May 24, 2022

Solutions for frontline worker resilience—dark chocolate, exercise, fresh air

By: Judith M. Mathias, MA, BS, RN

Cori L. Ofstead, MSPH

COVID-19 has had a tremendous impact on nurses and other frontline healthcare workers. Just about everyone has been affected by shortages of basic supplies like personal protective equipment (PPE), syringes, and IV tubing, and staffing issues are even more concerning, says Cori L. Ofstead, MSPH, president and CEO of Ofstead & Associates, Bloomington, Minnesota.

Nurses have had to endure extended work hours and higher workloads in addition to loss of coworkers due to sickness and quarantine, school closures, and childcare issues.

The prolonged period of stress has led to cognitive impairment as well as anxiety and sadness about their predicaments, which has led to exhaustion, reduced quality of life, mistakes, and fear of the unknown.

In an effort to help build frontline healthcare worker resilience, Ofstead and two of her colleagues developed a webinar, sponsored by Healthmark, in which they leverage scientific evidence to show how three simple, natural solutions can make healthcare workers feel less stressed out—dark chocolate, exercise, and fresh air.


Dark chocolate

“I love dark chocolate, and I eat or drink some every day,” says Ofstead. “I personally feel better when I have some. My thinking is sharper, and I handle stress better.”

To scientifically evaluate the impact of chocolate on health and well being, Ofstead begins with five main steps involved in doing science:

• Notice things. “I notice that chocolate makes me feel better.”

• Wonder about them. “I wonder if I feel better because I like the taste and the little ‘hit’ of sugar that goes along with it, or if something positive is truly happening to my body chemistry or physiology?” She notes that people often look for evidence that supports what they believe or what they wish was true.

• Explore to learn more. To find out if it is wishful thinking or true, Ofstead says to explore research on the topic and do a primary study. “Personally, I love the idea of doing a primary study on chocolate,” she says. Researchers can gather their own data, and they can explore how chocolate makes them feel by testing different dosages and formulations.

• Document what is observed. Next, researchers can document their observations in a journal or log.

Researchers also can expand their primary study by collecting data from other researchers. This can be as simple as asking friends whether they like chocolate, how often they eat or drink it, and how it makes them feel. Or they can ask volunteers to try different formulations and give feedback that they can document using surveys or interviews.

• Share the findings. Another way is to do secondary research, which is reviewing evidence and findings generated and shared by others in the field. Often this is a good place to start, she says, because “there is no point in reinventing the wheel.”

Ofstead’s secondary research gleaned several studies.

Study 1: Beneficial effects of dark chocolate on memory

In this study, researchers from the UK (Lamport et al) looked at the beneficial effects of dark chocolate on memory. Dark chocolate contains flavonoids, and flavonoid consumption has been linked to improved cognitive function or brain performance.

The researchers examined whether dark chocolate had an impact on verbal memory and mood in 98 healthy young adults, who they assigned to Group A or Group B. Group A was given 35 grams of a commercially available dark chocolate bar that was 70% cocoa, and group B was given 35 grams of a low-flavonoid white chocolate bar.

Assessing verbal memory and mood before eating the chocolate and again 2 hours later, the researchers found that verbal memory improved significantly with dark chocolate, but mood was not affected.

The researchers concluded that their findings support the notion that everyday available portions of dark chocolate can confer benefits to the brain.

When something sounds too good to be true, however, Ofstead says it is important to look critically at the study and the outcomes:

• It had clear objectives.

• They used strong methods, such as a formal study protocol, intervention groups that were randomly assigned, reasonable portion sizes of chocolate bars, standardized test of memory and mood, and a sample size large enough to perform statistical analysis.

• Their even-handed reporting of results, saying chocolate helped memory but not mood, instilled confidence in the merit of their evidence.

• The conclusions seemed fair based on the findings.

The study did have some limitations, however:

• They used only a simple test of short-term memory.

