Why bioavailability matters for food systems and planetary health
The transition toward more sustainable food systems requires consideration of both environmental impacts and nutritional adequacy. Bioavailability is therefore a critical factor in evaluating both food systems and planetary health.
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Global food systems are responsible for approximately one-third of all anthropogenic greenhouse gas emissions. Food systems also drive freshwater depletion and pollution from excessive chemical and nutrient inputs in agriculture, contributing significantly to biodiversity loss. In response, the past several years have seen a growing movement toward a new paradigm: the Planetary Health Diet, which seeks to improve human health while promoting environmental sustainability. From sustainability initiatives to public health campaigns, the message has been remarkably consistent: reduce animal-source food consumption and slowly shift toward more plant-based diets as one of the most effective strategies for minimizing environmental degradation.
At first glance, this seems like an almost perfect solution. Yet one fundamental question is often missing from the conversation: what if we have been replacing foods without accurately measuring their nutritional quality?
Food has traditionally been evaluated based on what it contains: grams of protein, micrograms of vitamin A, milligrams of iron, before substituting animal-source foods with plant-based alternatives that appear to provide equivalent nutrient levels. However, one milligram of iron from spinach does not function in the same way as one milligram of iron from beef. Quantitatively, both foods may contain one milligram of iron according to food composition tables. Physiologically, however, the body absorbs and utilizes that iron very differently. In other words, a diet that appears nutritionally adequate on paper may not necessarily meet the body's actual nutritional needs.
This is the paradox increasingly shaping discussions about the future of food systems. If the global transition toward environmentally sustainable diets proceeds without changing how we evaluate nutritional value, we risk building food systems that successfully reduce environmental impacts while failing to ensure nutritional adequacy for billions of people.
The answer to this challenge lies in a concept that is still rarely discussed outside the field of nutrition science: bioavailability. Despite its importance, nutrient bioavailability is often only partially considered or overlooked altogether in current food system assessments.
Nutrient bioavailability refers to the proportion of nutrients in food that can be digested, absorbed, metabolized, and ultimately utilized or stored by the body. Simply put, it represents the amount of nutrients that become physiologically available after food is consumed.
Bioavailability serves as the “missing link” connecting three fundamental issues at once: nutritional quality, food security, and environmental sustainability.
And bioavailability is not determined by a single factor. Rather, it emerges from a complex network of interacting influences.
From the food itself, nutrient absorption depends on factors such as the food matrix, processing methods including fermentation and cooking, and the presence of compounds that inhibit nutrient absorption. At the same time, every individual processes nutrients differently. Age, sex, genetics, health status, gastrointestinal function, and gut microbiota all influence how efficiently nutrients from the same meal are absorbed. As a result, two people can consume identical diets yet derive different nutritional benefits.
Once food enters the body, digestion, absorption, metabolism, and storage all involve interactions between nutrients and factors originating from both the food and the individual. Given this complexity, overlooking bioavailability inevitably creates risks. Within the context of food systems, one of the most significant consequences is the inaccurate estimation of global nutrient supplies.
On paper, a dietary pattern may appear sufficient to meet a population's micronutrient requirements. In reality, however, the amount of nutrients that the body actually absorbs can be substantially lower. As a consequence, dietary recommendations that appear healthy and sustainable may still fail to meet human physiological needs, particularly among nutritionally vulnerable populations.
Incorporating bioavailability into food system analyses brings evaluations closer to biological reality rather than relying solely on theoretical nutrient calculations. This approach enables researchers to locate the factors influencing nutrient absorption, including dietary patterns, the presence of antinutritional compounds, animal-source food consumption, and population-specific characteristics. The result is a more accurate assessment of nutritional adequacy, allowing dietary recommendations to better reflect real-world conditions.
This perspective is important within the framework of planetary health, which recognizes that human health and the health of Earth's natural systems must be pursued simultaneously.
To date, sustainable food systems have largely been evaluated through environmental indicators such as greenhouse gas emissions, land use, and freshwater consumption. Yet a truly sustainable food system must also provide nutrients in forms that the human body can effectively utilize. In other words, the success of food system transformation should not be measured only by its environmental footprint, but also by its ability to safeguard population nutrition.
Bioavailability bridges these two objectives, ensuring that efforts to build more environmentally sustainable diets do not come at the expense of nutritional quality.
Integrating bioavailability into food systems and planetary health research is therefore not simply about choosing between plant-based and animal-source foods. Rather, it is about accurately evaluating nutrient adequacy, particularly for nutrients such as vitamin B12, zinc, calcium, and selenium, which are commonly deficient in populations with low consumption of animal-source foods.
By considering bioavailability, food system models move beyond estimating theoretical nutrient supplies and instead provide a more realistic representation of biological nutrient adequacy.
Bioavailability also highlights the importance of developing dietary recommendations that are tailored to context. A diet that is appropriate for one country may not necessarily be suitable for another. Countries with high consumption of animal-source foods may indeed benefit from increasing plant-based food intake to reduce environmental impacts. However, such dietary shifts should be accompanied by adjustments that account for changes in nutrient bioavailability to ensure nutritional adequacy is maintained.
On the other hand, in regions where diets rely heavily on whole grains and legumes, dietary recommendations should consider factors such as phytate content, which can reduce the absorption of iron and zinc. Without these considerations, food policies risk perpetuating long-standing micronutrient deficiencies.
In conclusion, bioavailability should be recognized as an essential component of nutrition research, food policy, and food innovation. By considering not only how nutrients are produced but also how they are absorbed and utilized, we can design dietary patterns that are more accurate, context-specific, and equitable. In doing so, environmental sustainability and human health no longer need to be treated as competing priorities, but as complementary goals that can, and should, be achieved together.
References:
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Nicholas, K. M., Tone, A., Beal, T., Zamborain-Mason, J., Eneroth, H., Öhrvik, V., Troell, M., & Golden, C. D. (2026). Perspective: Nutrient bioavailability is the missing ingredient connecting food systems to nutrition security and environmental sustainability. The American Journal of Clinical Nutrition, 101253. https://doi.org/10.1016/j.ajcnut.2026.101253
te Wierik, S., DeClerck, F., Beusen, A., Gerten, D., Maggi, F., Norberg, A., Noone, K., Schulte-Uebbing, L., Springmann, M., Tang, F. H. M., de Vries, W., van Vuuren, D., Vermeulen, S., & Rockström, J. (2025). Identifying the safe operating space for food systems. Nature Food. https://doi.org/10.1038/s43016-025-01252-6