Where our answers come from

Every answer on Founded Health is drawn from a fixed list of approved sources and graded by how strong that evidence is. We never write an answer from general knowledge, and we never cite a source that is not on this list. If the research does not have a clear answer, we say so.

TIER 1

National and international guidelines

The strongest starting point. These are official recommendations written by expert panels who have already reviewed the underlying research and weighed it for real-world practice.

Sources: NICE and SIGN (UK), the US Preventive Services Task Force, CDC, the World Health Organization, the Government of Canada, the Canadian Task Force and CADTH, the NHS, and the major specialty societies — cardiology (the American Heart Association, the American College of Cardiology, the European Society of Cardiology), diabetes, oncology (ASCO, ESMO, NCCN), gastroenterology and hepatology, respiratory, kidney, endocrine, rheumatology, neurology, psychiatry, sleep and headache medicine, and obstetrics (ACOG, SOGC), among the others on the approved list.

TIER 2

Systematic reviews and meta-analyses

Studies that pool and assess all the available research on a question, rather than relying on any single trial. Very reliable, and often the basis for the guidelines above.

Sources: the Cochrane Library, the US Agency for Healthcare Research and Quality, CADTH, and systematic reviews and meta-analyses indexed on PubMed.

TIER 3

Randomized controlled trials

Individual experiments where participants are randomly assigned to different approaches. Strong evidence, but a single trial can still be limited by its size or the specific group it studied.

Sources: Peer-reviewed trials indexed on PubMed. We prioritise high-impact medical journals, ranked by study design and journal tier, though smaller journals are searched too.

TIER 4

Expert organizations

Well-established bodies that translate research into practical guidance. Useful for topics where formal guidelines do not exist or are still emerging.

Sources: established specialty-society pages within the approved domains.

What we leave out

Studies published before 1998.
Studies not performed in humans.
Any source not on the approved list above, including blogs, forums, news articles and social media.

How the grade is decided

Each answer carries a plain-language grade showing how confident the research allows us to be:

Strong means guidelines, reviews and trials broadly agree.
Good means solid research supports the answer, with minor gaps.
Mixed means credible studies point in different directions.
Limited means the answer rests on weaker study types and should be treated with caution.
Insufficient means we could not find enough quality research to answer confidently.

Where an answer relies on observational, cohort or case-control studies rather than a guideline, systematic review or randomized trial, we say so directly. That kind of evidence can show a pattern, but it cannot show cause and effect as reliably.

A note on limits

Founded Health summarizes published research. It is educational information, not a diagnosis or personalized medical advice, and it cannot account for your individual history. Always check with your own doctor for guidance specific to your situation. If this is a medical emergency, call your local emergency number. There is more in what Founded Health cannot do.

Educational information only. Not medical advice, not a diagnosis, and no doctor-patient relationship is created by using this. Founded Health has not examined you and does not know their history, so its answers may not apply to you. Never delay or disregard advice from a qualified health professional because of something you read here. In an emergency, call your local emergency number.