• All participants were young university students, less than 24 years old.

Study 2: Beneficial effects of dark chocolate on brain function

This Japanese study (Sumiyoshi et al) randomly assigned 20 healthy students to eat either dark chocolate daily for 30 days or white chocolate daily.

The researchers measured cognitive function, physical characteristics, and cerebral blood flow before and after the intervention period and 3 weeks later. They also did some blood and other tests.

They found that the dark chocolate group had higher blood levels of theobromine (a substance found in dark chocolate), increased nerve growth, and higher test scores, which improved from pre- to post-test, and they stayed higher for 3 weeks. This happened with just 35 grams of chocolate, which is about 3 little squares of a chocolate bar.

“They didn’t eat the whole thing or even half the bar,” says Ofstead, “and it had measurable impacts on their bodies and their cognitive function.

Study 3: Impact of dark chocolate on stress

To determine whether cocoa intake improves vascular function following stress, researchers (Baynham et al) had 30 healthy young men drink high- or low-flavanol cocoa.

This was a randomized, placebo-controlled, double-blinded, cross-over study, meaning the participants were randomly assigned to drink the high-flavanol cocoa or a beverage that was similar but did not have the active ingredient. Neither the participants nor the researchers knew which formulation each person had. After a week or so, the participants swapped groups, called cross-over, which is one of the strongest types of studies.

The researchers stressed out the participants by making them take a math test under stressful conditions that included bothersome noise and competition, and they monitored their vascular function for 90 minutes.

They found that the high-flavanol cocoa reduced the impact of stress on vascular function, meaning it helped their bodies cope with the stress. There were some limitations of the study, most notably that it was small and done in healthy young men.

Study 4: Impact of dark chocolate on stress

This is a similar study (Regecova et al), but the participants were healthy young women, and the dark or milk chocolate doses were based on body weight.

The researchers found that dark chocolate decreased systolic blood pressure somewhat at rest, which significantly reduced the negative impact of stress on blood pressure and pulse. Milk chocolate did not have these effects.

They concluded that dark chocolate may have a beneficial effect during acute stress because of its ability to buffer cardiovascular reactivity in young women.

Ofstead notes that these studies made her want to dig deeper into this topic and find some larger studies and research that involved middle-aged or older people.

Study 5: Impact of chocolate on blood pressure

In this study (Buijsse et al), researchers found that small amounts of chocolate can improve endothelial function (lining of the heart and blood vessels) and platelet function (blood cells that control bleeding, form clots). The study also found that chocolate can reduce blood pressure and inflammation.

Previous work by these authors found that 6 to 19 grams of dark chocolate per day decreased blood pressure by 2 to 4 mmHg among adults, including elderly men.

The researchers used 22 years of data from a long-term cancer study to evaluate the link between habitual chocolate consumption and the incidence of myocardial infarction and stroke in a large population that included 19,357 middle-aged German adults.

They found that those with higher chocolate consumption had a slightly lower blood pressure (1 mmHg) and a 39% lower risk of heart attack and stroke.

Ofstead notes that these findings sounded too good to be true, so she looked further to find the connections between platelets and dark chocolate.

Study 6: Link between dark chocolate and cardiovascular health

Researchers at the University of California (Rein et al) compiled results from a number of studies and found that flavanols in dark chocolate impacted platelets in three ways. They:

• lowered platelet activation

• reduced platelet stickiness

• slowed down clumping and clotting, similar to the effect of aspirin.

Study 7: Effects of dark chocolate and cocoa on heart health

Researchers from Harvard (Ding et al) reviewed data from 136 studies that included more than 100,000 patients and found that cocoa and dark chocolate had the following beneficial effects on heart health:

• anti-platelet

• anti-inflammation

• lower blood pressure

• lower LDL (ie, “bad”) cholesterol

• higher HDL (ie, “good”) cholesterol.

When the findings of all the studies were combined, the results were very consistent (sidebar, Dark chocolate and cardiovascular health).

