In connection with the outbreak of the coronavirus / COVID-19, many people are wondering what can be done to avoid getting sick from the virus. In addition to infection prevention measures, it seems that a healthy lifestyle can contribute to preventing a serious course of the disease. Among other things, it is seen that people with lifestyle diseases such as COPD, cardiovascular disease, diabetes and obesity have an increased risk of developing a more serious course of the disease (hospitalization and death)1. These observations seem to be consistent with what is already known about the link between lifestyle diseases and other respiratory infections such as colds, flu and pneumonia. People with, for example, diabetes, obesity, COPD and heart disease have an increased risk of contracting respiratory infections and / or developing a more serious course of the disease.
Below we will take a closer look at the connection between respiratory infections and various lifestyle factors.
Physical activity:2 Regular physical activity reduces the risk of respiratory infections. One possible reason is that there is increased activity of important immune cells that can detect bacteria and viruses, such as NK (natural killer) cells and other white blood cells, up to three hours after a workout. NK cells are an important part of the first-line defense in viral infections, and physical activity increases phagocytic activity (the ability to "eat" or engulf invaders). Furthermore, regular physical activity counteracts age-related immune weakening in several areas.
A Brazilian study found that people who trained 150 minutes a week with moderate intensity, or 75 minutes of intense training (e.g. jogging) had around 34% reduced risk of hospitalization with COVID-19 compared to inactive people. A number of studies show that regular moderate physical activity (e.g. 30 - 45 minutes five times a week) reduces the risk of developing upper respiratory tract infections of all kinds by about 25 - 50% over a period of 2 - 12 months, including the flu and pneumonia. In addition, studies show that people who exercise regularly and develop upper respiratory tract infections have milder respiratory problems than those who are physically inactive.
Body weight: People with obesity appear to be at increased risk for both upper and lower respiratory tract infections, even after adjusting for other relevant factors
3-4. Closer examination has shown reduced function and activation of certain immune cells in overweight and obese people, primarily NK cells, as well as CD4 and CD8 T cells. Since people with obesity have an increased risk of contracting COVID-19, of developing a more serious course requiring hospitalization and/or intensive care, as well as an increased risk of dying from the disease, obtaining a healthier body weight may be indicated for improved prevention and outcomes from COVID-19.
Diet:5 A well-functioning immune system depends on nutrients that we acquire through the diet. Malnutrition seems to be the most common cause of immune deficiency worldwide. Thus a primary goal is to have a healthy and varied diet that provides the immune system with the necessary nutrients it needs, such as:
vitamins A, B6, B12, folate, C, D and E, as well as the minerals
zinc, iron, magnesium, copper and selenium. They play an important role both in maintaining physical barriers that are part of the first-line defense against bacteria and viruses, and are also necessary for the optimal function of several types of immune cells. Furthermore, they are involved in a number of non-cellular components of the immune system.
Vitamin D deficiency is quite common. In Norway, many people have low values (<50 nmol/l) in winter and spring. The most at risk are the elderly, dark-skinned and overweight individulas. Vitamin D deficiency affects the immune system and leads to a reduced number of lymphocytes and reduced function in macrophages, among other things. People with vitamin D deficiency appear to be at increased risk of contracting respiratory infections. Supplementation of vitamin D (up to 3655 IU/day) has therefore been shown to reduce the risk of respiratory infections. The greatest effect has been seen in people who had low levels of vitamin D at the start of the study.
Vitamin C supplementation seems to reduce the risk of pneumonia in children and adults, especially in people who already have a low intake of the vitamin. There is relatively good evidence that vitamin C supplementation (up to 4-8g/d) can shorten the duration and reduce the symptoms of upper respiratory tract infections in children and adults. Furthermore, vitamin C supplementation can reduce the risk of developing pneumonia, especially if the intake was initially low. Vitamin C supplementation in adults appears to be able to shorten the duration of pneumonia, and this effect appears to be dose-dependent. There is also evidence to suggest that vitamin C supplementation in the elderly with pneumonia may reduce the severity of the disease and the risk of fatal outcome, especially if vitamin C intake had been previously lowe.
