About
Sources and References Policy
Our articles are only as reliable as the sources behind them. Here is how we choose and cite them.
Sources we prefer
- Government and public health agencies – for example, the U.S. Centers for Disease Control and Prevention (CDC), the National Institutes of Health (NIH) and its institutes, the Office of Disease Prevention and Health Promotion, MedlinePlus, the UK's National Health Service, and the World Health Organization.
- National guidelines and consensus reports – such as the Physical Activity Guidelines for Americans, the Dietary Guidelines for Americans, and reports from the National Academies of Sciences, Engineering, and Medicine.
- Recognized medical and professional institutions – academic medical centers, schools of public health, and professional bodies.
- Peer-reviewed research – preferably systematic reviews, meta-analyses, and large, well-designed studies. We describe single studies cautiously and avoid overstating their findings.
Sources we avoid
- Marketing materials and product claims from manufacturers.
- Press releases presented without the underlying research.
- Anonymous or unattributed health claims.
- AI-generated summaries that are not verified against the original source.
How we cite
Each article ends with a numbered Sources list naming the publisher, the title of the page or paper, and a link. Links open the original source so you can read it yourself. Because public web pages move, we check links when we update an article. If you find a broken link, please let us know.
Describing evidence
We use cautious language (“may,” “is associated with”) when evidence is observational or limited, and we say so when experts disagree or when research is still developing. We do not present general guidance as a personal recommendation.