Whole grains and cereal fiber have been associated with reduced risk of chronic diseases for some time. The study published in the journal BMC Medicine sought to assess their association with reduced mortality, both in general, and in regards to specific causes.
Those with the highest intake of whole grains had a 17% lower risk of death, compared to those with low intakes.
Dietary fiber and other nutrients
The study followed 367,442 participants, enrolled in 1995 and followed through to 2009. Participants with existing diseases at the start of the study (cancer, heart disease, stroke, diabetes and self-reported end-stage renal disease) were excluded.
Over the 14 years, researchers recorded 46,067 deaths, among them 11,283 from cardiovascular disease, 19,043 from cancer, 371 from diabetes, 3,796 from respiratory disease, 922 from infection, and 5,223 from other causes.
Those with the highest intake of whole grains had a 17% lower risk of all-cause mortality and 11–48% lower risk of disease-specific mortality (as compared to individuals with the lowest intakes of whole grains).
Those with the highest intake of cereal fiber had a 19% lower risk of all-cause mortality and 15–34% lower risk of disease-specific mortality.
‘Significant association’ of reduced risk
“Most whole grains are abundant sources of dietary fiber and other nutrients, such as minerals and antioxidants, which have shown beneficial effects on human health including improvement of weight loss, insulin sensitivity, and lipid profile, as well as inhibition of systemic inflammation,” wrote one of the authors, Lu Qi of Harvard Medical School.
“In epidemiology studies, evidence is accumulating indicating that consumption of whole grain products or their effective components, especially dietary fiber found in the grain (for example, cereal fiber) may reduce the risk of chronic disease.
“We found that high consumption of whole grains or cereal fiber was significantly associated with reduced risk of all-cause mortality and death from CVD, cancer, diabetes, respiratory disease, infections, and other causes.”
The findings are in agreement with previously observed protective effects of whole grain intake on CVD, diabetes, and some cancers, researchers add.
“Our results suggested that the protective effects of whole grains may be due, at least in the main part, to its cereal fiber component.”
Protective effect is ‘biologically plausible’
The authors found that participants with high intakes of whole grains and cereal fiber also tended to have high level of physical activity and better health, as well as a low BMI, low levels of smoking, and low intakes of alcohol and red meat.
However, they say the study makes adjustments to account for this.
“The protective effect of whole grains and fiber consumption on risk of mortality is biologically plausible,” said Qi.
“Dietary fiber intake is associated with lower levels of inflammation markers, such as C-reactive protein, and tumor necrosis factor α receptor 2, which play key roles in chronic inflammatory conditions.
“Whole grain foods are rich in fiber. Therefore, the anti-inflammatory effects of dietary fiber may help explain, at least in part, the inverse associations of whole grains and fiber consumption with chronic disease death.
“Moreover, whole grains and cereal fiber have a high content of antioxidants, vitamins, trace minerals, phenolic acids, lignans, and phytoestrogens, which have been associated with a reduced risk of colorectal cancer and lower risk of death from non-cardiovascular, non-cancer inflammatory diseases and respiratory system diseases.
“In addition, dietary fibers have specific and unique impacts on intestinal microbiota composition and metabolism.”
Title: “Consumption of whole grains and cereal fiber and total and cause-specific mortality: prospective analysis of 367,442 individuals”
T. Huang; M. Xu; A. Lee; S. Cho; and L. Qi.
Source: BMC Medicine, (2015) 13:59. DOI 10.1186/s12916-015-0294-7