There are a number of different ways to assess the most eco friendly, sustainable and ethical foods and food diet types.
There are different indicators and measurements that can be used, so, it’s something that can be very subjective.
In this guide, we explore those different indicators and measurements, to get a general idea of which foods and food diet types might be best overall.
*NOTE: this is a general information guide only. It is not professional advice. See a health professional before make changes to your health or diet.
Summary – Most Sustainable, Eco Friendly & Ethical Foods & Food Diet Types
Sustainable can take into account a range of indicators, but, generally includes food that makes efficient use of resources, doesn’t degrade the environment, and is sustainable economically.
Some types of wild caught food might fit this criteria (like pole caught fish from land as opposed to large scale bottom trawling caught seafood for example), some plant based foods might (as long as they aren’t wasted at a high rate at the consumer level), whilst some types of organically or sustainably farmed foods might as well (with a focus on using rainfed farming, preserving soil health and soil structure, and so on).
Smaller farmed animals like chickens might be more sustainable over larger ruminants like cattle according to some measurements.
Foods that are land efficient, and minimize their use of irrigated water, and synthetic fertilizers and pesticides might be generally seen as sustainable too.
Economically – heavier resource use might not be a bad thing if the agricultural activity creates incomes, employment and livelihoods for local people – so, socio impact must be looked at too, as well as that an agricultural practice actually provides a profit for the farmer.
Heavier resource usage may also not be as much of an issue if it comes from abundant or renewable resources (like rainfed crops, or sustainably managed water sources)
Foods coming from sustainable farming practices and systems might be more sustainable than those coming from an industrial or conventional farming system in some instances
Some food production types like farmed fish and aquaculture can vary with their sustainability footprint, depending on the variables in the farming process. As just one example, some types of farmed kelp can be reasonable sustainable
Most Eco Friendly
Foods that minimize pollution (air, water, land/soil), environmental degradation (carbon footprint for example), and waste (especially toxic or highly hazardous waste), might be the most eco friendly foods.
Beef is often a food that is referenced as having a higher water, land and carbon footprint relative to other foods.
Animal meats in general may have higher eco footprints.
Some plant based foods can have lower eco footprints in some ways, but may use higher amounts of synthetic pesticides and fertilizers (and, some plant based foods like rice can have large carbon footprints per calorie produced).
They may also use more energy in instances such as being grown in a greenhouse that uses electricity for lighting or heating.
Perhaps the most eco friendly food is wild caught food from plant based food that grows naturally in the wild, or from populations of animals that are either over populated or have little pressure on their population numbers (or from a pest, invasive or other problem species).
Food from a sustainably grown farm that uses mostly natural farming processes and materials (such as organic fertilizer and natural pest control), grows food with a lower eco footprint, might also be most eco friendly.
This is completely based on the individual ethics, morals, values and beliefs of the individual person.
Some people for example might have the value system that all animal based foods are unethical, and stick strictly to a plant based diet.
Lab grown meat is an interesting example of ethics in food production.
Lab grown meat, while not requiring direct farming, still needs body tissue from animals in order to produce it
*Note – the above are broad generalizations, and a guide only.
To get a more accurate picture, you need to look at the individual indicators and measurements for individual type of food, or food diet type. In addition to the individual food in question, the farming methods/systems being used, or the food gathering method (such as hunting or fishing), should be examined as well.
Different individual farms might be far more sustainable in their practices than others for example.
What Does Sustainable, Eco Friendly & Ethical Mean? – Broad Definitions
Everyone will have their own definitions and meanings, but in general, they might mean:
Sustainability is the ability to maintain something (and also not degrade the environment).
So, the food gathering (if wild caught), or food production process/method/system/approach should be able to be maintained over the long term without depleting resources, degrading the environment, and whilst also considering if something is economically sustainable or not.
It could involve the efficient use of resources (like agricultural land, water, fertilizers and pesticides, soil, and so on).
Eco friendliness is mainly pollution, waste, and damage to the environment, ecosystems, wild life and biodiversity.
Eco friendliness can be measured in many different ways – for example, the water footprint, the land footprint, or the carbon footprint of an individual food, or food diet type.
It could also measure the different types of pollution that a particular type of food could contribute to – air pollution, water pollution, land and soil pollution, waste pollution, and so on.
