Our ability to focus may falter after eating one meal high in saturated fat

Our ability to focus may falter after eating one meal high in saturated fat

Fatty food may feel like a friend during these troubled times, but new research suggests that eating just one meal high in saturated fat can hinder our ability to concentrate -- not great news for people whose diets have gone south while they're working at home during the COVID-19 pandemic.

The study compared how 51 women performed on a test of their attention after they ate either a meal high in saturated fat or the same meal made with sunflower oil, which is high in unsaturated fat.

Their performance on the test was worse after eating the high-saturated-fat meal than after they ate the meal containing a healthier fat, signaling a link between that fatty food and the brain.

Researchers were also looking at whether a condition called leaky gut, which allows intestinal bacteria to enter the bloodstream, had any effect on concentration. Participants with leakier guts performed worse on the attention assessment no matter which meal they had eaten.

The loss of focus after a single meal was eye-opening for the researchers.

"Most prior work looking at the causative effect of the diet has looked over a period of time. And this was just one meal -- it's pretty remarkable that we saw a difference," said Annelise Madison, lead author of the study and a graduate student in clinical psychology at The Ohio State University.

Madison also noted that the meal made with sunflower oil, while low in saturated fat, still contained a lot of dietary fat.

"Because both meals were high-fat and potentially problematic, the high-saturated-fat meal's cognitive effect could be even greater if it were compared to a lower-fat meal," she said.

The study is published in the American Journal of Clinical Nutrition.

Madison works in the lab of Janice Kiecolt-Glaser, professor of psychiatry and psychology and director of the Institute for Behavioral Medicine Research at Ohio State. For this work, Madison conducted a secondary analysis of data from Kiecolt-Glaser's study assessing whether high-fat meals increased fatigue and inflammation among cancer survivors.

Women in the study completed a baseline assessment of their attention during a morning visit to the lab. The tool, called a continuous performance test, is a measure of sustained attention, concentration and reaction time based on 10 minutes of computer-based activities.

The high-fat meal followed: eggs, biscuits, turkey sausage and gravy containing 60 grams of fat, either a palmitic acid-based oil high in saturated fat or the lower-saturated-fat sunflower oil. Both meals totaled 930 calories and were designed to mimic the contents of various fast-food meals such as a Burger King double whopper with cheese or a McDonald's Big Mac and medium fries.

Five hours later, the women took the continuous performance test again. Between one and four weeks later, they repeated these steps, eating the opposite meal of what they had eaten on the first visit.

Researchers also analyzed participants' fasting baseline blood samples to determine whether they contained an inflammatory molecule that signals the presence of endotoxemia -- the toxin that escapes from the intestines and enters the bloodstream when the gut barrier is compromised.

After eating the meal high in saturated fat, all of the participating women were, on average, 11 percent less able to detect target stimuli in the attention assessment. Concentration lapses were also apparent in the women with signs of leaky gut: Their response times were more erratic and they were less able to sustain their attention during the 10-minute test.

"If the women had high levels of endotoxemia, it also wiped out the between-meal differences. They were performing poorly no matter what type of fat they ate," Madison said.

Though the study didn't determine what was going on in the brain, Madison said previous research has suggested that food high in saturated fat can drive up inflammation throughout the body, and possibly the brain. Fatty acids also can cross the blood-brain barrier.

"It could be that fatty acids are interacting with the brain directly. What it does show is the power of gut-related dysregulation," she said.

The statistical analysis accounted for other potential influences on cognition, including depressive symptoms and the participants' average dietary saturated fat consumption. The women in the study ate three standardized meals and fasted for 12 hours before each lab visit to reduce diet variations that could affect their physiological response to the high-fat meals.

The findings suggest concentration could be even more impaired in people stressed by the pandemic who are turning to fatty foods for comfort, Kiecolt-Glaser said.

"What we know is that when people are more anxious, a good subset of us will find high-saturated-fat food more enticing than broccoli," she said. "We know from other research that depression and anxiety can interfere with concentration and attention as well. When we add that on top of the high-fat meal, we could expect the real-world effects to be even larger."