Zinc supplementation of 75 mg/d or higher doses (note: may cause side effects) has been shown to shorten symptoms of colds. Lower doses have not shown an effect.
Garlic studies suggest that one of the ingredients, allicin, has antiviral effects and may reduce the risk of colds at a dose of 180mg/day.
COVID-19: Many of the viruses that cause epidemics and pandemics originate in animals. A number of experts warn against eating and associating with animals that are known to cause human epidemics. The animals in question are often in the category of "unclean animals" such as bats (Ebola), camels (MERS), pigs (H1N1) and other wild animals. Regarding whether dietary factors affect COVID-19, vitamin D has been studied the most. Some studies suggest that vitamin D deficiency increases the risk of a more serious disease course.
Tobacco:6
Smoking leads to significant defects of the respiratory and immune systems. Smoking can lead to COPD, which reduces the lung reserves in the face of respiratory infections. Smoking also reduces the cilia in the airways that play an important role in cleansing the lungs of particles, microorganisms and dead cells. Smoking further leads to reduced phagocytic activity of the immune cells in the lungs. Thus there is an increased incidence of disease-causing bacteria in the lungs in smokers. Furthermore, smoking leads to impaired function of white blood cells including NK cells and reduced levels of antibodies.
These changes may explain why smoking increases the risk of contracting respiratory infections such as the flu and pneumonia. At the same time, smoking also increases the risk of a more serious course of the disease in these infections. After a number of studies suggested that smokers were protected against severe COVID-19, it now seems to be more certain to the contrary; that smoking increases the risk of becoming seriously ill from COVID-19.
Sleep:
Too little sleep affects the immune system and seems to make us more vulnerable to contracting infections such as colds and flu after exposure to a virus. In a study of 153 participants who were inoculated with a cold virus, it was found that participants who previously slept less than 7 hours a night were approximately 3x more likely to develop a cold compared with those who slept 8 hours or more. Reduced sleep efficiency (how much you sleep during the time you are in bed) also increased the risk of catching a cold.
7 One possible mechanism is that certain parts of the immune system that are extra active when sleeping function less optimally in people with too little sleep.
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Air pollution:
Some studies suggest that where you live or stay can affect the risk of contracting respiratory infections and also lead to a more serious disease development. A recent study from Harvard
9 observed that the risk of dying from COVID-19 increases 20 times if you live in an area with high air pollution. This is in line with findings in connection with the SARS virus in 2003, which showed that air pollution led to a significant increase in the death rate. In addition to this, there are several studies that show a connection between increased pollution and increased incidence of influenza. Air pollution also seems to aggravate cold symptoms. A study by Johns Hopkins
10 showed that air pollution increases symptoms of colds through increased production of cytokines (signaling molecules that regulate the immune system), which caused increased inflammation, fluid formation and swelling. Serious COVID-19 lung issues are often a result of too many cytokines ("cytokine storm").
Stress:
Stress seems to affect one's susceptibility to respiratory infections
11 both through changes in the immune response and also through direct effects on disease-causing microorganisms in the respiratory tract, primarily bacteria. In addition, stress can also make us more susceptible to respiratory infections through stress-related behavioral changes, such as increased alcohol intake, smoking, poorer diet and reduced physical activity.
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Conclusion:
A healthy lifestyle, which includes avoiding tobacco, being regularly physically active, eating a healthy and varied diet, maintaining a normal weight, getting enough sleep, as well managing or decreasing stress seems to reduce the risk of developing bacterial and viral upper and lower respiratory infections. Healthy living habits are important in preventing a number of diseases that increase the risk of developing a serious course of COVID-19, including COPD, obesity, type 2 diabetes and heart disease. Based on the positive effects that healthy living habits have on respiratory infections and the immune system in general, as well as the limited knowledge we have already gained about lifestyle and COVID-19, lifestyle improvements are a reasonable goal in the prevention and treatment of COVID-19.