University of Colorado, May 28, 2021
Waking up just one hour earlier could reduce a person's risk of major depression by 23%, suggests a sweeping new genetic study published May 26 in the journal JAMA Psychiatry.
The study of 840,000 people, by researchers at University of Colorado Boulder and the Broad Institute of MIT and Harvard, represents some of the strongest evidence yet that chronotype--a person's propensity to sleep at a certain time --influences depression risk.
It's also among the first studies to quantify just how much, or little, change is required to influence mental health.
As people emerge, post-pandemic, from working and attending school remotely-- a trend that has led many to shift to a later sleep schedule--the findings could have important implications.
"We have known for some time that there is a relationship between sleep timing and mood, but a question we often hear from clinicians is: How much earlier do we need to shift people to see a benefit?" said senior author Celine Vetter, assistant professor of integrative physiology at CU Boulder. "We found that even one-hour earlier sleep timing is associated with significantly lower risk of depression."
Previous observational studies have shown that night owls are as much as twice as likely to suffer from depression as early risers, regardless of how long they sleep. But because mood disorders themselves can disrupt sleep patterns, researchers have had a hard time deciphering what causes what.
Other studies have had small sample sizes, relied on questionnaires from a single time point, or didn't account for environmental factors which can influence both sleep timing and mood, potentially confounding results.
In 2018, Vetter published a large, long term study of 32,000 nurses showing that "early risers" were up to 27% less likely to develop depression over the course of four years, but that begged the question: What does it mean to be an early riser?
To get a clearer sense of whether shifting sleep time earlier is truly protective, and how much shift is required, lead author Iyas Daghlas, M.D., turned to data from the DNA testing company 23 and Me and the biomedical database UK Biobank. Daghlas then used a method called "Mendelian randomization" that leverages genetic associations to help decipher cause and effect.
"Our genetics are set at birth so some of the biases that affect other kinds of epidemiological research tend not to affect genetic studies," said Daghlas, who graduated in May from Harvard Medical School.
More than 340 common genetic variants, including variants in the so-called "clock gene" PER2, are known to influence a person's chronotype, and genetics collectively explains 12-42% of our sleep timing preference.
The researchers assessed deidentified genetic data on these variants from up to 850,000 individuals, including data from 85,000 who had worn wearable sleep trackers for 7 days and 250,000 who had filled out sleep-preference questionnaires. This gave them a more granular picture, down to the hour, of how variants in genes influence when we sleep and wake up.
In the largest of these samples, about a third of surveyed subjects self-identified as morning larks, 9% were night owls and the rest were in the middle. Overall, the average sleep mid-point was 3 a.m., meaning they went to bed at 11 p.m. and got up at 6 a.m.
With this information in hand, the researchers turned to a different sample which included genetic information along with anonymized medical and prescription records and surveys about diagnoses of major depressive disorder.
Using novel statistical techniques, they asked: Do those with genetic variants which predispose them to be early risers also have lower risk of depression?
The answer is a firm yes.
Each one-hour earlier sleep midpoint (halfway between bedtime and wake time) corresponded with a 23% lower risk of major depressive disorder.
This suggests that if someone who normally goes to bed at 1 a.m. goes to bed at midnight instead and sleeps the same duration, they could cut their risk by 23%; if they go to bed at 11 p.m., they could cut it by about 40%.
It's unclear from the study whether those who are already early risers could benefit from getting up even earlier. But for those in the intermediate range or evening range, shifting to an earlier bedtime would likely be helpful.
What could explain this effect?
Some research suggests that getting greater light exposure during the day, which early-risers tend to get, results in a cascade of hormonal impacts that can influence mood.
Others note that having a biological clock, or circadian rhythm, that trends differently than most peoples' can in itself be depressing.
"We live in a society that is designed for morning people, and evening people often feel as if they are in a constant state of misalignment with that societal clock," said Daghlas.
He stresses that a large randomized clinical trial is necessary to determine definitively whether going to bed early can reduce depression. "But this study definitely shifts the weight of evidence toward supporting a causal effect of sleep timing on depression."
For those wanting to shift themselves to an earlier sleep schedule, Vetter offers this advice:
"Keep your days bright and your nights dark," she says. "Have your morning coffee on the porch. Walk or ride your bike to work if you can, and dim those electronics in the evening."
Olive oil nutrient may help prevent brain cancer
University of Edinburgh, June 2, 2021
A compound found in olive oil may help to prevent cancer developing in the brain, a study shows.
Research into oleic acid – the primary ingredient in olive oil – has shown how it can help prevent cancer-causing genes from functioning in cells.
The oily substance – one of a group of nutrients known as fatty acids – stimulates the production of a cell molecule whose function is to prevent cancer-causing proteins from forming.
The study team says it is too soon to say whether dietary consumption of olive oil may help prevent brain cancer.
Their findings, however, point towards possible therapies based on the oil to prevent brain cancer from occurring.
Scientists from the University analysed the effect of oleic acid on a cell molecule, known as miR-7, which is active in the brain and is known to suppress the formation of tumours.
They found that oleic acid prevents a cell protein, known as MSI2, from stopping production of miR-7.
In this way, the olive oil component supports the production of miR-7, which helps prevent tumours from forming.
