Evidence library

Deep, sourced guides on food, animals and the planet

Long-form explainers built from peer-reviewed research, UN datasets and government dietary guidance — plus practical how-tos you can use the same day. Every number is attributed, every claim is checkable.

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13 guides
Protein on a plant-based diet: what the evidence actually saysNutrition scienceProtein on a plant-based diet: what the evidence actually saysProtein is a common worry on plant-based diets. Here is the requirement, the arithmetic, and the research on plant versus animal protein.9 min readRead the guide The climate footprint of food, measured properlyClimate scienceThe climate footprint of food, measured properlyFood causes roughly a quarter of global greenhouse-gas emissions. Life-cycle data shows where inside that quarter the emissions actually sit — and it is not transport.10 min readRead the guide Vitamin B12: an essential supplement, explained without hand-wavingNutrition scienceVitamin B12: an essential supplement, explained without hand-wavingB12 is made by bacteria, not by animals or plants. Here is why supplementation is the honest answer, what dose works, and how to test.7 min readRead the guide Iron, zinc, iodine, omega-3 and calcium without animal productsNutrition scienceIron, zinc, iodine, omega-3 and calcium without animal productsFive nutrients deserve attention on a plant-based diet. None require animal foods — they require knowing the absorption rules.11 min readRead the guide Animal sentience: what science established, and what law now recognisesEthics & scienceAnimal sentience: what science established, and what law now recognisesSentience stopped being a philosophical guess and became an empirical finding. Here is the evidence base, from mammals to cephalopods, and how legislation followed.9 min readRead the guide Land, forests and biodiversity: agriculture's biggest billEnvironmentLand, forests and biodiversity: agriculture's biggest billLivestock uses 77% of farmland and returns 18% of calories. That ratio is why land use — not emissions alone — is the sharpest environmental argument.9 min readRead the guide Water, pollution and food: from aquifers to dead zonesEnvironmentWater, pollution and food: from aquifers to dead zonesAgriculture accounts for about 70% of global freshwater withdrawals. Fertiliser and manure from crop and livestock production contribute substantially to nutrient pollution in rivers and coasts.8 min readRead the guide Antibiotic resistance and pandemic risk in animal agriculturePublic healthAntibiotic resistance and pandemic risk in animal agricultureMost antibiotics sold worldwide go to farmed animals, and dense confinement is an efficient laboratory for novel pathogens. This is the public-health argument.8 min readRead the guide What welfare labels actually guaranteeConsumer guideWhat welfare labels actually guaranteeFree-range, cage-free, grass-fed, humane-certified: each term has a legal or scheme-specific definition, and most guarantee far less than the picture on the box.8 min readRead the guide Batch cooking: two hours on Sunday, ten meals readyPractical how-toBatch cooking: two hours on Sunday, ten meals readyDeciding what to cook after a long day can be difficult. Preparing components ahead can make plant-based meals easier.7 min readRead the guide Shopping plant-based: a pantry, a list and a label-reading methodPractical how-toShopping plant-based: a pantry, a list and a label-reading methodA well-built pantry makes cooking a fifteen-minute job. Here is the core list, the price-per-protein maths and the hidden ingredients worth knowing.8 min readRead the guide How to build a plant-based plate that fills you upPractical how-toHow to build a plant-based plate that fills you upA satisfying plant-based meal needs enough energy and a useful mix of foods. Here is a practical plate formula to start with.6 min readRead the guide How to talk about this without losing the roomPractical how-toHow to talk about this without losing the roomAdvocacy research is fairly consistent about what changes minds: questions, specificity and respect. Here is a method you can use at a family dinner.7 min readRead the guide

Turn evidence into a week of meals

The 7-day starter plan translates everything above into a shopping list and simple recipes.

About this library

How the evidence library is built and how to read it

Each guide summarises a body of research on one question, states the strength of the evidence honestly, and links to the primary sources. It is written to be checkable rather than persuasive.

What counts as evidence here

Guides prioritise systematic reviews, meta-analyses and large prospective cohorts. Where only observational data exist — which is often the case in nutrition, since randomising decades of diet is impossible — that limitation is stated in the text rather than buried. Mechanistic and animal-model studies are used to explain plausibility, never as standalone proof of a human outcome.

Strength of evidence, plainly labelled

Claims fall into three tiers. Strong: consistent findings across multiple large cohorts and meta-analyses, with plausible mechanism — for example that plant-based dietary patterns lower LDL cholesterol. Moderate: consistent direction with residual confounding or smaller samples, such as effects on type 2 diabetes incidence. Emerging: promising but immature, such as much of the gut-microbiome and mood literature. Presenting all three at the same confidence is the most common failure in popular nutrition writing.

Confounding, and why it cuts both ways

People who eat plant-based diets in Western cohorts also smoke less, drink less and exercise more, which inflates apparent benefit. Good studies adjust for these, but adjustment is imperfect. The same problem also works in reverse: 'healthy user' effects can mask real benefits in populations where plant-based eating tracks with poverty rather than affluence, which is why cohorts outside high-income countries matter.

How to challenge a guide

Every claim carries its source. If a guide misreads a paper, overstates a finding or omits a significant contrary result, that is a correctable error and worth reporting. The measure of a library like this is not that it never gets things wrong but that its errors are traceable and fixed.

Evidence tiers used across the library

TierCriteriaExample claim
StrongMeta-analyses + consistent cohorts + mechanismPlant-based diets lower LDL cholesterol
StrongLarge-scale LCA consensusBeef has the highest footprint per kg of protein
ModerateConsistent cohorts, residual confoundingLower type 2 diabetes incidence
ModerateGood data, contested attributionLivestock's share of global emissions (~12–20%)
EmergingSmall or short-term studiesDiet effects on depression and anxiety
ContestedGenuine scientific disagreementSoil carbon offsets in managed grazing

Reading a guide critically

  1. 1

    Check the tier before the claim

    A moderate-tier finding stated confidently in conversation is how good evidence gets a bad name.

  2. 2

    Open one primary source

    Read the abstract and the limitations section. Ten minutes there beats an hour of secondary commentary.

  3. 3

    Look for the effect size

    Statistical significance does not establish that an effect is causal or important. Consider absolute risk, uncertainty, study design and effect size before judging relevance.

  4. 4

    Note what the guide says it does not know

    The uncertainty sections are the most informative part of any honest summary.

Standards this library holds itself to

Commitments

  • Every quantitative claim carries a citation and a year.
  • Evidence strength is labelled, not implied.
  • Contrary findings are included where they are methodologically sound.
  • Corrections are made and visible rather than quietly edited away.

What you won't find

  • Single-study headlines presented as settled science.
  • Health claims that promise cure or prevention of specific disease.
  • Numbers repeated from infographics without a traceable origin.
  • Silent deletion of claims that turned out to be wrong.

Library questions

Who writes the guides?

They are compiled from published literature and public datasets, with sources listed on each guide so any claim can be traced independently of who wrote it.

Is this medical advice?

No. It is a summary of research. Decisions about pregnancy, chronic illness, medication or feeding infants belong with a qualified clinician.

Why include contested topics at all?

Because omitting them would misrepresent the state of the evidence. Grazing and soil carbon, for example, is genuinely unresolved and is presented that way.

How current are the guides?

They are reviewed periodically against new meta-analyses and updated datasets; each guide carries the sources it relies on so you can check whether something newer has appeared.

Can I reuse the content?

Yes, under the site's Creative Commons licence, with attribution and a link. Sources should be cited to their original publishers rather than to this site.

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