Cocoa and dark chocolate:

• reduced the clumping of platelets in two studies

• reduced blood pressure in three studies

• reduced heart attack and stroke in one study

• reduced blood pressure, clumping of platelets, bad cholesterol, and heart attack in the largest study of more than 100,000 patients.

The Harvard researchers who analyzed the data on more than 100,000 patients concluded that flavonoid intake from chocolate is likely protective against cardiovascular disease, particularly mortality related coronary artery heart disease. They added that because dark chocolate has substantially higher levels of flavonoids than milk chocolate, and milk may inhibit absorption of flavonoids, it would be more prudent to consume dark chocolate rather than milk chocolate.

Ofstead summed up by saying: “To get the overall health benefits and feel better, you need to eat the high-flavanol chocolate, which is more than 70% cocoa, or you need to drink hot chocolate made with water or something other than milk. You don’t need to eat a lot of it. Just a couple of squares a day will give you a pick-me-up without adding a lot of calories to your diet.”



Krystina M. Hopkins, MPH

Rather than chocolate, Krystina M. Hopkins, MPH, research manager, Ofstead & Associates, turns to exercise to wash out stress and relax.

Regardless of how much exercise or what kind of exercise is done, the evidence shows it helps, says Hopkins, adding that “even the CDC’s [Centers for Disease Control and Prevention’s] physical activity guidelines say short bursts of exercise can immediately help you feel, function, and sleep better.”

Hopkins notes that her exercises of choice are running and yoga. “Yoga is good for our frontline workers who are looking for some stress relief because they don’t need a lot of space, equipment, or time,” she says.

Even though yoga makes her feel better when she does it, Hopkins wanted to know if it was actually good for her.

A literature review via PubMed, which is run by the National Library of Medicine and focuses only on articles in peer-reviewed journals, gave a good choice of current studies on the benefits of yoga.

Study 1: Yoga and burnout in nurses

To see if yoga helps reduce nurse burnout, researchers (Alexander et al) divided 40 nurses into two groups—one that did yoga for 8 weeks and a control group that did not do any yoga. “Having a control group is always a good idea,” says Hopkins, “because that way you can see if any change in the yoga group is because they did yoga or if something else was going on that made them feel better or worse.”

The nurses in both groups took a survey that measured how burned out they were before the study started, and then they took it again at the end of the study. “By doing the survey twice in both groups, the researchers could see if there was any change from beginning to end within each group as well as compare each group to each other,” Hopkins says.

Compared with controls, the yoga participants reported significantly higher self-care as well as less emotional exhaustion and depersonalization after 8 weeks of the yoga intervention. In other words, says Hopkins, the nurses who did yoga reported feeling better.

The study had its limitations in that it was small, it included nurses who were mostly women, and the symptoms were self-reported.

It is still a good study, and the researchers limit their conclusions to how the nurses felt and did not try to make wider generalizations, she says. However, Hopkins adds that she wanted to know if yoga just made the nurses feel good emotionally or if there was something chemical or physiological going on too.

Study 2: Laughter yoga in nursing students

The purpose of this study (Ozturk et al) was to see how yoga affects mental health and stress hormones. It is similar to Study 1, but it is larger with 75 nursing students.

The researchers divided the students into two groups—one that did laughter yoga (which incorporates laughter as a way of controlling breathing) sessions over 4 weeks, and one control group that did not do any yoga for those 4 weeks. Both groups completed a psychological survey at the beginning and end of the study.

The study also looked at the physiologic or chemical impact of yoga by having the nurses in both groups provide a saliva sample at the beginning and end of each yoga session.

The samples were tested for cortisol, which is a chemical secreted as a reaction to stress, so the researchers could actually measure the nurses’ biological response to the yoga rather than just relying on the nurses to tell them how they felt. The control group also provided samples at the same time without doing the yoga, so the researchers could compare the chemistry results.

