Understanding the health impacts of local, culturally relevant diets will be critical to advancing precision nutrition across diverse populations in a sustainable way.

Dietary habits constitute one of the most important modifiable risk factors for the development of chronic illnesses such as heart and metabolic diseases. Evidence continues to accumulate indicating that changing one’s diet can prevent disease and promote healthy longevity. These studies, in particular randomized controlled trials (RCTs) evaluating the health effects of dietary interventions, provide essential evidence for guidelines in the prevention and treatment of noncommunicable diseases.

Their impact in the real world, however, is limited by the fact that most studies are designed to evaluate health-promoting diets that are based on dietary habits of the westernized world — for example, the Mediterranean and Nordic diets. Beyond Western Europe or North America, ingredients such as olive oil, fresh fish or almond nuts are not available, unaffordable or culturally irrelevant to many groups of people. It is time for researchers studying nutritional interventions to break out of the Western ‘bubble’ and start putting locally relevant, culturally acceptable diets at the center of their study design.

The importance of studying locally relevant diets is not limited to understanding their health benefits, but is also tied to the fact that diets and, by extension, food systems have an outsized impact on planetary health. That is because the way in which humans produce and consume food is estimated to be the third largest driver of environmental degradation1. Interestingly enough, consuming diets that are environmentally sustainable also leads to better health outcomes. For example, dietary patterns rich in plant-based foods are strongly associated with maintaining cognitive health and surviving to the age of 70 years2. These patterns include a planetary health diet based on the EAT initiative, which emphasizes both human health and a reduced environmental impact by focusing on plant-based foods. More studies are urgently needed to better understand the health and environmental benefits of nutritional interventions centered on environmentally sustainable diets

Rapid urbanization and economic growth are also pushing low-income, middle-income and developing countries to embrace unhealthy, westernized diets at the expense of traditional local dietary habits, which increases the challenge of creating a healthy and sustainable food environment. The consequences of this transition are still poorly understood, and RCTs that compare the health outcomes of local diets versus those of westernized diets are still rare. For example, a comparison between a Kilimanjaro heritage-style diet versus an unhealthy Western-style diet in healthy men in Northern Tanzania showed that the Western-like diet was associated with a systemic pro-inflammatory profile, while transitioning to the traditional diet had anti-inflammatory properties3, which underscores the importance of assessing the health effects of traditional eating patterns.

Studies on the health and environmental benefits of local healthy diets will also need to consider real-world implementation challenges, such as adherence to and the palatability and affordability of the intervention. For example, during a 6-month behavioral intervention that favored the Atlantic diet — which is common in northwestern Spain and Portugal — participant families had greater adherence to the Atlantic diet than that of families following their habitual diet4. The former also lost weight and had lower blood levels of cholesterol and low-density lipoprotein cholesterol. In another study, researchers examined not only the health effects but also the palatability and affordability of a Chinese heart-healthy diet5. Beyond its cardioprotective effect, the Chinese heart-healthy diet was well accepted by the study participants in terms of palatability and affordability. More studies such as these will be key to supporting the recommendation and implementation of healthy local and regional diets as interventions to improve health.

Lastly, developing a more diverse range of nutritional interventions is relevant not only from cultural or environmental perspectives but also because different populations across the world have different genetic makeups that may translate into differences in disease risk across ethnic groups. Studying how diets interact with the biological makeup across populations will inform the path toward advancing precision nutrition in an equitable way, while being mindful of the environmental footprint of the diets.

Moving forward, nutrition science will require crossing discipline boundaries. It will need to leverage cultural anthropology, public health, environmental science and community engagement. Research should focus on the relationship between diet and disease in diverse populations, ideally through RCTs, but also through cohort and longitudinal studies assessing the effects of traditional diets against those of modern dietary transitions. Studies of any type will require collaboration with local stakeholders to ensure cultural alignment in the design of nutritional interventions, and to understand the motivations and barriers for dietary change across cultures. Finally, there should be more focus on understanding which foods can be produced locally to integrate into a healthy diet, at a lower ecological and economic cost. By embracing this complexity, it is possible to move beyond ‘one size fits all’ dietary recommendations and support precision nutrition strategies that are health-promoting, culturally respectful and environmentally sound.