Consumer Reports: 10 hidden dangers of vitamins

(CBS News) Many people take vitamins, minerals  or dietary supplements because they consider them to be a safe way to stay healthy. But supplements aren't as safe as one may think, warns Consumer Reports.

In its latest investigation, the consumer advocacy magazine conducted interviews, reviewed research and analyzed side effect reports submitted to the U.S. Food and Drug Administration's adverse event reporting program it obtained through a Freedom of Information Act request.

Are supplements as "natural" as the label says? Are claims of cancer prevention all they're cracked up to be? From Consumer Reports, here are 10 surprising dangers you - and the more than half of Americans who take supplements - may want to keep in mind next time you pop open that bottle...

Consumer Reports: 10 hidden dangers of vitamins

Supplements are not risk-free

According to Consumer Reports, 6,300 people reported serious side effects associated with dietary supplements to the FDA between 2007 and April of 2012. Of those, there were 10,300 serious side effects, 2,100 hospitalizations, 1,000 serious injuries or illnesses, 900 emergency room visits and 115 deaths.

The FDA however cannot easily take supplements off the market despite receiving these reports. To date, it has banned only one ingredient, ephedrine alkaloids (pictured), after a decade-long effort during which weight-loss products with ephedra were implicated in thousands of adverse events, including deaths.

How to protect yourself:

Go to the FDA website and type in the name of the supplement you're taking to see whether it has been subject to warnings, alerts or voluntary recalls. People having a bad reaction to a supplement should tell their doctor, and also report it to the FDA's adverse event system.

Consumer Reports: 10 hidden dangers of vitamins

Some supplements are actually prescription drugs

There have been more than 400 recalls of supplements since 2008, mostly for products marketed for bodybuilding, weight loss and sexual enhancement, says Consumer Reports. Many of these recalled products have contained similar active ingredients to their prescription counterparts, such as sildenafil (Viagra) and sibutramine (Meridia weight loss drug, pulled from the market in 2010 because of heart attack and stroke risk). The FDA has received reports of kidney failure, potentially deadly blood clots in the lungs and deaths associated with supplements tainted by drug ingredients.

"A number of the spiked sexual enhancement products claim to work within 20 to 45 minutes," Dr. Dana Fabriucant, director of the FDA's division of dietary supplement programs, told Consumer Reports. "When we see a product that makes claims above and beyond what a dietary supplement might do - above supporting health - and within a time frame of a few minutes, it tips us off that we might have a spiked product."

How to protect yourself: Looking to lose weight? Try diet and exercise. Want to bulk up? Try weight training. And for those experiencing issues in the bedroom, see a doctor, since it could be caused by an underlying health problem such as diabetes, high blood pressure or kidney disease.

Consumer Reports: 10 hidden dangers of vitamins

You can overdose on vitamins

Just because it's a supplement, doesn't mean you can't overdose. Mega-doses of vitamins A, D, E and K can cause health problems, says Consumer Reports, and may interfere with other prescription medications people are taking.

Too much vitamin A (in its retinol form) may lead to liver failure or even death, while pregnant women may risk birth defects. Overdoing vitamin D intake may lead to unhealthy weight loss, bone pain, vomiting, diarrhea and muscle problems.

A vitamin E overdose may increase a person's risk of bleeding, especially for those taking blood-thinning medication, according to Consumer Reports. Too much vitamin K may harm people with kidney or liver disease. An iron overdose from supplements could damage organ function, leading to death if untreated.

It's not very difficult to take more than a recommended dose either. For example, a woman worried about her bones might take a calcium supplement, a multivitamin that contains calcium and on top of that, she might eat calcium-fortified cereal with milk. In doing so, she will quickly approach the recommended daily calcium limit of 2,000 milligrams. Too much calcium may lead to kidney stones, says Consumer Reports.

How to protect yourself:

Add up your total daily supplement exposure - from foods or vitamins - and check with the Institute of Medicine for your daily recommended intakes to make sure you're not taking too much.

Consumer Reports: 10 hidden dangers of vitamins

You can't depend on warning labels

Supplements that contain iron must carry a warning about fatal poisoning in children, but otherwise the FDA doesn't require labels on supplements. However, some companies choose to put them on anyway.

Consumer reports reviewed the labels on 14 types of supplements - 233 products in all - from stores in the New York City area, and found major inconsistencies. Some supplement labels warned against unspecified drug interactions or taking while pregnant. Others warned about taking vitamins if you have a prior medical condition - but didn't specify the condition. Some labels mentioned there were possible side effects, without even detailing which ones.

How to protect yourself:

If you're taking other medication, make sure your doctor or pharmacist knows what supplements you are taking or thinking of taking. Or visit Consumer Reports for more information on 100 common supplements.

Consumer Reports: 10 hidden dangers of vitamins

No proof vitamins cure major diseases

Stay away from dietary supplements that claim treatments or cures for disease, warns Consumer Reports, because such health claims are not allowed by the FDA. "We'd like to see those things go away," Fabricant told the magazine. "Those are a direct threat to public health."

