Healthy food and health: The role of pollinators and urban gardening

In a recent study by Smith et al. (2022) published in the journal Environmental Health Perspectives, researchers “calculated that 3%–5% of fruit, vegetable, and nut production is lost due to inadequate pollination, leading to an estimated 427,000 (95% uncertainty interval: 86,000, 691,000) excess deaths annually from lost healthy food consumption and associated diseases. Modeled impacts were unevenly distributed: Lost food production was concentrated in lower-income countries, whereas impacts on food consumption and mortality attributable to insufficient pollination were greater in middle- and high-income countries with higher rates of noncommunicable disease. Furthermore, in the three case-study countries [Honduras, Nepal, and Nigeria], the authors calculated the economic value of crop production to be 12%–31% lower than if pollinators were abundant (due to crop production losses of 3%–19%), mainly due to lost fruit and vegetable production.”

According to the authors’ analysis (Smith et al., 2022), “insufficient populations of pollinators were responsible for large present-day burdens of disease through lost healthy food consumption.” In addition, the authors “calculated that low-income countries lost significant income and crop yields from pollinator deficits. These results underscore the urgent need to promote pollinator-friendly practices for both human health and agricultural livelihoods.”

“Despite large increases in global food production over the past half-century, providing adequate nutrition on a global scale has remained elusive for many populations.” Approximately 800 million people are undernourished worldwide, and that number has been growing steadily since 2015, following a decade of decline. In addition to those suffering from hunger, 2 billion people globally have been estimated to experience micronutrient deficiencies, although global monitoring data is infrequently collected. Inadequate intake of healthy foods, such as fruits, vegetables, and nuts, is also driving large burdens of disease. Considering these persistent challenges, strategies for global food and nutritional security have begun to shift from strictly producing adequate calories to providing more nutritious diets (Smith et al., 2022).

“Coincident with recognition of the need for more nutritious diets has been a growing awareness that we need to reduce the environmental toll of global food production. Agriculture is the single largest driver of biodiversity loss, land-use change, growing scarcity of freshwater, and land degradation globally” (Smith et al., 2022). Furthermore, the food system is a significant contributor to climate change, responsible for one-third of global greenhouse gas emissions (Crippa et al., 2021). As such, “growing more nutritious foods with lower environmental impact has become one of the great challenges of the 21st century” (Smith et al., 2022). Hence, Smith et al. 2022 concluded that: “Our results underscore the importance of pollinators for human health and increase the urgency of implementing pollinator-friendly policies to halt and reverse the trends of pollinator declines.”

Diverse Strategies to Support Pollination

“Diverse research investigating the optimal policies to benefit pollination have shown remarkable consensus around a short list of highly effective strategies: increase flower abundance and diversity on farms, reduce pesticide use, and preserve or restore nearby natural habitat. This encouraging scientific agreement has already spurred action worldwide, with many countries creating and implementing their own national pollinator protection strategies. Despite this promising momentum, immense challenges remain for the restoration of pollinator populations globally. In this analysis, we have demonstrated that the protection of animal pollinators is not solely an ecological or environmental issue but also has significant implications for human health and economic well-being” (Smith et al., 2022).

On December 21, 2022, there was a major development regarding a bee-killing pesticide:

Appeals court faults EPA for approving bee-killing pesticide

“EPA failed to properly consider the environmental impacts of a controversial pesticide, according to an appeals court decision that faulted the agency over a Trump-era decision that drew outrage from environmental groups.

In a decision issued Wednesday, the 9th U.S. Circuit Court of Appeals asserted that regulators should have considered the impacts of the bee-killing insecticide sulfoxaflor when it expanded that product’s use for long-term approval.

That action, taken under former President Donald Trump, drew legal wrath from beekeepers who argued that the agency had bypassed public comment in making its decision while also violating several protective statutes.”

Honeybees gather in a hive

Honeybees gather in a hive at Councell farms on Dec. 15 in Arcadia, Fla. Joe Raedle/Getty Images

Furthermore, as observed by the Food and Agriculture Organization of the United Nations (FAO, 2016), “The absence of an appropriate habitat for bees could lead to a continuous decline in pollination. Mono-cropping, pesticides, and higher temperatures associated with climate change all pose problems for bee populations and, by extension, the quality of food we grow. Declining pollination also poses an immediate threat on nutrition.” If this trend continues, nutritious crops such as fruits, nuts and many vegetable crops will be substituted increasingly by staple crops, such as rice and corn, eventually resulting in an imbalanced diet (FAO, 2016).


