Study: dairy, not plant based diets is the best way to feed the planet

Last Updated on July 10, 2023 by Keir Watson
Read Time: 5 min
  • A recent study demonstrates that dairy farming is a more efficient and cheaper method for providing human energy and protein requirements than growing grains or pulses.
  • This contradicts decades of claims that a plant based diet is the only way to feed a burgeoning world population.
  • The new analysis is based on whole year farm-to-plate production using  real world farm practises taking into account human protein needs not just calories.
  • In our commentary we show how vegan diets indirectly support animal farming, whilst contributing to obesity and food waste in the wider society.

You will often hear the mantra that a plant-based diet is the only option for feeding an ever growing world population. The argument is that you can produce more calories per acre by growing cereal grains or soy than you can from animal food systems. Jonathan Porritt writing in the guardian made a related point when he said:

The basic rule of thumb is that it takes 2kg of feed to produce every kilogram of chicken, 4kg for pork, and at least 7kg for beef.

It’s an argument loved by vegetarians and vegans and is regularly trotted out in an attempt to convince governments and the public to reduce meat consumption. Anyone with a green conscience will no doubt have been swayed by the force of such logic. I certainly know people who have reduced their consumption of animal products purely for environmental reasons such as these.

Personally, I have for a long time suspected that the metric of ‘calories per acre’ was somewhat arbitrary as humans need more than just calories. Another limitation of the standard grain v animal protein argument is that real farms have to rotate crops to avoid build up of pests and depletion of nutrients. So they can’t grow grains year after year anyway. Also, grains can only be grown through part of the year, whereas livestock can continue producing through the winter – especially dairy. Furthermore, forage crops that are suitable for animal fodder can be grown in the winter. Another oft-ignored fact, relevant to the Porritt claim above, is that most animal feed is produced from crops that are unfit for human consumption – for example where wet seasons have led to fungal damage.

What the new study found

In a paper, currently in peer review, Graeme D. Coles and Stephen D. Wratten of the Bio-Protection Research Centre, Lincoln University, New Zealand, along with Editor-in-Chief of the European Journal of Agronomy John R. Porter of the University of Copenhagen, Denmark, analyse a range of farm production systems (wheat, corn, dairy, pork, beef) for their ability to provide both the energy and protein needs of a population. Here are a couple of quotes from the paper:

We conclude that mixed dairy/cropping systems provide the greatest quantity of high-quality protein per unit price to the consumer, have the highest food energy production and can support the dietary requirements of the highest number of people, when assessed as all-year-round production systems.

This challenges the claims of those who argue that a global diet consisting entirely of plant-derived foods is the most efficient way to meet the dietary needs of the world’s population.

Particular strengths of their analysis, and what set it apart form previous work, include:

  1. Consideration of realistic whole year farming cycles
  2. Addressing human calorie and protein requirements.
  3. Including transport and processing costs from farm to table

How protein changes the picture

The study makes two very good points about protein – one I already knew, but the second has stimulated a whole lot of exciting new ideas – some of which I will discuss below.

Firstly, as is widely recognised, grains cannot provide the full range of amino-acids, being generally deficient in lysine, and depending on the species other amino acids as well. To improve the amino acid profile of the diet, grains can be consumed with suitable legumes which tend to be deficient in different amino acids. However, when the study authors analysed various grain and legume systems, as well as soy beans, (which provides complete protein) they found that in each case dairy systems with supporting forage crops came out top for cost, energy and protein production.

Secondly, when considering farming systems that provide both adequate protein and calories there is inevitably going to be an excess of one or the other. In other words, food production systems that provide adequate calories as well as protein fall into two groups: those that produce an excess of non-protein calories, and those that have an excess of protein. The latter systems are more efficient, as excess dietary protein can be converted in the body to calories, whereas excess calories cannot be converted to protein. This is a very important argument worthy of considerable reflection.

The consequence of these points in that a grain/legume based food system providing adequate protein for a population will inevitably deliver an excess of calories. For a population dependent on a largely plant based diet there are only two possibilities: either they eat enough protein and become obese or they eat enough calories and become protein deficient.

