Going to the store to pick up your monthly supply of vitamins or dietary supplements? One nutritionist says you might be wasting your money.

It will prevent deficiency, but it's not going to make up for a lot of the chronic disease risks and those sorts of things," said Brian Lindshield, who is a Kansas State University nutritionist.

Lindshield, who researches supplements to see if they contain what's on the label, says you aren't always buying what you think. The Food and Drug Administration doesn't regulate supplements the same way they regulate drugs, so the claims of health benefits or weight loss aren't always proven.

If you are purchasing supplements, here's what to look for: Lindshield says the more descriptive the label, the better.  He also says while you may not want to pay more for your supplements, you'll probably get a better product.

"Probably don't buy the cheapest one available because if they are cutting corners to get their price really cheap, they probably are not going through the same amount of standards that the more expensive ones are," he said.

Some supplements are true to their word. Lindshield's research found that supplements that may prevent prostate cancer did contain the ingredients they claimed.

Meantime, Consumer Reports' medical experts says if you do take supplements, there are three you should never take:  

The first one is Kava, taken to help relieve stress and anxiety.  Consumer Reports says it's been linked to liver damage, including cirrhosis and hepatitis.

The second one is Yohimbe. It's prescription form is used under close medical supervision to treat erectile dysfunction.  But Consumer Reports says it's risky to use the versions found over-the-counter because the ingredient can cause problems, including high or low blood pressure and rapid heart rate.

The third supplement is Aconite, taken to relieve inflammation and joint pain. Consumer Reports says it can cause nausea, vomiting. low blood pressure, respiratory system paralysis, heart-rhythm disorders, and even death.

Read Consumer Reports' 10 surprising dangers of vitamins and supplements.