It sounds so easy: Pop a pill (or pills) every day and enjoy radiant health. Unfortunately, our concierge doctors have to caution you that it may not be not that simple. And, according to a new study, the claimed benefits of taking supplements might not even be true.

The study, published this month in the journal BMJ, suggests that the perceived benefits of over-the-counter (OTC) vitamin and mineral supplements may largely be due to the power of the mind.

“The effect of positive expectations in those who take multivitamin or mineral supplements is made even stronger when one considers that the majority of them are sold to the so-called worried well,” lead study author Dr. Manish Paranjpe said in a statement. "The multibillion-dollar nature of the nutritional supplement industry means that understanding the determinants of widespread multivitamin or mineral use has significant medical and financial consequences,” he added.

The financial aspect is obvious. Dietary supplements are a $40-billion-a-year business in this country. And if the products don’t work as expected, that’s a huge waste of money.

The medical impact is less well known. Between 2007 and 2012, the U.S. Food and Drug Administration (FDA) received reports of more than 6,300 reports of serious adverse events linked to dietary supplements. These included 115 deaths and more than 2,100 hospitalizations.

What’s the harm in taking supplements?

This may surprise people who think that because these substances are sold over the counter they can’t do you harm. Others believe that the government wouldn’t allow their sale unless they were safe and effective. However, a 1994 law, the Dietary Health and Education Supplement Act, actually prevents the FDA from regulating dietary supplements or removing them from sale unless it can prove a supplement is unsafe.

But indiscriminate use of supplements can produce serious side effects. For example, Vitamin E and beta-carotene supplements can actually increase the chances of developing lung cancer in smokers.

St. John’s Wort is sold over the counter for mild depression. Some of its potential side effects include dizziness, sun sensitivity, insomnia, anxiety and headaches. It can also reduce the effectiveness of birth control pills and some heart medications.

Fish oil can cause nausea and diarrhea and increase the levels of LDL (bad) cholesterol. It can also increase the risk of bleeding. Some people have suffered such severe liver damage with green tea extract that they required a liver transplant.

Niacin, another popular supplement, has been shown to slightly increase the risk of death from any cause. So have calcium supplements, which one study suggested increased the risk of death from cancer when taken in amounts greater than 1,000 milligrams per day.

Little evidence for real benefits

Then there’s the question of whether these products are effective for the reasons we take them. Various studies have been performed on the efficacy of supplements in the prevention of many diseases. All have shown little-to-no benefits of dietary supplements and vitamins.

Those marketed for the prevention of cardiovascular disease (CVD) have, for example, been studied extensively. In 1996, the Physicians Health Study assigned 22,071 men to take either beta-carotene or a placebo for 12 years. They assessed the effect of the vitamin on the prevention or progression of the disease. The results showed no difference in either CVD occurrence or overall mortality.

A Women’s Health Study found a similar result when it looked at the effect of beta-carotene on 40,000 women. It found no differences in the incidence of heart disease between those taking the vitamin and those receiving the placebo.

Another study published in the Journal of the American College of Cardiology that examined multivitamins, calcium supplements, and vitamins C and D, found no measurable advantage in terms of preventing CVD, heart attack, stroke, or early death. A similar study found no CVD-associated benefits for vitamin D.

Yet the belief persists

Despite these findings, many people still swear they notice a difference in their health after taking supplements. The study this month attributes this to the power of belief. Consumers also point to studies that support their faith in these substances.

An article in Harvard Women’s Health Watch, however, explained that the benefits of supplements that often appear in some studies are based on observational research vs. clinical trials. That is, researchers ask study participants to self-report on their daily habits, vs. performing randomized controlled trials. Because observational studies don’t control for diet, exercise, and other variables, they can only suggest an association with better health benefits from particular supplements.

“People who take supplements tend to be more health conscious, exercise more, eat healthier diets, and have a whole host of lifestyle factors that can be difficult to control for fully in the statistical models,” Dr. JoAnn Manson, chief of preventive medicine at Brigham and Women’s Hospital and professor of medicine at Harvard Medical School, told the journal.

So whether you’re trying to improve your health or ward off illness, your best bet is to follow the time-honored advice: Consume a balanced diet, including fruits and vegetables, get plenty of exercise, don’t smoke, use alcohol in moderation, and avoid recreational drugs. It really is that simple.