The supplement market is booming. More than half of adults in the United States use vitamins, botanicals and other natural medicines to treat or pre-vent disease, spending $28 billion on them annually, according to Consumer Reports. Not surprisingly, products that promote joint health are top sellers.

Unfortunately, research hasn’t kept pace with consumer demand. Until fairly recently, “most of the scientific world was against most supplements,” says Gladys Block, PhD, professor emerita of public health nutrition at the University of California, Berkeley, so supplements were ignored by researchers. But, she adds, attitudes have changed in the past 15 years.

That’s good news because it means more natural medicines are being put to the test in well-designed clinical trials. The recommendations in this guide reflect findings from the best of those studies.

Learn about the top  supplements for osteoarthritis (OA) and rheumatoid arthritis (RA) – some of which have proven effective for both diseases, and some of which work for other conditions, too.

BEST FOR OA

SAM-e (S-adenosylmethionine)

WHAT IT IS: The synthetic form of a chemical found in all human cells

HOW IT WORKS: SAM-e is a natural analgesic and anti-inflammatory and may stimulate cartilage growth by signaling production of cartilage proteins. It also affects neurotransmitters such as serotonin.

STUDIES: Equivalency trials have shown that SAM-e relieves OA symptoms as effectively as nonsteroidal anti-inflammatories (NSAIDs), with fewer side effects and more prolonged benefit. A 2004 University of California, Irvine study found SAM-e equal to the prescription drug celecoxib (Celebrex) and a 2009 study found it comparable to the NSAID nabumetone.

HOW MUCH: Capsules (preferably in blister pack): 600 to 1,200 milligrams (mg) daily in three divided doses for OA; 200 to 800 mg twice daily for fibromyalgia; 800 to 1,600 mg twice daily for depression (but talk to your doctor if you have bipolar disorder). Taking with vitamin B12, B6 and folate improves absorption.

Boswellia serrata (Indian frankincense)

WHAT IT IS: Gum resin of the boswellia tree

HOW IT WORKS: Boswellic acids – the active components – have strong anti-inflammatory and analgesic properties. They also may help prevent cartilage loss and inhibit the autoimmune process, making boswellia a potential therapy for RA, too.

STUDIES: A 2008 study in India, where boswellia is a traditional remedy, found that a supplement called 5-Loxin significantly improved OA pain and function within seven days and slowed cartilage damage after three months.

HOW MUCH: Capsule or tablet: 300 to 400 mg three times daily. Look for 60 percent boswellic acids.

Capsaicin (Capsicum frutescens)

WHAT IT IS: The active, heat-producing component in chili peppers

HOW IT WORKS: Applied as a topical cream, gel or patch, capsaicin temporarily reduces substance P, a pain transmitter.

STUDIES: Many studies have shown that capsaicin effectively reduces pain from OA. In a 2010 study published in Phytotherapy Research, joint pain decreased nearly 50 percent after three weeks’ use of 0.05 percent capsaicin cream.

HOW MUCH: Most capsaicin products contain between 0.025 and 0.075 percent concentrations. Apply regularly three times a day.

NOTE: Studies show capsaicin may help reduce pain in RA and improve grip strength in fibromyalgia.

Turmeric/curcumin (Curcuma longa)

WHAT IT IS: An ingredient in many curries and often used in ayurvedic medicine, turmeric is the root of a plant in the ginger family. Curcumin is a key chemical in turmeric.

HOW IT WORKS: Curcumin blocks inflammatory cytokines and enzymes, including cyclooxygenase-2 (COX-2), the target of celecoxib.

STUDIES: A 2010 clinical trial found that a turmeric supplement called Meriva (standardized to 75 percent curcumin combined with phosphatidylcholine) provided long-term improvement in pain and function in 100 patients with knee OA. In a small 2012 pilot study, a curcumin product called BCM-95 reduced joint pain and swelling in patients with active RA better than diclofenac sodium did.

HOW MUCH: Extract, which is more likely to be free of contaminants, or capsule: 500 mg two to four times daily for OA; 500 mg twice daily for RA. “Curcumin makes up only about 2 to 6 percent of turmeric, so be sure to check the standardized amount of curcumin,” says Randy Horwitz, MD, medical director of the University of Arizona Center for Integrative Medicine in Tucson.