The only way round this would be to process the grains and legumes (by removing some of the starch for example). You see this in vegan food products which often contain pea protein, wheat protein (gluten) or soy protein, as in the example below.

Before anyone points out that many vegans avoid such highly processed products, let me be clear the argument I am making does not hinge on such foods. The point is that like everyone else vegans must consume adequate protein to stay healthy, and because of the protein:calorie imbalance in plant foods they have to deal with an excess of calories. To get their protein they must either consume these calories (in which case there would be more obese vegans), or they are being removed earlier in the supply chain. In the latter case where do those non-protein calories go?

Where crops are relied on to provide a populations protein there will inevitably be an excess of the low-protein, high-calorie fraction – mostly starches. These will either needs to be dumped or used as animal feed – either way there is an inevitable waste of human-grade food stuff. Yet without removing these non-protein food calories from the human food supply there are only two possible outcomes for the population: obesity or protein deficiency.

This is an inescapable logic, and vegans can only hide from it because they are a minority in a large and somewhat wasteful system that prevents them being faced with the consequences of their choices. To achieve their protein needs good food must go to waste or supply animal husbandry or contribute to the obesity epidemic. All of this tarnishes their eco-halo somewhat doesn’t it?

Obesity and protein

Having wandered somewhat from the study itself into musings about plant proteins and obesity, I’d like to share some further thoughts about animal compared to plant protein stimulated by Denise Minger’s recent post critiquing the book proteinaholic.

Protein in general, regardless of its source, is highly satiating compared to fat or carbohydrate. Multiple studies have shown that high protein meals lead to people feeling fuller for longer, snacking less often and generally finding it easier to reduce their calorie intake.

However, along with reducing excess calorie intake, protein consumption also increases daily energy expenditure by raising the basal metabolic rate. The mechanism for this appears to be through the upregulation of uncoupling protein in the mitochondria, leading to a diversion of energy into heat production rather than ATP formation. This thermogenic effect means that for the same calorie intake, replacing carbs with protein can increase resting energy expenditure by about 5% – a huge metabolic advantage equivalent to consuming 100 Calories fewer each day. Couple this with the fact that the body is highly inefficient at converting excess protein to fat and we can begin to see why protein is such an important aspect of the diet.

A further interesting aspect of the protein story is that different sources of protein have different thermogenic benefits. A study published in The American Journal for Clinical Nutrition found that animal protein (pork) increased thermogenesis twice as strongly as plant protein (soy).

The points I have covered in this post provide compelling evidence that a plant based diet cannot be the solution for a rising world population. Further moves in such a direction will be wasteful and threaten ever more obesity. Dairy farming and other sustainable animal husbandry look like being an essential part of food security. The political dominance of the save-the-world plant-diet eco-meme, however, threatens to keep this understanding hidden from view.

To that end, make sure you share this post please!

cow joke

25 thoughts on “Study: dairy, not plant based diets is the best way to feed the planet”

  1. It was seeming a reasonable, though I suspect in some peoples opinion a questionable, article until the penultimate paragraph.

    “……. the solution for a rising world population.”

    The population even now is unsustainable except by enormous fossil fuel derived inputs. Unpalatable as it might be, when these resourses, and mineral resources, are no longer available, the realistic “sustainable” population will be a fraction of today’s.

    • You may be right Red Squirrel, but to give them their due, that was not the main trust of the paper. I wouldn’t worry too much about ‘the world’ cottoning on, as they are heading rapidly in the opposite direction for the most part!

      • This is just not true. “Overpopulation” is a myth. About half the world’s food that is produced goes to waste. The richest 80 people in the world have as much wealth as the poorest 3 billion. The problem is not overpopulation. The problem is capitalism.

    • For those who think overpopulation is a myth, read “Man Swarm, How Overpopulation is Killing the Wild World” by David Foreman. You may change your view.

  2. 65% of the worlds population is lactose intolerant and up to 90% of the Asian population. Dairy is one of the cruelest of all industries!!!!

