By Soren Ghorai
Constantly dealing with colds or coughs? Always feeling exhausted? You have likely heard you should take a daily vitamin to prevent you from getting sick, but what about your daily dose of activity? Forget the expensive, over-the-counter supplements — exercise has been linked to a healthy immune system.
How do we stay healthy?
We hear a lot about the immune system, but how does it actually work and protect us from disease? The immune system is a complex network of cells that defend our bodies from harmful intruders. These cells are called white blood cells or leukocytes. Leukocytes are referred to as “immune cells” because they are the critical defenders against infection. Leukocytes circulate throughout our bodies, looking to neutralize foreign bacteria, viruses, or other pathogens. Thus, a high number of white blood cells ensures our body can combat a wide range of threats to keep us safe and healthy.
Exercise linked to immunity
In a clinical study, researchers were curious about how exercise impacted our immune systems. Specifically, they examined the effects of exercise on blood leukocyte count, which indicates the activity of the immune system. The study consisted of 8 healthy male volunteers who were randomly subjected to four experimental conditions: high-intensity cycling for five minutes, moderate-intensity cycling for two hours, resistance training with 15 sets of 10 reps, and no exercise (control). Participants performed their assigned exercise over the course of 9 weeks with regular assessments of heart rate, oxygen consumption, and leukocyte count. After each session, researchers collected the participants’ blood samples in order to accurately measure their blood cell counts.
The results demonstrated a clear relationship between exercise and white blood cell count. Compared to the control, all three types of exercise provoked leukocytosis. The prolonged cycling group resulted in the highest leukocyte count, approximately 1.4x greater than the high-intensity cycling. Participants who did resistance training had cell counts slightly lower than the high-intensity group. Finally, the control group displayed the lowest leukocyte counts by far.
These findings underline the immune-stimulating effects of exercise. While all types of physical activity boosted the immune system, aerobic exercise generated the greatest response. This is because high-intensity exercise causes muscular damage, leading to a temporary increase in inflammation as the body undergoes repairs. As a result, leukocyte levels rise immediately after exercise to aid recovery and strengthen the body for future physical challenges. This regular stimulation that comes with consistent exercise can keep the immune system in a state of readiness to reduce the likelihood of infection.
The above findings were supported in another clinical study, which monitored 1,002 adults (ages 18-85, both male and female) for upper respiratory tract infections (URTI), such as the common cold, sinus infections, or sore throats. After 12 weeks during the fall and winter seasons, researchers saw that daily aerobic activity reduced URTI frequency by 46% compared to those who did little to no exercise. Additionally, exercising reduced the severity of URTIs by 41%, meaning active individuals remained significantly healthier.
How much exercise do you need?
A key takeaway from both studies was that prolonged, high-intensity, or aerobic exercise yields the greatest immune effect. To keep exercise consistent, find an enjoyable routine that works for you. This could look like daily biking, playing golf, taking walks, or lifting weights at the gym. The CDC recommends at least 150 minutes of physical activity per week, with at least 2 days of muscle strengthening as well. See the CDC’s steps for getting started with exercise here.
Should you exercise when you’re sick?
Whether you should exercise when you’re sick largely depends on the severity of the illness and how you’re feeling. With mild symptoms like a runny nose or sore throat, light exercise such as walking or gentle yoga may be appropriate. However, it’s best to refrain from physical activity while suffering from moderate sickness like fever or fatigue. Make sure to prioritize rest and allow your body to recover smoothly. The bottom line? Listen to your body and don’t push yourself too hard while under the weather.
The TL;DR
Studies:
Natale VM, Brenner IK, Moldoveanu AI, Vasiliou P, Shek P, Shephard RJ. Effects of three different types of exercise on blood leukocyte count during and following exercise. Sao Paulo Med J. 2003 Jan 2;121(1):9-14. doi: 10.1590/s1516-31802003000100003. Epub 2003 Jul 4. PMID: 12751337.
Nieman DC, Henson DA, Austin MD, Sha W. Upper respiratory tract infection is reduced in physically fit and active adults. Br J Sports Med. 2011 Sep;45(12):987-92. doi: 10.1136/bjsm.2010.077875. Epub 2010 Nov 1. PMID: 21041243.
Strengths:
- Examines different types/durations of exercise to find optimal conditions
- Studies spanned over 9 and 12 weeks to capture reliable results
- 2nd study included diverse demographics to make data generalizable to large populations
Weaknesses:
- Not one “best” type of exercise. People should find what works for them
- External factors like diet, sleep, and stress levels affect the immune system and could have influenced the results
- Future research should examine how immunity is affected over years, not just months
Takeaway:
There is a positive correlation between exercise and increased immunity. Exercise induces inflammation to temporarily boost the immune system to assist in repairing working muscles, and consistent physical activity is proven to keep individuals healthier on a long-term basis. Focus on moderate movement throughout the day. Instead of prioritizing intensity, focus on consistency so your immune cells continually circulate and fight off infections. Finally, choose a physical activity that you enjoy, because exercise should be fun!