Urban Gardening Supports Pollinators

In addition to the strategies recommended by Smith et al. (2022), including increased flower abundance, diversity on farms, reduced pesticide use, and preserving and/or restoring natural habitats, recent research published in the Journal of Ecology (Tew et al., 2021) reported that “urban areas in the U.K. are a significant source of nectar and floral diversity for insects. The authors of the study aimed to understand how the nectar supply differs between urban and rural areas and where the nectar sources are concentrated in urban settings. It is the first study to quantify nectar in urban areas on the landscape level. The standard method for measuring an area’s nectar supply is by using a proxy like flower abundance.” (Tew et al., 2021) (McCoy, 2021).

“To understand the differences in pollinator food supply on different landscapes the researchers did indeed tally plant samples, but they also measured actual nectar production from hundreds of flowering plants in and around 12 towns and cities across the U.K. In each location, flora were sampled in an area that fell into one of three categories: urban, farmland or nature reserve. 

Although urban and farmland landscapes had much higher numbers of non-native plants than nature preserves, the team found that the three landscapes produced similar amounts of nectar. Among the urban sources of nectar, which were much more diverse compared to both farmland or nature preserve sources, 85 percent was attributed to gardens. Even paved areas contributed to nectar sources in some instances with flowering shrubs growing through cracks or in parking lots. Within gardens, 83 percent of nectar-producing plants were non-native.” (Tew et al., 2021) (McCoy, 2021).

This recent research underscores the role urban areas can play as nectar hotspots and the value that some non-natives plants may add to support pollinator health. More specifically, the study authors observed that, “This research highlights the importance of gardens in supporting our pollinating insects and how gardeners can have a positive impact through their planting decisions,” says Stephanie Bird, co-author and entomologist at the Royal Horticultural Society, in a press release. “Gardens should not be seen in isolation—instead they are a network of resources offering valuable habitats and provisions when maintained with pollinators in mind” (Tew et al., 2021) (McCoy, 2021).

The American Community Gardening Association (ACGA) notes that “Urban gardens can play an essential role in pollination conservation.” This is due to the fact that bees need the pollen and nectar that flowers provide, and flowers need bees’ pollination services (ACGA, 2022).

Here are some tips by Tew and colleagues (2022) on what to plant by season:

Urban gardens are critical food sources for pollinators: here’s what to plant every season (Tew et al., 2022)

  • What to plant in winter

“Few pollinators are still active in winter. Most species die off leaving the next generation behind as eggs, larvae or pupae.

But bumblebees and honeybees remain in flight, taking advantage of the warmer climate and winter flowers that cities can provide. By vibrating their wings, bumblebees can warm up to forage in temperatures barely exceeding freezing point, but they need a lot of energy-rich nectar to do so. If you want to attract bees into your garden during the winter some of the best options are Mahonia, sweet box, winter honeysuckle and the strawberry tree.

  • What to plant in spring

The first queen bumblebees emerge from winter hibernation in February and March. They need food straight away.

At this time of year nectar-rich plants are vital energy sources for warming up cold flight muscles, with pollen providing the necessary protein for egg laying and larval growth. In early spring much of the countryside is still bleak and inhospitable.

Gardeners can help by planting borders of hellebore, Pulmonaria and grape hyacinth. Trees and shrubs such as willow, cherry and flowering currant are also fantastic for packing a lot of food into a small space.

A bee on a willow flower
Willow in bloom. Ira Kalinicheva | Shutterstock
  • What to plant in summer

In late spring and early summer, pollinators have more food available – but there is also more competition for it. So it is crucial to ensure you have a diverse array of different flowering plants. This will guarantee there is attractive and accessible food to suit a wide range of insects and provide them with nutritionally balanced diets.

A great assortment of plants, including honeysuckle, Campanula and lavender, can provide floral resources in summer. Mowing the lawn a little less often will help too, giving the chance for important so-called weeds, such as clover and dandelion, to bloom.

Ivy in bloom with a red admiral.
Ivy in bloom with a red admiral. Seepix | Shutterstock
  • What to plant in autumn

By late summer and autumn there are fewer species still flowering in gardens. A handful dominate the nectar supplies, particularly FuchsiaSalvia and Crocosmia.

For many pollinators, however, these flowers are entirely useless. Their nectar is hidden away down a tube, only accessible to insects with long tongues, such as the garden bumblebee.

This means solitary bees and hoverflies may need to find other sources of food. The gardener can help by prioritizing open and accessible flowers. Opt for species such as ivy, SedumEchinacea and oregano.”

Urban Gardening Contributes to UN Sustainable Development Goals (SDGs): Zero Hunger (SDG 2) and Good Health and Well-Being (SDG 3)

In addition to supporting pollinators, urban gardening contributes to several of the UN SDGs, including Zero Hunger (SDG 2) and Good Health and Well-Being (SDG 3) (Nicholls et al., 2020).

The 17 Sustainable Development Goals (credit: yukipon on Shutterstock)

Urban gardening contributes to hunger prevention (Zero Hunger, SDG 2).