Over the past decade, the Federal Trade Commission - the FDA's regulatory partner - has brought more than 100 legal challenges to advertising claims about the effectiveness of supplements.

How to protect yourself:

Visit reliable government websites including the FDA, the National Institutes of Health's Office of Dietary Suppplements and the National Center for Complementary and Alternative Medicine when researching supplements.

Consumer Reports: 10 hidden dangers of vitamins

Buy with caution from botanicas

Botanicas, stores that sell medicinal plants and other healing artifacts, are frequently found in many Hispanic neighborhoods in the United States. When a Consumer Reports' reporter visited several New York-area botanicas asking for advice on treating diabetes, high blood pressure and impotence, healers offered a variety of herbs and instructions. They didn't offer information on side effects or risks from taking the mystery herbs, however.

When scientists analyzed the reporter's haul, they didn't find any relevant evidence on the plants' efficacy or safety, leaving Consumer Reports concerned. Experts also questioned the supply chain used by some of the stores to obtain the herbal ingredients, which may not meet industry standards.

How to protect yourself:

Check with your doctor before taking traditional herbs and make sure you know where they came from. If cultural health practices are important to you, visit an integrative physician who combines conventional medical treatments with holistic methods.

Consumer Reports: 10 hidden dangers of vitamins

Heart disease, cancer risk reduction from vitamins remain unproven

Omega-3 pills and antioxidants may not cut heart disease or cancer risk respectively, despite the common perceptions. Recent studies not only cast doubt on the protection supplements may provide against these leading causes of death, but some suggest they may even raise risk.

Consumer Reports cites a study in the June 11 issue of the New England Journal of Medicine that looked at 12,500 people with diabetes who were at risk for heart attack, and stroke found no differences in cardiovascular death rates between omega-3-takers and people taking a placebo.

When it comes to antoxidants like those found in vitamin A, C, E supplements, a study in the May 16 issue of the Journal of the National Cancer Institute found no protective benefits against risk for prostate or gastrointestinal cancers. In fact, the reasearchers wrote: "Some clinical trials show that some of these antioxidant nutrients may increase cancer risk."

How to protect yourself

The American Heart Association says that people who have coronary artery disease - a narrowing of the blood vessels that supply blood to the heart - may still want to talk to their doctor about omega-3 supplementation based on previous research. But most people can get enough omega-3s by eating fatty fish at least twice a week. If you want to reduce cancer risk, Consumer Reports says to "lay off the antioxidant supplements" and instead quit smoking, avoid excessive drinking and eat a healthy diet.

Consumer Reports: 10 hidden dangers of vitamins

Choking, esophageal irritation

A Consumer Reports review of the FDA database found more than 900 cases of choking on supplements over the past five years.

While risk may be small, Dr. Joel Blumin of the American Academy of Otolayrngology - Head and Neck Surgery says it's a medical emergency that requires immediate intervention.

Blumin also told the magazine that pills may irritate the esophagus, creating a spasm that may cause the pill to be stuck, a sensation that feels like choking.

How to protect yourself

"Sometimes all you need is a second swallow or extra water to get the pill down," says Blumin.

What's the best way to make sure a vitamin goes down safely? Before taking a pill, moisten your mouth and throat with a swig of water. Then place the pill on the tip of your tongue, sip some water, tilt your head back and swallow. Drinking the remainder of the cup will help propel the pill down. If you frequently have problems swallowing pills, consult an otolaryngologist, also known as an ear, nose and throat doctor.

Consumer Reports: 10 hidden dangers of vitamins

"Natural" products may be anything but

Even if your vitamin contains a USDA "organic" seal, it may still have been made in a lab.

The FDA says some products only contain synthetic copies of "botanicals" which don't even qualify as dietary supplements at all.

How to protect yourself

If you choose to take vitamins, botanicals or other supplements, look for those with the "USP Verified" mark, which means they meet standards of quality, purity, and potency set by the nonprofit U.S. Pharmacopeia.

Consumer Reports: 10 hidden dangers of vitamins

You may not need supplements at all

Many nutrients can really be found in nature - and don't need a label to prove it.

Vitamin A is found in eggs, liver and whole milk but even vegetarians can get a daily dose by eating five servings of produce, including green leafy vegetables, orange and yellow fruits. Most people get enough B vitamins through eating animal-derived products (although women who are pregnant or trying to get pregnant may want to consider taking folate acid to help prevent birth defects.

Vitamin C is not proven to prevent colds and too much of it could be dangerous for people who have hemochromatosis, a condition in which the body absorbs and stores too much iron. If you get some midday sun during the warmer months and eat vitamin D-rich foods, such as fatty fish, eggs and dairy products fortified with the vitamin, you probably don't need to take a supplement, according to Consumer Reports.

Vitamin E has been linked to a slightly but statistically significant increase in death risk. Large studies have found no evidence that multivitamins improve the health of the average person.

How to protect yourself

Do you eat fruits, vegetables, cereals, dairy and protein as part of your daily diet? Consumer Reports says there's little if any additional benefits from taking vitamins.