Dr. Adam: The vitamin and supplement industries are enormous. I don’t want them to get annoyed with me, but the reality is that if you eat a well-balanced diet with fruits, vegetables, protein, dairy and whole grains, you don’t need to take a multivitamin. This has been proven over and over again.

Though there are legitimate diagnoses of people who have multiple vitamin deficiencies, they are rare. Yet 70 percent of Americans over age 65 regularly take one or another daily multivitamin or mineral supplement. People often call me saying, “Adam, I was just watching an infomercial for an amazing supplement. It costs only $60 a month, and it’s guaranteed to help me sleep better and feel less stressed out.” When I hear this sort of endorsement, I’ll usually suggest an alternative and say, “Well, do you think going for a walk outside would make you feel better too?”

Although you’re wasting money, it’s unlikely you’ll get into any health trouble by taking these supplements. The joke is that many multivitamins are a mile wide and an inch deep. Meaning, if you look at the ingredients, a daily dose of a multivitamin typically contains 25 to 40 vitamins, but each one is in a very small amount.

Legitimate vitamin and mineral deficiencies come with specific medical signs and symptoms that may include hair loss, splitting nails, bleeding gums, cracks in the side of the mouth, muscle cramps or weakness. Your doctor can detect a deficiency by taking a careful medical history along with a physical exam, then following up with a blood test.

I don’t think it’s unreasonable at the time of your doctor’s visit to ask, “Are there any vitamins I should be taking?” That’s a great question to stimulate your doctor to be sure your vitamin D (frequently low in older adults), vitamin B12 and iron levels are checked—or to consider other possible deficiencies.

Iron and B12 deficiencies can lead to anemia. Though vitamin B12 and iron are two separate nutrients, they work together to produce healthy red blood cells. Anemia is not unusual among my older patients. Iron is difficult to absorb, and older patients who’ve decreased the amount of food they eat may have trouble absorbing iron.

People who follow certain dietary programs—for example, vegans or vegetarians—could also be at risk for iron-deficiency anemia. I’ve had patients who have given up meat, fish and chicken become iron-deficient. This condition can often be remedied simply by eating iron-rich foods. There are plenty of choices, including dark green vegetables such as spinach and kale, fortified cereals, oats and lentils, to name a few.

It’s true you can get too much of a good thing. Some vitamins can be toxic in doses larger than what’s recommended. The vitamins A, K, E and D are fat-soluble, which means they are stored in our liver and fatty tissue. High amounts can cause problems.

Vitamin E can interfere with blood clotting, and I’ve seen people who take too high a dose end up with a bleeding problem. For this reason, doctors instruct most people having surgery not to take supplements two to three weeks before the operation.

The bottom line? In most cases, multivitamins are unnecessary. If you’re eating a balanced diet, you’ll absorb more than enough nutrients—and you can take the need for a daily multivitamin off your plate.