Here's how to dose "vitamin N" for your brain
By Austin Perlmutter, MD
In recent years, multiple studies have demonstrated the physical and mental health benefits of nature exposure. The idea that nature exerts a healing power on our bodies and minds has led some to call it “Vitamin N.” While there’s increasing evidence that this green pill can help us with everything from lower stress to a longer lifespan, the question of how big of a dose of nature we need to enjoy these health benefits remains largely unanswered.
One of the reasons it’s so hard to find an exact nature prescription is the heterogeneity in trials on this subject. However, a few studies have looked at the health effects related to specific intervals of time spent in nature. Here’s a general idea of the timeframes in nature associated with better health
20 minutes in nature may be enough to lower stress
In 2019, a study looked at the effect of 20 minutes of nature exposure on Americans living near Ann Arbor, Michigan. Researchers showed that after just 20 minutes in a natural setting, study participants had lower cortisol levels, suggesting that even this short interval of green therapy could diminish stress.
30 minutes in nature may be enough to lower blood pressure and risk of depression
If you have more than 20 minutes a week to spare for nature therapy, some data suggests you could improve your blood pressure and mood. A 2016 study of over 1,500 Australians compared time in green spaces with rates of depression and high blood pressure. It concluded that if everyone visited an outdoor green space for 30 minutes or more each week, it could lower population rates of depression by 7 percent, and rates of high blood pressure by 9 percent. Considering the morbidity and cost imposed by these conditions, those are big numbers.
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90 minutes in nature may positively change thinking patterns
In 2015, researchers at Stanford wanted to see whether a 90-minute walk in nature led to different thinking and different brain blood flow compared to a similar amount of time walking in an urban environment. They randomized study participants to either spend 90 minutes walking in the green space around Stanford University or to walk next to a busy street in nearby Palo Alto
After completing the walk, those who were in nature reported significantly lower levels of rumination (repetitively going over a thought or problem in one’s mind). Since rumination is associated with mental illness, a longer nature walk could be a way to support better mental health.
120 minutes in nature may improve health and general well-being
For those who have the time, getting outside for a few hours a week may provide major benefits. A 2019 study from the UK looked at the association between recreational time in nature and self-reported health and well-being in over 19,000 people. After controlling for several variables, the researchers found that those who spent 120 or more minutes per week in nature were much more likely to report good or very good health, as well as high well-being compared to those who did not spend time outdoors.
The take-home prescription:
We’re still unsure exactly how much nature we need to get all its associated health perks. But given that the average American spends 93 percent of the day indoors or in enclosed vehicles, we are far from overdosing on Vitamin N. Like anything, the effects of nature will be different for each person, and the goal should be to find what works best for you.
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