by ecancer reporter Janet Fricker

Red meat consumption is associated with an increased risk of total, cancer and cardiovascular disease (CVD) mortality, finds a prospective longitudinal study published in Archives Internal Medicine.

The data showed that the association, was observed for both processed and unprocessed red meat, and furthermore that substitution of red meat for fish, poultry, nuts, legumes, low-fat dairy products and whole grains for red meat significantly lowered the mortality risk.

Red meat consumption has been associated with an increased risk of chronic diseases, but many of these studies have been performed in populations with particularly high proportions of vegetarians. In the current study Frank Hu, professor of nutrition and epidemiology at the Harvard School of Public Health, and colleagues analysed data from two large prospective cohorts - the Health Professionals Follow-up Study (HPFS) and the Nurses’ Health Study (NHS).

In both studies diet was measured at baseline and then every four years using a food frequency questionnaire.

Unprocessed red meat included beef, pork, lamb, or hamburger and processed red meat included bacon, hot dogs, sausage, salami, and bologna. The studies included data from 37,698 men and 83,644 women, with 23,926 deaths recorded in the 28 years of follow-up, which included 5,910 deaths from CVD and 9,464 deaths from cancer.

Findings of the pooled analysis showed that for a one-serving-per-day the risk of mortality increased by 13% for consuming unprocessed red meat, and 20% for processed red meat.  For cancer the risk of death increased by 10% for unprocessed red meat and 16 % for processed red meat.

The investigators estimated that that replacing one daily serving of total red meat with one serving of either fish, poultry, vegetables, nuts, low-fat dairy products or whole grains lowered the mortality risk by 7%, 14%, 10%, 19%, 10% and 14% respectively.

“These results indicate that replacement of red meat with alternative healthy dietary components may lower the mortality risk,” write the authors.

Regarding increased cancer mortality, they write, red meat intake has been associated with increased risks of colorectal cancer and several other cancers, with several compounds in red meat (including nitrosamines and nitrosamides) having the potential to be carcinogens.

Additionally, they add, iron overload may be associated with increased cancer risk through promotion of N-nitroso compound formation, increased colonic cytotoxicity, epithelial proliferation, oxidative stress and iron induced hypoxia.

The strengths of the study include its large sample size, high rates of long-term follow-up and detailed repeated assessments of diet and lifestyle. Additionally, say the authors, all the participants were health professionals, minimizing the potential for cofounders due to educational attainment or differing access to health care.

The study was limited, the authors acknowledge, by potential errors in measuring red meat intakes and whether the findings could be generalised outside of the study population, who were  predominantly white health professionals.

Reference

A Pan, O Sun, A Bernstein, et al. Red Meat Consumption and Mortality: Results from 2 Prospective Cohort Studies.  Published online  MARCH 12, 2012. doi:10.1001/archinternmed.2011.2287