Research Methodology

We search PubMed/MEDLINE and the Cochrane Library for systematic reviews and trials, and check clinical guidelines and public-health sources such as the NIH Office of Dietary Supplements, MedlinePlus Genetics, the CDC and the Dietary and Physical Activity Guidelines for Americans. Key studies are summarized in our Research Center.

We start from the top of the evidence hierarchy — systematic reviews, meta-analyses and randomized trials — and work down to cohort, laboratory and pilot studies only when better evidence doesn't exist. We look for consistency across studies, the size of the effect, whether findings apply to healthy adults, and who funded the research.

Strong: Consistent findings from multiple large studies, meta-analyses and/or randomized trials.

Moderate: Supportive evidence with some limitations — smaller trials, mostly observational or mixed results.

Emerging: Early, promising or mixed evidence. Worth watching; not yet proven.

Limited: Little high-quality human evidence for general wellness use.

Wellness genetic results describe tendencies, not diagnoses. We explain what a variant is associated with, how common it is, how strong the evidence is and which blood markers or professional conversations can confirm how your body is actually working. We follow professional guidance, including the ACMG's position on MTHFR testing.

The Biological Age Calculator adjusts your chronological age up or down based on lifestyle factors with well-studied links to longevity — smoking, physical activity, sleep duration, alcohol, body-mass index, diet quality and stress — weighted by the relative size of those associations in large cohort studies and meta-analyses. It produces an educational estimate, not a clinical epigenetic or blood-based biological-age test.

The Wellness Assessment and Wellness Type Quiz score your answers in your browser using transparent point systems. They show patterns and priorities; they don't diagnose anything.

State, metro and city guides combine public reference data (coordinates, approximate elevation, climate classification, notable public amenities) with values we calculate from that data — for example, shortest and longest day length from latitude using standard solar-declination formulas, and an estimate of the winter months when UVB is too weak for meaningful vitamin D production, based on published latitude research. Guidance is then matched to each location's climate and geography.

Science changes, individual responses vary and no website replaces a clinician who knows your history. We update pages on the schedule in our content review policy and welcome corrections.