This work was supported in part by the National Institutes of Health.

Additional co-authors, all from Ohio State, included Martha Belury, Rebecca Andridge, M. Rosie Shrout, Megan Renna, William Malarkey and Michael Bailey.

Story Source:

Materials provided by Ohio State University. Original written by Emily Caldwell. Note: Content may be edited for style and length.

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Journal Reference:

1. Janice K Kiecolt-Glaser, Michael T Bailey, William B Malarkey, Megan E Renna, M Rosie Shrout, Rebecca Andridge, Martha A Belury, Annelise A Madison. Afternoon distraction: a high-saturated-fat meal and endotoxemia impact postmeal attention in a randomized crossover trial. The American Journal of Clinical Nutrition, 2020; DOI: 10.1093/ajcn/nqaa085

Loss of smell and taste validated as COVID-19 symptoms in patients with high recovery rate

Loss of smell and taste has been anecdotally linked to COVID-19 infections. In a study published April 12, 2020 in the journal International Forum of Allergy & Rhinology, researchers at UC San Diego Health report the first empirical findings that strongly associate sensory loss with COVID-19, the respiratory disease caused by the novel coronavirus.

"Based on our study, if you have smell and taste loss, you are more than 10 times more likely to have COVID-19 infection than other causes of infection. The most common first sign of a COVID-19 infection remains fever, but fatigue and loss of smell and taste follow as other very common initial symptoms," said Carol Yan, MD, an otolaryngologist and head and neck surgeon at UC San Diego Health. "We know COVID-19 is an extremely contagious virus. This study supports the need to be aware of smell and taste loss as early signs of COVID-19."

Yan and colleagues surveyed 1,480 patients with flu-like symptoms and concerns regarding potential COVID-19 infection who underwent testing at UC San Diego Health from March 3 through March 29, 2020. Within that total, 102 patients tested positive for the virus and 1,378 tested negative. The study included responses from 59 COVID-19-positive patients and 203 COVID-19-negative patients.

Yan said the study demonstrated the high prevalence and unique presentation of certain sensory impairments in patients positive with COVID-19. Of those who reported loss of smell and taste, the loss was typically profound, not mild. But encouragingly, the rate of recovery of smell and taste was high and occurred usually within two to four weeks of infection.

"Our study not only showed that the high incidence of smell and taste is specific to COVID-19 infection, but we fortunately also found that for the majority of people sensory recovery was generally rapid," said Yan. "Among the Covid-19 patients with smell loss, more than 70 percent had reported improvement of smell at the time of survey and of those who hadn't reported improvement, many had only been diagnosed recently."

Sensory return typically matched the timing of disease recovery. Interestingly, the researchers found that persons who reported experiencing a sore throat more often tested negative for COVID-19.

In an effort to decrease risk of virus transmission, UC San Diego Health now includes loss of smell and taste as a screening requirement for visitors and staff, as well as a marker for testing patients who may be positive for the virus.

Other known symptoms of COVID-19 include fever, fatigue, cough and difficulty breathing. Respondents in Yan's study were most often persons with milder forms of COVID-19 infection who did not require hospitalization or intubation. The findings, she said, underline the importance of identifying early or subtle symptoms of COVID-19 infection in people who may be at risk of transmitting the disease as they recuperate within the community.

"It is our hope that with these findings other institutions will follow suit and not only list smell and taste loss as a symptom of COVID-19, but use it as a screening measure for the virus across the world," Yan said.

Co-authors include: Farhoud Faraji, Divya P. Prajapti, Christine E. Boone and Adam S. DeConde, all at UC San Diego.

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Story Source:

Materials provided by University of California - San Diego. Original written by Jeanna Vazquez. Note: Content may be edited for style and length.

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Journal Reference:

1. Carol H. Yan, Farhoud Faraji, Divya P. Prajapati, Christine E. Boone, Adam S DeConde. Association of chemosensory dysfunction and Covid-19 in patients presenting with influenza-like symptoms. International Forum of Allergy & Rhinology, 2020; DOI: 10.1002/alr.22579

High temperatures due to global warming will be dramatic even for tardigrades

Tardigrade (stock image).

