November/December 2020 Issue

Advocating Biodiversity in Diets
By Sharon Palmer, MSFS, RDN
Today’s Dietitian
Vol. 22, No. 9, P. 46

Learn about the benefits of growing and eating a wider variety of foods for the planet and human health.

As dietitians, we all have been trained in the language of “variety,” as we tell our clients and patients to focus on a variety of nutrient-dense foods daily. It’s written in our nutrition canons, from the Dietary Guidelines for Americans to National Nutrition Month messages.

Indeed, encouraging variety is one of the key things dietitians do in their work to ensure people have access to optimal diets that support human health. However, the word “variety” might be better traded for the term “diversity” today, as RDs explore the many facets related to diet quality, as well as their impacts on people and the planet.

Diversity opens up the diet conversation to not only include the array of nutrients found in high-quality diets but also explore the importance of biodiversity—the diversity of plants, animals, and other organisms used for food, both cultivated and from the wild—in our diet patterns.1 “Biodiversity is at the base of healthy ecosystem services that provide us with clean water, air, and nutrient-rich foods for a healthful life,” says Chris Vogliano, MS, RDN, a PhD candidate in biodiverse and sustainable food systems at Massey University in New Zealand and a global health consultant.

Biodiversity in our food system takes on another meaning: It speaks to preserving the variety of life in our ecosystems on Earth. Our food system shouldn’t come at the cost of further endangering the rich natural biodiversity of the planet, especially at a time during which the planet is experiencing accelerated species extinctions, loss of natural habitat, and changes in the abundance of species as the Earth’s systems are being pushed past their tipping points.2 The United Nations reports that nature is declining globally at rates unprecedented in human history, with around 1 million animal and plant species now threatened with extinction.3

Benefits of Biodiversity
“Without biodiversity, produce aisles would be barren, water would continue to become more polluted, and skies would become cloudy with pollution. Biodiversity is the essence of a functioning ecosystem,” Vogliano says.

At a basic level, our diets are poor because they lack diversity, even though we have high levels of obesity in the United States, says Robin Currey, PhD, faculty and director of sustainable food systems at Prescott College in Prescott, Arizona. A biodiverse diet offers the body a spectrum of protective antioxidants and an increased likelihood of meeting vitamin and mineral needs, says Mary Purdy, MS, RDN, known as the Integrative Eco-Dietitian. She says, “A more diverse dietary pattern also supports optimal gut microbiome health by increasing diversity within our internal microbial ecosystem, which is associated with a reduced risk of a host of chronic diseases. Studies show that consuming at least 30 different types of plants throughout the week helps ensure microbial diversity in our gut and a host of immune-supportive phytochemicals in our system. Different plants offer different benefits, so the goal is to include a variety to be able to tap into them all.”

There’s another connection between biodiversity and nutrition that’s less obvious but just as important. “When many different kinds of crops are grown together, or when crops and animals are integrated in the agricultural system, then there is more biodiversity in the agricultural ecosystem,” Currey explains. “Diverse agroecosystems are known to retain more water, prevent soil loss, and have better quality soil. Better quality soil means healthier plants, which are less vulnerable to pest damage and disease but also higher in micronutrients. The result is that we get more nutrient content per bite in the plants that we eat or the animals that we eat, which are eating those plants, when they are grown in a biodiverse agroecosystem. Pesticide and fungicide use can be lower in biodiverse systems, also, meaning fewer potentially harmful substances in our food due to the complicated biological interactions between pests and predatory insects.”

Wildlife, including pollinators and bugs, all have a role to play in the health of the soil that can determine how well food is grown, Purdy says. “A lack of biodiversity has been one of the contributing factors to environmental degradation, which is having a direct impact on our ability to grow nutritious food and making land more susceptible to the extreme weather patterns resulting from climate change like flood and drought. So, the more we focus on maintaining an environment that is welcoming to a diverse array of plant and animal life, the more likely we are to have a robust and resilient food system that supports our survival.”

Biodiversity on the Plate
What does biodiversity on the plate look like? Essentially, a biodiverse plate has smaller portions of more diverse foods, including proteins, grains, and vegetables. However, our Western-style diets are anything but diverse; 12 plants and five animals account for 75% of our global food supply.4 It may seem impossible, given the thousands of products on supermarket shelves; yet, if people looked more closely they’d recognize those familiar plants and animal foods, such as soy, corn, wheat, chicken, beef, and pork, over and over. Even in the produce section, the same standard varieties, such as romaine lettuce, beefsteak tomatoes, and Spanish onions, are sold. It’s no wonder diversity in our modern diets is an issue, as it’s simply not available to many.

Bioversity International, a global organization that aims to protect agricultural and tree biodiversity to attain sustainable food and nutrition security, outlines four key messages when it comes to promoting food biodiversity for healthful diets5:

• Food biodiversity—the diversity of plants, animals, and other organisms used for food, both cultivated and from the wild—is a critical element in response to global malnutrition, and it supports sustainable food systems.
• Food biodiversity reaches consumers through two principal pathways: 1) consumption via own production or gathering from the wild, and 2) purchase of wild or cultivated species.
• The nutrient content between different species, or different varieties or breeds of the same species, can vary one thousand–fold. This information can be used to maximize the nutritional adequacy of diets.
• Improved availability, accessibility, affordability, and acceptability of food biodiversity are key factors for achieving better diets.