Ethics are subjective/individual to a person, and can involve any aspect of food production or food gathering.
Some might only buy non animal based food products, some might only buy local food product, some might only buy food products with specific certifications or that has been produced in a certain way such as organic, where animals are humanely and safely farmed, and so on.
Hierarchy Of What Might Be The Most Sustainable, Eco Friendly & Ethical Foods
Eco Friendly & Sustainably
Some of the most eco friendly and sustainable food might be collected from (in the case of plant based foods) or caught/hunted in (in the case of animal based foods) the wild, as wild collected food relies on natural resources and processes only, doesn’t have to use additional resources like farms have to (such as fertilizer, pesticides, etc), and have a smaller impact on the environment (as a result of less waste, pollution, and so on).
If we use wild caught fish for example – pole caught fish might be better than bottom trawler fishing because of far less chance of overfishing and damage to the ocean floor.
It might also be better to catch fast growing, robust, bottom feeding/low on the food chain fish with stable population numbers (a sardine might be an example).
In regards to wild caught animals, it might even benefit the ecosystem if the species is an invasive species, pest species, overpopulated species or predator species degrading ecological systems and severely damaging the numbers of other species.
With certain types of wild animals around the world, local communities can use them to create an income, for employment, for their livelihoods, and to invest back in their communities and conserve the ecosystem – so, there’s more than just eco and resource sustainability benefits.
One of the problems with wild caught land food though in particular might be scale to provide enough food for the entire human population.
This is where farms are practical for food production …
The next most eco friendly and sustainable type of food might be smaller types of animals like rabbits or chickens that need very little feed (or can even get most or a portion of their feed from foraging about the land), and have a very small land footprint (and can also make use of grazing land and don’t need much cropland, if any).
Chicken eggs in particular can be sustainable when farmed organically, naturally or sustainably because there is no slaughtering required like a meat bird
The next most eco friendly and sustainable type of food might be farmed plant based foods, like fruits, vegetables, pulses, grains, and so on.
These foods often have lower eco footprints and don’t need grazing land, but might use more pesticides, and have higher waste rates at the consumer level
Animal by products like dairy and regular eggs might be next
Animal meat might be next (read more about the sustainability of different meats in this guide)
Ruminants and large animals that might eat more, take up more space, or have more intensive feed to produce in particular (we see this with fur farming where the meat based feed for Mink might make Mink farming less sustainable and eco friendly than rabbit and alpaca farming).
Certain foods like beef, lamb, and other foods can have especially high resource requirements and high eco impacts in certain ways.
The standard/average Western baseline diet with higher levels of sodium, added fats and sweeteners also looks to be less eco friendly and sustainable than some vegetarian, vegan, and ovo-lactarian diet types
*There is an asterisk on certain types of farming methods like land farmed seafood, greenhouse grown plant based foods, intensive agriculture vs sustainable agriculture, conventional agriculture vs organic agriculture, and so on.
How the food is farmed can change eco and sustainability outcomes and impact.
Also, there’s small scale vs large scale farms – small scale organic farms might have a lower eco impact overall and be more sustainable in some ways (like for example a family that gets eggs from it’s chickens that mostly free roam, or a family that gets milk from a cow that is mostly grass fed … but there’s sources that indicate grass isn’t the best diet for dairy cows), but larger farming operations might be more resource efficient on average and be able to more effectively feed larger populations, employ more people, and so on (one example – is the claim that some make that operations similar to CAFOs might be more environmentally friendly or resource efficient)
*Also, we touched upon it above briefly, but sustainability involves not just eco friendliness and natural resource sustainability, but sustainability of employment, income, profit and ultimately economic livelihood for people and families.
*Sustainability also involves other factors like nutrition (macro nutrients, micro nutrients, calories, complete proteins and amino acid profiles), food preferences, whether or not individuals and families can afford certain types of foods, time and geographical limitations and barriers, and other practical considerations for the types of foods that can be produced, and people can get physical access to.
Distribution of food worldwide might also be a consideration.
*There’s always variables and trade offs to consider with all foods and food production methods and practices – each situation has to be assessed separately on it’s own variables and trade offs/pros and cons.
Different wild food gathering practices can be compared, different farms can be compared in different regions and countries, and developed vs developing countries can be compared, just as a few examples.