Global warming, a major aspect of climate change, is already causing a wide range of negative impacts on many habitats of our planet. It is thus of the utmost importance to understand how rising temperatures may affect animal health and welfare.

A research group from Department of Biology, University of Copenhagen has just shown that tardigrades are very vulnerable to long-term high temperature exposures. The tiny animals, in their desiccated state, are best known for their extraordinary tolerance to extreme environments.

In a study published recently in Scientific Reports, Ricardo Neves and Nadja Møbjerg and colleagues at Department of Biology, University of Copenhagen present results on the tolerance to high temperatures of a tardigrade species.

Tardigrades, commonly known as water bears or moss piglets, are microscopic invertebrates distributed worldwide in marine, freshwater and terrestrial microhabitats.

Ricardo Neves, Nadja Møbjerg and colleagues investigated the tolerance to high temperatures of Ramazzottius varieornatus, a tardigrade frequently found in transient freshwater habitats.

"The specimens used in this study were obtained from roof gutters of a house located in Nivå, Denmark. We evaluated the effect of exposures to high temperature in active and desiccated tardigrades, and we also investigated the effect of a brief acclimation period on active animals," explains postdoc Ricardo Neves.

Rather surprisingly the researchers estimated that for non-acclimated active tardigrades the median lethal temperature is 37.1°C, though a short acclimation periods leads to a small but significant increase of the median lethal temperature to 37.6°C. Interestingly, this temperature is not far from the currently measured maximum temperature in Denmark, i.e. 36.4°C. As for the desiccated specimens, the authors observed that the estimated 50% mortality temperature is 82.7°C following 1 hour exposures, though a significant decrease to 63.1°C following 24 hour exposures was registered.

The research group used logistic models to estimate the median lethal temperature (at which 50% mortality is achieved) both for active and desiccated tardigrades.

Approximately 1300 tardigrade species have been described so far. The body of these minute animals is barrel-shaped (or dorsoventrally compressed) and divided into a head and a trunk with four pairs of legs. Their body length varies between 50 micrometers and 1.2 millimeters. Apart from their impressive ability to tolerate extreme environments, tardigrades are also very interesting because of their close evolutionary relationship with arthropods (e.g., insects, crustaceans, spiders).

As aquatic animals, tardigrades need to be surrounded in a film of water to be in their active state (i.e., feeding and reproducing). However, these critters are able to endure periods of desiccation (anhydrobiosis) by entering cryptobiosis, i.e., a reversible ametabolic state common especially among limno-terrestrial species. Succinctly, tardigrades enter the so-called "tun" state by contracting their anterior-posterior body axis, retracting their legs and rearranging the internal organs. This provides them with the capacity to tolerate severe environmental conditions including oxygen depletion (anoxybiosis), high toxicant concentrations (chemobiosis), high solute concentration (osmobiosis) and extremely low temperatures (cryobiosis).

The extraordinary tolerance of tardigrades to extreme environments includes also high temperature endurance. Some tardigrade species were reported to tolerate temperatures as high as 151°C. However, the exposure time was only of 30 minutes. Other studies on thermotolerance of desiccated (anhydrobiotic) tardigrades revealed that exposures higher than 80°C for 1 hour resulted in high mortality, with almost all specimens dying at temperatures above 103°C. It remained, yet, unknown how anhydrobiotic tardigrades handle exposures to high temperatures for long periods, i.e., exceeding 1 hour.

"From this study, we can conclude that active tardigrades are vulnerable to high temperatures, though it seems that these critters would be able to acclimatize to increasing temperatures in their natural habitat. Desiccated tardigrades are much more resilient and can endure temperatures much higher than those endured by active tardigrades. However, exposure-time is clearly a limiting factor that constrains their tolerance to high temperatures," says Ricardo Neves.

Indeed, although tardigrades are able to tolerate a diverse set of severe environmental conditions, their endurance to high temperatures is noticeably limited and this might actually be the Achilles heel of these otherwise super-resistant animals.

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Story Source:

Materials provided by Faculty of Science - University of Copenhagen. Note: Content may be edited for style and length.