its main ingredient is a vitamin lleded niacin, which raises so- called good cholesterol, or h.d.l.otaptive also contains a drug to reduce side effects. while tredaptive is not available in the u.s., over six rillion prescriptions are written each year for niacin o rne to raise h.d.l it was dped doing so would reduce heart attacks and strokes. the study showed it did not prevent those problems. cardiologist dr. steve nissen of nde cleveland bill clintonic has prescribed in niacin for years. >> it raised the good cholesterol. it lowered the bad cholesterol. it didn't improve clinical outcome. that is a stunning finding. >> reporter: more than 25,000 rttient as high risk for heart problems took part in the study. besides being ineffective at preventing heart attacks and strokes, tredaptive caused significant side effects. merck, the maker of tredaptive, would not specify what those side effects were. osey recommended that no new oatients start taking the drug ut stopped short of saying current patients should come off it. >> it is an agonizingly difficult question that have tians arou

niacin failed a large study and is said to have harmful side effects. fects. my spaghetti.dic levels in some foods can cause acid erosion. the enamel starts to wear down. and you can't grow your enamel back. i was quite surprised, as only few as four exposures a day what that can do to you. it's quite a lesson learned. my dentist recommended that i use pronamel. because it helps to strengthen the enamel. he recommended that i use it every time i brush. you feel like there is something that you're doing to help safeguard against the acid erosion. and i believe it's doing a good job. and how much rain can you et today.... lawrence karnow is tracking it on hi-def doppler. white-out conditions are stranding people out in the midwest. how that may affecy area travelers who are tryio go home for the holidays. he says, does this rock your faith in god and i said - absolutely not... newtown pays its final resp to the victims of the school shootings. this morning, a moment of silenc, >>> here's a look at the weather in some cities around the country. in washington, partly sunny, 48

a third of us take a multivitamin, d, b, niacins but research shows there's truth behind the pills.tor segal, good, bad? when you take it in the morning, you're like okay, i did the right thing. it's got that long list. i don't know what half the stuff is. >> before i vote i want to tell you it's an unprecedented study. very expensive. over 14,000 physicians were followed over ten years. we say give one a pill, don't give the other one a pill. that's how this was done. 14,000 of them, half got a multivitamin, the other half didn't get it. it was randomized, nobody knew who got what. they found over more than a decade there was an 8% decrease in the amount of cancer in the group that got multivitamins. the best study done. >> wow. >> the two groups that didn't show a change, prostate cancer, colon cancer wasn't diminished. physicians are more responsible in terms of reporting medical problems. the other thing is how many of those physicians have nutritional deficiencies and how many didn't? the holy grail is finding out whether it corrects a deficiency. a problem with vitamin e, it s