People who increase their intake of red meat – especially processed red meat – may be increasing their risk of death, suggests a large US study* published today in The BMJ.
Researchers also found, however, that by replacing red meat intake with healthy protein sources such as eggs and fish, whole grains and vegetables over time, could lower the risk.
Previous studies have suggested there is a link between eating a lot of red meat, such as beef, pork and lamb, and having a higher risk of type 2 diabetes, cardiovascular disease, certain types of cancers, and premature death.
However, little is known about how changes in red meat intake over time may influence the risk of death.
Therefore, a team of researchers based in the US and China looked at the link between changes in red meat consumption over an eight-year period with mortality during the next eight years, starting from 1986 to the end of follow-up in 2010.
They used data for 53,553 US registered female nurses (aged 30 to 55) from the Nurses’ Health Study (NHS) and 27,916 US male health professionals (aged 40 to 75) from the Health Professionals Follow-up Study (HPFS), who were free of cardiovascular disease and cancer at the start of the study.
Every four years, the participants completed a food frequency questionnaire where they were asked how often, on average, they ate each food of a standard portion size in the past year, ranging from “never or less than once per month” to “six or more times a day”.
The results showed that during the study period, the total number of deaths from any cause reached 14,019. The leading causes of death were cardiovascular disease, cancer, respiratory disease and neurodegenerative disease.
After adjusting for age and other potentially influential factors, increasing total red meat intake (both processed and unprocessed) by 3.5 servings a week or more over an eight-year period was associated with a 10% higher risk of death in the next eight years.
Similarly, increasing processed red meat intake, such as bacon, hot dogs, sausages and salami, by 3.5 servings a week or more was associated with a 13% higher risk of death, whereas increasing intake of unprocessed red meat was associated with a 9% higher risk.
These associations remained largely consistent across different age groups, levels of physical activity, dietary quality, smoking and alcohol consumption habits.
In addition, reducing red meat intake while eating more whole grains, vegetables, or other protein foods such as poultry without skin, eggs and fish, was associated with a lower risk of death among both men and women.
Swapping one serving per day of red meat for one serving of fish per day over eight years was linked to a 17% lower risk of death in the subsequent eight years.
Because this was an observational study, it could not establish cause and the authors acknowledged some limitations, including that they did not look at the reasons for changes in red meat consumption which could have influenced the results.
Nevertheless, the authors said that the data gathered covered a large number of people over a long follow-up period, with repeated assessment of diet and lifestyle factors, and consistent results between the two cohorts.
“The results of our short-term, medium-term, and long-term analyses provide a practical message to the general public of how dynamic changes in red meat consumption are associated with health,” they concluded.
“A change in protein source or eating healthy plant based foods such as vegetables or whole grains can improve longevity.”
* Zheng Y, et al. Association of changes in red meat consumption with total and cause-specific mortality among U.S. women and men: two large prospective cohort studies. BMJ 2019;365:l2110.