By Anya Higashionna
If your pets are anything like my dog, then the title of this article isn’t anything unusual. As much as I like to give my dog an opportunity to converse with the outside world, he thinks that it is more of an opportunity for him to take me for a walk where he wants to explore. While it does get a little frustrating when he decides to morph into a concrete post when we start to walk home, a 2017 research article titled “Dog Walking, the Human-Animal Bond and Older Adults’ Physical Health” talks about the benefits of my dog’s stubbornness to stay out walking.
After previous research was published that concluded dog ownership led to increased physical exercise, Dr. Curl et al. (2017) set out to discover if dog walking was the determinant of better health and health behaviors compared to those who don’t own dogs or don’t walk their dogs. Using data from the 2012 Health and Retirement Study run by the University of Michigan the authors tested if dog ownership was associated with health and health behaviors and if pet bonding was associated with dog walking characteristics (frequency, length in time, distance). To study the owner-pet bond relationship the researchers asked questions such as, “Do you consider your pet a friend?” and “Do you talk to others about your pet?” The amount and type of exercise, and the amount of contact they had with doctors and self-reported body mass index (BMI) were also measured.
Pawesome Findings
As hypothesized, “Dog walking was associated with lower BMI, fewer [Activities of Daily Living] ADL limitations, fewer chronic health conditions, and fewer doctor visits. It was also associated with more frequent moderate exercise and vigorous exercise”. All these health benefits that can come from giving our canine companions a good time outdoors. It is like your own lifetime workout program with additions that come with having a furry friend. Particularly in older populations there were also, “self-reports of walking more often, faster, and further with their dog(s) than without their dog(s)”. Thus, as we lace up our shoes and leash our furry companions, it is not just a walk in the park, but a walk towards improved health and vitality.
Based on the last paragraph, dog walking was specifically associated with all these benefits. This is important to note as one of the limitations to this study included the fact that this was a cross-sectional study which does not imply causality. Similar to the last post I had co-written called “A Step-Up to Health: The Power of Stairs”, dog walking is a small activity you can do consistently throughout your days that simply lowers your risk for chronic health conditions, but doesn’t make you immune. Lifestyle medicine is in the name and I find integrating healthy practices into your daily life make them feel like less of a chore and become lifelong habits. Even then, dog walking does not have the same effect on everyone. The breed of dog and even the owner’s bond to the dog may have impacts on how much activity is being done.
Time for a W-A-L-K!
Chaplain Bruce Feldstein, MD, BCC, leads Stanford Lifestyle Medicine’s Gratitude and Reflection pillar, offering insightful perspectives on the practice of gratitude and its positive effects on physical and mental well-being. He notes, “Relationships with pets can be a source of unconditional love, immense gratitude, caring and joy. In addition to exercise, taking a dog for a walk promotes social engagement. All together these provide a recipe for good health and well-being.” Chaplain Dr. Feldstein brings forth a unique perspective to this article. While the research focuses on how less sedentary behavior and more physical activity, can increase health outcomes, Feldstein notes the deeper gratitude and connection, that comes with this practice also benefits one’s health.
While it is not necessary to own a dog to unlock these benefits nor guaranteed just because of dog ownership, since these results are strictly associated with those who own dogs and walk them and not by non-dog owners or dog owners who don’t walk their dogs. The key is decreasing sedentary behavior, and owning a dog can boost this lifestyle choice. I find the feeling of being part of a team similar to my feelings of my dog. The days that I feel more tired than usual, but I have a basketball practice, I find myself more motivated to go because of my team. Similar to this situation, my dog relies on me (even in the winter days) and it is extra motivating when I know it will be a walk where I will have more fun than being on a walk by myself. As Levi Frehlich, a PhD Candidate notes, “My research looks at how where you live influences your physical activity, for example, high and low walkability. Interestingly I have to take into account if the people I am studying own dogs, because even if you live in a low walkable neighborhood, the dog needs to get walked.”
By Soren Ghorai
When you’re feeling down, it can be difficult to find the motivation to get up and exercise. Exercise may seem like the last thing you want to do, but it can make huge improvements for your mental health. So next time you’re feeling low, getting up and going for a jog could be exactly what you need.