Nurses in the laughter yoga group reported that their anxiety and depression were better after completing all of the yoga sessions, and their cortisol levels started to go down after at least four yoga sessions. This means their biology was shifting, Hopkins says.

The researchers did not see the same results with the control group, which suggests that the yoga was doing something.

The findings from this study supports the findings in Study 1, which means there are now two independent studies that both had good methods saying the same thing. “But, is this enough?” asks Hopkins. “What if we want to know if a different type of yoga works, or if it wasn’t yoga at all, but, maybe, it was just getting exercise that reduces stress?”

Rather than looking at more studies on the same topic, Hopkins suggests leveraging work from scientists who have already done just that by looking at review articles, which summarize relevant studies following very specific scientific criteria for searching and evaluating sources, or by looking at meta-analyses. For meta-analyses, researchers combine the data from all of the studies on a subject and reanalyze it to come up with overarching conclusions.

Meta-analyses can only be done when there are a number of studies that used similar methods and collected similar types of data.

Study 3: Review and meta-analysis of yoga and stress

In this meta-analysis (Pascoe et al), researchers wanted to know if yoga’s impact on stress was because of the mindfulness component or the physical activity component. They critically reviewed 42 studies that compared yoga with other interventions like exercise, therapy, or health education.

They found that yoga improved blood pressure, heart rate, and levels of cortisol, blood sugar, and cholesterol, more than non-yoga interventions.

The researchers concluded that their findings show yoga is an effective way to reduce stress in diverse populations.

“This is pretty convincing evidence for me that yoga doesn’t just make me feel better because I like doing it. It’s actually having physiological effects,” says Hopkins.

“But yoga isn’t for everyone,” she says. “And I was curious about the health benefits of other forms of aerobic exercise, such as walking.”

Study 4: Health benefits of walking

This review article (Kelly et al) summarizes the findings from five systematic reviews and 50 individual studies on the impact of walking on mental health.

The authors found that walking:

• can help with symptoms of depression and anxiety

• can potentially boost self-esteem even after one walking session

• may improve stress and well-being

• has no harmful side effects.

Another conclusion was that where people walked mattered. The authors cited another review that suggested walking outdoors was more beneficial than walking on a treadmill indoors.


Fresh air

Abigail G. Smart, MPH

“There’s a lot of scientific evidence about the health benefits of dark chocolate and exercise, particularly yoga, but maybe neither of those things appeal to you,” says Abigail G. Smart, MPH, research associate, Ofstead & Associates. She added that something she likes to do to relieve stress is spend time in nature.

A Google search of green space and mental health led her to a Psychology Today blog post (Johal) that claimed spending time in green space improves depression, anxiety, sleep, and stress.

Although those claims support her own experience, Smart notes that it is a pretty big claim, and it was not coming from a peer-reviewed journal article.

To find out if a non-peer-reviewed blog or magazine article would be a good source, Smart recommends asking the following questions:

• Who are the authors?

• What are their qualifications?

• Do their claims seem too good to be true?

• Are they trying to sell something?

• How old is the source?

• Do they explain the basis for their claims?

• Do they have references?

• Are their references credible?

Looking again at the Psychology Today blog post—“Did green space still boost mental health during the pandemic?”—with her questions in mind, Smart notes that the post was rather recent (July 2021), the author had two doctorate degrees in psychology, and he had written several books and peer-reviewed articles on mental health topics.

The post also had a reference list with three sources that included two peer-reviewed articles and one government survey. All three supported claims made by the author. Smart looked closer at one of the peer-reviews articles referenced on the impact of green space on depression and anxiety during the COVID-19 pandemic.

Primary Study 1: Impact of green space on depression and anxiety

This study (Heo et al) used an online survey to ask 322 adults, who were recruited through social media, about their green space use and mental health before and during the COVID-19 pandemic.

