For many parents, giving kids a vitamin is part of the daily routine. Some parents now question whether that is a good idea, because two studies published this week link supplement use in adults to prostate cancer and heart disease.

Researchers found that men who take Vitamin E have an increased risk for prostate cancer. Their discoveries were published in the Journal of the American Medical Association.

A study of older women who took daily multi-vitamins and other supplements found an increased risk of them dying from cancer or cardio vascular disease.

Dr. Cora Collette Breuner of Seattle Children's Hospital said there is some controversy about taking a multi-vitamin every day in childhood and teenage years. Breuner said a lot of kids vitamins have unnecessary additives, dyes and preservatives. But there is one vitamin that's important to give children starting at birth: Vitamin D.

"We are recommending 400 IU's of Vitamin D a day, and that goes all the way through adolescence and then we increase that to 800 IU's a day," Breuner said.

Breuner said it's important to feed your child a healthy, balanced diet but notes that many foods are also fortified with vitamins.

For example, Chocolate Frosted Mini-Wheats had 90 percent of the daily value of iron, Orange juice fortified with vitamins A, D, C and white bread had 40 percent of the recommended daily calcium intake. Doctors recommend getting those vitamins from healthy foods like fruits, vegetables, grains and proteins.

"We get into this semi cop-out position that if we give our kid a vitamin they're not going to need to finish their food or if they just want a piece of chocolate cake for dinner that's fine.  That is not a good stance to take as a parent. It isn't the same thing as eating food," Breuner said.

Breuner also advised to consult a child's doctor before giving him or her a supplement.

The American Academy of Pediatrics (AAP) does not recommend vitamin use in healthy children older than one year. In addition, overdose is more likely in 2-to 4-year-olds who may associate taking vitamins with eating candy, Breuner said.

Taken in large quantities, vitamin and mineral supplements can cause adverse effects ranging from vomiting to serious side effects, such as damage to the kidneys.

For some youngsters, pediatricians may recommend a daily sup­plement. If your child has a poor appetite or erratic eating habits or if they con­sume a highly selective diet, such as a vegetarian diet containing no dairy products, a vitamin supplement should be considered.