    • Depends how it is done, obviously. This was a New Zealand study where 90% of the population are actually lactose tolerant, and I think their cows are all out on grass, which, to a cow, is probably fabulous! One of the main thing the study authors found was that cheese is a particularly environmentally sustainable and sound product, and it does not contain lactose. It also travels well, keeps well, and can be eaten raw, so no need for cooking fuel. Good all round I’d say, unless you are casein intolerant.

    • Figures I can find for intolerance in the UK in one report is 5-15%, and in another report 20-30%, so the figures in general must be treated with caution. They may be based on meta-studies rather than on raw data. In many of the eastern countries it seems goats are the milk source, which appears to be less of a problem. It looks to be the case that intolerance is greater in hotter countries which may be a relevant factor. Unpasteurised milk has not had the lactase destroyed, unlike pasteurised milk, and so may be tolerated by more people.
      As to cruelty, this is possibly something that occurs in a minority of cases rather than being systemic in most countries. Unfortunately, getting food is a pretty ruthless occupation, however it is done. Nature in general does not do “kind”. Even when it comes to growing food crops, a lot of species lose their habitat, and some are even made extinct.

  3. I would like to know if they included the cost of killing the calves and disposing of them- many of us are vegan because of the chronic and systemic animal abuse that is inflicted onto farm animals.Sis they also include the damage that large scale farming does to the environment and the cost of slaughter houses vs processing vegetables/grains?

    thanks, francie

  4. Very interesting post. I’m a bit surprised that you didn’t talk about farm management and manure. How does a farmer without manure fertilize his land? A real farm is a beautiful, natural circle, and animals are an essentiel part of it.

    • The article is what it is and covers what it covers, but of course you are right. Manure is a concentrated form of nutrient application, without which soils degrade. Do you know the work of Allan Savory? His 22 minute long video ‘How to fight desertification and reverse climate change’ is superb, and he fully deserved his standing ovation!

  5. Your quote “For a population dependent on a largely plant based diet there are only two possibilities: either they eat enough protein and become obese or they eat enough calories and become protein deficient.”

    Do you have any evidence to support this conclusion? From my experience and studies most vegans have healthy weight and are not protein deficient. Medical journals claim that healthy vegan diets provide enough protein without excess calories. Most raw vegans would have to be protein deficient by your theory, but they are not. That’s why some even argue that the recommended intake of 0,8 grams protein per 1 kg of body weight is set too high.

    • The conclusion is a logical consequence of the cited study which found that when protein requirements were taken into account that dairy (cheese) farming beats plant based farming. The key reason is that plants are low in protein leading to a surfit of calories per cultivated acre. Vegans can get sufficient protein, or course, but those excess calories go somewhere: if not into the health-conscious vegan then into cheap junk food, or animal feed. Vegan food choices have hidden consequences. As for the health of long term vegans: they tend to suffer lower bone density and higher rates of sarcopenia. One ref, from among many:

      The idea that protein requirements might be lower than 0.8g per kg is contradicted by current research that indicates that age related muscle wasting that begins at age 40, can be prevented by increasing protein consumption:

      Recent findings
      Ageing does not inevitably reduce the anabolic response to a high-quality protein meal. Ingestion of approximately 25–30g of protein per meal maximally stimulates muscle protein synthesis in both young and older individuals. However, muscle protein synthesis is blunted in elderly when protein and carbohydrate are coingested or when the quantity of protein is less than approximately 20g per meal. Supplementing regular mixed-nutrient meals with leucine may also enhance the muscle protein synthetic response in elders.

      • I can not fully follow the argument, that there is *necessarily* a lot of waste because of calorie imbalance with a plant-based diet. The argument seems to assume, that anyone following a plant-based diet must need a significant amount of processed food to meet protein requirements. However, I see even some raw vegans with no signs of protein deficiency. It could be, that, for most people, such a diet is not practical, or, that not all necessary foods are available for local produce. But strictly speaking, the argument made does not seem valid for me, unless I am missing something.