Exercise linked to Emotional Well-Being
In a recent study, researchers examined the effects of exercise on how well people could regulate their emotions. The study consisted of 40 men and 40 women that were randomly assigned to either an aerobic exercise group or no exercise (stretching) group. After their assignment, participants completed an affective rating where they indicated their current emotional state on a scale from 0-100 for both positive emotions (happy, content, excited) and negative emotions (sad, angry, anxious). Then the aerobic exercise group jogged for 30 minutes around a track while the no exercise group simply stretched, serving as a control. After the exercise, participants watched a short clip from the movie The Champ to evoke sadness, and another brief clip from the film When Harry met Sally to promote feelings of happiness and amusement. In between each clip, participants repeated an affective rating again to examine how much the movie clips had influenced their emotional state. Also, participants performed the Difficulties in Emotion Regulation Scale (DERS) to determine their difficulty with regulating emotions.
The results demonstrated a clear relationship between exercise and the ability to regulate emotions. Participants who spent 30 minutes stretching had more difficulty regulating emotions and experienced persistent feelings of sadness. Those who ran were less affected by the emotional stimuli and reported significantly less sadness than those who had only stretched.
This study suggested that regular exercise may help improve emotion regulation. The authors noted that aerobic exercise is shown to improve attention and inhibitory control, and that attentional control is linked to stronger emotional regulation. Hence, participants who were runners perhaps already improved their attention and inhibitory control through regular exercise, allowing them to better regulate their emotions.
How does exercise help your brain?
Exercise triggers a variety of processes in the brain that can help improve your mood and alleviate any negative emotions. During exercise, the body releases chemicals called When you feel pain or stress, your body sends signals to the brain. Endorphins are released to block the signals, relieving any pain and creating a general sense of happiness and well-being. This is why people typically experience a “runner’s high,” since running stimulates a release of endorphins. Serotonin is another “happy” brain chemical produced from exercise that can improve mood. This was described in one study where researchers concluded that physical activity increased the release and synthesis of serotonin.
Exercise also activates the brain’s reward system. In one systematic review, researchers reviewed 940 articles and found that physical activity directly triggers the release of dopamine, a primary driver of the brain’s reward system that induces pleasure and motivation. This explains the immediate feelings of satisfaction during and after a workout. Over time, regular exercise prompts the brain to produce more dopamine and create more dopamine receptors, making you feel better and better after each workout. In this way, exercise establishes a positive cycle in the brain: as you work out, your brain responds by making you feel good, which motivates you to exercise even more. Hence, exercise can expand your capacity for joy.
Additionally, physical activity can improve your overall brain function. One study noted that exercise increases the production of growth factors, which are proteins in the brain that help nerve cells grow and make new connections. Specifically, exercise produces brain-derived neurotrophic factor (BDNF), which improves nerve cell growth in the hippocampus, the area of the brain responsible for mood. By producing BNDF, exercise supports nerve cell growth in the hippocampus, which can improve one’s ability to regulate and boost their emotions.
How much exercise do you need?
Luckily, you don’t have to run marathons to improve your mood. For healthy adults, the U.S. Department of Health and Human Services recommends 150 minutes of moderate aerobic activity per week. If that seems like a lot, being active for just 10-15 minutes throughout the day can still make major improvements for your mental health (Mayo Clinic). The key is finding a type of exercise that you enjoy. Choosing a fun activity will not only help you enjoy the exercise, but it will keep you more motivated to do it. Check with your doctor to find out how much exercise and what intensity level is appropriate for you.
By Claire Paul
Can food really impact your mood? Nutritional psychiatry, the use of food interventions as a form of mental health treatment, has gained popularity in recent years. While there’s an overwhelming amount of dietary suggestions out there, it is worth noting a 2023 comprehensive review assessing the relationship of the Ketogenic diet with neurodegenerative and psychiatric diseases. Although not recommended for everyone, the ketogenic diet may be one avenue for improving mental health through food. Moreover some principles of the ketogenic diet may be applied more broadly.
Dr. Shebani Sethi, founding director of the Metabolic Psychiatry Clinical Program at Stanford University explains that, “While the ketogenic diet may not be suitable for everyone, its underlying principles of reducing neuroinflammation and supporting cognitive function can be integrated into everyday habits.”
What is the Ketogenic Diet?