Dietitians will find examples of biodiverse diets all around them in traditional and Indigenous diet patterns. “Indigenous diets are those which have been adapted to meet the specialized growing conditions of a specific eco-region,” Vogliano says. “These foods work within planetary systems to provide sustenance for humans, while also giving back to the land in a regenerative fashion,” he says. These diet patterns often follow a simple formula: staples (grains, pulses) form the foundation—the canopy, if you will—for meals that are amplified with numerous plant and animal species and varieties. Think of rice dishes in countries in Asia, which are combined with a variety of vegetables, herbs, and animal proteins. Look to the pasta dishes in Italy, where they’re carriers for numerous types of vegetables, herbs, spices, nuts, seeds, and proteins. In fact, people who eat rice and pasta regularly eat more vegetables, according to research.5

From spaghetti alla puttanesca to Vietnamese soups to Middle Eastern grain salads, there are many classic examples of biodiversity on the plate in traditional diet patterns, where a variety of wild and cultivated foods are worked into foodways. Biodiversity in diets is based on the old principle of “making something of nothing.” Some examples include foraging for “free” food, such as greens, mushrooms, fruits, nuts, herbs, and even insects, small game, moss, and ferns, in the wild; planting backyard kitchen gardens, saving seeds, and sharing or trading foods among neighbors—thus cultivating hundreds and thousands of varieties over time; growing rotation crops, such as legumes, which also could be harvested and eaten; using the whole part of the plant from stem to leaf, and animal from nose to tail; and preserving foods to last over the lean times, thus enriching diversity of diets during the off-season.

“Our dietary patterns are about so much more than food. Sustainable diets are diets with low environmental impacts that play an important role in ensuring food and nutrition security. Plants and animals that are adapted to the conditions of a specific place are less likely to need extra water, or shade, or season extension. So, eating from your place has less environmental impact,” Currey says. “Historically, our diet patterns evolved with our place. The Mediterranean diet emerged in the Mediterranean region, which has a particular climate that supports particular plant, animal, and aquatic communities that people decided they could eat. Religious beliefs influence eating habits, as do cultural norms. But when Indigenous people are removed from their places due to colonization, conflict, land grabbing, or other forms of cultural disruption, diets are also disrupted. Food plants can be lost or ingredients not available for traditional recipes.”

Preserving Biodiversity
A growing body of literature shows that increases in agricultural diversity are linked with dietary diversity. Agricultural diversity refers to species and varieties, such as crops, animals, insects, and microorganisms, that are used directly or indirectly for food and agriculture in the range of ecosystems where agriculture is practiced, Currey says. She explains that agricultural diversity is linked with nutrient content, at the species level, as well as at the varietal level, offering the example of peppers and broccoli. Peppers can be higher in vitamins C and A but lower in vitamin K than broccoli. However, if individuals eat many different species (such as peppers and broccoli) and many different varieties of each species (such as red bell, poblano, and serrano peppers, and broccoli raab or Italian broccoli), they’re more likely to achieve micronutrient adequacy in their diets because nutrient content varies.

The plain truth is, if people eat it, farmers will grow it, Currey explains: “If we are only demanding rice, corn, wheat, beef, chicken, some broccoli, carrots, and iceberg lettuce, then farmers seeking living wages will have to grow what we, as consumers, are demanding. This leads to the simplification of our agricultural systems—more farmers growing or raising large amounts of just a few species and varieties.” On the other hand, if consumers demand diverse species and varieties, farmers will respond to that, “giving them the opportunity to diversify their own production systems,” she says.

One way to preserve genetic diversity in our diets is through collecting seeds. More than 1,700 gene banks around the world are holding collections of food crops for safekeeping. For example, the Svalbard Global Seed Vault is a long-term seed storage facility deep inside a mountain on a remote island between Norway and the North Pole. The Ark of Taste, a program of Slow Food, is a living catalog of foods that are facing extinction.6 Their goal is to inspire people to take action by rediscovering thousands of threatened foods, from Herat Abjosh Raisins from Afghanistan to spider flower leaves from Zimbabwe, by putting them back on the table so they’re preserved forever.

