The benefits of the forest on the human heart
Five questions for Dr. François Reeves
By Karina Durand
Dr. François Reeves is a cardiologist, researcher, author, and professor of medicine at Université de Montréal. For the past 15 years, he has been interested in environmental cardiology, i.e. the influence of environmental factors on cardiovascular health. His books Planète Cœur and Arbres en lumière have been acclaimed by the scientific community and have received prestigious awards. He is a member of several governmental advisory committees on health and environment. He was kind enough to explain to us the benefits of nature on human health.
Reeves, according to your research, the environment we live in has a significant impact on our heart health. What are the main factors to consider?
There are many risk factors for having a heart attack. Heredity, obesity, sedentary lifestyle, smoking, hypertension, and diabetes are some of them. But the environment in which we live is another element to take into consideration, and this is something that has been known for a very long time. Hippocrates, the great philosopher who is also recognized as the father of medicine, even said it four thousand years ago: there’s a link between our health and the air we breathe.
Today, four major environmental factors have been identified as having an impact on our heart health: air pollution, industrial food, tree planting, and environmental planning. To give you a concrete example, in some cases, second-hand smoke from cities, known as smog, is as toxic to humans as second-hand smoke from cigarettes. Therefore, the health effects are similar. Each year, it’s estimated that pollution is responsible for approximately 7 million deaths worldwide.
Video directed by Tom Patry and Charles Boutin (in French only)
Why does being in contact with nature have effects on human health?
First of all, we must remember something very important. Plants have been present on earth for a billion years, and humans, belonging to the animal kingdom, are creatures of nature. The millennial organization of cities has brought immense benefits to the human race. Concrete and asphalt cities appeared about a century and a half ago. Mineralized and polluted urban living environments are thus very recent in history and are not "natural" for human beings.
The problem that we’re facing nowadays is that we’ve migrated massively to the cities and we’re surrounded by fewer trees and forests and less natural bounty than ever before. In Québec, 85% of the population lives in cities, and in the rest of the world, the figure is about 50%. And this is trending ever upward. By 2050, it’s estimated that 75% of the world's population will live in cities.
Now, when human beings cut their ties with nature, they become sicker both physically and psychologically. Why so? Numerous scientific studies have rigorously examined the question and have shown that habitat plays an important role in the overall health of human beings. There are several reasons for this phenomenon. Forests are great air cleaners and pollution removers, among other things. Thus, their presence around us is fundamental to our quality of life.
Moreover, we sometimes forget it, but the forest is a place of perpetual renewal. It’s the world's largest food pantry and the most important pharmacy on the globe. It provides us with everything we need to eat healthily, but also to heal ourselves. The human being has evolved for thousands of years surrounded only by nature.
It’s often said that humans descended from the monkey, but in fact, and this is well known to biologists, we actually stem from the trees. When you compare a hemoglobin molecule (present in the blood of vertebrates) and a chlorophyll molecule (found in plants), you find the same molecular core. Humans and plants have the same origin.
What are the benefits of nature on human health?
There are all sorts of benefits! First, trees breathe powerfully, about a thousand times more than the lungs of a human being. By breathing, trees absorb air pollutants and purify the air. They extract sulfur dioxide, nitrogen dioxide, ozone, and a host of toxic fine particles that float in the air we breathe and that are caused by human activity. When there are trees around us, the air quality is greatly improved.
But there are other reasons as well. Trees, by the shade they create on asphalt surfaces, contribute to lowering temperatures and thus temper the environment, which plays an important role during heat waves. With the changes in climate that are currently affecting us, the presence of trees in certain cities of the world is crucial to reduce the overwhelming heat that is sometimes fatal for human beings. We can add that trees also protect against sunburns, especially UV rays that cause skin cancer.
Connecting with nature is also a monumental natural anti-stress measure, and this is scientifically documented by numerous studies. Spending time in nature brings us back to a rhythm that is closer to our biological makeup. A simple walk in the woods reduces symptoms of depression and negative emotions; lowers cortisol levels (the hormone that measures our stress levels); and brings down our blood pressure, for example. Studies also suggest that contact with nature reduces fatigue, boosts vitality, and improves concentration.
Forests also have a social impact. The calming effect of nature provides a general sense of health that is noticeable in the social climate. A sociological study has even shown that the rate of violence is lower in green areas than in cities.
There are a ton of studies that support this, but we all feel it intuitively. Forests are environments that calm us, soothe us, and bring us a very obvious sense of physical and psychological well-being. This makes a lot of sense when you stop for a minute to think about it, because the forest is the natural habitat of the human being.
How much and for how long should I do nature activities to get the best possible benefits?
This obviously depends on your goal. For people who want to stay healthy, the famous 10,000 steps per day is a good start. To help you reach this objective, you can use a watch or a mobile application that calculates your steps. Whether it's to prevent heart disease or to treat an illness like cancer, walking is an absolute must.
Among these 10,000 steps per day, I also recommend going for a 30 to 60 minute walk in nature or in a green environment, 3 to 4 times a week. This recommendation must be adjusted according to the health conditions of each person, but in general, integrating this lifestyle habit into one's daily life brings real benefits. People who are continuously active are in better physical shape, have fewer problems with weight or blood pressure, have better mental health, and age less quickly.
Staying active in a green environment leads to more positive spinoffs because one is more motivated to work out, but it also works better, since the air quality is better in the great outdoors than in the city. There are so many beautiful spots here in Québec! The advantage we have over other places in the world is that here, nature is easily accessible. The national parks, for example, offer many hiking trails that allow us to access beautiful landscapes, which can be a source of motivation for training.
Otherwise, a walk in the park near your home is also a good idea. To get the benefits of nature, you don't have to climb a high-altitude peak or go on a survival expedition in the forest. An activity as simple as walking in a green space around your home during lunchtime can do the trick.
I would also add that it’s important to heed the call of nature in the summer as well as in the winter, and not to stop when the weather is not so nice. You have to integrate this lifestyle habit all year long and adapt to the weather conditions. If it's cold or a few drops fall, the key is to dress accordingly. It’s said that there’s no such thing as bad weather, only bad clothing.
We hear more and more about natural prescriptions. What is a natural prescription and how does it work?
A natural prescription is a recommendation by a physician to a patient to spend time in a green environment on a regular basis. This recommendation often comes after a triggering event, such as a heart attack or an episode of illness. In addition to the appropriate medical treatment, the doctor suggests that the patient take advantage of this trigger to change his or her lifestyle habits.
Physical activity in a natural environment improves the quality of recovery and is as beneficial as a powerful drug. It’s also a preventive treatment against many diseases, starting with cardiovascular diseases. In the case of symptoms of depression, contact with nature has also shown impressive effects. Obviously, contact with nature is an "over-the-counter medication" if you will, because you don't need a doctor's prescription to benefit from it. However, when a health professional recommends that we integrate this habit into our daily lives, it’s a strong incentive for sure.
Physical inactivity and obesity are two very important risk factors for health, and in both cases, unfortunately, they’re increasing in Québec. Staying active every day and scheduling weekly outings in a green environment give concrete results on overall health. Those who do so testify to the benefits they feel, both in terms of physical fitness and mood. You have to experience it yourself to realize how much well-being this habit brings. As the old adage says,” Try it, you'll like it!”
About Karina Durand
Aside from walking alone in the forest, Karina enjoys trying her luck at fishing, grilling hot dogs over the coals of a campfire, reading at the end of a dock, and swimming in a lake when it rains. She has been Sépaq's content strategy director since 2017.