While popularized in the media as another low-carb weight loss fad, the ketogenic diet was actually developed initially as a treatment for epileptic patients. It has been used to treat epilepsy since 500 BC but was more popularized by physicians in the 1920s. The diet focuses on fats being the primary source of fuel instead of carbohydrates; however, the ratio of macronutrients is dependent on the use of the diet. A 4:1 fat-to-carbohydrate ratio is typically used in clinical treatment, whereas a 3:1 ratio will be suggested for those who require higher amounts of protein or carbohydrate intake. While many different iterations of this diet exist, the Mentzelou et al 2023 review defined it as follows: 1 gram of protein per kilogram of body weight, 10-15 grams of carbohydrates, and the remainder of daily caloric intake from fat. The ultimate goal of the diet is to induce the production of ketones, a chemical stored in the liver to break down fat. The state of ketosis modifies metabolic pathways and has been associated with the reduction of oxidative damage and inflammation regulation.
What did they find?
The Mentzelou et al 2023 review contains a comprehensive search of existing peer-reviewed journal papers published between 2000 and 2023. Notably, the authors only included studies based on the classical ketogenic diet, defined above, and for in vivo studies, only research on Caucasian individuals was included. With this inclusion criterion in mind, the authors still found a mountain of evidence, 101 articles to be exact. Interestingly, they excluded over 300 articles because they didn’t fit the classical ketogenic diet criteria, which goes to show much research is actually on this “fad” diet. After collating the data the articles were categorized into in vitro and in vivo research.
In vitro
In general, in vitro (cell culture/mechanism studies) research indicates that ketogenic diets can help to increase mitochondrial health. The authors indicate that this can happen in a few different ways, such as decreasing mitochondrial apoptosis (i.e., death), increasing mitochondrial biogenesis (i.e., birth), and improving the function of existing mitochondria. If you remember back to high school biology class the mitochondria are the “powerhouse of the cell” so having more of them, having them not prematurely die, and having them work better, all add up to a more efficient system. Interestingly , the ketogenic diet is postulated to help in other areas as well, such as the microbiome and synapse myelination. A summary of the molecular mechanisms is shown in Figure 1.
Figure from Mentzelou et al. (2023), pg 5.
In vivo
The study looked at the clinical implications of the Ketogenic diet for the treatment and management of neurodegenerative and psychiatric diseases. In a study without 31 individuals with psychiatric disease (major depression, bipolar disease, schizoaffective disease) who followed the ketogenic diet between 6 and 248, there was a considerable link between improvements in depressive and psychotic symptomatology. A study also examined the effects of the Ketogenic diet on Alzheimer’s disease. After following the diet for 16 weeks, mice showed lower amyloid plaque accumulation and thus decreased neuroinflammation. A study of 23 individuals with mild cognitive impairment also looked at the relationship between following the Ketogenic diet and their symptoms. After following the diet for 6 weeks, they displayed improved memory function. Figure 3 from the study displays the results of the Ketogenic Diet for each neurodegenerative and psychiatric disease in the specific study.
Figure from Mentzelou et al. (2023), pg 8.
Another notable case study examined long-term Ketosis associated with considerable mood stabilization. A 70-year-old women experienced therapy-tolerant schizophrenia for 53 years and implemented the Ketogenic diet. She was able to stay off all psychiatric medications for 11 years and her symptoms subsided.
What can you do?
The principles of the KD can still be implemented by individuals looking to reduce neuroinflammation, diversify the microbiota, and improve overall cognitive functioning.
- Reduce Processed Carbohydrate intake
- Increase Healthy Fats, especially omega-3 fats
- Consume moderate amounts of protein
- Incorporate a variety of fiber-rich plants into the diet
While the ketogenic diet is just one avenue of doing such, the principles listed above are all tied to improved mental health. While food is not the sole determinant of mood, there’s certainly something to be said about its impact on mental health and well-being.
Precautions and Things to Note
It’s important to be aware of many limitations to the findings and potential side effects of the Ketogenic diet. While these are individual studies, clinical evidence remains scarce due to their short term, lack of a control group, or large dropout rates. Though all meta-analyses support the efficiency of the ketogenic diet as a treatment for epilepsy, further studies need to be implemented to draw this conclusion for other mental health disorders. Certain side effects are also necessary to be aware of, including the phenomenon of the “keto flu,” a sickness which typically subsides after a few days. Additionally, maintenance of the diet can be challenging which is why it’s necessary to follow the protocol in accordance to one’s individual needs.
Dr. Shebani Sethi notes that, “Optimizing brain health goes beyond symptom management; it requires addressing the metabolic underpinnings of psychiatric conditions. The ketogenic diet, with its emphasis on enhancing mitochondrial function and reducing oxidative stress, aligns with the goals of promoting mental health and vitality.”
However, it’s necessary that “As we continue to explore the relationship between nutrition, metabolism, and mental health, it’s essential to approach lifestyle changes with caution and under the guidance of healthcare professionals.”
As always, before starting any new diet to treat a specific symptom or disorder, it is imperative to first talk with your healthcare provider.