5 Popular Supplements Scrutinized

Last Editorial Review: 8/30/2005

There are a lot of unknowns about some of the most used supplements

By Michael Smith, MD
WebMD Weight Loss Clinic - Feature

Reviewed By Cynthia Haines, MD

When it comes to supplements, "buyer beware" only goes so far these days. Patients have been interested in supplements for years, but doctors have been slow to recommend them. Don't be too hard on doctors. It's ingrained in us to look for strong evidence that a treatment works without doing harm. That's a good thing.

But as more research comes out, more doctors are getting on board. But we still know very little about supplement effectiveness, and what we do know doesn't look all that great.

So, if you're going to take supplements, which ones are most likely to give you the effect that you're looking for without causing you harm?

Here's a summary of what we do -- and don't -- know about five of the most popular supplements based on current research.

Glucosamine and Chondroitin

These two supplements -- both components of natural joint cartilage -- have been fairly well-studied in the treatment of osteoarthritis -- also called degenerative arthritis.


  • It may improve pain, mobility, and quality of life for people suffering from osteoarthritis.
  • These supplements may slow progression of osteoarthritis by controlling inflammation. They are believed to stimulate the growth of cartilage cells which have been broken down in this arthritis. Chondroitin may also provide cartilage with strength and resilience.
  • They are generally safe.


  • Derived from shellfish so people with shellfish allergies should check with their doctor first
  • May be linked to higher blood sugar in people with type 2 diabetes (glucosamine only)

There are many different brands of glucosamine and chondroitin. Do your research and find a reputable brand. Take it for at least four to eight weeks before deciding if it works for you.


If bigger muscles are what you're looking for, creatine may be the supplement for you.


  • Can help build muscle size and even improve athletic performance -- at least a little -- when combined with exercise


  • Unknown effects in kids
  • Can build up in the bloodstream and may cause kidney and liver damage
  • Linked to muscle cramps when taken immediately before exercise or when exercising in intense heat

A few years back, St. John's wort was looking like one herb that might effectively treat a common medical problem -- depression.
But as more research was unveiled, a different story unfolded.

What we don't know:

  • How creatine works. Theories range from increasing water content in the muscle -- thus increasing muscle size -- to improvements in energy production. Naysayers believe the increase in muscle size from water buildup only encourages athletes to work harder -- thereby improving performance.

Creatine does appear to increase muscle size -- at least in young men who hit the gym pretty hard -- but the question remains if it's from the creatine or just harder work.


DHEA (dehydroepiandrosterone) is a naturally occurring hormone in the body produced by the adrenal glands, which are located on top of the kidneys. DHEA supplements are made from plant chemicals.


  • There are some positive effects, but mostly in people who have certain conditions, such as lupus and advanced HIV.
  • It might help fight heart disease. One study shows an improvement in blood vessel function and in the body's ability to handle sugars -- both factors in the development of heart disease. But some studies have suggested an increase in heart disease linked to DHEA so more research is needed.
  • Might improve sexual spontaneity, arousal, and enjoyment for women. Sexual problems have been linked to a fall in certain male-type hormones (androgens), which are derived from DHEA.


  • There are uncertain benefits for the average, healthy person.
  • There are uncertain effects on memory and muscle-building.
  • There are potential increased risks of breast and prostate cancers because, in the body, DHEA is converted to estrogen and testosterone, which feed these cancers and can help them grow.

Since DHEA levels fall as we age, the theory is that DHEA supplements might help fight the effects of aging. But there's still way too little research at this point to claim much of anything.


Red, white, Korean, Siberian... ginseng comes in many varieties and is accompanied by even more health claims.


  • It might help people with diabetes control their blood sugar when used with conventional treatment.
  • There is significant improvement in erections with Korean red ginseng -- even rivaling impotence drugs such as Viagra.
  • There are few side effects in healthy people with regular doses of ginseng.


  • It may decrease the effectiveness of the blood thinner Coumadin.

What We Don't Know:

  • The effects of ginseng on the immune system's ability to fight off cancer and infection are uncertain.
  • Cancer effects are unknown but one study showed white ginseng -- but not red -- decreased recurrence of intestinal cancer, while another showed red ginseng powder decreased recurrence of a different type of cancer -- stomach cancer.
  • There is an increased number and activity of infection-fighting immune cells with both Korean and Siberian ginseng, but no evidence of actual decreased infections.
  • There are mixed study results for memory- and energy-boosting abilities with ginseng.

A fair amount of research has been done on ginseng -- looking at many different possibilities -- but so far, very few of them -- if any -- have produced conclusive results.

St. John's Wort

A few years back, St. John's Wort was looking like one herb that might effectively treat a common medical problem -- depression. But as more research was unveiled, a different story unfolded.


  • It is possibly effective in treating mild to moderate depression -- maybe even as effectively as prescription antidepressants and possibly with fewer side effects. However, recent studies show that St. John's Wort is of no benefit in treating major depression of moderate severity. More studies are needed to see whether it really has much antidepressant effect at all.
  • It might help obsessive-compulsive disorder and even severe PMS.


  • It is linked to potentially deadly drug interactions. Researchers discovered that St. John's Wort decreases the effectiveness of some lifesaving drugs -- including cancer chemotherapy drugs, medications to fight HIV infection, and drugs, such as cyclosporine, to prevent organ rejection after a transplant. And a recent study even showed the herb likely interferes with some 50% of all over-the-counter and prescription medications.

Preliminary studies have show that St. John's Wort may work by preventing nerve cells in the brain from reabsorbing the chemical called serotonin, or by reducing levels of a protein involved in the body's immune system functioning. The take-home message so far with this supplement's effectiveness is we really don't know. But we do know it could be potentially very dangerous in anyone taking lifesaving medications.

And always keep in mind that we still know relatively very little about all of these supplements. Don't assume they are natural and harmless. Before venturing out, it's best to discuss these and other supplements with your doctor -- especially if you are on other medications.

Originally published July 26, 2004.

Medically updated August 2005.

SOURCES: WebMD Medical News: "Glucosamine Ups Ibuprofen's Pain Relief." WebMD Medical News: "Glucosamine Stops Knee Arthritis in Women." WebMD Medical Reference in collaboration with The Cleveland Clinic: "Dietary Supplements for Treatment of Arthritis." WebMD Medical News: "Whey Protein Plus Creatine Boosts Strength." Rawson, E. Journal of Strength Cond Res, February 2004; vol 18: pp 162-167. Kreider, R. Molecular Cell Biochemistry, February 2003; vol. 244: pp 89-94. WebMD Medical News: "Supplement May Be Linked to Prostate Growth." WebMD Medical News: "DHEA May Fight Heart Disease, but How?" WebMD Medical News: "Hormone DHEA Helps Some Women Feel Better, Enjoy Sex." WebMD Medical News:"DHEA Supplement Linked to Heart Disease." WebMD Medical News: "Ginseng a No-No for Patients on Coumadin." WebMD Medical News: "Ginseng May Enhance Immune Function." WebMD Medical News: "Ginseng May Help Treat Diabetes." WebMD Medical News: "Natural Sex Boosters Gaining Ground." WebMD Medical Reference in collaboration with The Cleveland Clinic: "St. John's Wort for Treating Depression." WebMD Medical News: "St. John's Wort Helps Beat the Blues." WebMD Medical News: "St. John's Wort Depletes Cancer-Fighting Drug." WebMD Medical News: "St. John's Wort Affects Other Drugs." WebMD Medical News: "St. John's Wort Reduces Chemotherapy Effects." WebMD Medical News: "St. John's Wort Interferes With Lifesaving Drugs."

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