Gardening contributes to hunger prevention through increased availability of and access to fresh fruits and vegetables whereas conventional agriculture produces more grains, fats, and sugar than fruits, vegetables, and sources of plant-based protein (Nicholls et al, 2020).

In South Africa, Modibedi et al. (2021) found that sustainable food production in community gardens can improve food availability in urban communities. The authors reported that, “Community gardens were able to sustainably provide vegetables to about two-thirds of the farmers throughout the year because of high yields even though harvests declined during dry months (March to August).”  The urban farmers also reduced their reliance on markets and supermarkets as sources of vegetables (Modibedi et al., 2021). 

In a recent meta-analysis published in the journal Earth’s Future (2022), researchers reported that when they ran a crop-by-crop comparison, they discovered that urban farms across all these contexts were producing even more food, or at least the same amount, as regular fields (Payen et al., 2022; Bryce, 2022).

Finally, a review by Rahimi et al. (2022) found that, “Urban environments have a high diversity of plants and bees that provides a good opportunity to increase agricultural production in these environments. Planting native plants and creating artificial nests for solitary bees and bumblebees can help attract more bees to urban environments. Converting lawns into floral resources or carrying out agricultural activities around green spaces can also effectively help to increase agricultural production in the city.”

Urban gardening contributes to good health and well-being (Good Health & Well-Being, SDG 3).

“Urban gardening contributes to better health because it improves both physical and mental health. Physical health is improved as working on a farm or allotment is a good exercise; mental health is improved because of being able to reconnect with nature, and with other community members. Some research indicates that people who have their own gardens consume more nutritious, health-promoting foods – including fruits and vegetables – than people without gardens (Nicholls et al., 2020).

The Magic Harvest program is a community gardening program initiated in outer metropolitan South Australia in 2010. The program provided education and support for community members to grow fruits and vegetables in their backyards or community spaces. Through their involvement in growing and sharing food via a community gardening program, participants reported higher levels of household fruit and vegetable consumption” (Mehta et al., 2019). The authors noted that, “This is particularly salient because the two MH [Magic Harvest] programs are located in areas of relative socio-economic disadvantage where residents are considered to be at greater risk of poor nutrition and associated chronic diseases. Low socio-economic communities are often assessed as hard-to-reach by primary health care services and requiring programs of high relevance and trust in order to elicit community engagement” (Mehta et al., 2019).

“Apart from enhancing fruit and vegetable consumption, the MH [Magic Harvest] program also influenced participants to be more aware about the food system and sustainability. In this way, they became more conscious food citizens, making active and thoughtful food choices rather than passively consuming what was available in the stores. Through the sharing of food with each other and their wider community, participants engaged in food democracy whereby a more sustainable and community-centered food system is created” (Mehta et al., 2019).

Finally, the Magic Harvest program afforded participants some empowerment to shape their food environment through engaging in an alternative, local food production system, albeit at a micro-level. The authors stated that, “As a community gardening initiative, the MH [Magic Harvest] program offers a holistic approach to health and creates opportunities for health promotion as outlined in the Ottawa Charter for Health Promotion such as a) creating supportive environments, b) strengthening community action and c) developing personal skills” (Mehta et al., 2019).

Another advantage of urban gardening is that it makes more sustainable farming methods possible because fewer pesticides are used, and crops can be grown organically (Nicholls et al., 2020). The environmental and biodiversity benefits of organic farming are widely recognized (Rempelos et al., 2021). In an extensive 3-year study, researchers found that organic farming methods can contribute to halting the pollinator decline, due to both the absence of insecticides and a higher provision of flower resources (Carrié et al., 2018).

In addition to being harmful to pollinators (Eng et al., 2017), a recent study published in the journal Environment International found that neonicotinoid insecticides can promote breast cancer progression (Li et al., 2022).

Finally, in a review published in the journal Agronomy (Rempelos et al., 2021), scientists reported that, “the evidence now available suggests that there are nutritionally relevant composition differences between organic and conventional crops and that, overall, organic plant-foods contain higher concentrations of nutritionally desirable (phenolics, other antioxidants and/or mineral micronutrients) and lower concentrations of nutritionally undesirable chemicals (pesticide residues, cadmium, and/or Fusarium mycotoxins) (Rempelos et al., 2021).

However, the authors also stated that, “Although organic food consumption was linked to positive health impacts in observational studies, one important limitation in the currently available evidence is that controlled clinical trials to confirm and provide a mechanistic understanding of the positive health impacts of organic food consumption reported in observational studies, have not yet been carried out.” (Rempelos et al., 2021; Vigar et al., 2020).

Even so, the authors observed, “mounting evidence that (i) conventional fruit, vegetable and whole-grain consumption substantially increases pesticide exposure and (ii) consumption of fruit and vegetables with high pesticide loads may have negative effects on reproductive health.” (Rempelos et al, 2021). Based on the above observations, additional research is needed. Until then, use of organic production practices in urban gardening and agriculture, as a precautionary measure, are advisable.

