Table 1 Description of selected indicators and calculation of the total sustainable diet index-US and sub-index scores

Sub-index

Measure^a

Relationship with sustainable diets^a

Indicators in the sub-index

Points allocating

Assessment

Nutritional (/5)

Dietary diversity index

Diet diversity with nutrient adequacy is essential to avoid malnutrition and negative health outcomes.

1–1) Nutrient-Rich Foods9.3 Index^b

1-point: ind ≤ 4.1

2-point: 4.1 < ind ≤ 10.6

3-point: 10.6 < ind ≤ 18.2

4-point: 18.2 < ind ≤ 30.5

5-point: ind > 30.5

Nutrition sub-index=

the sum of points from indicator 1–1 to 1–2 × 1/2

Micronutrient (vitamins and minerals) deficiencies

1–2) Mean Nutrient Adequacy Ratio^c

1-point: ind ≤ 60.2

2-point: 60.2 < ind ≤ 68.1

3-point: 68.1 < ind ≤ 74.2

4-point: 74.2 < ind ≤ 80.5

5-point: ind > 80.5

Environmental (/5)

Water footprint

Clean water resource is becoming scarce in zones.

2 − 1) Freshwater withdrawals (L) per serving food^d

1-point: ind > 549.9

2-point: 377.1 < ind ≤ 549.9

3-point: 263.7 < ind ≤ 377.1

4-point: 161.5 < ind ≤ 263.7

5-point: ind ≤ 161.4

Environment sub-index=

the sum of points from indicator 2 − 1 to 2–6 × 1/6

2–2) Stress-weighted water use (L) per serving food^d

1-point: ind > 18,475

2-point: 12,806 < ind ≤ 18,475

3-point: 9079 < ind ≤ 12,806

4-point: 5601 < ind ≤ 9079

5-point: ind ≤ 5601

Nitrogen footprint

Nitrogen balance is essential to avoid eutrophication

and harmful algae blooms.

2–3) Acidifying emissions (g SO₂eq, CML2 baseline) per serving food^d

1-point: ind > 34.4

2-point: 22.6 < ind ≤ 34.4

3-point: 15.4 < ind ≤ 22.6

4-point: 9.3 < ind ≤ 15.4

5-point: ind ≤ 9.3

2–4) Eutrophying emissions (g PO₄³⁻eq, CML2 Baseline) per serving food^d

1-point: ind > 28.0

2-point: 16.3 < ind ≤ 28.0

3-point: 10.2 < ind ≤ 16.3

4-point: 6.1 < ind ≤ 10.2

5-point: ind ≤ 6.1

Carbon footprint

Anthropogenic greenhouse gas emissions contribute to climate change.

2–5) Greenhouse gas emissions (kg CO₂eq, IPCC 2013 includes feedbacks) per serving food^d

1-point: ind > 5.8

2-point: 3.4 < ind ≤ 5.8

3-point: 2.2 < ind ≤ 3.4

4-point: 1.4 < ind ≤ 2.2

5-point: ind ≤ 1.4

Land use

The availability of arable land is limited; moreover, land use change impacts the biodiversity preservation.

2–6) Land use (m²) per serving food^d

1-point: ind > 13.0

2-point: 5.9 < ind ≤ 13.0

3-point: 3.7 < ind ≤ 5.9

4-point: 2.1 < ind ≤ 3.7

5-point: ind ≤ 2.1

Economic (/5)

Affordability

Healthy diet should be available at affordable prices to all, specifically to low-income consumers.

3) Proportion of income devoted to diet

1-point: ind > 34.1

2-point: 20.0 < ind ≤ 34.1

3-point: 13.3 < ind ≤ 20.0

4-point: 9.0 < ind ≤ 13.3

5-point: ind ≤ 9.0

Economic sub-index=

the sum of points × 1

Sociocultural (/5)

Ready-made products

The use of ready-made products minimizes cooking activities and thus limit the opportunity for social exchange, cultural

heritage preservation and trying diverse recipes.

4 − 1) Frequency of meals not home prepared and from a fast-food or pizza place

1-point: ind > 4

2-point: 2 < ind ≤ 4

3-point: 1 < ind ≤ 2

4-point: 0 < ind ≤ 1

5-point: ind = 0

Sociocultural sub-index=

the sum of points from indicator 4 − 1 to 4 − 3 × 1/3

4 − 2) Frequency of ready-to-eat products

1-point: ind > 5

2-point: 3 < ind ≤ 5

3-point: 1 < ind ≤ 3

4-point: 0 < ind ≤ 1

5-point: ind = 0

4 − 3) Frequency of frozen meals/pizza

1-point: ind > 7

2-point: 3 < ind ≤ 7

3-point: 2 < ind ≤ 3

4-point: 0 < ind ≤ 2

5-point: ind = 0

Total SDI-US = nutritional + environmental + economic + sociocultural (range: 4–20)