Even developed countries can differ in their farming methods used for the same food product (e.g. US vs Australian beef production)
As mentioned above, ethics is very subjective, and people will have to determine what ethical means to them
Apart from obvious actions like eating plant based foods if people believe it’s unethical to eat animal based foods, people might individually research companies that offer foods (on their website and on the food packaging), and also look for any relevant guarantees or certifications that a company’s food might carry
For example, a company or farm that offers free range chicken eggs specify on their packaging or on their website how many birds are on the farm per hectare, whether they have access to roam and forage, whether the farm is independently audited and accredited, and where the farm is located within a country (perhaps locally).
This might be in comparison to caged chickens for example
Similarly, a company might offer canned seafood that is caught according to a recognised sustainably fished/caught certification that you can check the criteria for, before purchasing the seafood
In regards to ethics, if animals are caught in the wild – it might be more ethical to make sure the death is quick and humane, as opposed to delayed suffering and pain, such as some types of trapping as one example
An interesting ethical question for vegans and those who only eat plant based foods is – some people are only able to survive in low income regions of the world via animal agriculture, or utilising wild animals for different products.
When the alternative for some of these people might be no income, or unsafe work – animal based food products look like the more ethical option.
Measurements/Indicators For Different Foods, & Food Diet Types
Some of the following considerations may come up when assessing the sustainability, eco friendliness and ethics of eating some foods, and food diet types:
In terms of water per weight produced – animal meat, and in particular beef can be one of the most water intensive foods.
Poultry can be one of the least water intensive meats.
Other foods containing animal by products, and processed foods can also be water intensive, such as dairy (milk, cheese, butter), chocolate, and even beverages like coffee, soda, beer and wine, and fruit juices (as these beverages often require the growing of plants or crops as part of the ingredients)
Drinking pure water may be the more sustainable option compared to the above beverages
Some sources in particular identify chocolate as being one of the most water intensive foods to produce per kg of weight. Although, per serving, chocolate can fall further down the list
Nuts like peanuts, almonds and ground nuts can fall somewhere between moderate to high water use
Cabbage and lettuce, cucumber, tomatoes, oranges corn and potatoes can be some of the least water intensive foods per unit of weight produced
Not all plant based foods have low water footprints though – with olives and rice paddy requiring more water than other plant based foods
When looking at food from a water usage per unit of nutritional value produced, the picture looks similar – with beef requiring a lot of water per gram of protein and fat produced, as well per kilocalorie produced.
But fruits for protein, and fruits and starchy roots for fat need far more water than beef, which is interesting – they move much further up the water footprint list
Note that there’s a different between the types of water used – depleting slow to renew groundwater sources with heavy irrigation might be far worse (especially in areas with low rainfall or increased occurrence of droughts) than the use of highly renewable water sources, or using rain fed agriculture.
Land Use Efficiency (Agricultural Land – Grazing Land, And Cropland)
Per gram of protein, beef/mutton by far uses the most land, followed by pork
Chicken and pork are more land efficient than beef, but still require more land than beans per unit of protein
Reducing beef and mutton intake and switching to meats like poultry and pork can decrease a person’s food related land footprint
Switching to a vegetarian or predominantly plant based food diet type with little to no animal products such as meat, dairy, fish and eggs, can further decrease a person’s food related land footprint
The standard American food diet that uses more animal meat, added fats, and sweeteners may also use more land compared to vegetarian and vegan type diets
Some of these trends can change when measuring other indicators such as per calorie produced, per gram of fat produced, per serving produced, per kg produced, and so on
Trends can also change based on the farming method used, and when measuring total land use as opposed to land use efficiency
Most diets might use a similar amount of crop type land, but animal product foods might use far more grazing land
Synthetic Pesticides & Fertilizers
Different foods use different amounts of total synthetic pesticide and fertilizer chemicals, as well as have different amounts of chemicals applied per square area
In terms of pesticide use by crop in the US, as a percent of total pounds of active ingredient applied, corn uses the most pesticide. It is followed by soybeans, potatoes, cotton and wheat (in that order)
In the US, livestock production is responsible for 37 percent of all applied pesticides – so, livestock is an indirect cause of pesticide use via the animal feed that is grown for them
In the US, kale and spinach have had different studies conducted that show a variety of pesticides found on them
Strawberries, apples, cherries, spinach, and nectarines are some of the other foods that might be found with more pesticide residue on them
In terms of total nitrogen fertilizer applied in California in 2007, cotton received the largest fraction of the total nitrogen applied, 16%, while almond received 15%, rice and wheat each received 10%, processing tomatoes received 7% and lettuce received 6%. Altogether these six crops account for 64% of the total nitrogen use.
