Dietary Decisions: Part 2 - Lettuce is Worse Than Bacon!?

Source: www.cohabitaire.com

I cannot lie, and say that I haven’t found writing this post incredibly difficult! First of all, reaching a scientific consensus was a bit of a challenge, with many conflicting opinions and interests on the issue, and many studies only focusing on certain impacts (direct emissions, land-use, etc.). You begin to wonder who you can really trust. Despite this, after many days of research, I finally felt that I had reached a solid understanding of the literature and concluded that plant-based diets are the clear winners when it comes to the environment (as is often echoed). "Yay!", I thought, now I can commence the writing process... However, literally minutes before my fingers hit the keyboard, I come across this article boldly claiming “Lettuce is ‘three times worse than bacon’ for emissions and vegetarian diets could be bad for the environment”. Sensationalist to the max, I know, but I couldn’t help getting caught up in the drama and feeling like my many hours of research were nothing but a complete waste of time and effort. Luckily, I manage to trundle through the article and associated research paper, and deduce that the conclusion was based upon dietary recommendations, not vegetarian diets, and that it was totally twisted out of context. Not to mention that lettuce is very water and carbon intensive as vegetables go. So, finally, I manage to regain my confidence and comprehension.. And then, BAM! I realise that, although I don’t eat a great deal of meat, sometimes I really love beef burgers, cheese and bacon, and I start to feel the need to totally reassess my life and values…

But, fear not! All hope is not lost for the meat enthusiasts… If you dare to read further, you may find some surprising (and some not so surprising) results.

An Emissions-Based Approach

The most common measure of climate impact within the food industry is the amount of direct greenhouse gas emissions produced, equivalent to the mass of CO₂. This excludes any emissions produced by land use, deforestation, transportation, cooking, storage, etc.

My research began through the investigation of five American diets – Meat Lover, Average, No Beef, Vegetarian, and Vegan – compiled by the USDA’s Economic Research Service and adapted by Shrink That Footprint, inferring a consumption of approximately 2,600kcal per day.

Source: Shrink That Footprint

Unsurprisingly, the results showed that GHG emissions escalated with increased meat consumption, with vegans at the low end of the scale, and meat lovers at the other. Interestingly, vegetarianism did not fall too short behind veganism, despite the vast proportion of animal products consumed by vegetarians coming from dairy cows – which are shown here (and in my previous blog post) to contribute massively to potent greenhouse gas emissions. An even more surprising finding is that simply omitting red meat from the diet has a drastic reduction in carbon footprint, and contributes to a similar measure of emissions compared to vegetarianism. It seems maybe we should consider ending our romanticism with beef and lamb, and rediscover our love for white meats (or none at all). The research concluded that, in the average American diet, 60% of emissions were produced by meat and dairy, although only equating to 25% of the energy in the diet.

Source: Shrink That Footprint

However, plant-based diets aren’t totally off the hook, as fruit is shown to be the second most carbon intensive food group measured for direct emissions, likely due to the high volume of fruit that becomes waste and is often grown out of season. Although, with that being said, this still only contributes to a third of the average emissions produced by ruminant animals, and is almost identical to the amount produced by dairy. Additionally, meat eaters still eat 80+kcal of fruit on average, reinforcing that this is not just the responsibility of herbivores!

Source: Hallstrom et al., 2015

It cannot be ignored that this study does carry limitations, particularly as it only takes into account American dietary habits and fails to include the amount of studies it includes. Despite this, the findings are supported by another paper, conducted by Hallström et al., 2015, which compiles together twelve independent studies, between 2009 and 2014, looking at the emissions produced by various diets. This report confirmed that vegan, vegetarian and diets without red meat contributed to the lowest amount of greenhouse gas emissions, with a reduction of approximately 20 to 55% in total. However, interestingly, a moderate reduction of about 20% of average meat intake had an insignificant effect, due to the common replacement of meat with equally highly carbon intensive food groups, such as dairy, and out of season and imported fruit and vegetables. It is abundantly clear from the evidence that meat derived from ruminant animals is the main driving force that causes devastation to the environment in terms of greenhouse gas emissions.

An additional component of this study was the inclusion of the “healthy” diet, characterised by an omnivorous palette, abiding by an array of different dietary guidelines. The reduction of emissions were highly variable (between 0 to 35%) with nine out of fifteen studies closer to a 10% reduction or less. The definition of a healthy diet was very loosely described, and is therefore difficult to take seriously into consideration.

Land-Use Contribution

Within the same paper, the impact of diets on land-use were also examined, compiling evidence from four separate studies which compared the diets of vegans, vegetarians, meat partially replaced by plant-based food and healthy diet with an average meat-eating diet. Again, the results deduced that ruminant livestock farming was the main driver of land-use change in agriculture.

