Eating at least three servings of whole grain a day may reduce risks of dying early, a study found.

Public health researchers at the Harvard University analyzed the results of 14 previous studies conducted between 1970 and 2010 in the U.S., UK and Scandinavian countries involving 786,076 male and female respondents.

They found that people who eat at least three servings of whole grains (or 48 grams) daily are 20 percent less likely to die from any cause than those who eat less than one serving a day.

Researchers also found that eating three servings of whole grains a day is associated with a 25 percent lower risk of death from heart disease and a 14 percent lower risk of death from cancer, compared with those who eat one serving of whole grains daily or less.

Examples of whole grain include oats, barley, quinoa, brown rice and whole wheat. These foods are rich in fiber, which is known to improve cholesterol levels and lower the risks of heart disease, stroke, obesity and type 2 diabetes.

The U.S. Dietary Guidelines recommend eating three or more servings of whole grains daily, LiveScience reported. However, Americans consume an average of less than one serving per day, according to the study.

"These findings lend further support to the U.S. government's current Dietary Guidelines for Americans, which suggest high consumption of whole grains to facilitate disease prevention," Dr. Qi Sun, assistant professor of nutrition at the Harvard School of Public Health in Boston and senior author of the study, said in a statement published on LiveScience.

Of the total participants in the study, there were 97,867 deaths, including 23,597 deaths from cardiovascular diseases and 37, 492 deaths from cancer.

The researchers also found that one serving of whole grain (16 grams) lowers the risk of death from any cause by 7 percent, including a 9 percent decrease in risk of heart disease death and 5 percent decrease in risk of cancer death.

The study also warned people against low-carbohydrate diets without whole grain content as these may be linked to higher risk of heart diseases and death.

The study was published online in the journal of the American Heart Association.