29 Mar The true cost of food
Many researchers have proposed scores and methods for reducing the nutritional value of foods down to a single number – as covered in a recent Thought for Food. A new method takes an approach rooted in population dietary intakes.
There are many challenges to this: which nutrients to include? How to weight components without introducing bias? A recent paper has avoided these issues by including all nutrients in the Australia and New Zealand Nutrient Reference Values, weighted by the degree to which the Australian population under- or overconsumes them.
The NRF-ai metric (Nutrient-Rich Food Index – adequate intake) means that foods containing under consumed nutrients like calcium, magnesium, vitamin B6 and zinc will receive higher scores than those containing the same amount of vitamin C or phosphorus, which are consumed at adequate levels by most of the population. Conversely, foods containing free sugars will be penalised, as intake of these is above recommendations in most populations.
The score can be made specific to age and gender groups, as the prevalence of deficiency for each nutrient varies between these groups. Ultimately, this leads to a metric that ranks a food item on its ability to address the nutritional needs of the population.
There are many applications for this metric for comparing foods. In the paper, the author considers the score per $ retail price, to understand the cost-effectiveness of a food for meeting nutritional needs. Per environmental impact examples are also given.
NRF-ai represents an unbiased approach to reducing the nutritional value of a food down to a single number. While this approach still loses information compared to the full nutritional composition, it is still valuable for comparisons between like products. A similar approach is applied by the DELTA Model® for the nutritional value of food items for meeting global nutrient requirements.