High egg intake tied to lower all-cause mortality
High fish and legume intake is tied to lower cancer mortality, while higher egg intake is associated with reduced all-cause mortality, reports a new prospective population-based study.
The study drew information of 42,403 participants (18,261 males) from the Golestan Cohort Study, which excludes individuals with a history of upper gastrointestinal cancer. Additional exclusion criteria were extreme energy intake and prior chronic diseases.
Information on dietary intake and frequency was collected via questionnaires upon enrolment. Questionnaires and interviews for lifestyle, medical and demographic factors were also administered. Reports from families, friends and local health workers were used for death records.
Over a median follow-up of 8.1 years, a total of 3,291 deaths were recorded. Of these, 1,938 were in males and 1,353 were in females. Cardiovascular diseases and cancer were the cause of 1,467 and 859 of these deaths, respectively. [Am J Prev Med 2017;52:237-248]
In the entire study sample, the mean total red meat consumption was 0.19 servings per day, including a mean of 0.04 servings per day of processed red meat. Participants were divided into quintiles according to red meat intake.
Increasing consumption of total red meat (hazard ratio [HR], 1.04; 95 percent CI, 0.93 to 1.17; p=0.25) and poultry (HR, 1.02; 0.91 to 1.14; p=0.54) was not associated with all-cause mortality risk. Adjustment for age showed that higher fish (HR, 0.77; 0.69 to 0.85; p<0.0001) and legumes (HR, 0.85; 0.77 to 0.94; p=0.01) intake was associated with reduced all-cause mortality.
However, after including other covariates in the adjustment, only the increased consumption of eggs (HR, 0.88; 0.79 to 0.97; p=0.03) remained significantly associated with lower all-cause mortality risks.
Interestingly, substituting one serving per day of eggs (HR, 0.65; 0.43 to 0.98), legumes (HR, 0.68; 0.50 to 0.93) or fish (HR, 0.63; 0.47 to 0.84) for one serving per day of red meat reduced the risk of all-cause mortality.
Higher intake of fish was significantly associated with lower total cancer (HR, 0.79; 0.64 to 0.98; p=0.03) and gastrointestinal cancer (HR, 0.75; 0.56 to 1.00; p=0.02) mortality risks. Adjusting for total red meat (HR, 0.79; 0.64 to 0.98; p=0.03), low-fat dairy (HR, 0.79; 0.64 to 0.99; p=0.03) or fruit and vegetable (HR, 0.81; 0.66 to 1.01; p=0.07) intake does not affect the significant relationship between fish intake and total cancer mortality risk.
Similarly, higher consumption of legumes was associated with decreased risks of total cancer (HR, 0.72; 0.58 to 0.89; p=0.004), gastrointestinal cancer (HR, 0.76; 0.58 to 1.01) and other cancer (HR, 0.66; 0.47 to 0.93; p=0.004) mortality.
There were no significant associations between increased total intake of red meat, legume, fish, egg or poultry with risk of mortality from cardiovascular diseases, including stroke and coronary heart disease (CHD).
The findings are in conflict with numerous American and European studies which report that high levels of red meat intake, particularly processed red meat, are tied to worse all-cause and specific-cause mortality. [BMC Med 2013;11:63; Arch Intern Med 2009;169:562-571; Cancer Causes Control 2011;22:1699]
On the other hand, the present report corroborates the findings of a recent pooled analysis of Asian cohort studies. The large difference in the amount of red meat and processed red meat consumed in the studies may account for this discrepancy, the investigators said. [Am J Clin Nutr 2013;98:1032-1041]
Similarly, the literature is conflicted about fish intake and mortality. In published meta-analyses, for instance, high levels of fish intake are associated with improved all-cause and CHD mortality. The disparity in findings may be explained by differences in levels of fish consumption and by the involvement of socioeconomic status in the association to mortality.
Differences in the volume of egg intake may also explain the inconsistencies of the current literature and the present study about the effect of egg consumption on mortality risk, they explained.
Despite these deviations from the literature, the present study has nevertheless provided solid evidence linking intake of protein from different sources to all-cause or specific-cause mortality.
“In this prospective community-based cohort study […], high consumption of fish and legumes was associated with lower cancer mortality risk, independent of other dietary factors. Lowered all-cause mortality risk was observed among participants with high egg consumption,” the investigators wrote.