Just Read: Nutritional and greenhouse gas impacts of removing animals from US agriculture

GHG emissions associated with food production with animals eliminated in the US 225
GHG emissions associated with food production with animals eliminated in the US 225 (View on Flickr.com)

GHG emissions associated with food production in a system representative of the current United States and a modeled system in which animal-derived food inputs are eliminated.

Nutritional and greenhouse gas impacts of removing animals from US agriculture 224
Nutritional and greenhouse gas impacts of removing animals from US agriculture 224 (View on Flickr.com)

Total HRYs (Human Requirement Years) produced in 2013-based US food production systems with actual animal-derived food inputs or modeled without animal-derived food inputs (plants-only). The gray vertical rectangle indicates the number of HRYs needed to meet requirements of the US population. Grayed boxes indicate HRY production inadequate to meet US population requirements. Energy and protein HRYs required for pets were subtracted from the plants-only diet.

Cite: White RR, Hall MB. Nutritional and greenhouse gas impacts of removing animals from US agriculture. Proc Natl Acad Sci [Internet]. 2017 Nov 28;114(48):E10301–8. Available from http://www.pnas.org/lookup/doi/10.1073/pnas.1707322114

Images @CreativeCommons licensed

This study, published in November, 2017, is authored by scientists at Virginia Tech and the US Department of Agriculture, and models a food production scenario in the United States that eliminates animals.

This view is interesting because it requires several assumptions to be made, which the authors list:

Assumptions when animals are removed from US agriculture included:

  1. grain previously consumed by animals will be available for human consumption;
  2. tillable land previously used for hay, green chop, and silage production, and tillable pasture and grazing land will be used for human food production directly;
  3. the nutrients from animal products previously provided to humans will no longer be available for human consumption;
  4. GHGs from livestock production will no longer occur;
  5. a large amount of feed processing byproducts pre- viously consumed by animals will need to be disposed of;
  6. N, P, K, and S fertilizer previously sourced from manure will need to be synthesized;
  7. animal production byproducts previously available for pet food production will need to be replaced with plant nutrients;
  8. humans can and will consume soy flour with no negative health impacts.

Number 7 above is not trivial as pointed out by the authors – humans have special bonds with animals as pets and they will need to be fed, too. Number 8 is potentially problematic for many reasons.

Greenhouse Gas Emissions reduction from elimination of animals from US Agriculture

Put together, the greenhouse gas emissions from removing animals from US agriculture is less than expected – 28% less GHG emissions compared to 49% less GHG emissions previously modeled. With 9% of US GHG emissions coming from agriculture, this translates into 2.6% less GHG emissions for the United States if the country went completely plant based.

Health effects from elimination of animals from US Agriculture

What could come with that would be some untoward health effects:

The challenges in meeting essential vitamin, mineral, and fatty acid requirements in plant-based diets are supported by previous works. It is entirely possible to meet the nutrient requirements of individual humans with carefully crafted, unsupplemented plant- based rations, but this can be a challenge to achieve in practice for an entire population.

What is not modeled in this study is the impact of moving Americans to an even higher carbohydrate diet than they are on today, which is what the current recommendation is, even though it doesn’t have evidence to support it.

In the scenarios presented, 78 – 85% of food comes from grains. The impact of health care on the US GHG footprint is similar to agriculture, about 10%, so that could increase with increased prevalence of diabetes in the US Population (modeled to between 21% to 33% by 2050 – not incidence, prevalence).

Climate change is a threat

  • Climate change is a risk to human health.
  • Climate change increases disparities because it disproportionally affects vulnerable populations.
  • Diversity allows the human species to survive 🙂

I am interested in reconciling human health and the health of the planet and realize that it’s possible that alignment between the two is more nuanced than I previously thought. A look at the Altmetric page of this study shows the challenge – the news presented the pieces refer to yet another study which I reviewed and will post on next. That study also contains assumptions about diet that may no longer be current.

The desire to know

Copying from this previous post (Just Read: Alzheimer’s Disease Is Type 3 Diabetes—Evidence Reviewed).

What I find the physicians in this field have in common is that they want to know what’s best for health, even at the cost of challenging their own long-held beliefs (Just Read: Diet: Less a Debate, More an Interest to Know What a Healthy Diet Is).

I mentioned in one of my first posts on the topic how I strove to adhere to the low fat diet mandated for humans when I began my medical career, even though our own pathology textbook curiously listed “high carbohydrate diets” as a risk factor for heart disease. I didn’t follow-up then, but I’m following up now, and I thank other physicians for doing the same.

What’s new for me since that post is that I now see the correlations to my work to support LGBTQ communities as I work to understand LCHF communities. There is one, I discovered, and it’s about listening. Posting on that soon as well.

Comments welcome as always.

2017.12.12 Sustainable Diet, Washington, DC USA 1359
What’s better for human health, the products in the foreground, or the products in the background? | 2017.12.12 Sustainable Diet, Washington, DC USA 1359 (View on Flickr.com)

Citation: White RR, Hall MB. Nutritional and greenhouse gas impacts of removing animals from US agriculture. Proc Natl Acad Sci [Internet]. 2017 Nov 28;114(48):E10301–8. Available from: http://www.pnas.org/lookup/doi/10.1073/pnas.1707322114

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