How to Read Health Information: A Guide to Judging Studies and Claims

To read health information well, check who is making the claim, whether the study was planned and registered, what it actually measured, and how big the effect really is. This guide takes you through those checks one step at a time.

Maybe it started with a headline that said a food or supplement was “linked to” sharper focus, a friend’s post, or a sales page full of percentages. You want to know whether it holds up before you spend money or change anything.

That instinct is worth trusting. Health information is often written to get attention, and the details that matter are usually in the study record, the numbers and the label rather than the headline.

Step 1: Know what kind of source you are reading

A health guide is a page that explains a condition, a habit or a product in plain language so you can decide what to do next. Headlines, sales pages and guides are written for different reasons, so start by asking which one you have.

Your reading ability changes how much of a source you can take in. A JAMA review of brief literacy screening questions found that asking “How confident are you in filling out medical forms by yourself?” was moderately effective at identifying limited literacy, with answers of “a little” or “not at all” the strongest signal. This is a screen, not a diagnosis, so if it fits you, ask for a plain-language summary or go through the material with a clinician.

Once you know the source type, the next question is whether the study behind it was planned in advance.

Step 2: Find the study record and check that it was planned

Look for the study’s registration number first. Then compare what the registry record promised with what the article reports, because a plan written before the work is easier to trust than one written after the results are in.

For more help, read the Study Status vs. Posted Results guide and the registration number guide.

With the record in hand, check who the study actually included and what it was built to measure.

Step 3: Check who was studied and what was measured

A result speaks first to the people who were in the study. Look at who could join and who was kept out, then find the main outcome the trial set out to measure.

Reviews that combine several treatments need extra care. A 2023 mini-review on network meta-analysis explains how these comparisons are built from direct and indirect evidence. Registry studies, which record outcomes in everyday care, are observational and can complement randomized trials, according to a review of the AHRQ registry guide.

Read the inclusion and exclusion guide to see whether people like you were in the study, and the primary outcomes guide to see what the trial was built to measure.

Once you know who was studied, the numbers are where most headlines go wrong.

Step 4: Turn the numbers into plain meaning

A claim can sound large in relative terms while the actual change for a person is small. Ask for the absolute number, the starting risk and the range around the estimate, not only the headline percentage.

The confidence intervals guide shows how to read the range, and the relative and absolute risk guide explains why both numbers change the meaning of a headline.

Numbers also show up on everyday labels, which is the next place to check.

Step 5: Read food and salt labels with the same care

On a label, the amount per serving and the unit matter more than the name on the front.

The salt labels guide explains that unit difference, and the sea salt and table salt guide compares the two on taste, cooking and health points. If you are considering a salt substitute, the potassium salt substitutes guide covers why it is not a universal swap.

Supplements and products need a different set of checks, because the label is only part of the story.

Step 6: Check supplements and products before you pay

When a product promises brain or general health benefits, the maker’s statement is the maker’s statement, and you should read it as that. The safety record is often thinner than readers expect. A 2023 narrative review reported 79,071 dietary supplement adverse event reports made to the FDA’s Center for Food Safety and Applied Nutrition between 2004 and 2021.

A 2017 systematic review looked at 26 published supplement studies of heart rhythm effects, with sample sizes from nine to 206 people. Most were well performed, but more than 30% showed some ECG change, which the authors said supports continued safety assessment.

Compare the research dose with the label using the supplement dosage guide, and read the NeuroLift guide for what that product’s maker says it does.

Once you have checked the product, decide what your next step should be.

Step 7: Choose your next step

Most readers do best by taking what they have learned to a clinician rather than buying something first. If a concern involves substance use, the program guide below describes one type of outpatient care.

Your next step

1. Write down the claim and who is making it.
2. Find the registration number and compare the plan with the published result.
3. Ask what the result was compared with, and who was in the study.
4. Check the absolute numbers and the range, not only the headline percentage.
5. Compare the label amounts, using the same units.
6. Take the question to a clinician or pharmacist before any new supplement, especially if you take prescriptions.

Every guide on this topic

Reading studies and registries

• Crossover CBD Trials: Washout Period
• Study Status and Posted Results
• Correlation and Causation in Health Headlines
• Clinical Trial Status Labels
• Study Funding and Conflicts of Interest
• Systematic Review Protocols
• Primary Outcomes and Secondary Outcomes
• Adverse Event Tables in Clinical Trials
• Preprints, Peer Review, and Published Papers
• Inclusion and Exclusion Criteria
• Systematic Reviews and Meta-Analyses
• Clinical Trial Registration Numbers
• Randomized Trial Abstracts: Primary Outcome and Time Frame
• Per-Protocol and Intention-to-Treat Analysis
• Active Comparator and Placebo Trials
• Clinical Study Participant Flow and CONSORT Diagram
• Clinical Trial Protocol Amendments

Numbers and risk

• Confidence Intervals in Health Research
• Relative and Absolute Risk in a Trial
• Absolute, Relative, and Baseline Risk: A Reader Worksheet

Food and salt labels

• Salt Labels: Grams and Sodium Milligrams
• Sea Salt vs Table Salt: Taste, Cooking, and Health
• Sea Salt vs Himalayan Salt: Labels and Safety
• Salt With the Least Microplastics: Study Guide
• Potassium Salt Substitutes

Supplements and products

• Supplement Study Dosage: Compare Research and Label
• NativePath Native Creatine: Price and Safety
• NeuroLift Supplement: Does It Work?
• Lion’s Mane for Brain Fog: Research, Doses, Safety
• Lion’s Mane for Brain Fog
• Lion’s Mane Medication Interactions Checklist
• Loti Labs Peptides: Ingredients, Amounts, Research
• CBD Product Studies: Route and Formulation Matter
• CBD Complaint Pages, Billing, and Health Claims
• FocusMax Price, Shipping and Refund Guide
• Henry Meds Reviews, ED Price and Safety
• Undecylenic Acid for Nail Fungus: Safety and Options
• Honey Trick for Erectile Dysfunction: Safety
• Kratom and Opioid Receptor Binding Explained
• Do Anti-Snoring Mouthpieces Really Work?
• Reduce Belly Fat in Seven Days: Is It Realistic?

Care and next steps

• What Is Intensive Outpatient Program (IOP) Addiction
• How to Improve Memory and Focus

Med Clin Res is a publication for education. It does not replace care from a qualified professional.

By MedClinRes.org Editorial Team