Worldwide, the crop with the highest fertilizer application rates in kg per hectare (of nitrogen, phosphate and potash) is bananas
Cereal crops top the total fertilizer usage worldwide as a % at 64% of total fertilizer used
Animal based foods tend to have the highest carbon footprint (meats, dairy, some seafood, etc.), along with highly processed foods
Meats like chicken tend to have a lower carbon footprint compared to meats like beef and lamb (beef and lamb/mutton tend to have some of the highest carbon footprints)
Vegetables, fruits, grains and plant based foods tend to have a lower carbon footprint
There are exceptions – some plant based foods grown in some hot and dry climates in the world can have higher carbon footprints, as well as greenhouse grown plant based food that use electricity for lights and so on
Vegetarian type food diets, followed by vegan, and then ovo-lactarian food diets might have the largest carrying capacities, in terms of the number of people they can feed in total.
The standard american diet, diets with more animal meats, added fats and added sweeteners, and some highly omnivorous diets tend to have lower carrying capacities
Perishables and foods that are sold fresh like fruits and vegetables are some of the foods with the highest food waste rates by consumers – read more about food waste in this guide
Consumer Level Food Waste Leading To Production Level Resource Waste
When foods are wasted at the consumer level, there is an indirect waste in agricultural resources (irrigated water, cropland, fertilizers, pesticides) at the production level
Higher quality diets (that are more plant based) were associated with greater amounts of food waste at the consumer level, and also greater amounts of wasted irrigation water and wasted pesticide chemicals at the production level
A more Western diet heavier in animal products was associated with more cropland waste and more fertilizer waste (nitrogen, phosphorus and potash fertiliser applied to animal feed) at the production level
Extrapolating information over from our analysis of the farming of organic cotton – we can see that organic farming in general has a list of potential pros and cons to consider for farming food.
For example, there might be more of an emphasis on soil health and naturally derived fertilizers and pest control, but organic farming may lead to lower yields/productivity, and there can be some questions over the real benefits of naturally derived pesticide chemicals – read more about the pros and cons of organic cotton
Although there appears to be a current scientific consensus on GMO crops and foods, there is still debate as to whether they should be used or not – read more about the pros and cons of GMO crops and foods
Most Commonly Produced Foods Worldwide
Matching up different indicators with the foods that are actually produced the most worldwide can add some context to the discussion
Specifically – beef is a food that is popular in some countries – read more about the impact of producing beef
Overall Potential Positive Impact Of Agriculture
It can help to know the overall potential positive impact of agriculture on different parts of the world:
Overall Potential Negative Impact Of Agriculture
It can help to know the overall potential negative impact of agriculture on different parts of the world:
Other Individual Factors, Indicators & Measurements
Some people prefer to look at the different levels of indicators.
The simple way might be to look at:
Land (both crop land and grazing land) footprint to produce (both total land, and land efficiency per calorie or gram of protein produced) – compare this to amount of available cropland, and grazing land in the area
Carbon footprint to produce (CO2e, but also individual gases like carbon dioxide, nitrous oxide and methane)
Water footprint to produce (irrigated water) – compare this to available water resources in the area, and level of rainfall
Synthetic pesticide footprint to produce – total amount, but also application rates per hectare
Synthetic fertilizer footprint to produce (nitrogen, potash, phosphorus) – total amount, but also application rates per hectare
Whether natural resources are used efficiently and sustainably or not – look at types of resources and inputs used, renewal rates, yields and production, and so on
Going a level deeper, you might look at the above factors plus these factors:
Level of food wastage at the consumer level
Level of resource wastage at the producer level resulting from food waste rates of different foods at the consumer level (irrigated water, cropland, pesticides, fertilizers, topsoil)
The maximum carrying capacity a diet type can provide for (population size of people)
Going a level deeper than that, you might look at the above factors plus these factors (these factors often have little of no study done on them yet):
Impact on deforestation (if forests are converted into farms or ranches or plantations)
Impact of land clearing and conversion
Impact on the different types of land degradation
Impact on top soil loss and soil health
Pollution caused – air, water, land, soil … and also how it happens e.g. leaching, run off, air drift, etc.