        • [edited after I read the whole of your comment] In relation to the standard “we should eat grains to feed the planet” argument the point is that grains are protein deficient in relation to calories. (Hence if we ate sufficient grains to reach protein requirements then we would have eaten more calories than we needed. Conversely, if we only ate 2000 kCal of grains per day then we would become protein deficient). Also, farms cannot produce grains all year round. When the protein needs of humans are taken into account, along with the realities of the whole farm cycle, dairy farming was found to provide the best fit for protein/calories. Sure a plant based diet can be formulated to avoid protein deficiency, but the argument here is about the most efficient way to feed the population.

      • Afifah: no, I am asking if it is reasonable to assume, that, a plant-based diet is necessarily a grain-based diet, too. The argument against the “eat grains to feed the planet” idea is good, there’s no need to repeat it. But isn’t it possible to get enough protein from other diverse plant sources? If yes, you are not really attacking the strongest arguments in favor of a plant-based diet. I know people on a raw vegan diet who manage, though I don’t know the details. Scaling their diet up might still have its own problems, though. I am not here to advocate for either side, I would like to understand the facts.

        • Oh, I see. Yes, sure, you can get enough protein from a plant based diet; and no, that doesn’t mean eating grains necessarily. No one would argue otherwise. But in this and other posts we have shown that vegetarians/vegans do not live any longer than meat eaters in the UK or Australia (where the studies have been done), so health-wise there doesn’t seem to be much in it either way does there? In which case, people might base their choices on environmental concerns. What this post (and several others on this blog) does is challenge the assumed eco-benefits of a plant-based diet. So again there is no strong argument one way or the other. Finally, there are ethical argument (animal rights etc) which we will address in an future post. When people realise that all of the big claims for a plant based diet are over-blown, and the supposed harms of an omnivorous diet are not supported by good evidence they can make their choice free of the influence of propaganda. Most, then, choose to eat animal products.

      • Afifah: I am still not sure, that, considering only sustainability and meeting protein requirements (and ignoring eg. animal rights), the optimal (wrt. sustainability) diet has an “animal product” share of greater that zero. If “grain waste” can be minimized, and alternative protein sources eg. algae can be efficiently transported across the globe, it still seems likely to me, that it would be more sustainable, than having animals convert food for us at a loss. Neither diet comes for free, that is clear. But it seems to me, that both sides (you included) argue, that, because the other option comes at a cost, then, its own option is necessary better. Which is simply not a valid conclusion.
        One thing I certainly accept is, that, a fully plant-based diet is also quite costly when scaled up to 7 billion people. The reason I think it is not realistic is not because it couldn’t be the most sustainable. It is just too different from what we have now, both individually, and system-wise. Eating less in general, and especially eating less meat is desirable in my opinion. But essentially, I think, we agree: given our current civilization, at most places, the best realistic diet will include some meat and dairy. The more important question is: how much?
        From what I read here, it is not clear to me, how much consumption of meat and dairy is advocated. Is it daily consumption? Even I remember, growing up on the countryside, that, in my parents’ time, one pig was slaughtered per yer, and one chicken per week at most, and the family didn’t eat much meat except weekends or feasts. That is quite different now, that such constraints are removed, and I do see daily meat consumption as a serious environmental problem.

  6. Considering 75% of the world population is lactose intolerant, not a good idea! And for good reason, we aren’t dairy calves and we aren’t suppose to be drinking their milk! Humans eating some meat is better than consuming dairy. Think of all the people that don’t consume dairy, so what now how’ve more factory farms and force people to drink milk? That would not only be horrific for our health but the environment too! I’m guessing this study was paid for by the New Zealand Dairy Association. Research what having a high calcium diet from dairy actually does to human bones!!

    • Hello Lori, and thanks for leaving a comment. First, the paper was not connected to the dairy industry, nor funded by it. The study was based in New Zealand and is applicable to modern economies in temperate climates such as Europe, Canada, USA. In these countries the rates of lactose intolerance is considerably lower. Furthermore, the study found that cheese was the best product, environmentally, that met human protein needs. Cheese is very low in lactose, indeed early pastoralists in Europe (4000 BC) appear to have produced cheese prior to the emergence of lactase persistence. As for your last point, My reading of the literature shows fairly conclusively that dairy is a major source of bone health. If you can point me to any research to the contrary I would be very interested to read it.


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