting the muscles surrounding the eye.

However, these spasms will eventually spread to other muscles on the same side of the face, causing the jaw, mouth, cheek, and neck muscles to contract spontaneously.

Hemifacial spasm is also a rare condition, but it is not caused by malfunction of any deep-brain structures. Instead, researchers believe that hemifacial spasm is caused by irritation of the facial nerve. This irritation could happen if a neighboring blood vessel puts too much pressure on the nerve.

Some other differences that might be useful in telling hemifacial spasm apart from blepharospasm and basic eye twitch are:

• the condition will usually affect one eye
• a person may experience facial muscle weakness between contractions
• hemifacial spasms tend to be consistent in intensity
• some people will hear a clicking sound in the ear on the affected side of the head
• hemifacial spasms can last anywhere from several days to a few months

Source: Medical News Today