(KMOV)- A doctor from Harvard is saying not only do multi-vitamins not work, they might even cause health problems.

Doctor Harvey Simons points to research that shows they don't protect against heart disease or cancer.

Other studies suggesting high amounts of some vitamins might actually raise the risk of certain cancers.

Doctor Simon said healthy adults only need a small amount of vitamins that come from foods.

But many experts disagree saying multivitamins are beneficial, and vital for pregnant women, senior citizens and anyone with deficiencies.