More vitamin K and a good night’s sleep might make you feel better the next day

SINGAPORE (July 3): New US research has found that a good intake of vitamin K, which is found in leafy greens and vegetable oils, could help reduce the risk of death as we age. Led by researchers at Tufts University and Tufts Medical Center, the new meta-analysis looked at 3,891 American adults aged 54 to 76, who were all free of heart disease at the start of the study.

The participants were categorized into groups according to their vitamin K blood levels, before being followed for around 13 years to assess their risk of heart disease and risk of death. The findings, published in The American Journal of Clinical Nutrition, showed that although there was no significant association between vitamin K levels and heart disease, participants with the lowest vitamin K levels had a 19 percent higher risk of death, compared those with vitamin K levels that suggested an adequate vitamin K intake.

The findings also held true even after the researchers had taken into account other factors such as age, gender, body mass index (BMI), medication and smoking status. Vitamin K is important for healthy blood vessels, with first author Kyla Shea explaining that, “The possibility that vitamin K is linked to heart disease and mortality is based on our knowledge about proteins in vascular tissue that require vitamin K to function. These proteins help prevent calcium from building up in artery walls, and without enough vitamin K, they are less functional.”

“Similar to when a rubber band dries out and loses its elasticity, when veins and arteries are calcified, blood pumps less efficiently, causing a variety of complications. That is why measuring risk of death, in a study such as this, may better capture the spectrum of events associated with worsening vascular health,” said last author Dr Daniel Weiner.

The researchers point out that as the study is an observational one, they cannot establish cause and effect, and further studies are now needed to clarify why vitamin K was linked with a lower risk of death, but not heart disease. Vitamin K is found in leafy greens, such as lettuce, kale, and spinach, and in some vegetable oils, notably soybean and canola. 

Sleep well and watch how your mood improves

A new European study has found that not getting enough sleep can leave us feeling less positive than usual the next day. Carried out by researchers at the Norwegian University of Science and Technology, the new small-scale study looked at 52 healthy participants aged 18 to 35 over a period of 11 days.

The participants were asked to sleep at home and maintain their normal sleep habits for the first seven days of the study, and then sleep two hours less than normal for the last three nights to mimic short sleep caused by the demands of work and daily life. They were also asked to keep a diary about their sleep schedule as well as wear an actigraph, which measures periods of rest and activity.

On five of the mornings, they were asked to complete a series of tests around an hour and half after getting up — and before having any coffee — which tested the accuracy and speed of their response to seeing a series of different pictures. In a second part of the test, the participants were asked to answer a questionnaire to measure 20 positive and negative emotions.

The findings, published in the journal Sleep, showed that although the participants performed better and better every day when they took the test after sleeping normally, their accuracy was worse every day after a night of sleeping less. There was also a decline in the participants’ positive emotions after a night of insufficient sleep.

“Not in the sense that we have more negative feelings, like being down or depressed,” explained researcher Associate Professor Ingvild Saksvik-Lehouillier, “but participants in our study experienced a flattening of emotions when they slept less than normal. They felt less joy, enthusiasm, attention and fulfillment.”

“We didn’t find clear differences when it came to the negative emotions, but there were marked differences for the positive ones. Positive feelings scored worse after just one night of reduced sleep, and dropped even more after three nights. I think this is a really interesting find. We already know that fewer positive emotions have a major impact on mental health. We also know that poor sleep is included in virtually all mental health diagnoses,” Saksvik-Lehouillier said.

“Sleep is individual. Not everyone needs to sleep seven and a half hours every night. And we’re A and B people. Some of us like to stay up till the wee hours, others love to rise and shine early in the morning. The most important thing is how you feel. If you’re in a good mood and alert when you get up, those are indications that your sleep habits are working for you,” says Saksvik-Lehouillier.