A total of 65% said they visited green space less than they did before the pandemic, and that group was more than two times as likely to have symptoms of major depression. They also had more symptoms of generalized anxiety disorder.

The authors concluded that spending time in green space could improve mental health. However, Smart says, there could be another conclusion to explain what they discovered. Perhaps people who were feeling depressed or anxious were not as likely to seek out green space.

“The problem with this kind of study is that it can tell you if two things might be related to each other, but not necessarily how they’re related or which came first,” she says.

Primary Study 2: Impact of nature activities on stress and mental health

A study that might be better at finding cause and effect looked at the mental health of 30 people before and after completing a 1-week nature program (Rajoo et al). All participants spent 20 minutes every day in an urban green space, like a park or rooftop garden.

Half were randomized to do a 20-minute exercise program, and the other half were randomized to do 20 minutes of meditation and stretching.

After 1 week, both groups reported having significantly less stress, anxiety, and depression, with nature therapy appearing to be slightly more effective at reducing serious mental health symptoms.

The problem with this study was that it did not have a control group, so Smart says she wondered if nature was having a real impact or if it was just the activities the participants were doing.

Primary Study 3: Impact of nature exposure on health and well-being

In this very large study from the UK (White et al), 19,806 adults were surveyed on how much time they had spent in nature in the last 7 days, and they were asked to rate their overall health and well-being. Importantly, the study did not require the participants to exercise, just spend time in nature.

Those who reported spending at least 2 hours per week in nature were significantly more likely to report their health was good and their overall well-being was high. These results remained the same across important demographic categories like age, health status, and level of physical activity.

The researchers concluded that spending just 2 hours a week in nature appeared to be good for overall health and well-being, whether that time occurred all at once or was divided across several days.

Further research found 82 studies, review articles, and meta-analyses on the physical and psychological benefits of what is called “forest therapy.”

One meta-analysis (Ideno et al) reviewed 20 studies that compared participants’ blood pressure after activities performed in forest or nonforest environments. Participants’ blood pressures were measured after activities like walking in the woods or sitting and observing the forest, while control groups had their blood pressure measured after doing the same activities in urban environments, sitting in a room, or going about normal daily activities.

Results showed that participants’ blood pressures were significantly lower after activities in the forest group compared to the non-forest control groups.

Other meta-analyses have found similar results for cortisol levels (Antonelli et al) and symptoms of depression and anxiety (Yeon et al).

“Overall,” Smart notes, “these analyses show there is a lot of strong evidence for the physical and mental health benefits of forest therapy.”

She decided to look into this further and find out if there is a biological reason that spending time in nature improved mental health. She found that breathing fresh air or digging in the dirt can change a person’s microbiome, which is the bacteria that live on the outside and inside of the human body and are essential for a healthy immune system and digestion.

Primary Study 4: Impact of digging in dirt on microbiome

For this study (Nurminen et al), 14 participants were randomized to either rub a mixture of soil and plant material on their hands for 20 seconds, 3 times per day, for 2 weeks, or do nothing.

At the end of the study, those who got their hands dirty had more diverse bacteria on their skin and in their guts and more immune system activity.

Smart adds that a lot of research has found a relationship between gut bacteria and mental health. “One way bacteria can affect our mood and stress is by changing how much serotonin we produce,” she says. Serotonin is a chemical that enables brain cells and the nervous system to communicate, and one of its main jobs is to help regulate mood and emotions.

“The big takeaway is that taking some time to get out in nature can be really good for our minds and bodies,” says Smart.

“The pandemic and other challenging circumstances have us feeling pretty stressed and exhausted. It’s more important now than ever to find things that can help us keep going. Dark chocolate, exercise, and getting some fresh air are great options with a lot of scientific evidence showing they can help our well-being and improve how we show up at work and at home,” she says.


—Judith M. Mathias, MA, BS, RN, is clinical editor of OR Manager. Previously, she was clinical editor of AORN Journal and a cardiac surgical nurse.



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