Can too much of a good thing be deadly?

The vitamin industry is a big, multi-million dollar business, but can your daily multivitamin supplement be bad for your health? New studies reveal that even though there's a supplement for everyone, from menopause pills for women to chewable vitamins for kids, some may actually be taking years off of your life, the Daily Mail reports.

Last week, fish oil capsules were linked to prostate cancer in a study that evaluated more than 2,000 men. The men with the highest levels of the fatty acid omega-3, thought to help ease joint pain and improve overall health, were 71 percent more likely to develop deadly prostate cancer, and 44 percent more likely to develop low-grade prostate cancer.

Alan Kristal, who led the study at the Fred Hutchinson Cancer Research Centre in Seattle, told the Daily Mail that it's not just fish oil that puts people at risk.

"As we do more and more of these studies, we find high doses of supplements have no effect or increase the risk of the disease you are trying to prevent," he explained.

One out of every three people take a daily supplement, and Americans spent an estimated $20.3 billion on vitamins, herbs and supplements in 2004.

Although links to illness do not determine cause and effect, there is also little evidence to support that multivimans do any good.

"Dozens of studies of multivitamins show that they do absolutely nothing at the recommended doses," Dr. Kristal said.

In 2010, researchers from France had volunteers either take a multivitamin or a placebo pill for six years. It turns out that those who popped the vitamin pill were just as likely to suffer from heart disease or cancer as those who took the dummy pill. Previous research in 2008 involving over 200,000 people found no evidence that multivitamins prolonged people's lives, while other studies have suggested that high doses of multivitamins can do more harm than good.

If your diet contains plenty of fresh food, many researchers say that multivitamins aren't even necessary.

And although doctors have known for centuries that Vitamin C is essential for health, little evidence exists that it works as a supplement, though it can help shorten the duration of a cold.

An 11-year study published in February of more than 23,000 men found that those who take high doses of Vitamin C (around 1,000 mg) were twice as likely to develop kidney stones than the men who did not take the pills.

While the Department of Health says adults need 40 mg per day, people should keep their doses under 1,000 mg. "The effervescent vitamin drink Berocca contains 476 mg. Two doses would take you close the recommended limit," Dr. Kristal advised.

Vitamin E in high doses can also cause health risks.

It increased the risk of prostate cancer by 17 percent," Dr. Kristal said. "We don't know why. But one thing to remember is that, unlike vitamin C, it is soluble in fat and so levels build up in the body over time."

In addition, too much calcium, selenium and beta carotene can prove harmful to the body. Increased calcium doses have been linked to heart attacks in men, and high doses of selenium have been linked to type 2 diabetes. Beta ceratone can cause upset stomachs, joint pain and dizziness when taken exceedingly.

The bottom line? Researchers say to stick to safe doses recommended by doctors, and make sure to eat a healthy diet full of fresh foods, as just a glass of milk and a cup of yogurt meets our daily calcium minimum.