Gardening and Outdoor Time - An Overview of Health Benefits
by Philip Rouchotas, MSc, ND
Bolton Naturopathic Clinic
64 King St W
Are you spending enough time outdoors? A recent study found that gardening can be a promising strategy to improve fruit and vegetable consumption, physical activity, and physical function in cancer survivors. When we think about all of the different health habits that could have high return on investment, fruit and vegetable consumption and physical activity are at the top of the list. A large meta-analysis (basically a way of assessing all of the best available evidence) examined fruit and vegetable consumption and the risks of death. What do you think they found? Higher consumption of fruits and veggies was significantly associated with a lower risk of all-cause mortality. Each increment of one serving a day of fruit and vegetables helped prevent death, with a threshold of around five servings a day, after which there was no additional benefit. So the translation of that is that eating more fruits and vegetables will help you live longer.
How does this work? That’s always a tricky question to ask, because we don’t always know the answer and what we think we know may not be accurate. Fruits and vegetables contain vitamins, minerals, and fibre. More importantly, the research available shows that they can help prevent a number of chronic degenerative and metabolic health conditions. They can also have additional benefits, like regulating bowel movements. Furthermore, fruits and vegetables may replace other foods. If those other foods are unhealthy or calorie-dense, then fruits and vegetables may be displacing them in the overall diet.
If gardening can promote an increased consumption of healthy foods, it’s definitely worth exploring further. Oftentimes, people will have a number of reasons as to why they are unable to perform a health-promoting behaviour. They may feel that they don’t have enough time, knowledge, skill, or motivation. So anything that can help move things in the right direction for even some people can have tremendous benefit. As we will see, how this is set up might matter. Mentors, teams, and responsibility are all potentially important factors to keep in mind to overcome some of the common obstacles. In this article, we’ll outline the benefits of gardening and outdoor time, including a focus on vitamin D. We’ll summarize and report on the studies that have been conducted.
Let us examine the recent study on gardening for cancer survivors. Cancer survivors are at high risk of multiple health problems, including cardiovascular disease, diabetes, and recurrence of cancer. The researchers conducted a feasibility study of vegetable gardening that paired adult and children cancer survivors with master gardeners to explore fruit and vegetable intake, physical activity, quality of life, and physical function. This was done over one year. The participants had to plant three gardens, harvest and rotate plantings, and troubleshoot problems. Information was collected through surveys and through objective measures.
The results of the study showed that gardening was feasible, in the sense many people chose to enrol and there was minimal attrition (these are both signs of a very strong intervention). Improvements in three measures were found: strength, agility, and endurance. This was seen in 90% of survivors. Increases of one fruit and vegetable serving per day and more than 30 minutes a week of physical activity were observed in 40% and 60% of people, respectively. Overall, this study shows that a seemingly simple intervention like gardening can provide numerous health improvements across the board by promoting health-promoting behaviours.
Gardening may have the added benefit of improving mental health. There are studies available that show that time outside, or time in nature or natural environments, can improve mood and self-esteem, and even reduce anxiety. Even viewing scenes of nature reduces anger, fear, and stress. This reduces blood pressure and heart rate. Some research on the topic shows that even adding a plant to a room can have a significant impact on stress and anxiety.
There’s also probably a sense of responsibility that develops with gardening. This may be because an initial investment is made (time, effort, possibly finances) and people often want to see the fruits of their labour (literally). Gardening takes time, and it’s not something that you can set and forget. It requires ongoing investing and check-ins, a continuous amount of monitoring needs to be conducted, and new problems need to be solved; if these steps are not taken, the whole thing can fail. For children in particular, gardening can help train them to care about things, as they will likely enjoy eating what they’ve grown themselves and feel good about it.
Spending time outside in the sun is considered the most important determinant for increasing vitamin D levels (known as serum 25(OH)D status). In a study conducted in patients with kidney problems, the researchers assessed their vitamin D levels and the prevalence of vitamin D deficiencies. They surveyed dietary vitamin D intake, degree of sun exposure, and outdoor activities. The results of the study showed that vitamin D intake and sun exposure time were not significantly different between groups of patients with different vitamin D levels. Specifically, dietary intake of vitamin D did not contribute to increased vitamin D levels. The main factors affecting vitamin D levels were sun exposure and active outdoor exercise (which also obviously provides sun exposure).
Another study examined UVR exposure and vitamin D levels in a rural population of outdoor-working male farmers, their indoor-working spouses, and their children. The researchers performed a prospective cohort study, where UVR exposure and sun behaviour were recorded by dosimetry and diaries. Vitamin D was measured at the end of summer and the following winter. The results showed that risk behaviour (defined as exposure of the shoulders and upper body to the sun), beach days, sunscreen use, and sunburns were infrequent. Farmers and boys had the highest UVR exposure (which was probably expected), and both for work and nonwork days. The farmer’s spouses had the lowest amount of UVR exposure. Vitamin D levels did not differ between family members, and they found that by the end of summer, 16% of the participants were vitamin D–insufficient; following winter, it was 61%. Thus, the authors conclude that vitamin D levels still dropped below the recommended level during winter for most participants. The evidence shows that not only is vitamin D extremely important for health and wellbeing, but that dietary vitamin D is not necessarily a good substitute for outdoor time.
In terms of health functions, vitamin D promotes calcium absorption and helps maintain calcium and phosphate concentrations. Overall, that helps with bone health, and vitamin D also helps with maintaining bone growth and remodeling. It helps with cell growth, nerve and immune function, and even reduces inflammation. Several genes that regulate the functions of cells are modulated by vitamin D.
Some of the most important health habits that can be implemented include the consumption of fruits and vegetables, physical activity, and sun exposure. In this article, we outlined the various benefits of fruit and vegetable consumption. With a ceiling of around five servings per day, they decrease all-cause mortality. They have the added benefits of containing vitamins and minerals, displacing unhealthy foods from the diet, and decreasing cardiovascular disease and chronic degenerative health conditions.
Physical activity helps to control weight, build muscle, reduce cardiovascular disease, improve bone and muscle health, improve mood, and has other wide-reaching health benefits. The problem for many people is that they make excuses as to why they can’t do it, or they don’t exercise as much as they should. Think of all the gym memberships that happen in January and then don’t get used only a few months later. Gardening was an intervention we discussed that helped across the board: it increased physical activity, increased fruit and vegetable consumption, and lead to greater sun exposure.
We discussed how sun exposure is the best way to improve blood levels of vitamin D. Even for those who eat foods high in vitamin D and for those who get exposed to sun, it seems that seasonality can greatly impact vitamin D levels. This means it’s important to not only get adequate sun exposure, but to ensure that if you can’t, you at least do your best to consume more dietary vitamin D or supplement it appropriately. As is typically recommended, see your naturopathic doctor prior to implementing any new therapies to ensure they are safe and effective for your particular case.