A key strategy for increasing biodiversity is to support direct-to-consumer food purchases, such as farmers’ markets or CSAs (community-supported agriculture) from local, biodiverse farms. This is often the primary way consumers, especially in cities, may have access to more diverse foods, such as different animal species and vegetable species and varieties. You might never have seen a Romanesco cauliflower or kohlrabi without visiting a farmers’ market, as these less common vegetables often aren’t worth stocking in supermarkets. Both farmers’ markets and CSAs, in which consumers purchase a share (or box) of the harvest from a local farm, are linked with better food quality. CSAs can encourage diversity in diets, as people are forced to use vegetables they might not otherwise have selected—CSA members report increased consumption of a variety of fruits and vegetables.7 Home gardening is one of the best ways to increase diversity in diets, improve human nutrition, and provide greater food access. A meta-analysis on gardening effects found a wide range of health outcomes, such as reductions in depression, anxiety, and BMI, and increases in life satisfaction, quality of life, and sense of community.8

Home gardening also can increase food security and dietary diversity in many different settings.9 What about ways to access this strategy in urban settings, where access to land is less available? Urban gardens, school gardens, and community gardens can help fill that need, offering opportunities for the community to learn about growing food, eating more healthfully, and living more sustainably.10

Protecting Biodiversity on Earth
While many dietitians want their clients to eat a nutritionally diverse diet for human health, it’s clear that this shouldn’t be achieved at the risk of further harming the planet. This means humanity must be fed through existing agricultural lands and not by deforesting the planet’s diverse ecosystems to support the human race. The “Half Earth” strategy for biodiversity conservation suggests conserving at least 80% of preindustrial species’ richness by protecting the remaining 50% of Earth’s intact ecosystems. This also includes managing the world’s oceans to ensure aquaculture doesn’t harm habitats. However, it will take our most ambitious action plans to protect biodiversity on the planet.1

“Westernized diets have encouraged the decline of many of the ecosystem services once provided by a wide range of biodiversity, with monoculture crops such as corn, soy, or wheat,” Vogliano says. “Northwest Ohio once housed ‘The Great Black Swamp’ covering over 1,500 square miles of terrain. Swamps serve as one of the most important ecosystems on Earth and provide habitat for an incredible number of plant and animal species. However, this swamp was drained centuries ago to make room for monoculture corn as far as the eye can see,” Vogliano says.

Purdy adds that the destruction of habitats also is due to deforestation to grow crops for animal feed and house livestock, as well as reliance on chemical fertilizers and pesticides that affect the habitats of surrounding wildlife and the microbial ecosystem of the soil. She says, “Genetic diversity is what helps plants maintain resilience and supports the ability to fend off disease and other unwanted adversities.”

In contrast, indigenous foods often are grown using more regenerative agricultural practices, which are in harmony with nature rather than against it, Purdy says. “This means fewer pesticides, less fertilizer, and reduced reliance on monocultures. Their traditional farming methods often use more eco-friendly techniques that actually help to regenerate the soil, like using cover crops, manure and compost, and planting crops together which work symbiotically with one another, the classic example being the ‘Three Sisters,’ corn, beans, and squash.”

Tips for Eating a Diverse Diet
Currey offers the following tips dietitians can share with clients to promote biodiversity on the plate:

1. Aim for colorful meals. Eating something red, purple, green, orange, and yellow at every meal or through the day ensures that you’re consuming a diverse array of plants and getting the micronutrients you need.

2. Try a new variety. The more varieties you eat, the more agrobiodiversity you support, providing farmers with more flexibility in their planting plans.

3. Think about species diversity and food groups. Did you eat any nuts or seeds today? What about something yellow or orange? What about dark leafy greens? Whole grain starch? Dairy, eggs, and lean meat (for nonvegetarians)?

4. Join a CSA. CSAs work on a model where a member receives a portion of the yield that’s ripe from the farmer each week. The research shows that CSA box recipients eat more species and varietal diversity, supporting biodiverse farmers.

— Sharon Palmer, MSFS, RDN, is known as The Plant-Powered Dietitian. She’s an author, blogger, and expert in plant-based nutrition and sustainability.


1. EAT-Lancet Commission. Food planet health: healthy diets from sustainable food systems: summary report of the EAT-Lancet Commission. Published 2019.

2. Food and Agriculture Organization of the United Nations. Sustainable diets and biodiversity: directions and solutions for policy, research, and action. Published 2012.

3. UN report: nature's dangerous decline 'unprecedented'; species extinction rates 'accelerating'. United Nations website. Published May 6, 2019.

4. McCarthy K. Eating biodiversity. RSA website. Published December 10, 2018.

5. Kennedy G, Stoian D, Hunter D, Kikulwe E, Termote C; Bioversity International. Food biodiversity for healthy, diverse diets.

6. The Ark of Taste. Slow Food USA website.

7. Vasquez A, Sherwood NE, Larson N, Story M. Community-supported agriculture as a dietary and health improvement strategy: a narrative review. J Acad Nutr Diet. 2017;117(1):83-94.

8. Soga M, Gaston KJ, Yamaura Y. Gardening is beneficial for health: a meta-analysis. Prev Med Rep. 2017;5:92-99.

9. Rammohan B, Pritchard B, Dibley M. Home gardens as a predictor of enhanced dietary diversity and food security in rural Myanmar. BMC Public Health. 2019;19(1):1145.

10. Christiansen J. Urban gardens promote education, nutrition, and more. US Department of Agriculture website. Published February 21, 2017.