A Counter To ‘Plant-Based Junk Food Is Bad News For The Planet’
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Editor’s Note: This piece came about because Dan commented on a Linkedin post about our original article. We appreciated his insights so we invited him to write this piece to share his thoughts.
I am writing this rebuttal in response to the recent article “Our Junk Food Addiction Is Bad News For The Planet, Study Finds” and the publication by Musicus et al, which the article references. I want to contest some of the statements made in the article, starting with the title and the associated cover figure of the news article, which incorrectly associates plant-based meat with adverse environmental and health impacts.
The goal of the recent study by Musicus et al. was to determine health and environmental impact as a function of diet, from a longitudinal prospective study. One-hundred fifty foods were included in the survey, and the authors split a subset of these foods into different categories, according to four established health indices – the alternative healthy eating index-2010 (AHEI), plant-based diet index (PDI), unhealthy PDI, and healthy PDI. For each index, study participants were split into five groups of equal size (quintiles) based on their score – i.e., the first quintile is the 20% of participants with the lowest scores, the fifth quintile is the 20% of participants with the highest scores. Then for each group/quintile, the authors calculated some environmental and health impacts.
Before looking at how the different subgroups compare, it’s worth looking at the sum of the data first. Across all participants in the survey, animal-derived products account for the vast majority of environmental impact. For instance, red and processed meat accounts for 31% of greenhouse gas contributions and 59% of cropland needs. If we group the categories into animal, healthy plant-based (vegetable, fruit, tea and coffee, legumes, nuts, whole grains, vegetable oils) and unhealthy plant-based (fruit juice, sweets, sugar-sweetened beverages, refined grains), the overall contributions are largest for animal foods by a wide margin. For instance, 78% of greenhouse gas emissions and 88% of cropland needs are accounted for by animal foods (including “other foods”, which are largely animal-derived).
Because the environmental impact of animal products, particularly red and processed meat, is so large, variation in their consumption drives most of the differences across the diet indices, including the plant ones. For instance for AHEI, the decrease in red meat consumption was by far the largest difference in environmental impact between the first and fifth quintiles (the data for other diets is not presented in the paper). Red and processed meat, not plant foods, also explains the modest differences in environmental impact comparing the 1st and 5th quintiles of the unhealthy PDI.
The authors gauged healthiness by comparing the relative risk of cardiovascular disease in study participants across each dietary index. As presented in Table 1, the relative risk of cardiovascular disease decreases monotonically across the quintiles for AHEI, PDI and healthy PDI and the three indices are basically indistinguishable in terms of relative risk of cardiovascular disease (note however, that the plot of these data in Supplemental Figure 1 does not match the data presented in Table 1!). As noted by the authors “Reduced red and processed meat consumption was the largest contributor to these observed beneficial effects”.
In contrast, there is a modest increase in the risk of cardiovascular disease for those with a diet disproportionately high in unhealthy plant-based foods, which is why the authors write “whereas healthy plant-based patterns were associated with indicators of better human and environmental health, including significantly reduced cardiovascular disease risk; greenhouse gas emissions; and use of cropland, irrigation water, and fertiliser; unhealthy plant-based patterns were associated with adverse human and environmental health effects, including significantly increased cardiovascular disease risk and use of cropland and fertiliser.” We already covered that the environmental impact of those in the 5th quintile of unhealthy PDI is driven by differences in red and processed meat. The specific foods contributing to the moderate health effects are not probed in the paper (and the authors informed me that said data is not available). But based on Supplemental Figure 3, the categories with the biggest increases in consumption are red and processed meat, sweets and sugar-sweetened beverages, all of which are linked to cardiovascular disease when consumed in excess. So rather than emphasizing that not all plant-based diets are equal, I think a better takeaway is that excess sweets and sugar-sweetened beverages can offset some of the health benefits of a plant-based diet.
But what about the environmental and health impacts of plant-based meat and dairy? The food survey started over 30 years ago and so has limited inclusion of plant-based meat and dairy. Under “vegetables”, there is a category “Tofu, soy burger, soybeans, miso or other soy protein.” However, no plant-based meat or dairy are included in the PDI scoring system, so this study does not directly address the relative environmental or health impacts of plant-based meat and dairy products.
While plant-based meat and dairy foods were not included in this study, we can apply the same approach to assess environmental impact. For instance, Impossible Foods (my employer) performed a life cycle assessment comparing the potential environmental impacts of an Impossible Burger and conventional, industrially-reared ground beef burger from farm field to manufacturing gate. Producing an Impossible Burger took 10X fewer greenhouse gas emissions and 20X less cropland than a ground beef burger. Likely, these dramatic differences broadly apply to plant-based meats and dairy.
But what about the health impacts of plant-based meat and dairy? Unlike environmental impact, there is not a simple categorical answer. One, there is tremendous variation among these products (e.g., soy milk vs. almond milk). Two, health benefits depend on what you are comparing them to (e.g., broccoli vs. a hamburger) and are influenced by the other foods you eat (e.g., burger with salad and water vs burger with french fries and a soda). Third, the metrics by which nutrition and health benefits are assessed are generally rudimentary (and often wrong) – e.g., the degree of “processing” has a negative health connotation and is considered in current nutrition guidelines, but has little to no correlation with actual micro- and macronutrient content.
We can at least compare nutrition profiles of plant-based replacements and their animal counterparts. Compared to an industrial ground beef burger, the Impossible Burger macronutrient content is purposely similar, with matching protein quantity and quality, and similar total fat. Both burgers have high levels of heme iron, which is absorbed much better than non-heme iron. The Impossible Burger has 20% less saturated fat than the beef burger and does not contain cholesterol. Saturated fat and cholesterol intake have repeatedly been linked to negative health outcomes, in particular cardiovascular disorders. Micronutrient content is pretty similar too, but with the Impossible Burger having higher levels of several vitamins and minerals. Impossible Burger has some fiber, whereas ground beef has none. The Impossible Burger also has a modest amount of sodium (~1/6th of daily recommendation). All in all, the nutrition profile of the Impossible Burger is superior to its animal counterpart.
More sophisticated health comparisons are now emerging. For instance, a recent randomized crossover clinical trial showed that replacing animal burgers with Beyond Meat burgers led to improved cardiovascular disease risk factors.
In addition to nutrition content, we should consider (and emphasize) the many indirect positive impacts on population health from replacing animal products with plant-based counterparts. Without a doubt, animal agriculture is the most destructive practice in the history of the planet. Animals in the food system are the primary drivers of climate catastrophe and biodiversity collapse, which have profound indirect effects on health and life quality everywhere. Additionally, animals in the food system contribute to widespread antibiotic resistance and are the driver of most zoonotic diseases.
In conclusion: as a general good rule of thumb, the best diet for you and the planet is one rich in plant foods, which can include plant-based meats and dairy, and low in animal products and junk food.
About the author: Dan Hogan is a Research Fellow at Impossible Foods developing transformative protein technologies for plant-based foods. Prior to joining Impossible Foods in 2020, he led the bioinformatics and core technology groups at Tocagen Inc, which utilized retroviral gene therapies for cancer treatment. He earned his PhD in Biochemistry from Stanford University.