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Evidence-led reference

A reference for the curious

Make sense
of your health.

From your morning coffee to the science of sleep. Clear explanations, the sources behind them, and room for uncertainty.

Start withCoffeeFood processingSleepAll topics
1,010introductory guides
8,638published questions
8,313reference entries

Made for understanding.
Selected-source overviews. Independent review pending.

01 / The essentials

Explore by subject.

Choose a subject to find its guides, from the basics to specific questions.

Browse all guides
Sleep & recoverySleep, body-clock timing, environments, and recovery.49 guidesFood & nutritionEveryday foods, drinks, nutrients, and eating patterns.185 guidesMovement & fitnessTraining, strength, equipment, and getting back to activity.122 guidesSupplementsVitamins, minerals, protein, herbs, and other ingredients. Explore forms, evidence, and safety.112 guidesMental wellbeingMood, stress, relationships, habits, and mental healthcare.93 guidesPrevention & careSymptoms, conditions, tests, medicines, and care through life.757 guidesHealthy agingAging, function, healthspan, and longevity claims.46 guidesProducts & safetyWater, food safety, personal care, household products, and exposures.329 guides

Recently added & expanded

A little more
understanding.

Explore everyday questions, useful distinctions and the evidence behind familiar claims.

See all 10 guides

The plain-English series

What does this
actually mean?

The words you hear. The context you need.

All 100 explanations
  1. Food & nutrition

    Ultra-processed food: does bread, yogurt or cereal count?

    Start with the four processing groups, then look at familiar foods.

    26 references Read explanation
  2. Products & safety

    EMFs: what about your car and the router beside your bed?

    Understand the different fields around everyday devices.

    13 references Read explanation
  3. Products & safety

    BPA and receipts: what does touching one mean for your health?

    Separate contact, absorbed exposure and evidence about health outcomes.

    12 references Read explanation

A connected collection

What’s in
the water?

From the bottle material to the words on its label. Explore the measurements, the health claims, and the evidence behind them.

Explore all 8 guides
Copper bottlesWhat can enter the water, and does an essential mineral make a bottle beneficial?Hydrogen waterWhat does a hydrogen measurement tell you, and what have human trials actually tested?

A closer look · Food & nutrition

There’s more to
food processing.

Start with what “ultra-processed” means. Compare the four NOVA groups, then explore the findings and the questions they leave open.

  1. 01
    Unprocessed or minimally processedFoods from plants or animals, including simple preservation or preparation.
  2. 02
    Processed culinary ingredientsIngredients used in preparing food.
  3. 03
    Processed foodsGroup 1 foods combined with culinary ingredients, often for preservation.
  4. 04
    Ultra-processed foodsIndustrial formulations with distinctive ingredients and processes.

Processing categories, rather than nutrition scores. Definitions: Louie (2025).

Explore food processing26 sources

Read with perspective

Read beyond
the headline.

Every guide puts foundational explanations before evidence, and keeps its scope and review status visible.

  1. 01
    Understand the basics.Definitions, categories, and context.
  2. 02
    Look at the evidence.What the cited studies and guidance report.
  3. 03
    Keep uncertainty in view.Limits, disagreements, and unanswered questions.
  4. 04
    Follow the sources.References and related reading to go further.
Learn to read evidenceUnderstand risk

02 / Everyday questions

Follow your curiosity.

Find an answer
Ultra-processed foodsWhat is an ultra-processed food (UPF)?Read the answer and its limitsCoffee: what is in the cup, caffeine amounts, filtering, sleep, and the health evidenceHow much caffeine is in a cup of coffee?Read the answer and its limitsIntermittent fastingIs intermittent fasting better than calorie restriction for weight loss?Read the answer and its limitsSleepIs seven hours the right sleep target for everyone?Read the answer and its limits

03 / The things around us

Understand the everyday.

Reading the evidence

Products & safety

Water filters

A household water-treatment system changes water by filtering substances, removing selected dissolved contaminants or disinfecting germs. A drinking-water tap system and a whole-house system treat different volumes and uses.

12 published questions · 14 sources

Products & safety

Sun protection and sunscreen

Sun protection combines shade, clothing and sunscreen to reduce ultraviolet exposure. Sunscreen labels answer separate questions: SPF concerns sunburn protection, broad spectrum concerns UVA and UVB coverage, and water resistance describes tested persistence on wet skin. Effectiveness also depends on how the product is applied.

15 published questions · 13 sources

A connected reference

Every topic leads
to something else.

The topic map connects 3,888 indexed topics across 60 health domains. Topics without a written guide are clearly marked.

Explore the topic map