Researchers made their discoveries in tests on human cell extracts and in living cells in the lab.
The study, published in the Journal of Molecular Biology, was funded by the Medical Research Council and the Wellcome Trust.
"While we cannot yet say that olive oil in the diet helps prevent brain cancer, our findings do suggest that oleic acid can support the production of tumour-suppressing molecules in cells grown in the lab. Further studies could help determine the role that olive oil might have in brain health," says Dr Gracjan Michlewski.
Study: Boosting selenium intake can help reduce osteoporosis risk
Central South University (China), May 29, 2021
Researchers from China have found that increased selenium intake may reduce a person’s risk for osteoporosis. In their report, experts from Central South University in Changsha recruited over 6,200 participants and measured the bone mineral density in the middle phalanges of the second to fourth fingers of their non-dominant hand. The team then assessed the participants’ dietary patterns, particularly their selenium intake, through a validated semi-quantitative food frequency questionnaire which the subjects answered twice within three weeks.
After analyzing the participants’ bone mineral density using a compact radiographic absorptiometry system, the team discovered that 9.6 percent of the subjects have osteoporosis. The majority of the cases were reported among women, with 19.7 percent having been diagnosed with the disease. Among men, only 2.3 percent were diagnosed with osteoporosis.
The researchers also compared the dietary data of those diagnosed with osteoporosis to those who were not. They found that there are significant differences between the participants in terms of age, gender, smoking and drinking habits, BMI, blood pressure levels, physical activity levels, nutrient supplementation, dietary calcium intake, dietary fiber intake and dietary energy intake. The factors above were measured as they are considered to be vital for the development and prevention of osteoporosis.
But most of all, the team observed a significant difference between the subjects with osteoporosis and those who don’t have the disease in terms of dietary selenium intake. The researchers found that those who have osteoporosis also have lower levels of dietary selenium consumption.
A person can increase his selenium intake by eating Brazil nuts, fish, shellfish, beef, turkey, chicken, fortified cereals, whole-wheat bread, beans, lentils and eggs. The recommended dietary allowance for selenium is 55 micrograms per day for adult men and women above 19 years old. For pregnant and lactating women, the recommended intake is between 60 to 70 micrograms per day.
However, in the study, which involved Chinese citizens, the participants’ selenium intake averaged only 43.5 micrograms per day. This is comparable to the average daily selenium intake of Europeans, which is 40 micrograms per day. The low selenium intake of both populations could be due to the low-selenium content of the soil in both areas.
Selenium and thyroid hormones
Selenium primarily functions in the body as an essential component of selenoproteins, composed of various enzymes and proteins that help protect the cells from damage and infections. Selenoproteins are also needed in producing DNA and in the metabolism of thyroid hormones. The thyroid glands have the highest concentration of selenium in the body.
In connection to thyroid hormones, the researchers postulated that low selenium levels might have increased the level of thyroid hormones in the blood, which may have caused an accelerated bone loss and osteoporosis in the subjects with low dietary selenium intake. Thyroid problems have indirect correlations with osteoporosis and are considered as secondary causes. This means that elevated thyroid hormone levels don’t directly cause osteoporosis, but they can influence how the body maintains a healthy mineral bone density.
In addition, hyperthyroidism, a thyroid disorder characterized by too much production of a thyroid hormone thyroxine, is considered as having a close link to the development of osteoporosis. This is because elevated levels of thyroxine accelerate the process of bone degradation, which is conducted by the osteoclasts. Osteoclasts are the cells that dissolvethe bones, initiating new bone production, which is conducted by another cell — the osteoblasts. Excessive thyroxine levels make the osteoclasts work faster than the osteoblasts, causing the bones to be fragile or brittle.
However, the researchers in the study did not confirm a causal relationship between dietary selenium intake and osteoporosis, but future studies are underway to provide support to their findings.
Juvenile selenium deficiency impairs cognition and energy homeostasis
University of Hawaii, May 26, 2021
According to news originating from Honolulu, Hawaii, by NewsRx correspondents, research stated, “Selenium (Se) is an essential micronutrient of critical importance to mammalian life.”
The news reporters obtained a quote from the research from University of Hawaii: “Its biological effects are primarily mediated via co-translational incorporation into selenoproteins, as the unique amino acid, selenocysteine. These proteins play fundamental roles in redox signaling and includes the glutathione peroxidases and thioredoxin reductases. Environmental distribution of Se varies considerably worldwide, with concomitant effects on Se status in humans and animals. Dietary Se intake within a narrow range optimizes the activity of Se-dependent antioxidant enzymes, whereas both Se-deficiency and Se-excess can adversely impact health. Se-deficiency affects a significant proportion of the world’s population, with hypothyroidism, cardiomyopathy, reduced immunity, and impaired cognition being common symptoms. Although relatively less prevalent, Se-excess can also have detrimental consequences and has been implicated in promoting both metabolic and neurodegenerative disease in humans.”
According to the news editors, the research concluded: “Herein, we sought to comprehensively assess the developmental effects of both Se-deficiency and Se-excess on a battery of neurobehavioral and metabolic tests in mice. Se-deficiency elicited deficits in cognition, altered sensorimotor gating, and increased adiposity, while Se-excess was surprisingly beneficial.”