The current availability of agricultural land globally per capita is estimated to be 7000m². As developing countries continue to grow economically, and Western countries continue to indulge, the global average per capita land demand is set to reach a whopping 5000m² by 2050. This will begin to put a serious strain on humanity, as we edge closer toward a self-inflicted carrying capacity. However, if the consumption of red meat can be reduced through any of the dietary scenarios investigated, it is predicted that the land demand could potentially reduce to between 2200 to 3500 m². This could significantly reduce environmental damage caused by land-use change, reduce deadly climate change, and allow us to continue expanding our population more freely.

Source: Hallstrom et al., 2015

How much of an impact do these diets appear to have? Replacing all food products from animals with plant-based alternatives, i.e. veganism, on average, decreases the land demand by 60% compared to an average meat-eating diet. Fascinatingly, a substitution of 75% of red meat with poultry or pork has the potential to reduce the land demand by 40%. Whereas, contrarily, substituting half of monogastric meat consumption with plant-based food has little effect, with an estimated 5% reduction on land demand. Therefore, it is apparent that pork and poultry have fairly similar demands on land-use to plant-based foods.

There are, unarguably, some uncertainties within these studies, due to individual differences and the difficulty in accurately modelling certain processes, such as predicting the emissions produced by ruminant animals and soils, variability in socioeconomic status, geographical location, temporal variability, gender and age. Despite this, the results overall consistently reach the same conclusion, that plant-based diets are generally kinder to the environment.

Alternative Diets

So, “what about all those other diets that haven’t been included in the context of this study?” I hear you say. Let’s take a look at a few of these individually!

Paleo Diet

If you are unaware, the so-called “paleo” or “paleolithic” diet is based upon the perception of what our early, nomadic ancestors, who once foraged and hunted for their food, used to eat. (If you’ve forgotten about our hunter-gatherer friends, you can check out my blog post about it here). This relatively new diet consists of largely meat, fish, nuts, berries and vegetables, with no grains, dairy, sugar, legumes or alcohol allowed - encouraging a high protein, low carbohydrate diet. It is shown that eating food of this nature on a regular basis puts unnecessary strain on the body and can lead to serious health problems, such as, heart disease, renal failure, high cholesterol and cancer.

Source: www.blakebeckford.co.uk

To not forget that the high meat content within the diet (which particularly focuses on red meat) puts mass pressure on the environment through increased greenhouse gas emissions and land-use change, as discussed above. This makes the paleo diet a poor contender for being environmentally friendly, as well as for sustaining a healthy lifestyle.

Additionally, the diet has been heavily criticised as the circumstances in which animals are bred within modern agriculture are not representative of the wild animals hunted thousands years ago. For example, today livestock are fed with high-protein and high carb feed, alongside an abundance of antibiotics, which contradicts the “healthy” and grain-less demure of the paleolithic diet.

Raw Diet

Source: http://rawgourmets.com

Another diet which claims to be the best for health and the environment is the raw food diet, consisting of purely uncooked and unprocessed ingredients. This diet is relatively variable as some continue to eat raw meat and dairy, while others maintain vegan or vegetarian diets as well. Regardless, the main argument for raw foodism is that recipients believe that they’re acquiring all the nutrients available within their food, as they are not “destroying” them by cooking. However, contrary to popular belief, cooking food aids digestion and allows our bodies to access more nutrients, compared to raw ingredients. It is common for women to stop ovulating due to the lack of nutrients being absorbed, despite them being abundantly available within the food. This is no surprise when we acknowledge the fact that civilisations expanded greatly after the discovery of fire, due to prevalence of cooked food, which continues to be a central element of almost all cultures in modern day.

However, from an environmental standpoint, raw food does reduce the emissions caused by cooking, processing and packaging food. Despite this, the ingredients needed to sustain such a diet may be more resource and carbon intensive, due to the high consumption of fruit, and out of season produce, which potentially puts additional strain on the environment compared to other diets.

Top Tips for a Healthy and Environmentally Friendly Diet

1.      Reduce red meat intake to a minimum, preferably omit completely
2.      Purchase seasonal and local produce
3.      If you wish to consume monogastric meat, elect for grass-fed or pasture-raised
4.      If you wish to consume fish, stick to sustainably sourced
5.      Reduce food waste – waste not, want not!
6.      Buy certified organic produce
7.      Consider reducing your dairy intake
8.      Try composting
9.      Only eat as much as you need!!

Source: https://extraportionnatur.files.wordpress.com/