Too much of this will kill you

It has long been thought that certain foods and vitamins improve health, but recent research finds that some of these foods may actually do more harm than good.

Take folate, for example. Found naturally in foods like asparagus and dark leafy greens, it's important to increase your levels of folate while pregnant. However, a new study out of the University of Colorado Cancer Center concludes that, when the elderly consume too much folic acid -- the synthetic form of folate found in vitamin supplements -- it can actually increase their chances of developing colon cancer.

Beta-carotene

Here, a young mandrill enjoys a carrot on March 16, 2015 at a zoo in Dresden, Germany, blissfully unaware of the risks linked to too much beta-carotene intake.

Luckily, eating too many carrots probably won't harm this primate; but a new study out of the University of Colorado concluded that when smokers consume too much beta-carotene, it can increase their risk of lung cancer.

Vitamin E

Likewise, the University of Colorado 2015 meta-analysis of more than two decades worth of research on more than 300,000 people found that consuming too much Vitamin E can increase your risk of developing prostate cancer.

Selenium

Healthy doses of selenium can help your thyroid function properly; but if you're a person at risk of skin cancer, you might want to stay away from foods like oysters, tuna and Brazil nuts... or at least, enjoy them in moderation.

Too much selenium can actually increase your chances of developing certain types of skin cancer.

Too much of a good thing

Doctors have traced a man's kidney failure to his habit of drinking a gallon of iced tea each day.

Black tea has a chemical called oxalate, known to cause kidney stones or even kidney failure in excessive amounts.

But tea isn't the only everyday ingestible that could kill you.

Black licorice

These licorice-clad models may look delicious, but beware.

According to the Food and Drug Administration, people 40 or older who eat 2 ounces of black licorice a day for at least two weeks could end up in the hospital with an irregular heart rhythm or arrhythmia.

Black licorice

The reason? Black licorice contains the compound glycyrrhizin, a sweetener that comes from licorice root.

Glycyrrhizin can cause potassium levels in the body to fall.

Water

Water is the stuff of life, of course. That said....

Water

In 2007, a woman died after drinking too much water as part of a radio station giveaway contest.

Drinking large quantities of water rapidly can throw off the body's balance of electrolytes, causing brain swelling and leading to seizures, coma, or even death.

Salt

Scientists say a "surprisingly small amount" of salt can prove fatal. As little as 2 teaspoons of table salt can raise sodium in the body to dangerous levels.

In one case cited in medical research, a 45-year-old woman with an eating disorder became comatose and died after consuming 3 or 4 tablespoons of salt.

Salt

In March 2015, New York mom Lacey Spears, left, was convicted of killing her 5-year-old son, Garnett, by putting salt into his hospital feeding tube.

Caffeine powder

A few cups of coffee? No problem. But it is possible to OD on caffeine.

Beware of caffeine powder, which is sometimes promoted to give your workout a kick...

Caffeine powder

Logan Stiner, 18, of LaGrange, Ohio, died of a caffeine powder overdose in May 2014, an autopsy found.

He was found to have more than 70 micrograms of caffeine per milliliter of blood in his system. Only 50 micrograms is considered a lethal dose.

Energy drinks

Energy drinks are wildly popular, but drinking too much has been blamed for the deaths of several teens.

Energy drinks

A lawsuit filed by the family of Anais Fournier, 14, says the girl died of cardiac arrest after drinking two, 24-ounce cans of Monster energy drinks in a 24-hour period. A trial date is pending in that case.

A lawsuit related to another death, that of Alex Morris, 19, was recently "resolved," according to attorneys representing Morris's family. Morris died of cardiac arrest in 2012 after consuming at least two cans of Monster energy drink.

Liver

Some people love the taste of liver.

But overindulging in the livers of certain animals may not be wise.

Liver

There's a reason why the Inuit shun the liver of polar bears and bearded seals; experts estimate that a mere 500 grams of polar bear liver has enough vitamin A to kill a human. Other animal livers, such as moose and seal, also contain a very high amount of vitamin A.

The good news: Beef livers are considered much safer when it comes to vitamin A levels.