Therapies Research and Evidence: How Much Research Exists and How to Read It

Why look at research volume

How many studies exist is not the same as whether a therapy works. But a quick look at the research landscape shows where evidence is thick, where it is thin, and why some pages in this section say "insufficient evidence." This page explains who studies these approaches and shows a small snapshot of published research.

Who funds and leads US research

NCCIH is the U.S. Federal Government's lead agency for scientific research on complementary and integrative health approaches. [1] Its listed funding was $170.3 million for fiscal year 2024. [1] NCCIH says scientific research on many complementary health approaches is relatively new, so reliable information may not be available for each one. [2] Americans also spend large sums out of pocket: NCCIH reports about $30.2 billion yearly on complementary products and practices (2012 survey data). [3]

A PubMed snapshot (October 22, 2026)

We searched PubMed (the U.S. National Library of Medicine's index of biomedical articles) for each term in titles and abstracts, then narrowed to articles tagged as randomized controlled trials or systematic reviews. [4] The counts are rough: tags are applied by indexers, and some relevant papers are missed or mislabeled.

All figures above come from our search on that date. [4]

How to read the table

• More trials means more to examine, not a better result. A large body of research can show benefit, no benefit or harm.
• Quality varies. Small studies are more likely to give results due to chance. [5] Many trials of body-based or mind-body practices cannot be fully blinded. [6]
• The type of study matters. Clinical trials give the clearest information about whether a treatment is effective and safe in humans, and systematic reviews look for converging evidence across studies. [7]
• Different versions of a practice are counted together. NCCIH notes that differences in the types of yoga used in studies may make research harder to evaluate. [8]

What this shows for this section

Acupuncture has by far the most trials in this snapshot, while homeopathy has few trials relative to its total publications. We make no claim that these counts rank effectiveness. For findings, read each therapy's evidence page, such as yoga evidence by outcome, massage evidence by goal or TCM evidence by use. Other traditions, such as Ayurveda, Siddha or Kampo, are not included here because we did not run comparable searches.

Finding the studies themselves

Study records and summaries are in the Research Library. To understand a paper, use NCCIH's "Know the Science" guide and understanding evidence. To check a claim you saw, use how to evaluate a therapy claim.