LCA Food 2012 in Saint Malo, France! - Manifestations et colloques ...

PARALLEL SESSION 4B: DIET 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
4. Discussion
4.1. Nutrient index scores
Nutrient indexes quantify an average share (%) of selected nutrients in 100 g of a product with reference
to the daily nutrient recommendation. Differences between results for nutrient indexes (Figure 1) highlight
the fact that it is crucial to decide which nutrients to include in the index. Vitamins from group B favour
meat products (scores of NNR15 and NAR15) while MUFA (monounsaturated fat acids) favours vegetable
oils (scores of NNR15).
It is also notable that the index with the lowest number of nutrients (NRF9) provides the most stable outcome.
Fulgoni and colleagues (2009) validated nutrient indexes, which contain different numbers of nutrients,
against the healthy eating index (HEI) in the USA. They established that index NRF9.3 correlated best
with the HEI. The index consists of nine recommended nutrients, as in this study for index NRF9, and three
nutrients to be limited, which are saturated fatty acids, added sugar and Na. In this study, the order of foods
would be dramatically different if the nutrients to be limited were included in the indexes. Olive oil, rainbow
trout, pork, light bread and sausage would lose ground most, while strawberry, orange, white cabbage, potato,
fortified soy drink, whole grain macaroni, fortified oat drink, skimmed milk, oatmeal and macaroni
would most clearly improve in their performance. The nutrients to limit have to be built into the nutrient
index before further application in the context of LCA.
It is also still questionable as to the most important recommended nutrients included in the indexes. For
example, unsaturated fatty acids and antioxidants are currently regarded as very important to our health.
Eventually, however, selection of nutrients depends on a selective approach. The approach of the indexes
considered in this study is to generate a general nutrient value for food, which is generally applicable to all
humans. Alternative approaches might be more culture dependent or even genotype dependent.
4.2. E/N index
The E/N index quantifies environmental impact of the nutrient index unit in a selected impact category.
The calculation is based on 100 g of product, but the E/N index value is independent of the amount of food.
The preliminary results should not be interpreted to represent an exact order for the foods considered.
General findings regarding the logic of the method can however be made. Environmental impact seems to
dominate the E/N index results to a small degree. An order of foods by climate impact does not change the
order of foods much by the NRF9 index value compared to the order of foods by the E/N index value (Table
2).
Plant-based products seem to maintain their environmental benefit compared with animal-based products
when nutrient content is taken into account in the study approach. However, some shifts occur within the
plant-based foods and within the animal-based foods. For example, fat-free yoghurt with jelly loses to natural
(2.5%) yoghurt in E/N ranking, but not in the ranking by CO2 eq. This kind of comparison might be clearer if
the index were more sensitive to differences between product croups (and using better defined data). This
idea takes us back to the start; would this kind of general nutrient index provide the information that would
take account of the nutritional function of food so that it would help consumers choose more sustainable food
products? I would say, probably not in the best possible manner, but product-category-specific indexes (and
more specific data) may be needed. This is most obvious when vegetable oils are compared with other products
and each other. Both olive oil and rapeseed oil act quite unexpectedly in the calculations. There are two
main factors behind this: 1) typical portion size differs considerably from other foods studied here and 2)
exceptional nutrient composition. These kinds of feature could be taken into account in a product-groupspecific
index. Also Fulgoni and colleagues (2009) proposed that development of a nutrient index within a
product group should be examined. The problem still is how to define the product groups.
5. Conclusion
The study provides an interesting new approach and methodological framework for linking food’s nutritional
function to food LCA. Nutrient indexes are worth using, but before practical applications are possible,
nutrient composition of the nutrient indexes should be evaluated against current nutritional science and nutritional
requirements of consumers. There might be a need for a newly composed nutritional index, and its
product-group-specific applications. Definition of product groups should be based on a manner to use foods,
not on, for example, raw material base of foods. Nutrients to be limited have to be incorporated to the index,
but not in the way that they are in the current indexes. And last but not least, more specific data should be
used in the practical calculations. The target should be to use production-chain-specific data.
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