References:

Smith,MR, Mueller ND, Springmann M, et al. Pollinator deficits, food consumption and consequences for human health: A modeling study. Environmental Health Perspectives 2022;130:12 CID: 127003 https://doi.org/10.1289/EHP10947

Crippa M, Solazzo E, Guizzardi D, et al. Food systems are responsible for a third of global anthropogenic GHG emissions. Nature Food 2021;2:198-209. https://doi.org/10.1038/s43016-021-00225-9.

Food and Agriculture Organization of the United Nations (FAO). The power of pollinators: why more bees means better food. FAO: Rome, Italy. August 24, 2016. Available at: https://www.fao.org/zhc/detail-events/en/c/428504/

Tew NE, Memmott J, Vaughan IP, et al. Quantifying nectar production by flowering plants in urban and rural landscapes. Journal of Ecology 2021;109(4):https://doi.org/10.1111/1365-2745.13598

McCoy B. Trailblazing research uncovers urban gardens as a hidden powerhouse for pollinators. Anthropocene Magazine, March 31, 2021. Available at: https://www.anthropocenemagazine.org/2021/03/urban-gardeners-have-a-big-role-to-play-in-protecting-pollinators/

American Community Gardening Association (ACGA). The Cultivator. Community Gardening Association Newsletter. December 2022. ACGA: Atlanta, GA; 2022.

Tew N, Memmott J, Buldock K. Urban gardens are critical food sources for pollinators: here’s what to plant every season. The Conversation. January 24, 2022. Available at: https://theconversation.com/urban-gardens-are-crucial-food-sources-for-pollinators-heres-what-to-plant-for-every-season-174552

Nicholls E, Ely A, Birkin L, et al. The contribution of small-scale food production in urban areas to the sustainable development goals: A review and case study. Sustainability Science 2020;15(6):1585-1599.

Modibedi, T.P., Masekoameng, M.R. & Maake, M.M.S. The contribution of urban community gardens to food availability in Emfuleni Local Municipality, Gauteng Province. Urban Ecosyst 2021;24:301–309.

Payen FT, Evans DL, Falagan N, et al. How much food can we grow in urban areas? Food production and crop yields of urban agriculture: A meta-analysis. Earth’s Future 2022;10(8): e2022EF002748.

Bryce E. A crop-by-crop comparison of urban vs conventional farms yields turns up some surprising results. Anthropocene Magazine. August 26, 2022. Available at: https://www.anthropocenemagazine.org/2022/08/can-cities-grow-more-food-than-conventional-farms/?

Rahimi, E, Barghjelveh, S, Dong P. A review of diversity of bees, the attractiveness of host plants and the effects of landscape variables on bees in urban gardens. Agric & Food Security 2022;11:6 https://doi.org/10.1186/s40066-021-00353-2

Mehta, K., Lopresti, S., & Thomas, J. Addressing nutrition and social connection through community gardening: A South Australian study. Health Promotion Journal of Australia. 2019; https://doi.org/10.1002/hpja.235

Carrié R, Johan Ekroos J, Smith HG. Organic farming supports spatiotemporal stability in species richness of bumblebees and butterflies. Biological Conservation 2018; 227:48 DOI: 10.1016/j.biocon.2018.08.022

Eng, ML, Stutchbury BJM, Morrissey CA. Imidacloprid and chlorpyrifos insecticides impair migratory ability in a seed-eating songbird. Scientific Reports 2017; 7:15176.

Li X, He S, Xiao H, et al. Neonicotinoid insecticides promote breast cancer progression via G protein-coupled estrogen receptor: In vivo, in vitro and in silico studies. EnvironmentInternational 2022;170:107568, https://doi.org/10.1016/j.envint.2022.107568.

Rempelos, L.; Baranski, M.; Wang, J, et al. Integrated soil and crop management in organic agriculture: A logical framework to ensure food quality and human health? Agronomy 2021;11: 2494. https://doi.org/10.3390/agronomy11122494

Vigar V, Myers S, Oliver, C, et al. A systematic review of organic versus conventional food consumption: Is there a measurable benefit on human health? Nutrients 2020;12:7.

Published by greengrass50

My name is Christine McCullum-Gomez, PhD, RDN. I am a registered dietitian nutritionist with expertise in environmental nutrition, food and nutrition policy, food and nutrition security, food justice, chronic disease prevention, regenerative & organic agriculture, and sustainable healthy dietary patterns. Currently, I serve on the Editorial Review Board and as a Column Editor for the Journal of Hunger & Environmental Nutrition. I live in Bogota, Colombia with my husband, two teenagers (boy-girl twins), and our dog Honey. My website is: www.sustainablerdn.com. You can follow me on Instagram at: https://www.instagram.com/cmccullumgomez/

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