Had a heart attack? Eating more fiber helps you live longer, study finds

If you've had a heart attack, eating more fiber -- especially from cereal -- cuts the risk of dying from heart disease or stroke by 35 percent, according to a new Harvard study.

"Whole grain cereal, at least in this study, seemed to have the highest benefit, but you can talk about oats, barley, anything that's got bran or whole wheat in it -- those are all great options," CBS News contributor Dr. Tara Narula, associate director of Lenox Hill Hospital's Cardiac Care unit, said Wednesday on "CBS This Morning."

Narula said fiber helps lower blood pressure and bad cholesterol in addition to decreasing inflammation; it can also help modulate blood sugar and decrease the chances of developing diabetes.

"It also makes you feel full quicker and stay full longer, so you tend to eat less, which helps you manage your weight," Narula said.

However, the study has its limitations. It is not proven that fiber specifically caused the decrease in mortality, but there is an association, Narula said. The participants had to self-report their fiber intake from the prior year.

"So if they forgot or they didn't report it accurately, that could affect the results. We also don't know if the people who ate more fiber made other healthy lifestyle choices that could have influenced the outcome," she said.

Yet the study had a large sample size of about 4,000 people with a long follow-up of nine years, Narula said.

"I think the key point, and we always try to emphasize this is -- it's not just one thing. It's not just medications, it's not just fiber. It would be great if fiber has this effect because it's easy to get into your diet and it makes sense to people, but the big thing is lifestyle," Narula said.

She recommended a good diet, exercise, no smoking, moderate consumption of alcohol and a decrease in stress levels in addition to a fiber intake of 25 grams for women and 38 grams for men.