Level and types of waste generated, and how the waste is managed (livestock waste like manure, and general agricultural waste like ag plastics)
Can waste be re-used or recycled – such as turned into compost, organic fertilizer or biogas?
Use of other harmful agricultural chemicals and substances – release of chemicals, bacteria, pathogens, heavy metals, antibiotics etc.
There’s realistically many environmental indicators that foods or any product can be compared against each other in – a few examples are chemistry, resource depletion, eutrophication, global warming, and water scarcity (as we outline in our real leather vs faux leather comparison guide). Toxicity of the farming process, and how farms are powered might be some others
If livestock are treated in an ethical, humane and safe way during farming, and whether any pain or suffering is involved at the birthing, storing/confinement/housing, vet and medical procedure, transport/export, and slaughtering stage. Also look at the health care available to livestock during farming. Is there any risk of development and spread of animal diseases and sicknesses?
How wildlife and plant species are impacted from production
Impact on biodiversity (specifically with biodiversity, farmers have to weigh this issue up, along with meeting the nutritional needs of the population, and profitably running their own business. So, there can be tradeoffs. Additionally, most of the energy intake for humans currently comes from a small number of crops and animals, which is less biodiverse than a century ago – we might ask how sustainable this is). Smithsonianmag.com mentions how the Irish potato famine was related to lack of biodiversity
How much income and employment the agricultural activity generates, and it’s value to the economy
Whether the food products provide a sole source or majority source of income for people in the area, and whether it contributes to better investment in the local community and conservation of the environment and ecosystem
Where the food comes from – local, or non local?
How and where is the food packaged?
How far does the food have to travel/be transported to get to the consumer, and what type of transport is used (air, road, water, rail?)? What is the impact of that transport? In some instances, a longer sea freight can be better than a shorter road freight (but it depends)
Are GMOs used for the seeds?
Are hormones used? What about vet medicines?
Are there problems with food distribution system in terms of ensuring everyone in the world has enough food to produce and eat?
Does the food or food diet type have the adequate nutrition, and is it healthy and safe for the person eating it? (fao.org has a good resource that outlines the main nutrients in different food groups, such as roots and tubers, animal products, and so on)
Is the food or food diet type affordable, accessible and convenient enough for individuals to buy, store, prepare and eat?
Does the food or food diet type cater to everyone’s health and nutrition requirements?
How does the farming method used (sustainable, organic, conventional, intensive, commercial, industrial, etc) impact the environment, resources, animals, wildlife, biodiversity, the economy, profit, employment, yields and so on?
How do the types of foods being produced and imported within a country contribute to providing food for the whole population, and a growing population into the future?
Zooming out and looking at how some countries are net exporters of certain foods, and some countries are net importers of certain foods, how does the overall food export and import situation around the world impact what foods might be available to populations in different countries? (nationalgeographic.org and many other resources point out that crops grown in one place are often exported to another, and don’t always feed the local population)
What types of foods can realistically be grown in the area given the climate/weather conditions, soil and land types available, rainfall and water supplies for agriculture, and given the economy and agricultural technology and resources available?
What sort of guarantees or certifications does the farm offer or list for how they produce their food?
How safe is the food – does it contain pesticide residue or expose people to animal antibiotics or certain bacteria and pathogens (directly or indirectly)
Does the food production have a higher level of occupational health and safety risk for farm workers – from organic matter, animal manure, pesticides, farm machinery, farm conditions etc.
