Elderflower syrup. Turmeric milk. Cannabidiol oil. Natural health trends come and go. So how should you decide which ones to chase?

Part of the National Institutes of Health, the agency is devoted to determining what complementary and alternative medical approaches are useful and safe — and which ones aren’t.

The NCCIH’s website offers a trove of research-based information. It can help you find and evaluate online resources about health approaches, understand the results of medical studies and learn more about how dietary supplements can interact with medication.

One of the agency’s strongest messages is that “natural” isn’t necessarily synonymous with healthy. It can be tempting to pursue the latest health fad, but claims of benefits such as better sleep, weight loss and vitality aren’t necessarily based on solid research. According to the Pew Research Center, about a fifth of Americans say they’ve tried alternative instead of conventional medicine.

Dietary and herbal supplements aren’t regulated as stringently as pharmaceuticals, and the Food and Drug Administration can take action only against contaminated or unsafe products once they’re already on the market. Some alternative health practices simply aren’t effective. For example, “There’s little evidence to support homeopathy as an effective treatment for any specific health condition,” the site says.

So how can you spot a treatment worth pursuing? Ask yourself whether scientific evidence backs up the claims, the NCCIH suggests, and consider the source. The agency also warns against approaches that promise quick fixes or miracle cures. If it seems too good to be true, it probably is.

Need more help? The website at nccih.nih.gov has you covered with an extensive database of products and complementary health approaches, from acupuncture to zinc. Each entry summarizes what’s known about the product or approach, discusses safety and provides links to scientific and medical literature.