The FDA, once the most respected of federal agencies, has had its effectiveness stripped away over the past decade because of budget slashing and the creeping influence of large pharmaceutical companies in its decision-making. A de-fanged FDA has been no match for greedy Big Pharma in stopping Vioxx and other questionable drugs from reaching the marketplace.

Now more than ever, you need to be your own watchdog — your own FDA — in deciding what you ingest and what you don’t. And that’s especially true when it comes to supplements, which are largely unregulated by the FDA.

Dr. Mike Roizen and Dr. Mehmet Oz suggest asking yourself the following five questions when buying supplements or food products claiming to “fortified” with nutritional or other health benefits :

1. Is this the best way to get the nutrients I need?

Here’s all most of us need to fill any gaps in our diet: a moderate-dose multivitamin, cut in half and taken morning and night, plus additional supplements for vitamin D (1,000-1,200 IU per day), calcium-plus-magnesium (600 mg calcium plus 200 mg magnesium twice a day) and B 12 (25 micrograms). If you like soft drinks, enjoy a no-calorie version once in a while, but there’s no way they can make up for nutrients you should be getting every day.

2. Does the health claim make sense?

FDA rules say products can’t claim to treat or cure diseases, but marketers are sneaky. Be skeptical. Sorry, but as of now you can’t take a “miracle” weight-loss pill and eat what you want “without worry.” And a cholesterol-lowering supplement won’t make your numbers plummet in a few weeks…

3. Can I reach the same health goal by a safer route?

Losing weight with a questionable product may bring on far more problems than the extra pounds did, especially if substances in the supplement interact with other medications you’re taking. Eating smart (lots of fruits, vegetables and fiber) and exercising regularly might take a little longer, but it won’t land you in the emergency room…

4. Is it really safe?

Don’t assume that over-the-counter drugs are harmless. Fact is, almost anything can be harmful when taken in large enough doses for a long enough time, especially when combined with other supplements or meds you may be taking.

5. Is it USP-verified?

When we … buy supplements, we look for the “USP verified” mark on the label. This means the United States Pharmacopeia, a reliable nonprofit science organization, has tested and verified its contents. It’s the best evidence that a supplement actually contains the ingredients listed on the label, in the quantities claimed, and that it doesn’t contain contaminants. You can find a list of supplements tested by the USP at www.usp.org.