As more aging adults consume supplements, an increasing number of myths have also begun to circulate online. For starters, many people who think that a specific supplement to aid an ailment coupled with a healthy diet provides adequate nourishment for the body. But depending on a few factors, that may or may not be true.

Here’s the truth about that belief, plus 4 other commonly believed supplement myths:

1. Eating a healthy diet means you don’t need a multivitamin

If you think getting all your fruits and veggies is enough to nourish your body, you’re overlooking one important fact: A plant is only as nutritious as the soil in which it was grown. It doesn’t matter how much produce you’re eating if your fare is grown in nutrient-poor soil. And the unfortunate truth is that the nutrient content of our soil— and thus our crops— has been steadily declining for decades.

Today’s population faces another barrier to nutrition that previous generations haven’t: toxicity. In the United States, an astonishing 84,000 synthetic chemicals are manufactured or processed today, and about 1,000 new chemicals are introduced each year.

2. Supplements can’t help relieve stress

Today’s 24-hour, information-saturated, digitally connected way of living is a recipe for chronic stress. Various burdensome demands are placed on us, all of which we feel must be addressed immediately.

Stress may seem insignificant. But it’s killing us, literally. A landmark study published in 1999 in the Journal of the American Medical Association found a link between chronic stress and a higher risk of mortality in older adults.

Thus, if you have daily stress, a strong case can be made for supplementing with a daily multivitamin— even when you follow a healthy diet.

3. ‘Suggested dose’ is just a suggestion

Just about everything we consume or apply— from prescription drugs and dietary supplements to face creams and skin serums— has a specific amount that maximizes benefit and minimizes risk.

Taking less than the suggested dose of a supplement is probably a waste of money, as there’s very little chance that you’ll experience any benefit. However, taking more than suggested can increase your risk of developing side effects, and that’s why it’s important to take the amount specified on the label.

But there’s a caveat to this myth. Some multivitamins are actually under-dosed. They are formulated based on the Recommended Daily Intake or Recommended Daily Allowance (RDI/RDA). Both of the dosing systems are too low— as they were designed during World War II to protect the public against vitamin and mineral deficiencies. Instead, there’s a better, more optimal dosing system called the Ideal Daily Intake, or IDI.

The IDI is an average of the doses of all vitamins and minerals that pertains to when a clinical benefit can be seen. Take, for instance, vitamin C: The RDI/RDA for this vitamin is between 50 and 100 mg/day. At this dose, you won’t develop scurvy, a disease that results from vitamin C deficiency. But what about all the other health benefits attributed to vitamin C, like improved cardiovascular health? Based on the vitamin C studies published within the last 10 to 15 years, the ideal daily dose starts at 500 mg/day.

4. Everything you need to know is on the label

Although the Food and Drug Administration (FDA) is responsible for ensuring proper labeling, if you want to be absolutely sure that the supplement or multivitamin you’re taking is the right fit for you, I’d advise calling the manufacturing number on the back of the label.

Ask the manufacturer’s representative if they’ve tested the product and can provide proof of its claims. You can specifically ask for a Certificate of Analysis. If they can provide such proof, then that builds confidence that product you’re about to purchase contains what the label says it contains and that it’s the best option for your nutritional needs.

5. Miracle cures exist

That miracle cures are available is another myth that needs to be put to rest. Good companies producing quality supplements don’t have to stoop to this level to get you to buy their products.

A supplement formulated with quality nutrients and backed by rigorous published science is all that’s needed. Supplements, when combined with a healthy diet and exercise, can play a role in helping you stay healthy.

Michael A. Smith, MD is the author of The Supplement Pyramid: How to Build Your Personalized Nutritional Regimen. He is also host of Healthy Talk on www.RadioMD.com and Senior Health Scientist for the Life Extension Foundation.