Are farm workers paid fairly and do they work in fair conditions
Does the food production negatively impact a country or specific countries in any way – for example, avocado production in Mexico can have negative consequences
Consider the whole lifecycle of the food product and the results/impact at each stage – growing/farm, processing, transport, stocking/storefront for purchase, eating, and disposal or waste
Agriculture and food production is ultimately influenced by:
– the wants and needs of the population and the consumer (diet choices and requirements, as well as nutrition and other factors)
– agricultural policies, incentives, markets or consumption patterns
– geographic factors like climate, accessibility, trade and culture. smithsonianmag.com for example mentions how coffee yields have been cut in half in Tanzania since 1960 because of droughts and temperature changes. There’s also several factors to keep in mind that can impact how and where crops grow worldwide. fao.org mentions how crops need to be suitable for the source area they are grown in, and list other characteristics of staple foods in a local area
– increasingly in some countries, the influence of biotechnology and GMO crop/food technology, GMO companies, and other modern agricultural technology
Potential Competing Factors To Eating A Sustainable, Eco Friendly & Ethical Food Diet
For The Buyer/Consumer
Price of the food for consumers – affordable vs expensive
How practical/convenient is it to purchase the food – from a time and location perspective for the consumer – can they go to the local supermarket, or do they have to make trips to specialty stores and markets further from their homes
Knowledge of how to prepare, or ease to prepare the food – can the food be eaten as it is, or does it take time and certain knowledge to cook and prepare it
Buying for several people in the same house – families and purchasing for families will have different food purchasing consideration to people who are single for example
What is going to last, or what is going to waste – vegetables and fruits tend to waste quicker than processed and canned foods
What is healthy – Foods with saturated fat, sodium, and added sugar might present more of a long term health risk in developing certain health conditions than healthier non processed foods
What is nutritious – nutrients can be macro or micro nutrients. Some people may be concerned whether they are getting enough of the nutrients they want or need with a change in foods/diet
What fits in with allergies, intolerances and any individual dietary requirements – some people may not be able to eat certain foods due to certain dietary requirements or medical conditions. Some people may have intolerances to plant based foods, and may need animal meat in their diet for example
What has enough calories – some vegetables for example you my have to purchase and eat a lot more of than processed foods (which are usually loaded with calories) to get the same amount of calories
Taste – some people may really not like the taste of some plant based foods compared to processed foods for example. It’s hard to stick to foods long term that you don’t enjoy the taste of
The person themselves – some people may be more willing than other to do what is required to change their diet and the foods they eat. Also, what an individual thinks is morally right and not right will be an influence (some people might have differing views on using animals in different ways for food production)
Information available – measuring sustainability, eco friendliness and ethics can get very detailed and complex. Some factors haven’t been studied or reported on yet.
Also, there’s no real way of guaranteeing how some foods you buy were produced unless you buy direct from the supplier.
These things can make it hard to buy truly sustainable, eco friendly and ethical. It’s logical to say most people probably don’t have the time to research the information and find out where foods are sourced from (and know how exactly they are made) either.
For Farmers & Producers
What is profitable – making money, having low financial risk and ultimately being able to operate a sustainable business is a huge priority for farmers and food producers
What is practical – how easy the food is to produce, available resources (water, land and types of land, soil, nutrients, seeds, animals, machinery etc.), growing conditions and seasons (different geographic locations can differ with what can and can’t be produced in a particular place), what can be transported, and other factors, are all things farmers have to consider from a practicality standpoint in deciding what they can produce
Government, Policy Makers & Others
There are other bodies and organisations that can have an impact on the food supply and food production within countries, and between countries. This can happen through laws, regulations, guidelines, policies, systems, relations, economics and more
A Note On Food Nutrition
A few additional notes on food nutrition are:
– The type of diet can impact morbidity and mortality, including what additives and bad nutrients are in the foods in the diet
– Undernutrition can be a problem specifically in less developed countries
– The overall quality and diversity of food available to a population matter. There should obviously be food with quality nutrients, and diversity of nutrients available
– Individuals will have different health requirements, intolerances and negative reactions to certain foods, and preferences
[what several sources point out is that] a Western diet (high in bad fats, sodium, sweeteners, and animal based products) has present prominent risk factors linked to higher rates of morbidity and mortality
Undernutrition causes over 15% of the global disease burden.
Protein energy and micronutrient malnutrition remain challenges, with high variability between and within countries.
Food security can be improved through policies and programs to increase dietary diversity and through development and deployment of existing and new technologies for production, processing, preservation, and distribution of food.
Reduced dietary quality and diversity and inexpensive foods with low nutrient density have been associated with increasing rates of worldwide obesity and chronic disease.
Poor diet throughout the life course is a major risk factor for chronic diseases, which are the leading cause of global deaths.
9. Conrad, Z., Niles, M.T., Neher, D.A., Roy, E.D., Tichenor, N.E. and Jahns, L., 2018. Relationship between food waste, diet quality, and environmental sustainability. PloS one, 13(4), p.e0195405. – https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0195405