Food production is among the largest drivers of climate change, due to its contributions to greenhouse gases, biodiversity loss, and freshwater use. Some foods have a lower environmental cost than others, however; there is evidence that plant-based diets might benefit both our planet (by reducing cropland use and greenhouse-gas emissions) and our health (by reducing mortality rates from noncommunicable diseases).
While public-health recommendations generally focus on dietary patterns, can specific foods affect mortality or environmental outcomes?
This study assessed dietary recall data from participants in the What We Eat in America 2011–2016 database, assigning 167 common foods a health nutritional index (HENI) score, which quantified the minutes of healthy life gained or lost (from all-cause premature mortality and morbidity) per serving of food consumed. In addition, life-cycle assessments were used to quantify the environmental burden associated with the most consumed HENI foods.
A life-cycle assessment considers all aspects of human health and natural resources to estimate a product’s potential environmental effects throughout its “life cycle” — from raw-material acquisition and transformation, to product usage, to waste management. This assessement has four phases:
Goal and scope: How much of a product’s life cycle is assessed and the reasons for completing the assessment
Life-cycle inventory: The material and energy flows within the product system, focusing on the raw materials consumed and various interactions with the environment
Impact assessment: The magnitude and significance of the environmental effects of the product system, based on the findings of the life-cycle inventory
Interpretation: Conclusions and practical recommendations
Of all the included foods, a beef hotdog in a bun was associated with the greatest loss of life per serving (−36 minutes), whereas a peanut-butter-and-jelly sandwich was associated with the greatest extension of life per serving (+33 minutes). Scores for burgers, red meat, and breakfast sandwiches were almost always negative (they decreased lifespan), whereas scores for seafood, fruits, legumes, nonstarchy vegetables, ready-to-eat cereals, and snack bars were positive (they increased lifespan).
The authors then divided foods between green, amber, and red zones, based on their effects on mortality and the environment:
Foods in the green zone (foods made out of nuts, fruits, legumes, vegetables, whole grains, and some seafood) had a positive HENI score and were below the 50th percentile for CO2 emissions.
Foods in the amber zone (most poultry, dairy products, egg-based foods, cooked grains, and vegetables produced in a greenhouse) had a HENI score between 0 and −3.2 minutes and were between the 50th and 75th percentiles for CO2 emissions.
Foods in the red zone had either a HENI score lower than −3.2 minutes (processed meats and sugar-sweetened beverages) or were above the 75th percentile for CO2 emissions (beef, pork, lamb, processed meat, cheese-based foods, and some salmon dishes).
The authors calculated HENI scores for the included foods based on the presence or absence of 16 dietary factors in a given food.
The following factors in a food improved its HENI score (they added minutes of healthy life):
Seafood omega−3 fats
Nuts and seeds
Conversely, the following factors in a food worsened its HENI score (they removed minutes of healthy life):
Trans fatty acids
It’s unsurprising that a hotdog on a bun would have the worst HENI score after sugar-sweetened beverages’ — it’s high in sodium and saturated fat, its meat is both red and processed, and it’s devoid of most of the factors that improve HENI scores.
While well-intentioned, this classification of nutrients and food groups as “good” or “bad” is simplistic. For example, sodium isn’t inherently unhealthy; it’s an essential electrolyte. Similarly, the health effects of saturated fatty acids (SFAs) depend on the type of SFA and the food source.
Additionally, the authors did not intend for the HENI scores to be taken literally — eating a hotdog will not literally take 36 minutes off your life. Instead, the authors intended the HENI scores to be used to compare foods in a format the average consumer would find easy to understand.
The big picture: While other dietary indices — such as the Dietary Approaches to Stop Hypertension (DASH) score, the Dietary Inflammatory Index (DII), the Healthy Eating Index (HEI), and the Alternate Healthy Eating Index (AHEI) — have shown relevancy in predicting health outcomes, they serve to assess dietary patterns, rather than individual foods, limiting their utility for consumers.
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