To define a generic diet to protect human health and food system sustainability based on three dimensions: animal:plant ratio, degree of food processing and food diversity.

The percentages of maximum animal and ultra-processed energy content were evaluated from scientific papers (Web of Science database) and reports from international scientific institutions. Then, a weekly French standard diet, including these percentages and food diversity (≥42 different foods), was designed to calculate adequacy to nutritional needs.

Based on traditional and scientifically based healthy diets, and on foresight scenarios for sustainable diets at horizon 2050, a median daily animal energy content intake of 15 % was found to be protective towards both human health and environment. Based on epidemiological studies associating ultra-processed energy consumption with increased overweight/obesity risk, a precautionary threshold of approximately 15 % ultra-processed energy content was observed. The French diet allows addressing all nutritional needs and other nutritional indicators such as maximum salt and simple sugar consumption, α-linolenic acid:linoleic acid ratio and essential amino acids. This diet was named the ‘3V rule’ for Végétal (plant), Vrai (real) and Varié (varied, if possible organic, local and seasonal). This generic diet can be adapted according to regional traditions and environmental characteristics. Excluding only one dimension of it would threaten both health and food system sustainability.

Tending towards a 3V-based diet, while respecting local constraints, should allow preserving human health, environment (greenhouse gas emissions, pollution, deforestation, etc.), small farmers, animal welfare and biodiversity, culinary traditions and socioeconomics (including an alleviation of public health cost).

To assess public health nutrition practice within the public health system in Ontario, Canada to identify provincial-wide needs for scientific and technical support.

A qualitative descriptive study was conducted to identify activities, strengths, challenges and opportunities in public health nutrition practice using semi-structured key informant interviews (n 21) and focus groups (n 10). Recorded notes were analysed concurrently with data generation using content analysis. System needs were prioritised through a survey.

Public health units.

Eighty-nine practitioners, managers, directors, medical officers of health, researchers and other stakeholders were purposively recruited through snowball and extreme case sampling.

Five themes were generated: (i) current public health nutrition practice was broad, complex, in transition and collaborative; (ii) data/evidence/research relevant to public health needs were insufficiently available and accessible; (iii) the amount and specificity of guidance/leadership was perceived to be mismatched with strong evidence that diet is a risk factor for poor health; (iv) resources/capacity were varied but insufficient and (v) understanding of nutrition expertise in public health among colleagues, leadership and other organisations can be improved. Top ranked needs were increased understanding, visibility and prioritisation of healthy eating and food environments; improved access to data and evidence; improved collaboration and coordination; and increased alignment of activities and goals.

Collective capacity in the public health nutrition can be improved through strategic system-wide capacity-building interventions. Research is needed to explore how improvements in data, evidence and local contexts can bridge research and practice to effectively and efficiently improve population diets and health.